Science.gov

Sample records for plane arrays based

  1. Optical-based spectral modeling of infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Mouzali, Salima; Lefebvre, Sidonie; Rommeluère, Sylvain; Ferrec, Yann; Primot, Jérôme

    2016-07-01

    We adopt an optical approach in order to model and predict the spectral signature of an infrared focal plane array. The modeling is based on a multilayer description of the structure and considers a one-dimensional propagation. It provides a better understanding of the physical phenomena occurring within the pixels, which is useful to perform radiometric measurements, as well as to reliably predict the spectral sensitivity of the detector. An exhaustive model is presented, covering the total spectral range of the pixel response. A heuristic model is also described, depicting a complementary approach that separates the different optical phenomena inside the pixel structure. Promising results are presented, validating the models through comparison with experimental results. Finally, advantages and limitations of this approach are discussed.

  2. Improved interframe registration based nonuniformity correction for focal plane arrays

    NASA Astrophysics Data System (ADS)

    Zuo, Chao; Chen, Qian; Gu, Guohua; Sui, Xiubao; Ren, Jianle

    2012-07-01

    In this paper, an improved interframe registration based nonuniformity correction algorithm for focal plane arrays is proposed. The method simultaneously estimates detector parameters and carries out the nonuniformity correction by minimizing the mean square error between the two properly registered image frames. A new masked phase correlation algorithm is introduced to obtain reliable shift estimates in the presence of fixed pattern noise. The use of an outliers exclusion scheme, together with a variable step size strategy, could not only promote the correction precision considerably, but also eliminate ghosting artifacts effectively. The performance of the proposed algorithm is evaluated with clean infrared image sequences with simulated nonuniformity and real pattern noise. We also apply the method to a real-time imaging system to show how effective it is in reducing noise and the ghosting artifacts.

  3. Focal plane array based infrared thermography in fine physical experiment

    NASA Astrophysics Data System (ADS)

    Vainer, Boris G.

    2008-03-01

    By two examples of dissimilar physical phenomena causing thermophysical effects, the unique capabilities of one of the up-to-date methods of experimental physics—focal plane array (FPA) based infrared (IR) thermography (IRT), are demonstrated distinctly. Experimenters inexperienced in IRT can grasp how this method provides a means for combining real-time visualization with quantitative analysis. A narrow-band short-wavelength IR camera was used in the experiments. It is discussed and stated that IRT is best matched and suited to the next two test conditions—when a heated specimen is thin and when heat is generated in the immediate region of a surface of a solid. The first prerequisite is realized in the search for directional patterns of combined low-power radiation sources with the use of the IRT-aided method. The second one is realized in studies of water vapour adsorption on uneven (irregular) surfaces of solid materials. With multiple swatches taken from a set of different fabrics and used as experimental samples, a sharp distinction between adsorptivities of their surfaces is strikingly illustrated by IRT time-domain measurements exhibiting the associated thermal effect ranging within an order of magnitude. It is justified that the described IRT-aided test can find practical implementation at least in the light industry. Emissivities of different fabrics are evaluated experimentally with the described reflection method based on the narrow spectral range of IRT. On the basis of direct IR observations, attention is paid to the need for close control over the surface temperature increase while the adsorption isotherms are being measured. Sensitivity of the FPA-based IRT method, as applied to examine the kinetics of initial stages of adsorption of gaseous molecules on the solid surface, is evaluated analytically and quantitatively. The relationship between the amount of adsorbate and the measurable excess of adsorbent temperature is found. It is discovered

  4. Compact polarimeters based on polarization-sensitive focal plane arrays

    NASA Astrophysics Data System (ADS)

    Vorobiev, Dmitry; Ninkov, Zoran

    2014-08-01

    We report on the design, fabrication and performance of the Rochester Institute of Technology Polarization Imaging Camera (RITPIC). Despite great advances in astronomical (and terrestrial remote sensing) instrumentation, the measurement of polarization of light remains challenging and infrequent. Recently, the fabrication of micropolarizer arrays has allowed the development of compact polarimeters which promise to make polarimetry more accessible. These devices are capable of measuring the degree of polarization (DoP) and angle of polarization (AoP) across a scene using a single exposure ("snapshot"). They are compact, light-weight and mechanically robust, making them ideal for deployment on space-based platforms. We present the performance of such a polarimeter and describe the kind of science that is possible with RITPIC and future generations of these revolutionary devices.

  5. Performance of ground-based high-frequency receiving arrays with electrically-small ground planes

    NASA Astrophysics Data System (ADS)

    Weiner, M. M.

    1991-09-01

    Electrically-small ground planes degrade the performance of ground-based high-frequency receiving arrays because the arrays are more susceptible to earth multipath, ground losses, and external currents on element feed cables. Performance degradations include a reduction in element directive gain near the horizon, distortion of the element azimuthal pattern, an increase in the system internal noise factor, and increases in the array factor root-mean-squared (rms) phase error and beam-pointing errors. The advantage of electrically-small ground planes is their relatively low cost of construction and maintenance.

  6. Infrared focal plane arrays based on dots in a well and strained layer superlattices

    NASA Astrophysics Data System (ADS)

    Krishna, Sanjay

    2009-01-01

    In this paper, we will review some of the recent progress that we have made on developing single pixel detectors and focal plane arrays based on dots-in-a-well (DWELL) heterostructure and Type II strained layer superlattice (SLS). The DWELL detector consists of an active region composed of InAs quantum dots embedded in InGaAs/GaAs quantum wells. By varying the thickness of the InGaAs well, the DWELL heterostructure allows for the manipulation of the operating wavelength and the nature of the transitions (bound-to-bound, bound-to-quasibound and bound-to-continuum) of the detector. Based on these principles, DWELL samples were grown using molecular beam epitaxy and fabricated into 320 x 256 focal plane arrays (FPAs) with Indium bumps using standard lithography at the University of New Mexico. The FPA evaluated was hybridized to an Indigo 9705 readout integrated circuit (ROIC). From this evaluation, we have reported the first two-color, co-located quantum dot based imaging system that can be used to take multicolor images using a single FPA. We have also been investigating the use of miniband transitions in Type II SLS to develop infrared detectors using PIN and nBn based designs.

  7. Development of noncryogenic cooled carbon nanotube-based infrared focal plane array with integrated readout circuitry

    NASA Astrophysics Data System (ADS)

    Xi, Ning; Lai, King Wai Chiu; Chen, Hongzhi; Chen, Liangliang; Fung, Carmen Kar Man

    2011-06-01

    Infrared (IR) detectors are enormously important for various applications including medical diagnosis, night vision etc. The current bottleneck of high-sensitive IR detectors is the requirement of cryogenic cooling to reduce the noise. Carbon nanotubes (CNTs) exhibit low dark current which allows CNTs to work without cooling. This paper presents the development of noncryogenic cooled IR focal plane array (FPA) using CNTs. The FPA consists of an array of CNTbased IR detectors which are sensitive to IR signal at room temperature. The CNT-based detectors can be made by our nanomanufacturing process. And the sensitivity of the detectors at a special wavelength can be achieved by selecting and controlling the bandgap of CNTs during the process. Besides, a readout circuitry has been integrated with the FPA to retrieve signals from the detectors for high throughput applications.

  8. Non-local means-based nonuniformity correction for infrared focal-plane array detectors

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Zhang, Zhi-jie; Chen, Fu-sheng; Wang, Chen-sheng

    2014-11-01

    The infrared imaging systems are normally based on the infrared focal-plane array (IRFPA) which can be considered as an array of independent detectors aligned at the focal plane of the imaging system. Unfortunately, every detector on the IRFPA may have a different response to the same input infrared signal which is known as the nonuniformity problem. Then we can observe the fixed pattern noise (FPN) from the resulting images. Standard nonuniformity correction (NUC) methods need to be recalibrated after a short period of time due the temporal drift of the FPN. Scene-based nonuniformity correction (NUC) techniques eliminate the need for calibration by correction coefficients based on the scene being viewed. However, in the scene-based NUC method the problem of ghosting artifacts widely seriously decreases the image quality, which can degrade the performance of many applications such as target detection and track. This paper proposed an improved scene-based method based on the retina-like neural network approach. The method incorporates the use of non-local means (NLM) method into the estimation of the gain and the offset of each detector. This method can not only estimates the accurate correction coefficient but also restrict the ghosting artifacts efficiently. The proposed method relies on the use of NLM method which is a very successful image denoising method. And then the NLM used here can preserve the image edges efficiently and obtain a reliable spatial estimation. We tested the proposed NUC method by applying it to an IR sequence of frames. The performance of the proposed method was compared the other well-established adaptive NUC techniques.

  9. Design of readout circuit for microcantilever-based ripple uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Cao, Junmin; Chen, Zhongjian; Lu, Wengao; Zhang, Yacong; Lei, Ke; Zhao, Baoying

    2009-07-01

    A readout integrated circuit (ROIC) for uncooled microcantilever infrared focal plane arrays (IRFPAs) based on capacitive readout is proposed. The ROIC is optimized according to noise modeling and analysis to reduce noise. An experimental chip of 16×16 FPAs readout circuit has been designed and fabricated using 0.35um CMOS technology. The measurement results showed that the power dissipation is 16.5mW from a 5V supply voltage at 50Hz frame rate, the linearity is 99.2% at the typical mode; the uniformity is larger than 97% and the equivalent noise charge (ENC) is below 150e. It is believed that the ROIC has a great potential in the applications of large-scale micro-cantilever-based uncooled IRFPAs.

  10. Model based on-chip 13bits ADC design dedicated to uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Dupont, Benoit; Robert, Patrick; Dupret, Antoine; Villard, Patrick; Pochic, David

    2007-10-01

    This paper presents an on-chip 13 bits 10 M/S Analog to Digital Converter (ADC) specifically designed for infrared bolometric image sensor. Bolometric infrared sensors are MEMs based thermal sensors, which covers a large spectrum of infrared applications, ranging from night vision to predictive industrial maintenance and medical imaging. With the current move towards submicron technologies, the demand for more integrated, smarter sensors and microsystems has dramatically increased. This trend has strengthened the need of on-chip ADC as the interface between the analog core and the digital processing electronic. However designing an on-chip ADC dedicated to focal plane array raises many questions about its architecture and its performance requirements. To take into account those specific needs, a high level model has been developed prior to the actual design. In this paper, we present the trade-offs of ADC design linked to infrared key performance parameters and bolometric technology detection method. The original development scheme, based on system level modeling, is also discussed. Finally we present the actual design and the measured performances.

  11. An uncooled microbolometer focal plane array using heating based resistance nonuniformity compensation

    NASA Astrophysics Data System (ADS)

    Tepegoz, Murat; Oguz, Alp; Toprak, Alperen; Senveli, S. Ufuk; Canga, Eren; Tanrikulu, M. Yusuf; Akin, Tayfun

    2012-06-01

    This paper presents the performance evaluation of a unique method called heating based resistance nonuniformity compensation (HB-RNUC). The HB-RNUC method utilizes a configurable bias heating duration for each pixel in order to minimize the readout integrated circuit (ROIC) output voltage distribution range. The outputs of each individual pixel in a resistive type microbolometer differ from each other by a certain amount due to the resistance non-uniformity throughout the focal plane array (FPA), which is an inevitable result of the microfabrication process. This output distribution consumes a considerable portion of the available voltage headroom of the ROIC unless compensated properly. The conventional compensation method is using on-chip DACs to apply specific bias voltages to each pixel such that the output distribution is confined around a certain point. However, on-chip DACs typically occupy large silicon area, increase the output noise, and consume high power. The HB-RNUC method proposes modifying the resistances of the pixels instead of the bias voltages, and this task can be accomplished by very simple circuit blocks. The simplicity of the required blocks allows utilizing a low power, low noise, and high resolution resistance nonuniformity compensation operation. A 9-bit HB-RNUC structure has been designed, fabricated, and tested on a 384x288 microbolometer FPA ROIC on which 35μm pixel size detectors are monolithically implemented, in order to evaluate its performance. The compensation operation reduces the standard deviation of the ROIC output distribution from 470 mV to 9 mV under the same readout gain and bias settings. The analog heating channels of the HB-RNUC block dissipate around 4.1 mW electrical power in this condition, and the increase in the output noise due to these blocks is lower than 10%.

  12. VO II-based microbolometer uncooled infrared focal plane arrays with CMOS readout integrated circuit

    NASA Astrophysics Data System (ADS)

    Chen, Xiqu; Yi, Xinjian

    2005-11-01

    Thin films of vanadium dioxide (VO II) were selected for microbolometers. The thin films were fabricated with a novel method mainly including ion-sputtering and annealing. It is found that the electrical properties of these thin films can be controlled by adjusting the time of ion-sputtering and annealing. A standard microbolometer pixel structure of micro-bridge has been applied. Two-dimensional arrays of microbolometers have been fabricated on silicon integrated circuit wafers using a surface micromachining technique. A new type of on-chip readout integrated circuit (ROIC) for 32×32 pixel bolometric detector arrays has been designed and fabricated using a 1.5μm double metal poly complementary metal oxide semiconductor (CMOS) processing. The readout circuit consists of three stages, which provides low noise, a highly stable detector bias, high photon current injection efficiency, high gain, and high speed. Several prototypes of 32×32 pixel bolometric detector arrays have been designed and fabricated. These arrays consist of detectors with lateral dimensions of 50μm 50μm, and each bolometric detector is on a 100μm pitch. The results of measurement show that the fabricated uncooled infrared focal plane arrays (UIRFPAs) have excellent performance. The frame rate is 50Hz, the pixel operability is above 96%, the responsivity (R) @ f/1 value is up to 15000V/W, the noise equivalent temperature difference (NETD) @ f/1 and 30Hz is about 50mK, and the average power dissipation is only 24.7mW. The results indicate that the technology of fabricating these 32×32 UIRFPAs has potential to be utilized for fabricating low cost and large-scale UIRFPAs.

  13. Portable sequential multicolor thermal imager based on a MCT 384 x 288 focal plane array

    NASA Astrophysics Data System (ADS)

    Breiter, Rainer; Cabanski, Wolfgang A.; Mauk, Karl-Heinz; Rode, Werner; Ziegler, Johann

    2001-10-01

    AIM has developed a sequential multicolor thermal imager to provide customers with a test system to realize real-time spectral selective thermal imaging. In contrast to existing PC based laboratory units, the system is miniaturized with integrated signal processing like non-uniformity correction and post processing functions such as image subtraction of different colors to allow field tests in military applications like detection of missile plumes or camouflaged targets as well as commercial applications like detection of chemical agents, pollution control, etc. The detection module used is a 384 X 288 mercury cadmium telluride (MCT) focal plane array (FPA) available in the mid wave (MWIR) or long wave spectral band LWIR). A compact command and control electronics (CCE) provides clock and voltage supply for the detector as well as 14 bit deep digital conversion of the analog detector output. A continuous rotating wheel with four facets for filters provides spectral selectivity. The customer can choose between various types of filter characteristics, e.g. a 4.2 micrometer bandpass filter for CO2 detection in the MWIR band. The rotating wheel can be synchronized to an external source giving the rotation speed, typical 25 l/s. A position sensor generates the four frame start signals for synchronous operation of the detector -- 100 Hz framerate for the four frames per rotation. The rotating wheel is exchangeable for different configurations and also plates for a microscanner operation to improve geometrical resolution are available instead of a multicolor operation. AIM's programmable MVIP image processing unit is used for signal processing like non- uniformity correction and controlling the detector parameters. The MVIP allows to output the four subsequent images as four quarters of the video screen to prior to any observation task set the integration time for each color individually for comparable performance in each spectral color and after that also to determine

  14. Monolithic in-based III-V compound semiconductor focal plane array cell with single stage CCD output

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Cunningham, Thomas J. (Inventor); Krabach, Timothy N. (Inventor); Staller, Craig O. (Inventor)

    1994-01-01

    A monolithic semiconductor imager includes an indium-based III-V compound semiconductor monolithic active layer of a first conductivity type, an array of plural focal plane cells on the active layer, each of the focal plane cells including a photogate over a top surface of the active layer, a readout circuit dedicated to the focal plane cell including plural transistors formed monolithically with the monolithic active layer and a single-stage charge coupled device formed monolithically with the active layer between the photogate and the readout circuit for transferring photo-generated charge accumulated beneath the photogate during an integration period to the readout circuit. The photogate includes thin epitaxial semiconductor layer of a second conductivity type overlying the active layer and an aperture electrode overlying a peripheral portion of the thin epitaxial semiconductor layer, the aperture electrode being connectable to a photogate bias voltage.

  15. Monolithic in-based III-V compound semiconductor focal plane array cell with single stage CCD output

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Cunningham, Thomas J. (Inventor); Krabach, Timothy N. (Inventor); Staller, Craig O. (Inventor)

    1995-01-01

    A monolithic semiconductor imager includes an indium-based III-V compound semiconductor monolithic active layer of a first conductivity type, an array of plural focal plane cells on the active layer, each of the focal plane cells including a photogate over a top surface of the active layer, a readout circuit dedicated to the focal plane cell including plural transistors formed monolithically with the monolithic active layer and a single-stage charge coupled device formed monolithically with the active layer between the photogate and the readout circuit for transferring photo-generated charge accumulated beneath the photogate during an integration period to the readout circuit. The photogate includes thin epitaxial semiconductor layer of a second conductivity type overlying the active layer and an aperture electrode overlying a peripheral portion of the thin epitaxial semiconductor layer, the aperture electrode being connectable to a photogate bias voltage.

  16. Random laser speckle based modulation transfer function measurement of midwave infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Barnard, Kenneth J.; Anisimov, Igor; Scheihing, John E.

    2012-08-01

    Direct measurement of the modulation transfer function (MTF) of focal plane arrays (FPAs) using random laser speckle approaches for the visible/near-infrared wavelength band has been well documented over the last 20 years. These methods have not transitioned to the midwave infrared (MWIR) primarily because other techniques have been sufficient and MWIR laser sources with sufficient output power have been unavailable. However, as the detector pitch decreases, MTF measurements become more difficult due to diffraction, while potential MTF degradation due to lateral carrier diffusion crosstalk makes accurate MTF characterization critical for sensor system design. Here, a random laser speckle FPA MTF measurement approach is adapted for use in the MWIR that utilizes a quantum cascade laser coupled with an integrating sphere to generate the appropriate in-band random speckle. Specific challenges associated with the technique are addressed including the validity of the Fresnel diffraction assumptions describing the propagation of the random speckle field from the integrating sphere to the FPA. Improved methods for estimating the power spectral density (PSD) of the measured speckle that reduce data requirements are presented. The statistics and uniformity of the laser speckle are presented along with PSD measurements and estimated MTFs of a MWIR FPA.

  17. Focal plane array with modular pixel array components for scalability

    SciTech Connect

    Kay, Randolph R; Campbell, David V; Shinde, Subhash L; Rienstra, Jeffrey L; Serkland, Darwin K; Holmes, Michael L

    2014-12-09

    A modular, scalable focal plane array is provided as an array of integrated circuit dice, wherein each die includes a given amount of modular pixel array circuitry. The array of dice effectively multiplies the amount of modular pixel array circuitry to produce a larger pixel array without increasing die size. Desired pixel pitch across the enlarged pixel array is preserved by forming die stacks with each pixel array circuitry die stacked on a separate die that contains the corresponding signal processing circuitry. Techniques for die stack interconnections and die stack placement are implemented to ensure that the desired pixel pitch is preserved across the enlarged pixel array.

  18. Dual band QWIP focal plane array

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D. (Inventor); Choi, Kwong Kit (Inventor); Bandara, Sumith V. (Inventor)

    2005-01-01

    A quantum well infrared photodetector (QWIP) that provides two-color image sensing. Two different quantum wells are configured to absorb two different wavelengths. The QWIPs are arrayed in a focal plane array (FPA). The two-color QWIPs are selected for readout by selective electrical contact with the two different QWIPs or by the use of two different wavelength sensitive gratings.

  19. Performance of MWIR and SWIR HgCdTe-based focal plane arrays at high operating temperatures

    NASA Astrophysics Data System (ADS)

    Melkonian, Leon; Bangs, James; Elizondo, Lee; Ramey, Ron; Guerrero, Ernesto

    2010-04-01

    Raytheon Vision Systems (RVS) is producing large format, high definition HgCdTe-based MWIR and SWIR focal plane arrays (FPAs) with pitches of 15 μm and smaller for various applications. Infrared sensors fabricated from HgCdTe have several advantages when compared to those fabricated from other materials -- such as a highly tunable bandgap, high quantum efficiencies, and R0A approaching theoretical limits. It is desirable to operate infrared sensors at elevated operating temperatures in order to increase the cooler life and reduce the required system power. However, the sensitivity of many infrared sensors, including those made from HgCdTe, declines significantly above a certain temperature due to the noise resulting from increasing detector dark current. In this paper we provide performance data on a MWIR and a SWIR focal plane array operating at temperatures up to 160K and 170K, respectively. The FPAs used in the study were grown by molecular beam epitaxy (MBE) on silicon substrates, processed into a 1536x1024 format with a 15 μm pixel pitch, and hybridized to a silicon readout integrated circuit (ROIC) via indium bumps to form a sensor chip assembly (SCA). This data shows that the noise equivalent delta temperature (NEDT) is background limited at f/3.4 in the SWIR SCA (cutoff wavelength of 3.7 μm at 130K) up to 140K and in the MWIR SCA (cutoff wavelength of 4.8 μm at 115K) up to 115K.

  20. Al(x)Ga(1-x)N-based deep-ultraviolet 320×256 focal plane array.

    PubMed

    Cicek, Erdem; Vashaei, Zahra; Huang, Edward Kwei-wei; McClintock, Ryan; Razeghi, Manijeh

    2012-03-01

    We report the synthesis, fabrication, and testing of a 320×256 focal plane array (FPA) of back-illuminated, solar-blind, p-i-n, Al(x)Ga(1-x)N-based detectors, fully realized within our research laboratory. We implemented a pulse atomic layer deposition technique for the metalorganic chemical vapor deposition growth of thick, high-quality, crack-free, high Al composition Al(x)Ga(1-x)N layers. The FPA is hybridized to a matching ISC 9809 readout integrated circuit and operated in a SE-IR camera system. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower, and falling off three orders of magnitude by ~285 nm. By developing an opaque masking technology, the visible response of the ROIC is significantly reduced; thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allows the FPA to achieve high external quantum efficiency (EQE); at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated. PMID:22378430

  1. Deep ultraviolet (254 nm) focal plane array

    NASA Astrophysics Data System (ADS)

    Cicek, Erdem; Vashaei, Zahra; McClintock, Ryan; Razeghi, Manijeh

    2011-10-01

    We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

  2. Improved performance of HgCdTe infrared detector focal plane arrays by modulating light field based on photonic crystal structure

    SciTech Connect

    Liang, Jian; Hu, Weida Ye, Zhenhua; Li, Zhifeng; Chen, Xiaoshuang Lu, Wei; Liao, Lei

    2014-05-14

    An HgCdTe long-wavelength infrared focal plane array photodetector is proposed by modulating light distributions based on the photonic crystal. It is shown that a promising prospect of improving performance is better light harvest and dark current limitation. To optimize the photon field distributions of the HgCdTe-based photonic crystal structure, a numerical method is built by combining the finite-element modeling and the finite-difference time-domain simulation. The optical and electrical characteristics of designed HgCdTe mid-wavelength and long-wavelength photon-trapping infrared detector focal plane arrays are obtained numerically. The results indicate that the photon crystal structure, which is entirely compatible with the large infrared focal plane arrays, can significantly reduce the dark current without degrading the quantum efficiency compared to the regular mesa or planar structure.

  3. Towards Dualband Megapixel QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Hill, C. J.; Rafol, S. B.; Salazar, D.; Woolaway, J.; LeVan, P. D.; Tidrow, M. Z.

    2006-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 x 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEDT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEDT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In addition, we have demonstrated MWIR and LWIR pixel co-registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency, NEDT, uniformity, operability, and modulation transfer functions of the 1024 x 1024 pixel arrays and the progress of dualband QWIP focal plane array development work.

  4. Solid-state curved focal plane arrays

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh (Inventor); Hoenk, Michael (Inventor); Jones, Todd (Inventor)

    2010-01-01

    The present invention relates to curved focal plane arrays. More specifically, the present invention relates to a system and method for making solid-state curved focal plane arrays from standard and high-purity devices that may be matched to a given optical system. There are two ways to make a curved focal plane arrays starting with the fully fabricated device. One way, is to thin the device and conform it to a curvature. A second way, is to back-illuminate a thick device without making a thinned membrane. The thick device is a special class of devices; for example devices fabricated with high purity silicon. One surface of the device (the non VLSI fabricated surface, also referred to as the back surface) can be polished to form a curved surface.

  5. Real-time 3D millimeter wave imaging based FMCW using GGD focal plane array as detectors

    NASA Astrophysics Data System (ADS)

    Levanon, Assaf; Rozban, Daniel; Kopeika, Natan S.; Yitzhaky, Yitzhak; Abramovich, Amir

    2014-03-01

    Millimeter wave (MMW) imaging systems are required for applications in medicine, communications, homeland security, and space technology. This is because there is no known ionization hazard for biological tissue, and atmospheric attenuation in this range of the spectrum is relatively low. The lack of inexpensive room temperature imaging systems makes it difficult to give a suitable MMW system for many of the above applications. 3D MMW imaging system based on chirp radar was studied previously using a scanning imaging system of a single detector. The system presented here proposes to employ a chirp radar method with a Glow Discharge Detector (GDD) Focal Plane Array (FPA) of plasma based detectors. Each point on the object corresponds to a point in the image and includes the distance information. This will enable 3D MMW imaging. The radar system requires that the millimeter wave detector (GDD) will be able to operate as a heterodyne detector. Since the source of radiation is a frequency modulated continuous wave (FMCW), the detected signal as a result of heterodyne detection gives the object's depth information according to value of difference frequency, in addition to the reflectance of the image. In this work we experimentally demonstrate the feasibility of implementing an imaging system based on radar principles and FPA of GDD devices. This imaging system is shown to be capable of imaging objects from distances of at least 10 meters.

  6. CLAES focal plane array. [Cryogenic Limb Array Etalon Spectrometer

    NASA Technical Reports Server (NTRS)

    Roche, A. E.; Sterritt, L. W.; Kumer, J. B.; Callary, P. C.; Nielsen, R. L.

    1989-01-01

    The Cryogenic Limb Array Etalon Spectrometer for the NASA Upper Atmospheric Research Satellite uses solid-state focal plane arrays to detect emission from the earth's atmosphere over the IR wavelength range 3.5 to 13 microns. This paper discusses the design of the focal plane detector assembly and compares calculated performance with measurements. Measurements were made of focal plane noise and responsivity as functions of frequency (2 to 500 Hz) and temperature (12 to 19 K), pixel-to-pixel and across-array crosstalk, and linearity over a dynamic range of 100,000. The measurements demonstrate that the arrays satisfy the science requirements, and that, in general, there is reasonable agreement between the measurements and the analytical model.

  7. Nonuniformity correction for an infrared focal plane array based on diamond search block matching.

    PubMed

    Sheng-Hui, Rong; Hui-Xin, Zhou; Han-Lin, Qin; Rui, Lai; Kun, Qian

    2016-05-01

    In scene-based nonuniformity correction algorithms, artificial ghosting and image blurring degrade the correction quality severely. In this paper, an improved algorithm based on the diamond search block matching algorithm and the adaptive learning rate is proposed. First, accurate transform pairs between two adjacent frames are estimated by the diamond search block matching algorithm. Then, based on the error between the corresponding transform pairs, the gradient descent algorithm is applied to update correction parameters. During the process of gradient descent, the local standard deviation and a threshold are utilized to control the learning rate to avoid the accumulation of matching error. Finally, the nonuniformity correction would be realized by a linear model with updated correction parameters. The performance of the proposed algorithm is thoroughly studied with four real infrared image sequences. Experimental results indicate that the proposed algorithm can reduce the nonuniformity with less ghosting artifacts in moving areas and can also overcome the problem of image blurring in static areas. PMID:27140891

  8. Low SWaP MWIR detector based on XBn focal plane array

    NASA Astrophysics Data System (ADS)

    Klipstein, P. C.; Gross, Y.; Aronov, D.; ben Ezra, M.; Berkowicz, E.; Cohen, Y.; Fraenkel, R.; Glozman, A.; Grossman, S.; Klin, O.; Lukomsky, I.; Marlowitz, T.; Shkedy, L.; Shtrichman, I.; Snapi, N.; Tuito, A.; Yassen, M.; Weiss, E.

    2013-06-01

    Over the past few years, a new type of High Operating Temperature (HOT) photon detector has been developed at SCD, which operates in the blue part of the MWIR window of the atmosphere (3.4-4.2 μm). This window is generally more transparent than the red part of the MWIR window (4.4-4.9 μm), especially for mid and long range applications. The detector has an InAsSb active layer, and is based on the new "XBn" device concept. We have analyzed various electrooptical systems at different atmospheric temperatures, based on XBn-InAsSb operating at 150K and epi-InSb at 95K, respectively, and find that the typical recognition ranges of both detector technologies are similar. Therefore, for very many applications there is no disadvantage to using XBn-InAsSb instead of InSb. On the other hand XBn technology confers many advantages, particularly in low Size, Weight and Power (SWaP) and in the high reliability of the cooler and Integrated Detector Cooler Assembly (IDCA). In this work we present a new IDCA, designed for 150K operation. The 15 μm pitch 640×512 digital FPA is housed in a robust, light-weight, miniaturised Dewar, attached to Ricor's K562S Stirling cycle cooler. The complete IDCA has a diameter of 28 mm, length of 80 mm and weight of < 300 gm. The total IDCA power consumption is ~ 3W at a 60Hz frame rate, including an external miniature proximity card attached to the outside of the Dewar. We describe some of the key performance parameters of the new detector, including its NETD, RNU and operability, pixel cross-talk, and early stage yield results from our production line.

  9. Optical interconnections to focal plane arrays

    SciTech Connect

    Rienstra, J.L.; Hinckley, M.K.

    2000-11-01

    The authors have successfully demonstrated an optical data interconnection from the output of a focal plane array to the downstream data acquisition electronics. The demonstrated approach included a continuous wave laser beam directed at a multiple quantum well reflectance modulator connected to the focal plane array analog output. The output waveform from the optical interconnect was observed on an oscilloscope to be a replica of the input signal. They fed the output of the optical data link to the same data acquisition system used to characterize focal plane array performance. Measurements of the signal to noise ratio at the input and output of the optical interconnection showed that the signal to noise ratio was reduced by a factor of 10 or more. Analysis of the noise and link gain showed that the primary contributors to the additional noise were laser intensity noise and photodetector receiver noise. Subsequent efforts should be able to reduce these noise sources considerably and should result in substantially improved signal to noise performance. They also observed significant photocurrent generation in the reflectance modulator that imposes a current load on the focal plane array output amplifier. This current loading is an issue with the demonstrated approach because it tends to negate the power saving feature of the reflectance modulator interconnection concept.

  10. Large Format Multicolor QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Soibel, A.; Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Ting, D. Z.; Hill, C. J.; Nguyen, J.

    2009-01-01

    Mid-wave infrared (MWIR) and long-wave infrared (LWIR) multicolor focal plane array (FPA) cameras are essential for many DoD and NASA applications including Earth and planetary remote sensing. In this paper we summarize our recent development of large format multicolor QWIP FPA that cover MWIR and LWIR bands.

  11. SOI diode uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Kimata, Masafumi; Ueno, Masashi; Takeda, Munehisa; Seto, Toshiki

    2006-02-01

    An uncooled infrared focal plane array (IR FPA) is a MEMS device that integrates an array of tiny thermal infrared detector pixels. An SOI diode uncooled IR FPA is a type that uses freestanding single-crystal diodes as temperature sensors and has various advantages over the other MEMS-based uncooled IR FPAs. Since the first demonstration of an SOI diode uncooled IR FPA in 1999, the pixel structure has been improved by developing sophisticated MEMS processes. The most advanced pixel has a three-level structure that has an independent metal reflector for interference infrared absorption between the temperature sensor (bottom level) and the infrared-absorbing thin metal film (top level). This structure makes it possible to design pixels with lower thermal conductance by allocating more area for thermal isolation without reducing infrared absorption. The new MEMS process for the three-level structure includes a XeF II dry bulk silicon etching process and a double organic sacrificial layer surface micromachining process. Employing advanced MEMS technology, we have developed a 640 x 480-element SOI diode uncooled IR FPA with 25-μm square pixels. The noise equivalent temperature difference of the FPA is 40 mK with f/1.0 optics. This result clearly demonstrates the great potential of the SOI diode uncooled IR FPA for high-end applications. In this paper, we explain the advances and state-of-the-art technology of the SOI diode uncooled IR FPA.

  12. Guided filter and adaptive learning rate based non-uniformity correction algorithm for infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Sheng-Hui, Rong; Hui-Xin, Zhou; Han-Lin, Qin; Rui, Lai; Kun, Qian

    2016-05-01

    Imaging non-uniformity of infrared focal plane array (IRFPA) behaves as fixed-pattern noise superimposed on the image, which affects the imaging quality of infrared system seriously. In scene-based non-uniformity correction methods, the drawbacks of ghosting artifacts and image blurring affect the sensitivity of the IRFPA imaging system seriously and decrease the image quality visibly. This paper proposes an improved neural network non-uniformity correction method with adaptive learning rate. On the one hand, using guided filter, the proposed algorithm decreases the effect of ghosting artifacts. On the other hand, due to the inappropriate learning rate is the main reason of image blurring, the proposed algorithm utilizes an adaptive learning rate with a temporal domain factor to eliminate the effect of image blurring. In short, the proposed algorithm combines the merits of the guided filter and the adaptive learning rate. Several real and simulated infrared image sequences are utilized to verify the performance of the proposed algorithm. The experiment results indicate that the proposed algorithm can not only reduce the non-uniformity with less ghosting artifacts but also overcome the problems of image blurring in static areas.

  13. Development of High-Performance eSWIR HgCdTe-Based Focal-Plane Arrays on Silicon Substrates

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Pepping, J.; Mukhortova, A.; Ketharanathan, S.; Kodama, R.; Zhao, J.; Hansel, D.; Velicu, S.; Aqariden, F.

    2016-09-01

    We report the development of high-performance and low-cost extended short-wavelength infrared (eSWIR) focal-plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates. High-quality n-type eSWIR HgCdTe (cutoff wavelength ˜2.68 μm at 77 K, electron carrier concentration 5.82 × 1015 cm-3) layers were grown on CdTe/Si substrates by MBE. High degrees of uniformity in composition and thickness were demonstrated over three-inch areas, and low surface defect densities (voids 9.56 × 101 cm-2, micro-defects 1.67 × 103 cm-2) were measured. This material was used to fabricate 320 × 256 format, 30 μm pitch FPAs with a planar device architecture using arsenic implantation to achieve p-type doping. The dark current density of test devices showed good uniformity between 190 K and room temperature, and high-quality eSWIR imaging from hybridized FPAs was obtained with a median dark current density of 2.63 × 10-7 A/cm2 at 193 K with a standard deviation of 1.67 × 10-7 A/cm2.

  14. Labeled RFS-Based Track-Before-Detect for Multiple Maneuvering Targets in the Infrared Focal Plane Array

    PubMed Central

    Li, Miao; Li, Jun; Zhou, Yiyu

    2015-01-01

    The problem of jointly detecting and tracking multiple targets from the raw observations of an infrared focal plane array is a challenging task, especially for the case with uncertain target dynamics. In this paper a multi-model labeled multi-Bernoulli (MM-LMB) track-before-detect method is proposed within the labeled random finite sets (RFS) framework. The proposed track-before-detect method consists of two parts—MM-LMB filter and MM-LMB smoother. For the MM-LMB filter, original LMB filter is applied to track-before-detect based on target and measurement models, and is integrated with the interacting multiple models (IMM) approach to accommodate the uncertainty of target dynamics. For the MM-LMB smoother, taking advantage of the track labels and posterior model transition probability, the single-model single-target smoother is extended to a multi-model multi-target smoother. A Sequential Monte Carlo approach is also presented to implement the proposed method. Simulation results show the proposed method can effectively achieve tracking continuity for multiple maneuvering targets. In addition, compared with the forward filtering alone, our method is more robust due to its combination of forward filtering and backward smoothing. PMID:26670234

  15. Labeled RFS-Based Track-Before-Detect for Multiple Maneuvering Targets in the Infrared Focal Plane Array.

    PubMed

    Li, Miao; Li, Jun; Zhou, Yiyu

    2015-01-01

    The problem of jointly detecting and tracking multiple targets from the raw observations of an infrared focal plane array is a challenging task, especially for the case with uncertain target dynamics. In this paper a multi-model labeled multi-Bernoulli (MM-LMB) track-before-detect method is proposed within the labeled random finite sets (RFS) framework. The proposed track-before-detect method consists of two parts-MM-LMB filter and MM-LMB smoother. For the MM-LMB filter, original LMB filter is applied to track-before-detect based on target and measurement models, and is integrated with the interacting multiple models (IMM) approach to accommodate the uncertainty of target dynamics. For the MM-LMB smoother, taking advantage of the track labels and posterior model transition probability, the single-model single-target smoother is extended to a multi-model multi-target smoother. A Sequential Monte Carlo approach is also presented to implement the proposed method. Simulation results show the proposed method can effectively achieve tracking continuity for multiple maneuvering targets. In addition, compared with the forward filtering alone, our method is more robust due to its combination of forward filtering and backward smoothing. PMID:26670234

  16. Development of High-Performance eSWIR HgCdTe-Based Focal-Plane Arrays on Silicon Substrates

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Pepping, J.; Mukhortova, A.; Ketharanathan, S.; Kodama, R.; Zhao, J.; Hansel, D.; Velicu, S.; Aqariden, F.

    2016-06-01

    We report the development of high-performance and low-cost extended short-wavelength infrared (eSWIR) focal-plane arrays (FPAs) fabricated from molecular beam epitaxial (MBE)-grown HgCdTe on Si-based substrates. High-quality n-type eSWIR HgCdTe (cutoff wavelength ˜2.68 μm at 77 K, electron carrier concentration 5.82 × 1015 cm-3) layers were grown on CdTe/Si substrates by MBE. High degrees of uniformity in composition and thickness were demonstrated over three-inch areas, and low surface defect densities (voids 9.56 × 101 cm-2, micro-defects 1.67 × 103 cm-2) were measured. This material was used to fabricate 320 × 256 format, 30 μm pitch FPAs with a planar device architecture using arsenic implantation to achieve p-type doping. The dark current density of test devices showed good uniformity between 190 K and room temperature, and high-quality eSWIR imaging from hybridized FPAs was obtained with a median dark current density of 2.63 × 10-7 A/cm2 at 193 K with a standard deviation of 1.67 × 10-7 A/cm2.

  17. Miniaturized imaging spectrometer based on Fabry-Perot MOEMS filters and HgCdTe infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Velicu, S.; Buurma, C.; Bergeson, J. D.; Kim, Tae Sung; Kubby, J.; Gupta, N.

    2014-05-01

    Imaging spectrometry can be utilized in the midwave infrared (MWIR) and long wave infrared (LWIR) bands to detect, identify and map complex chemical agents based on their rotational and vibrational emission spectra. Hyperspectral datasets are typically obtained using grating or Fourier transform spectrometers to separate the incoming light into spectral bands. At present, these spectrometers are large, cumbersome, slow and expensive, and their resolution is limited by bulky mechanical components such as mirrors and gratings. As such, low-cost, miniaturized imaging spectrometers are of great interest. Microfabrication of micro-electro-mechanicalsystems (MEMS)-based components opens the door for producing low-cost, reliable optical systems. We present here our work on developing a miniaturized IR imaging spectrometer by coupling a mercury cadmium telluride (HgCdTe)-based infrared focal plane array (FPA) with a MEMS-based Fabry-Perot filter (FPF). The two membranes are fabricated from silicon-oninsulator (SOI) wafers using bulk micromachining technology. The fixed membrane is a standard silicon membrane, fabricated using back etching processes. The movable membrane is implemented as an X-beam structure to improve mechanical stability. The geometries of the distributed Bragg reflector (DBR)-based tunable FPFs are modeled to achieve the desired spectral resolution and wavelength range. Additionally, acceptable fabrication tolerances are determined by modeling the spectral performance of the FPFs as a function of DBR surface roughness and membrane curvature. These fabrication non-idealities are then mitigated by developing an optimized DBR process flow yielding high-performance FPF cavities. Zinc Sulfide (ZnS) and Germanium (Ge) are chosen as the low and the high index materials, respectively, and are deposited using an electron beam process. Simulations are presented showing the impact of these changes and non-idealities in both a device and systems level.

  18. 320x256 solar-blind focal plane arrays based on Al{sub x}Ga{sub 1-x}N

    SciTech Connect

    McClintock, R.; Mayes, K.; Yasan, A.; Shiell, D.; Kung, P.; Razeghi, M.

    2005-01-03

    We report AlGaN-based backilluminated solar-blind ultraviolet focal plane arrays operating at a wavelength of 280 nm. The electrical characteristics of the individual pixels are discussed, and the uniformity of the array is presented. The p-i-n photodiode array was hybridized to a 320x256 read-out integrated circuit entirely within our university research lab, and a working 320x256 camera was demonstrated. Several example solar-blind images from the camera are also provided.

  19. Identification and Quantification of Microplastics in Wastewater Using Focal Plane Array-Based Reflectance Micro-FT-IR Imaging.

    PubMed

    Tagg, Alexander S; Sapp, Melanie; Harrison, Jesse P; Ojeda, Jesús J

    2015-06-16

    Microplastics (<5 mm) have been documented in environmental samples on a global scale. While these pollutants may enter aquatic environments via wastewater treatment facilities, the abundance of microplastics in these matrices has not been investigated. Although efficient methods for the analysis of microplastics in sediment samples and marine organisms have been published, no methods have been developed for detecting these pollutants within organic-rich wastewater samples. In addition, there is no standardized method for analyzing microplastics isolated from environmental samples. In many cases, part of the identification protocol relies on visual selection before analysis, which is open to bias. In order to address this, a new method for the analysis of microplastics in wastewater was developed. A pretreatment step using 30% hydrogen peroxide (H2O2) was employed to remove biogenic material, and focal plane array (FPA)-based reflectance micro-Fourier-transform (FT-IR) imaging was shown to successfully image and identify different microplastic types (polyethylene, polypropylene, nylon-6, polyvinyl chloride, polystyrene). Microplastic-spiked wastewater samples were used to validate the methodology, resulting in a robust protocol which was nonselective and reproducible (the overall success identification rate was 98.33%). The use of FPA-based micro-FT-IR spectroscopy also provides a considerable reduction in analysis time compared with previous methods, since samples that could take several days to be mapped using a single-element detector can now be imaged in less than 9 h (circular filter with a diameter of 47 mm). This method for identifying and quantifying microplastics in wastewater is likely to provide an essential tool for further research into the pathways by which microplastics enter the environment. PMID:25986938

  20. Plane wave imaging using phased array

    NASA Astrophysics Data System (ADS)

    Volker, Arno

    2014-02-01

    Phased arrays are often used for rapid inspections. Phased arrays can be used to synthesize different wave fronts. For imaging, focused wave fronts are frequently used. In order to build an image, the phased array has to be fired multiple times at the same location. Alternatively, different data acquisition configurations can be designed in combination with an imaging algorithm. The objective of this paper is to use the minimal amount of data required to construct an image. If a plane wave is synthesized, the region of interest is illuminated completely. For plane wave synthesis, all elements in the phase array are fired. This ensures a good signal to noise ratio. Imaging can be performed efficiently with a mapping algorithm in the wavenumber domain. The algorithm involves only two Fourier transforms and can therefore be extremely fast. The obtained resolution is comparable to conventional imaging algorithms. This work investigates the potential and limitations of this mapping algorithm on simulated data. With this approach, frame rates of more than 1 kHz can be achieved.

  1. Short wavelength infrared hybrid focal plane arrays

    NASA Technical Reports Server (NTRS)

    Vural, K.; Blackwell, J. D.; Marin, E. C.; Edwall, D. D.; Rode, J. P.

    1983-01-01

    The employment of area focal plane arrays (FPA) has made it possible to obtain second generation infrared imaging systems with high resolution and sensitivity. The Short Wavelength Infrared (SWIR) region (1-2.5 microns) is of importance for imaging objects at high temperature and under conditions of reflected sunlight. The present investigation is concerned with electrooptical characterization results for 32 x 32 SWIR detector arrays and FPAs which are suitable for use in a prototype imaging spectrometer. The employed detector material is Hg(1-x)Cd(x)Te grown by liquid phase epitaxy on a CdTe transparent substrate. Attention is given to details of processing, the design of the detector array, the multiplexer, the fabrication of the hybrid FPA, and aspects of performance.

  2. Infrared focal plane array crosstalk measurement

    NASA Astrophysics Data System (ADS)

    Dang, Khoa V.; Kauffman, Christopher L.; Derzko, Zenon I.

    1992-07-01

    Crosstalk between two neighboring elements in a focal plane array (FPA) occurs when signal incident on one element in the array is seen on another. This undesired effect can occur due to both the electrical and optical properties of the FPA. An effort is underway at the U.S. Army's Night Vision and Electro-Optics Directorate to develop a capability to measure crosstalk on both mid-wave infrared and long-wave infrared FPAs. A single detector in an array is illuminated using a laser source coupled with a beam expander, collimating lens, and focusing lens. The relative response of that detector to that of its neighboring detectors is measured to calculate crosstalk. The various components of the test station, the methodology for implementing the crosstalk measurement, and a model of the laser spot size are discussed.

  3. Short Wavelength Infrared Hybrid Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Vural, K.; Blackwell, J. D...; Marin, E. C.; Edwall, D. D...; Rode, J. P.

    1983-11-01

    Short wavelength (λc = 2.5 μm) 32 x 32 HgCdTe focal plane arrays have been fabricated for use in an Airborne Imaging Spectrometer (AIS) developed by the Jet Propulsion Labora-tory for NASA. An Imaging Spectrometer provides simultaneous imaging of several spectral bands for applications in the sensing and monitoring of earth resources. The detector material is HgCdTe grown on CdTe substrates using liquid phase epitaxy. Planar processing is used to make photovoltaic detectors on 68 um centers. The detector array is mated to a silicon charge coupled device multiplexer to make hybrid focal plane arrays. Results show high performance detectors with a mean RoA = 9.6 x 107 Ω --cm2 and IleakAge (-100 mV) = 0.037 pA at 120K and near zero background. The yield and uniformity are high. The ratio of the standard deviation of the dc responsivity to the mean is 3% for 98.5% of the pixels. The D1.0 = 1.3 x 1012 cm - âœ"fiz/W at a background of 1013 ph/cm2-s and 120K which is close to the background limited (BLIP) D* of 1.9 x 1012 cm- âœ"Hz/W.

  4. Uncooled infrared sensors with digital focal plane array

    NASA Astrophysics Data System (ADS)

    Marshall, Charles A.; Butler, Neal R.; Blackwell, Richard; Murphy, Robert; Breen, Thomas

    1996-06-01

    Loral Infrared & Imaging Systems is developing low cost, high performance, uncooled infrared imaging products for both military and commercial applications. These products are based on the microbolometer technology, a silicon micromachined sensor which combines the wafer level silicon processing with a device structure capable of yielding excellent infrared imaging performance. Here, we report on the development of an uncooled sensor, the LTC500, which incorporates an all digital focal plane array and has a measured NETD of less than 70 mK. The focal plane array and the electronics within the LTC500 have been designed as an integrated unit to meet a broad range of end user applications by providing features such as nonuniformity correction, autogain and level, NTSC video, and digital outputs. The 327 X 245 element focal plane array has a 46.25 micrometers pixel pitch and an on focal plane array 14 bit to analog to digital converter (ADC). The ADC has a measured instantaneous dynamic range of more than 76 dB at a 6.1 MHz output data rate and 60 Hz frame rate. The focal plane array consumes less than 500 mW of power, of which less than 250 mW is used in the ADC. An additional 36 dB of digital coarse offset correction in front of the ADC on the focal plane array results in a total electronic dynamic range of 112 dB. The MRT of the LTC500 camera has been measured at less 0.2 C at f(subscript o).

  5. MCT-Based LWIR and VLWIR 2D Focal Plane Detector Arrays for Low Dark Current Applications at AIM

    NASA Astrophysics Data System (ADS)

    Hanna, S.; Eich, D.; Mahlein, K.-M.; Fick, W.; Schirmacher, W.; Thöt, R.; Wendler, J.; Figgemeier, H.

    2016-09-01

    We present our latest results on n-on- p as well as on p-on- n low dark current planar mercury cadmium telluride (MCT) photodiode technology long wavelength infrared (LWIR) and very long wavelength infrared (VLWIR) two-dimensional focal plane arrays (FPAs) with quantum efficiency (QE) cut-off wavelength >11 μm at 80 K and a 512 × 640 pixel format FPA at 20 μm pitch stitched from two 512 × 320 pixel photodiode arrays. Significantly reduced dark currents as compared with Tennant's "Rule 07" are demonstrated in both polarities while retaining good detection efficiency ≥60% for operating temperatures between 30 K and 100 K. This allows for the same dark current performance at 20 K higher operating temperature than with previous AIM INFRAROT-MODULE GmbH (AIM) technology. For p-on- n LWIR MCT FPAs, broadband photoresponse nonuniformity of only about 1.2% is achieved at 55 K with low defective pixel numbers. For an n-on- p VLWIR MCT FPA with 13.6 μm cut-off at 55 K, excellent photoresponse nonuniformity of about 3.1% is achieved at moderate defective pixel numbers. This advancement in detector technology paves the way for outstanding signal-to-noise ratio performance infrared detection, enabling cutting-edge next-generation LWIR/VLWIR detectors for space instruments and devices with higher operating temperature and low size, weight, and power for field applications.

  6. MCT-Based LWIR and VLWIR 2D Focal Plane Detector Arrays for Low Dark Current Applications at AIM

    NASA Astrophysics Data System (ADS)

    Hanna, S.; Eich, D.; Mahlein, K.-M.; Fick, W.; Schirmacher, W.; Thöt, R.; Wendler, J.; Figgemeier, H.

    2016-04-01

    We present our latest results on n-on-p as well as on p-on-n low dark current planar mercury cadmium telluride (MCT) photodiode technology long wavelength infrared (LWIR) and very long wavelength infrared (VLWIR) two-dimensional focal plane arrays (FPAs) with quantum efficiency (QE) cut-off wavelength >11 μm at 80 K and a 512 × 640 pixel format FPA at 20 μm pitch stitched from two 512 × 320 pixel photodiode arrays. Significantly reduced dark currents as compared with Tennant's "Rule 07" are demonstrated in both polarities while retaining good detection efficiency ≥60% for operating temperatures between 30 K and 100 K. This allows for the same dark current performance at 20 K higher operating temperature than with previous AIM INFRAROT-MODULE GmbH (AIM) technology. For p-on-n LWIR MCT FPAs, broadband photoresponse nonuniformity of only about 1.2% is achieved at 55 K with low defective pixel numbers. For an n-on-p VLWIR MCT FPA with 13.6 μm cut-off at 55 K, excellent photoresponse nonuniformity of about 3.1% is achieved at moderate defective pixel numbers. This advancement in detector technology paves the way for outstanding signal-to-noise ratio performance infrared detection, enabling cutting-edge next-generation LWIR/VLWIR detectors for space instruments and devices with higher operating temperature and low size, weight, and power for field applications.

  7. Tohoku University Focal Plane Array Controller (TUFPAC)

    NASA Astrophysics Data System (ADS)

    Ichikawa, Takashi; Matsumoto, Daigo; Yanagisawa, Kenshi; Katsuno, Yuka; Suzuki, Ryuji; Tokoku, Chihiro; Asai, Ken'ichiro; Nishimura, Tetsuo

    2003-03-01

    TUFPAC (Tohoku University Focal Plane Array Controller) is an array control system originally designed for flexible control and efficient data acquisition of 2048 x 2048 HgCdTe (HAWAII-2) array. A personal computer operated by Linux OS controls mosaic HAWAII-2s with commercially available DSP boards installed on the PCI bus. Triggered by PC, DSP sends clock data to front-end electronics, which is isolated from the DSP board by photo-couplers. Front-end electronics supply powers, biases and clock signals to HAWAII2. Pixel data are read from four outputs of each HAWAII2 simultaneously by way of four channel preamps and ADCs. Pixel data converted to 16 bit digital data are stored in the frame memory on the DSP board. Data are processed in the memory when necessary. PC receives the frame data and stores it in the hard disk of PC in FITS format. A set of the DSP board and front-end electronics is responsible for controlling each HAWAII-2. One PC can operate eight mosaic arrays at most. TUFPAC is applicable to the control of CCDs with minor changes of front-end electronics.

  8. Small pixel oversampled IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Caulfield, John; Curzan, Jon; Lewis, Jay; Dhar, Nibir

    2015-06-01

    We report on a new high definition high charge capacity 2.1 Mpixel MWIR Infrared Focal Plane Array. This high definition (HD) FPA utilizes a small 5 um pitch pixel size which is below the Nyquist limit imposed by the optical systems Point Spread Function (PSF). These smaller sub diffraction limited pixels allow spatial oversampling of the image. We show that oversampling IRFPAs enables improved fidelity in imaging including resolution improvements, advanced pixel correlation processing to reduce false alarm rates, improved detection ranges, and an improved ability to track closely spaced objects. Small pixel HD arrays are viewed as the key component enabling lower size, power and weight of the IR Sensor System. Small pixels enables a reduction in the size of the systems components from the smaller detector and ROIC array, the reduced optics focal length and overall lens size, resulting in an overall compactness in the sensor package, cooling and associated electronics. The highly sensitive MWIR small pixel HD FPA has the capability to detect dimmer signals at longer ranges than previously demonstrated.

  9. Uncooled infrared focal plane array imaging in China

    NASA Astrophysics Data System (ADS)

    Lei, Shuyu

    2015-06-01

    This article reviews the development of uncooled infrared focal plane array (UIFPA) imaging in China in the past decade. Sensors based on optical or electrical read-out mechanism were developed but the latter dominates the market. In resistive bolometers, VOx and amorphous silicon are still the two major thermal-sensing materials. The specifications of the IRFPA made by different manufactures were collected and compared. Currently more than five Chinese companies and institutions design and fabricate uncooled infrared focal plane array. Some devices have sensitivity as high as 30 mK; the largest array for commercial products is 640×512 and the smallest pixel size is 17 μm. Emphasis is given on the pixel MEMS design, ROIC design, fabrication, and packaging of the IRFPA manufactured by GWIC, especially on design for high sensitivities, low noise, better uniformity and linearity, better stabilization for whole working temperature range, full-digital design, etc.

  10. Multispectral linear array (MLA) focal plane mechanical and thermal design

    NASA Technical Reports Server (NTRS)

    Mitchell, A. S.; Kaminski, E. F.

    1982-01-01

    The mechanical and thermal design of an integrated focal plane subsystem of a Multispectral Linear Array (MLA) instrument is discussed in terms of focal-plane alignment, thermoelastic performance, and thermal requirements. The modular construction and thermal control of the focal plane array are discussed.

  11. Smart trigger logic for focal plane arrays

    SciTech Connect

    Levy, James E; Campbell, David V; Holmes, Michael L; Lovejoy, Robert; Wojciechowski, Kenneth; Kay, Randolph R; Cavanaugh, William S; Gurrieri, Thomas M

    2014-03-25

    An electronic device includes a memory configured to receive data representing light intensity values from pixels in a focal plane array and a processor that analyzes the received data to determine which light values correspond to triggered pixels, where the triggered pixels are those pixels that meet a predefined set of criteria, and determines, for each triggered pixel, a set of neighbor pixels for which light intensity values are to be stored. The electronic device also includes a buffer that temporarily stores light intensity values for at least one previously processed row of pixels, so that when a triggered pixel is identified in a current row, light intensity values for the neighbor pixels in the previously processed row and for the triggered pixel are persistently stored, as well as a data transmitter that transmits the persistently stored light intensity values for the triggered and neighbor pixels to a data receiver.

  12. Low dark current MCT-based focal plane detector arrays for the LWIR and VLWIR developed at AIM

    NASA Astrophysics Data System (ADS)

    Gassmann, Kai Uwe; Eich, Detlef; Fick, Wolfgang; Figgemeier, Heinrich; Hanna, Stefan; Thöt, Richard

    2015-10-01

    For nearly 40 years AIM develops, manufactures and delivers photo-voltaic and photo-conductive infrared sensors and associated cryogenic coolers which are mainly used for military applications like pilotage, weapon sights, UAVs or vehicle platforms. In 2005 AIM started to provide the competences also for space applications like IR detector units for the SLSTR instrument on board of the Sentinel 3 satellite, the hyperspectral SWIR Imager for EnMAP or pushbroom detectors for high resolution Earth observation satellites. Meanwhile AIM delivered more than 25 Flight Models for several customers. The first European pulse-tube cooler ever operating on-board of a satellite is made by AIM. AIM homes the required infrared core capabilities such as design and manufacturing of focal plane assemblies, detector housing technologies, development and manufacturing of cryocoolers and also data processing for thermal IR cameras under one roof which enables high flexibility to react to customer needs and assures economical solutions. Cryogenically cooled Hg(1-x)CdxTe (MCT) quantum detectors are unequalled for applications requiring high imaging as well as high radiometric performance in the infrared spectral range. Compared with other technologies, they provide several advantages, such as the highest quantum efficiency, lower power dissipation compared to photoconductive devices and fast response times, hence outperforming micro-bolometer arrays. However, achieving an excellent MCT detector performance at long (LWIR) and very long (VLWIR) infrared wavelengths is challenging due to the exponential increase in the thermally generated photodiode dark current with increasing cut-off wavelength and / or operating temperature. Dark current is a critical design driver, especially for LWIR / VLWIR multi-spectral imagers with moderate signal levels or hyper-spectral Fourier spectrometers operating deep into the VLWIR spectral region. Consequently, low dark current (LDC) technologies are the

  13. Two-color quantum well infrared photodetector focal plane arrays

    NASA Astrophysics Data System (ADS)

    Bundas, Jason; Patnaude, Kelly; Dennis, Richard; Burrows, Douglas; Cook, Robert; Reisinger, Axel; Sundaram, Mani; Benson, Robert; Woolaway, James; Schlesselmann, John; Petronio, Susan

    2006-05-01

    QmagiQ LLC, has recently completed building and testing high operability two-color Quantum Well Infrared Photodetector (QWIP) focal plane arrays (FPAs). The 320 x 256 format dual-band FPAs feature 40-micron pixels of spatially registered QWIP detectors based on III-V materials. The vertically stacked detectors in this specific midwave/longwave (MW/LW) design are tuned to absorb in the respective 4-5 and 8-9 micron spectral ranges. The ISC0006 Readout Integrated Circuit (ROIC) developed by FLIR Systems Inc. and used in these FPAs features direct injection (DI) input circuitry for high charge storage with each unit cell containing dual integration capacitors, allowing simultaneous scene sampling and readout for the two distinct wavelength bands. Initial FPAs feature pixel operabilities better than 99%. Focal plane array test results and sample images will be presented.

  14. Focal Plane Arrays and Electronics for WISE

    NASA Astrophysics Data System (ADS)

    Masterjohn, Stacy; Hogue, H.; Mattson, R.; Dawson, L.; Bojorquez, A.; Muzilla, M.

    2009-01-01

    DRS provided the four channel focal plane array system for the Wide-field Infrared Survey Explorer (WISE) payload. The two shorter wavelength bands, centered near 3.2 and 4.5 µm, employed 1024x1024 HAWAII 1RG Mercury Cadmium Telluride (MCT) FPAs obtained from Teledyne Imaging Systems, Inc. The two longer wavelength bands, centered near 12 and 24 µm, utilized 1024x1024 arsenic doped silicon (Si:As) Blocked Impurity Band (BIB) FPAs, which were developed for the program by DRS. DRS packaged the 4 FPAs into similar custom cryogenic modules, each with its own flexible cryogenic ribbon cable to route FPA image output signals from within the WISE cryogenic telescope assembly through the cryostat walls. DRS also designed the cables and a common flight electronics box (FEB) to operate all 4 FPAs to provide their multiplexed digital image data streams to subsequent on-payload data processing and downlink systems. Fully functional, non-flight versions of the cabling and FEB were built to operate the FPAs during payload integration. The FPA system was delivered to the WISE payload integrator Space Dynamics Laboratory (SDL) in late 2007, and it is currently being integrated in to the WISE payload.

  15. Terahertz detectors and focal plane arrays

    NASA Astrophysics Data System (ADS)

    Rogalski, A.; Sizov, F.

    2011-09-01

    Terahertz (THz) technology is one of emerging technologies that will change our life. A lot of attractive applications in security, medicine, biology, astronomy, and non-destructive materials testing have been demonstrated already. However, the realization of THz emitters and receivers is a challenge because the frequencies are too high for conventional electronics and the photon energies are too small for classical optics. As a result, THz radiation is resistant to the techniques commonly employed in these well established neighbouring bands. In the paper, issues associated with the development and exploitation of THz radiation detectors and focal plane arrays are discussed. Historical impressive progress in THz detector sensitivity in a period of more than half century is analyzed. More attention is put on the basic physical phenomena and the recent progress in both direct and heterodyne detectors. After short description of general classification of THz detectors, more details concern Schottky barrier diodes, pair braking detectors, hot electron mixers and field-effect transistor detectors, where links between THz devices and modern technologies such as micromachining are underlined. Also, the operational conditions of THz detectors and their upper performance limits are reviewed. Finally, recent advances in novel nanoelectronic materials and technologies are described. It is expected that applications of nanoscale materials and devices will open the door for further performance improvement in THz detectors.

  16. Digital-pixel focal plane array development

    NASA Astrophysics Data System (ADS)

    Brown, Matthew G.; Baker, Justin; Colonero, Curtis; Costa, Joe; Gardner, Tom; Kelly, Mike; Schultz, Ken; Tyrrell, Brian; Wey, Jim

    2010-01-01

    Since 2006, MIT Lincoln Laboratory has been developing Digital-pixel Focal Plane Array (DFPA) readout integrated circuits (ROICs). To date, four 256 × 256 30 μm pitch DFPA designs with in-pixel analog to digital conversion have been fabricated using IBM 90 nm CMOS processes. The DFPA ROICs are compatible with a wide range of detector materials and cutoff wavelengths; HgCdTe, QWIP, and InGaAs photo-detectors with cutoff wavelengths ranging from 1.6 to 14.5 μm have been hybridized to the same digital-pixel readout. The digital-pixel readout architecture offers high dynamic range, A/C or D/C coupled integration, and on-chip image processing with low power orthogonal transfer operations. The newest ROIC designs support two-color operation with a single Indium bump connection. Development and characterization of the two-color DFPA designs is presented along with applications for this new digital readout technology.

  17. Multiwavelength infrared focal plane array detector

    NASA Technical Reports Server (NTRS)

    Forrest, Stephen R. (Inventor); Olsen, Gregory H. (Inventor); Kim, Dong-Su (Inventor); Lange, Michael J. (Inventor)

    1995-01-01

    A multiwavelength focal plane array infrared detector is included on a common substrate having formed on its top face a plurality of In.sub.x Ga.sub.1-x As (x.ltoreq.0.53) absorption layers, between each pair of which a plurality of InAs.sub.y P.sub.1-y (y<1) buffer layers are formed having substantially increasing lattice parameters, respectively, relative to said substrate, for preventing lattice mismatch dislocations from propagating through successive ones of the absorption layers of decreasing bandgap relative to said substrate, whereby a plurality of detectors for detecting different wavelengths of light for a given pixel are provided by removing material above given areas of successive ones of the absorption layers, which areas are doped to form a pn junction with the surrounding unexposed portions of associated absorption layers, respectively, with metal contacts being formed on a portion of each of the exposed areas, and on the bottom of the substrate for facilitating electrical connections thereto.

  18. System and method for generating a deselect mapping for a focal plane array

    SciTech Connect

    Bixler, Jay V; Brandt, Timothy G; Conger, James L; Lawson, Janice K

    2013-05-21

    A method for generating a deselect mapping for a focal plane array according to one embodiment includes gathering a data set for a focal plane array when exposed to light or radiation from a first known target; analyzing the data set for determining which pixels or subpixels of the focal plane array to add to a deselect mapping; adding the pixels or subpixels to the deselect mapping based on the analysis; and storing the deselect mapping. A method for gathering data using a focal plane array according to another embodiment includes deselecting pixels or subpixels based on a deselect mapping; gathering a data set using pixels or subpixels in a focal plane array that are not deselected upon exposure thereof to light or radiation from a target of interest; and outputting the data set.

  19. Mid-Wave and Long-Wave Infrared Dualband Megapixel QWIP Focal Plane Array

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Hill, C. J.; Ting, D. Z.; Kurth, E.; Woolaway, J.; LeVan, P. D.; Tidrow, M. Z.

    2008-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel InGaAs/GaAs/AlGaAs based quantum well infrared photodetector (QWIP) focal planes and a 320x256 pixel dual-band pixel co-registered simultaneous QWIP focal plane array have been demonstrated as pathfinders. In this paper, we discuss the development of 1024x1024 MWIR/LWIR dual-band pixel co-registered simultaneous QWIP focal plane array.

  20. An inverter-based capacitive trans-impedance amplifier readout with offset cancellation and temporal noise reduction for IR focal plane array

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Han; Hsieh, Chih-Cheng

    2013-09-01

    This paper presents a readout integrated circuit (ROIC) with inverter-based capacitive trans-impedance amplifier (CTIA) and pseudo-multiple sampling technique for infrared focal plane array (IRFPA). The proposed inverter-based CTIA with a coupling capacitor [1], executing auto-zeroing technique to cancel out the varied offset voltage from process variation, is used to substitute differential amplifier in conventional CTIA. The tunable detector bias is applied from a global external bias before exposure. This scheme not only retains stable detector bias voltage and signal injection efficiency, but also reduces the pixel area as well. Pseudo-multiple sampling technique [2] is adopted to reduce the temporal noise of readout circuit. The noise reduction performance is comparable to the conventional multiple sampling operation without need of longer readout time proportional to the number of samples. A CMOS image sensor chip with 55×65 pixel array has been fabricated in 0.18um CMOS technology. It achieves a 12um×12um pixel size, a frame rate of 72 fps, a power-per-pixel of 0.66uW/pixel, and a readout temporal noise of 1.06mVrms (16 times of pseudo-multiple sampling), respectively.

  1. Signal processing of microbolometer infrared focal-plane arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Junju; Qian, Yunsheng; Chang, Benkang; Xing, Suxia; Sun, Lianjun

    2005-01-01

    A 320×240-uncooled-microbolometer-based signal processing circuit for infrared focal-plane arrays is presented, and the software designs of this circuit system are also discussed in details. This signal processing circuit comprises such devices as FPGA, D/A, A/D, SRAM, Flash, DSP, etc., among which, FPGA is the crucial part, which realizing the generation of drive signals for infrared focal-plane, nonuniformity correction, image enhancement and video composition. The device of DSP, mainly offering auxiliary functions, carries out communication with PC and loads data when power-up. The phase locked loops (PLL) is used to generate high-quality clocks with low phase dithering and multiple clocks are to used satisfy the demands of focal-plane arrays, A/D, D/A and FPGA. The alternate structure is used to read or write SRAM in order to avoid the contradiction between different modules. FIFO embedded in FPGA not only makes full use of the resources of FPGA but acts as the channel between different modules which have different-speed clocks. What's more, working conditions, working process, physical design and management of the circuit are discussed. In software designing, all the function modules realized by FPGA and DSP devices, which are mentioned in the previous part, are discussed explicitly. Particularly to the nonuniformity correction module, the pipeline structure is designed to improve the working frequency and the ability to realize more complex algorithm.

  2. Antenna coupled detectors for 2D staring focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gritz, Michael A.; Kolasa, Borys; Lail, Brian; Burkholder, Robert; Chen, Leonard

    2013-06-01

    Millimeter-wave (mmW)/sub-mmW/THz region of the electro-magnetic spectrum enables imaging thru clothing and other obscurants such as fog, clouds, smoke, sand, and dust. Therefore considerable interest exists in developing low cost millimeter-wave imaging (MMWI) systems. Previous MMWI systems have evolved from crude mechanically scanned, single element receiver systems into very complex multiple receiver camera systems. Initial systems required many expensive mmW integrated-circuit low-noise amplifiers. In order to reduce the cost and complexity of the existing systems, attempts have been made to develop new mmW imaging sensors employing direct detection arrays. In this paper, we report on Raytheon's recent development of a unique focal plane array technology, which operates broadly from the mmW through the sub-mmW/THz region. Raytheon's innovative nano-antenna based detector enables low cost production of 2D staring mmW focal plane arrays (mmW FPA), which not only have equivalent sensitivity and performance to existing MMWI systems, but require no mechanical scanning.

  3. Integration of advanced optical functions on the focal plane array for very compact MCT-based micro cameras

    NASA Astrophysics Data System (ADS)

    Fendler, Manuel; Lasfargues, Gilles; Bernabé, S.; Druart, Guillaume A.; de La Barriere, Florence; Rommeluere, Sylvain; Guérineau, Nicolas; Lhermet, Nicolas; Ribot, Hervé

    2010-04-01

    Over the past decade, several technological breakthroughs have been achieved in the field of optical detection, in terms of spatial and thermal resolutions. The actual trend leads to the integration of new functions at the vicinity of the detector. This paper presents two types of integrated optics in the cryo-cooler, close to the MCT (CdHgTe) infrared detector array. The first one, for spectro-imaging applications, is a Fourier-transform microspectrometer on chip (MICROSPOC), developed for very fast acquisition of spectral signatures. Experimental results will be presented. The second one, for large field of view applications, illustrates the high potentiality of the integration of advanced optical functions in the Dewar of MCT detectors.

  4. Comparing viewer and array mental rotations in different planes

    NASA Technical Reports Server (NTRS)

    Carpenter, M.; Proffitt, D. R.; Kaiser, M. K. (Principal Investigator)

    2001-01-01

    Participants imagined rotating either themselves or an array of objects that surrounded them. Their task was to report on the egocentric position of an item in the array following the imagined rotation. The dependent measures were response latency and number of errors committed. Past research has shown that self-rotation is easier than array rotation. However, we found that imagined egocentric rotations were as difficult to imagine as rotations of the environment when people performed imagined rotations in the midsagittal or coronal plane. The advantages of imagined self-rotations are specific to mental rotations performed in the transverse plane.

  5. MWIR and LWIR Megapixel QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Bandara, S. V.; Liu, J. K.; Rafol, S. B.; Thang, J.; Mumolo, Jason; Tidrow, M.; LeVan, P. D.; Hill, C.

    2004-01-01

    A mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal plane array has been demonstrated with excellent imagery. MWIR focal plane has given noise equivalent differential temperature (NETD) of 19 mK at 95K operating temperature with f/2.5 optics at 300K background and LWIR focal plane has given NEDT of 13 mK at 70K operating temperature with same optical and background conditions as MWIR array. Both of these focal plane arrays have shown background limited performance (BLIP) at 90K and 70K operating temperatures with the same optics and background conditions. In this paper, we will discuss their performance in quantum efficiency, NETD, uniformity, and operability.

  6. Synchrotron based infrared imaging and spectroscopy via focal plane array on live fibroblasts in D2O enriched medium

    SciTech Connect

    Quaroni, Luca; Zlateva, Theodora; Sarafimov, Blagoj; Kreuzer, Helen W.; Wehbe, Katia; Hegg, Eric L.; Cinque, Gianfelice

    2014-03-26

    We tested the viability of using synchrotron based infrared imaging to study biochemical processes inside living cells. As a model system, we studied fibroblast cells exposed to a medium highly enriched with D2O. We could show that the experimental technique allows us to reproduce at the cellular level measurements that are normally performed on purified biological molecules. We can obtain information about lipid conformation and distribution, kinetics of hydrogen/deuterium exchange, and the formation of concentration gradients of H and O isotopes in water that are associated with cell metabolism. The implementation of the full field technique in a sequential imaging format gives a description of cellular biochemistry and biophysics that contains both spatial and temporal information.

  7. In-plane photonic transduction for microcantilever sensor arrays

    NASA Astrophysics Data System (ADS)

    Nordin, Gregory P.; Noh, Jong Wok; Kim, Seunghyun

    2007-02-01

    Microcantilevers show significant promise in sensing minute quantities of chemical and biological analytes in vapor and liquid media. Much of the reported work on microcantilever sensors has made use of single functionalized microcantilevers, usually derived from commercially available atomic force microscope (AFM) cantilevers. However, arrays with hundreds to thousands of microcantilevers on a single chip are required to create sophisticated, broad spectrum chemical and biological sensors in which individual microcantilevers have different bio- or chemoselective coatings. Unfortunately, the most sensitive microcantilever readout mechanisms (such as laser beam reflection as used in atomic force microscopy) are not readily scalable to large arrays. We therefore introduce a new microcantilever transduction mechanism for silicon-on-insulator (SOI) microcantilevers that is designed to scale to large arrays while maintaining a very compact form factor and high sensitivity. This mechanism is based on in-plane photonic transduction of microcantilever deflection in which the microcantilever itself forms a single mode rib waveguide. Light from the end of the microcantilever is directed across a small gap to an asymmetric receiving waveguide with two outputs that enables differential detection of microcantilever deflection. Initial noise and optical power budget calculations indicate that deflection sensitivities in the 10's of picometer range should be achievable.

  8. Antenna arrays for producing plane whistler waves

    NASA Astrophysics Data System (ADS)

    Stenzel, Reiner; Urrutia, J. Manuel

    2015-11-01

    In a large uniform laboratory plasma helicon modes with mode numbers 1 - 8 have been excited. Using a circular phased array it is shown that positive and negative modes can propagate equally well. The phase fronts of helicons form Archimedian screw surfaces. The electromagnetic field carries linear momentum due to the axial propagation and angular momentum due to the azimuthal propagation. Associated with the orbital angular momentum is a transverse Doppler shift. It is demonstrated that a rapidly rotating ``receiver'' observes a different frequency than the wave. This implies that a rotating electron can undergo cyclotron resonance when moving against the field rotation. Analogous to the axial Doppler shift cyclotron damping and cyclotron instabilities are possible due to the field rotation in helicons. Since helicons exist in unbounded laboratory plasma they should also exist in space plasmas. The angular wave-particle interaction may be an alternate approach for the remedial of energetic electrons. Work supported by NSF/DOE.

  9. Self-calibration of Antenna Errors Using Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Napier, P. J.; Cornwell, T. J.

    The thery of focal-plane correlation is reviewed and applied to the problem of the self-calibration and self-correction of a radio telescope with errors in its reflecting surface. Curves are presented which allow the estimation of focal-plane array size and integration time needed for telescopes with varying amounts of error. It is suggested that the technique may have application to the problem of the construction of large telescopes in space.

  10. Megapixel Multi-band QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Rafo, S. B.; Hill, C.; Mumolo, J.; Thang, J.; Tidrow, M.; LeVan, P. D.

    2004-01-01

    A mid-wavelength 1024x1024 pixel quantum well infrared photodetector (QW) focal plane array has been demonstrated with excellent imagery. Noise equivalent differential temperature (NETD) of 19 mK was achieved at 95K operating temperature with f/2.5 optics at 300K background. This focal plane array has shown background limited performance (BLIP) at 90K operating temperature with the same optics and background conditions. In this paper, we will discuss its performance in quantum efficiency, NETD, uniformity, and operability.

  11. Combatting infrared focal plane array nonuniformity noise in imaging polarimeters

    NASA Astrophysics Data System (ADS)

    Ratliff, Bradley M.; Kumar, Rakesh; Black, Wiley; Boger, James K.; Tyo, J. Scott

    2005-08-01

    One of the most significant challenges in performing infrared (IR) polarimetery is the focal plane array (FPA) nonuniformity (NU) noise that is inherent in virtually all IR photodetector technologies that operate in the midwave IR (MWIR) or long-wave IR (LWIR). NU noise results from pixel-to-pixel variations in the repsonsivity of the photodetectors. This problem is especially severy in the microengineered IR FPA materials like HgCdTe and InSb, as well as in uncooled IR microbolometer sensors. Such problems are largely absent from Si based visible spectrum FPAs. The pixel response is usually a variable nonlinear response function, and even when the response is linearized over some range of temperatures, the gain and offset of the resulting response is usually highly variable. NU noise is normally corrected by applying a linear calibration to the data, but the resulting imagery still retains residual nonuniformity due to the nonlinearity of the photodetector responses. This residual nonuniformity is particularly troublesome for polarimeters because of the addition and subtraction operations that must be performed on the images in order to construct the Stokes parameters or other polarization products. In this paper we explore the impact of NU noise on full stokes and linear-polarization-only IR polarimeters. We compare the performance of division of time, division of amplitude, and division of array polarimeters in the presence of both NU and temporal noise, and assess the ability of calibration-based NU correction schemes to clean up the data.

  12. Optical Link For Readout From Focal-Plane Array

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.; Larsson, Anders G.; Maserjian, Joseph

    1992-01-01

    Outputs of photodetectors modulate beam of light. Proposed optical link carries analog readout signals from photodetectors in focal-plane array to external signal-processing circuitry. Insensitive to electromagnetic interference at suboptical frequencies, and imposes smaller heat load on cryogenic apparatus because it does not include high-power electronic amplifier or laser transmitter within cold chamber.

  13. Testing of focal plane arrays at the AEDC

    NASA Astrophysics Data System (ADS)

    Nicholson, Randy A.; Mead, Kimberly D.; Smith, Robert W.

    1992-07-01

    A facility was developed at the Arnold Engineering Development Center (AEDC) to provide complete radiometric characterization of focal plane arrays (FPAs). The highly versatile facility provides the capability to test single detectors, detector arrays, and hybrid FPAs. The primary component of the AEDC test facility is the Focal Plane Characterization Chamber (FPCC). The FPCC provides a cryogenic, low-background environment for the test focal plane. Focal plane testing in the FPCC includes flood source testing, during which the array is uniformly irradiated with IR radiation, and spot source testing, during which the target radiation is focused onto a single pixel or group of pixels. During flood source testing, performance parameters such as power consumption, responsivity, noise equivalent input, dynamic range, radiometric stability, recovery time, and array uniformity can be assessed. Crosstalk is evaluated during spot source testing. Spectral response testing is performed in a spectral response test station using a three-grating monochromator. Because the chamber can accommodate several types of testing in a single test installation, a high throughput rate and good economy of operation are possible.

  14. Arrayed Ultrasonic Transducers on Arc Surface for Plane Wave Synthesis

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Soon; Kim, Jung-Ho; Kim, Moo-Joon; Ha, Kang-Lyeol; Yamada, Akira

    2004-05-01

    In ultrasonic computed tomography (UCT), it is necessary to synthesize a plane wave using waves emitted from sound sources arranged in the interior surface of a cylinder. In order to transmit a plane wave into a cylindrical surface, an ultrasonic transducer which has many vibrating elements with piezoelectric transverse effect arrayed on an arc surface is proposed. To achieve a wide beam width, the elements should have a small radiation area with a much narrow width. The measured electroacoustic efficiency for the elements was approximately 40% and the beam width defined by -3 dB level from the maximum was as wide as 120 deg. It was confirmed that plane wave synthesis is possible using the proposed transducer array.

  15. Next Generation Submillimeter Heterodyne Focal Plane Array Technology

    NASA Astrophysics Data System (ADS)

    Goldsmith, Paul; Mehdi, I.; Kawamura, J. H.; Siles, J. V.; Lee, C.; Chattoopadhyay, G.; Bumble, B.; Stern, J. A.

    2014-01-01

    The results from the Heterodyne Instrument for the Far Infrared (HIFI) on the Herschel Space Observatory have had a major impact on astronomy, including the first velocity-resolved survey of the critical 158 micron fine structure line of C+ to observations of water in comets. To follow up on Herschel’s discoveries we need to be able to image significant areas with high angular resolution. This requires high-sensitivity focal plane heterodyne arrays, which is the driver for the present effort. The current state of the art for mixers at frequencies above ~1200 GHz utilizes Hot Electron Bolometer (HEB) mixers that have remarkably good sensitivity (noise temperature < 1000 K) and require low local oscillator power. One significant limitation is the IF bandwidth of < few GHz for NbN devices. At 2 THz, 1 GHz corresponds to a Doppler width of 150 km/s, less than seen in the 1900 GHz [CII] line. For higher frequency transitions, such as the [OI] fine structure line at 4.7 THz (63 micron wavelength), this bandwidth is insufficient. Development of new HEB materials such as magnesium based alloys may overcome this challenge, and promising results have been reported in the literature. A characteristic of all HEB mixers is their high sensitivity to local oscillator power variations. We have developed an architecture for array local oscillator power production and distribution that is based on a chain of multipliers starting from a Ka band source. Improved multiplier diodes as well as circuit designs have made it possible to obtain adequate LO power to 2.7 THz, with extension to 4.7 THz promising. We have developed a system design for a 1.9 THz [CII] array with a separate chain of multipliers for each pixel allowing individual control of LO power, together with efficient LO-signal combination in a single beamsplitter. We will present results from multiplier tests and results of measurements on a 4 pixel prototype of a full 16 or more pixel system. This robust and efficient

  16. Curved-Focal-Plane Arrays Using Deformed-Membrane Photodetectors

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh; Jones, Todd

    2004-01-01

    A versatile and simple approach to the design and fabrication of curved-focal-plane arrays of silicon-based photodetectors is being developed. This approach is an alternative to the one described in "Curved Focal-Plane Arrays Using Back- Illuminated High-Purity Photodetectors" (NPO-30566), NASA Tech Briefs, Vol. 27, No. 10 (October 2003), page 10a. As in the cited prior article, the basic idea is to improve the performance of an imaging instrument and simplify the optics needed to obtain a given level of performance by making an image sensor (in this case, an array of photodetectors) conform to a curved focal surface, instead of designing the optics to project an image onto a flat focal surface. There is biological precedent for curved-focal-surface designs: retinas - the image sensors in eyes - conform to the naturally curved focal surfaces of eye lenses. The present approach is applicable to both front-side- and back-side-illuminated, membrane photodetector arrays and is being demonstrated on charge-coupled devices (CCDs). The very-large scale integrated (VLSI) circuitry of such a CCD or other array is fabricated on the front side of a silicon substrate, then the CCD substrate is attached temporarily to a second substrate for mechanical support, then material is removed from the back to obtain the CCD membrane, which typically has a thickness between 10 and 20 m. In the case of a CCD designed to operate in back-surface illumination, delta doping can be performed after thinning to enhance the sensitivity. This approach is independent of the design and method of fabrication of the front-side VLSI circuitry and does not involve any processing of a curved silicon substrate. In this approach, a third substrate would be prepared by polishing one of its surfaces to a required focal-surface curvature. A CCD membrane fabricated as described above would be pressed against, deformed into conformity with, and bonded to, the curved surface. The technique used to press and

  17. Modulation transfer function of QWIP and superlattice focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Rafol, S. B.; Ting, D. Z.; Soibel, A.; Liu, J. K.; Khoshakhlagh, A.; Keo, S. A.; Mumolo, J. M.; Nguyen, J.

    2013-07-01

    Modulation transfer function (MTF) is the ability of an imaging system to faithfully image a given object. The MTF of an imaging system quantifies the ability of the system to resolve or transfer spatial frequencies. In this paper we will discuss the detail MTF measurements of a 1024 × 1024 pixel multi-band quantum well infrared photodetector and 320 × 256 pixel long-wavelength InAs/GaSb superlattice infrared focal plane arrays.

  18. Precise annealing of focal plane arrays for optical detection

    SciTech Connect

    Bender, Daniel A.

    2015-09-22

    Precise annealing of identified defective regions of a Focal Plane Array ("FPA") (e.g., exclusive of non-defective regions of the FPA) facilitates removal of defects from an FPA that has been hybridized and/or packaged with readout electronics. Radiation is optionally applied under operating conditions, such as under cryogenic temperatures, such that performance of an FPA can be evaluated before, during, and after annealing without requiring thermal cycling.

  19. Hyperspectral modeling of an infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Mouzali, Salima; Lefebvre, Sidonie; Rommeluère, Sylvain; Ferrec, Yann; Primot, Jérôme

    2014-10-01

    Infrared Focal Plane Arrays (FPA) are increasingly used to measure multi- or hyperspectral images. Therefore, it is crucial to control and modelize their spectral response. The purpose of this paper is to propose a modeling approach, adjustable by experimental data, and applicable to the main cooled detector technologies. A physical model is presented, taking into account various optogeometrical properties of the detector, such as disparities of the pixels cut-off wavelengths. It describes the optical absorption phenomenon inside the pixel, by considering it as a stack of optical bulk layers. Then, an analytical model is proposed, based on the interference phenomenon occurring into the structure. This model considers only the three major waves interfering. It represents a good approximation of the physical model and a complementary understanding of the optical process inside the structure. This approach is applied to classical cooled FPAs as well as to specific instruments such as Microspoc (MICRO SPectrometer On Chip), a concept of miniaturized infrared Fourier transform spectrometer, integrated on a classical Mercury-Cadmium-Telluride FPA, and cooled by a cryostat.

  20. Modulation transfer function of infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Rafol, S. B.; Ting, D. Z.; Soibel, A.; Hill, C. J.; Khoshakhlagh, A.; Liu, J. K.; Mumolo, J. M.; Keo, S. A.; Höglund, L.; Luong, E. M.

    2015-09-01

    Modulation transfer function (MTF) is the ability of an imaging system to faithfully image a given object. The MTF of an imaging system quantifies the ability of the system to resolve or transfer spatial frequencies. In this presentation we will discuss the detail MTF measurements of 1024x1024 pixels mid-wavelength and long-wavelength quantum well infrared photodetector, and 320x256 pixels long-wavelength InAs/GaSb superlattice infrared focal plane arrays (FPAs). Long wavelength Complementary Barrier Infrared Detector (CBIRD) based on InAs/GaSb superlattice material is hybridized to recently designed and fabricated 320x256 pixel format ROIC. The n-type CBIRD was characterized in terms of performance and thermal stability. The experimentally measured NEΔT of the 8.8μm cutoff n-CBIRD FPA was 18.6 mK with 300 K background and f/2 cold stop at 78K FPA operating temperature. The horizontal and vertical MTFs of this pixel fully delineated CBIRD FPA at Nyquist frequency are 49% and 52%, respectively.

  1. Focal-Plane Array Receiver Systems for Space Communications

    NASA Astrophysics Data System (ADS)

    Britcliffe, M.; Hoppe, D.; Vilnrotter, V.

    2007-08-01

    Typical ground antennas intended for use in space communications require large apertures operating at high frequencies. The challenge involved with these applications is achieving the required antenna performance in terms of antenna aperture efficiency and pointing accuracy. The utilization of a focal-plane array in place of a standard single-mode feed minimizes these problems. This article discusses the key elements required to implement a focal-plane array on a large high-frequency antenna. The example of the NASA Deep Space Network 70-m antennas operating at 32 GHz has been chosen to illustrate these advantages. The design of a suitable feed and low-noise cryogenically cooled amplifier and the required signal-processing techniques are described. It is shown that adaptive least mean-square algorithms can be applied to the output of the array elements, in order to obtain the optimum combining weights in real time, even in the presence of dynamic interference (nearby spacecraft in the array's field of view or planetary radiation). This adaptive optimization capability maximizes the combined output signal-to-noise ratio in real time, ensuring maximum data throughput in the communications link when operating in the presence of receiver noise and external interference generally present during planetary encounters.

  2. Technological developments of the OGRE focal plane array

    NASA Astrophysics Data System (ADS)

    Tutt, James H.; McEntaffer, Randall L.; DeRoo, Casey; Schultz, Ted; Rogers, Thomas; Murray, Neil; Holland, Andrew; Weatherill, Daniel; Holland, Karen; Colebrook, David; Farn, David

    2015-09-01

    The Off-plane Grating Rocket Experiment (OGRE) is a high resolution soft X-ray spectrometer sub-orbital rocket payload designed as a technology development platform for three low Technology Readiness Level (TRL) components. The incident photons will be focused using a light-weight, high resolution, single-crystal silicon optic. They are then dispersed conically according to wavelength by an array of off-plane gratings before being detected in a focal plane camera comprised of four Electron Multiplying Charge-Coupled Devices (EM-CCDs). While CCDs have been extensively used in space applications; EM-CCDs are seldom used in this environment and even more rarely for X-ray photon counting applications, making them a potential technology risk for larger scale X-ray observatories. This paper will discuss the reasons behind choosing EM-CCDs for the focal plane detector and the developments that have been recently made in the prototype camera electronics and thermal control system.

  3. Strained layer superlattice focal plane array having a planar structure

    DOEpatents

    Kim, Jin K; Carroll, Malcolm S; Gin, Aaron; Marsh, Phillip F; Young, Erik W; Cich, Michael J

    2012-10-23

    An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

  4. Blocked impurity band hybrid infrared focal plane arrays for astronomy

    NASA Technical Reports Server (NTRS)

    Reynolds, D. B.; Seib, D. H.; Stetson, S. B.; Herter, T.; Rowlands, N.

    1989-01-01

    High-performance infrared hybrid focal plane arrays using 10- x 50-element Si:As blocked-impurity-band (BIB) detectors (cutoff wavelength = 28 microns) and matching switched MOSFET multiplexers have been developed and characterized for space astronomy. Use of impurity-band-conduction technology provides detectors which are nuclear-radiation-hard and free of the many anomalies associated with conventional silicon photoconductive detectors. Emphasis in the present work is on recent advances in detector material quality which have led to significantly improved detector and hybrid characteristics. Results demonstrating increased quantum efficiency (particularly at short-wavelength infrared), obtained by varying the BIB detector properties (infrared active layer thickness and arsenic doping profile), are summarized. Measured read noise and dark current for different temperatures are reported. The hybrid array performance achieved demonstrates that BIB detectors are well suited for use in astronomical instrumentation.

  5. MAGPIS: A MULTI-ARRAY GALACTIC PLANE IMAGING SURVEY

    SciTech Connect

    Helfand, D J; Becker, R H; White, R L; Fallon, A; Tuttle, S

    2005-11-10

    We present the Multi-Array Galactic Plane Imaging Survey (MAGPIS), which maps portions of the first Galactic quadrant with an angular resolution, sensitivity and dynamic range that surpasses existing radio images of the Milky Way by more than an order of magnitude. The source detection threshold at 20 cm is in the range 1-2 mJy over the 85% of the survey region (5{sup o} < l < 32{sup o}, |b| < 0.8{sup o}) not covered by bright extended emission; the angular resolution is {approx} 6''. We catalog over 3000 discrete sources (diameters mostly < 30'') and present an atlas of {approx} 400 diffuse emission regions. New and archival data at 90 cm for the whole survey area are also presented. Comparison of our catalogs and images with the MSX mid-infrared data allow us to provide preliminary discrimination between thermal and non-thermal sources. We identify 49 high-probability supernova remnant candidates, increasing by a factor of seven the number of known remnants with diameters smaller than 50 in the survey region; several are pulsar wind nebula candidates and/or very small diameter remnants (D < 45''). We report the tentative identification of several hundred H II regions based on a comparison with the mid-IR data; they range in size from unresolved ultra-compact sources to large complexes of diffuse emission on scales of half a degree. In several of the latter regions, cospatial nonthermal emission illustrates the interplay between stellar death and birth. We comment briefly on plans for followup observations and our extension of the survey; when complemented by data from ongoing X-ray and mid-IR observations, we expect MAGPIS to provide an important contribution to our understanding of the birth and death of massive stars in the Milky Way.

  6. High operating temperature interband cascade focal plane arrays

    SciTech Connect

    Tian, Z.-B.; Godoy, S. E.; Kim, H. S.; Schuler-Sandy, T.; Montoya, J. A.; Krishna, S.

    2014-08-04

    In this paper, we report the initial demonstration of mid-infrared interband cascade (IC) photodetector focal plane arrays with multiple-stage/junction design. The merits of IC photodetectors include low noise and efficient photocarrier extraction, even for zero-bias operation. By adopting enhanced electron barrier design and a total absorber thickness of 0.7 μm, the 5-stage IC detectors show very low dark current (1.10 × 10{sup −7} A/cm{sup 2} at −5 mV and 150 K). Even with un-optimized fabrication and standard commercial (mis-matched) read-out circuit technology, infrared images are obtained by the 320 × 256 IC focal plane array up to 180 K with f/2.3 optics. The minimum noise equivalent temperature difference of 28 mK is obtained at 120 K. These initial results indicate great potential of IC photodetectors, particularly for high operating temperature applications.

  7. Radiometric infrared focal plane array imaging system for thermographic applications

    NASA Technical Reports Server (NTRS)

    Esposito, B. J.; Mccafferty, N.; Brown, R.; Tower, J. R.; Kosonocky, W. F.

    1992-01-01

    This document describes research performed under the Radiometric Infrared Focal Plane Array Imaging System for Thermographic Applications contract. This research investigated the feasibility of using platinum silicide (PtSi) Schottky-barrier infrared focal plane arrays (IR FPAs) for NASA Langley's specific radiometric thermal imaging requirements. The initial goal of this design was to develop a high spatial resolution radiometer with an NETD of 1 percent of the temperature reading over the range of 0 to 250 C. The proposed camera design developed during this study and described in this report provides: (1) high spatial resolution (full-TV resolution); (2) high thermal dynamic range (0 to 250 C); (3) the ability to image rapid, large thermal transients utilizing electronic exposure control (commandable dynamic range of 2,500,000:1 with exposure control latency of 33 ms); (4) high uniformity (0.5 percent nonuniformity after correction); and (5) high thermal resolution (0.1 C at 25 C background and 0.5 C at 250 C background).

  8. On-chip ADC for infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Chen, Guo-qiang; Wang, Pan; Ding, Rui-jun

    2013-09-01

    This paper presents a low power and small area analog-digital converter (ADC) for infrared focal plane arrays (IRFPA) readout integrated circuit (ROIC). Successive approximation register (SAR) ADC architecture is used in this IRFPA readout integrated circuit. Each column of the IRFPA shares one SAR ADC. The most important part is the three-level DAC. Compared to the previous design, this three-level DAC needs smaller area, has lower power, and more suitable for IRFPA ROIC. In this DAC, its most significant bit (MSB) sub-DAC uses charge scaling, while the least significant bit (LSB) sub-DAC uses voltage scaling. Where the MSB sub-DAC consists of a four-bit charge scaling DAC and a five-bit sub-charge scaling DAC. We need to put a scaling capacitor Cs between these two sub-DACs. Because of the small area, we have more design methods to make the ADC has a symmetrical structure and has higher accuracy. The ADC also needs a high resolution comparator. In this design the comparator uses three-stage operational amplifier structure to have a 77dB differential gain. As the IR focal plane readout circuit signal is stepped DC signal, the circuit design time without adding the sample and hold circuit, so we can use a DC signal instead of infrared focal plane readout circuit output analog signals to be simulated. The simulation result shows that the resolution of the ADC is 12 bit.

  9. Electronic Processing And Advantages Of CMT Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Murphy, Kevin S.; Dennis, Peter N.; Bradley, Derek J.

    1990-04-01

    There have been many advances in thermal imaging systems and components in recent years such that an infrared capability is now readily available and accepted in a variety of military and civilian applications. Conventional thermal imagers such as the UK common module imager use a mechanical scanning system to sweep a small array of detectors across the thermal scene to generate a high definition TV compatible output. Although excellent imagery can be obtained from this type of system, there are some inherent disadvantages, amongst which are the need for a high speed line scan mechanism and the fundamental limit in thermal resolution due to the low stare efficiency of the system. With the advent of two dimensional focal plane array detectors, staring array imagers can now be designed and constructed in which the scanning mechanism is removed. Excellent thermal resolution can be obtained from such imagers due to the relatively long stare times. The recent progress in this technology will be discussed in this paper together with a description of the signal processing requirements of this type of imaging system.

  10. Reusable, adhesiveless and arrayed in-plane microfluidic interconnects

    NASA Astrophysics Data System (ADS)

    Lo, R.; Meng, E.

    2011-05-01

    A reusable, arrayed interconnect capable of providing multiple simultaneous connections to and from a microfluidic device in an in-plane manner without the use of adhesives is presented. This method uses a 'pin-and-socket' design in which an SU-8 anchor houses multiple polydimethysiloxane septa (the socket) that each receive a syringe needle (the pin). A needle array containing multiple commercially available 33G (203 µm outer diameter) needles (up to eight) spaced either 2.54 or 1 mm (center-to-center) pierces the septa to access the microfluidic device interior. Finite element modeling and photoelastic stress experiments were used to determine the stress distribution during needle insertion; these results guided the SU-8 septa housing and septa design. The impact of needle diameter, needle tip style, insertion rate and number of needles on pre-puncture, post-puncture and removal forces was characterized. Pressurized connections to SU-8 channel systems withstood up to 62 kPa of pressurized water and maintained 25 kPa of pressurized water for over 24 h. The successful integration and functionality of the interconnect design with surface micromachined Parylene C microchannels was verified using Rhodamine B dye. Dual septa systems to access a single microchannel were demonstrated. Arrayed interconnects were compatible with integrated microfluidic systems featuring electrochemical sensors and actuators.

  11. Design, fabrication and characterization of a polarization-sensitive focal plane array

    NASA Astrophysics Data System (ADS)

    Vorobiev, Dmitry; Ninkov, Zoran

    2015-03-01

    Measurement of polarization is a powerful yet underutilized technique, with potential applications in remote sensing, astronomy, biomedical imaging and optical metrology. We present the design, fabrication and characterization of a CCD-based polarization-sensitive focal plane array (FPA). These devices are compact permanently aligned detectors capable of determining the degree and angle of linear polarization in a scene, with a single exposure, over a broad spectral range. To derive the polarization properties, we employ a variation of the division-of-focal plane modulation strategy. The devices are fabricated by hybridizing a micropolarizer array (MPA) with a CCD. The result is a "general-purpose" polarization-sensitive imaging sensor, which can be placed at the focal plane of a wide number of imaging systems (and even spectrographs). We present our efforts to date in developing this technology and examine the factors that fundamentally limit the performance of these devices.

  12. Focal-Plane Arrays of Quantum-Dot Infrared Photodetectors

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath; Wilson, Daniel; Hill, Cory; Liu, John; Bandara, Sumith; Ting, David

    2007-01-01

    Focal-plane arrays of semiconductor quantum-dot infrared photodetectors (QDIPs) are being developed as superior alternatives to prior infrared imagers, including imagers based on HgCdTe devices and, especially, those based on quantum-well infrared photodetectors (QWIPs). HgCdTe devices and arrays thereof are difficult to fabricate and operate, and they exhibit large nonunformities and high 1/f (where f signifies frequency) noise. QWIPs are easier to fabricate and operate, can be made nearly uniform, and exhibit lower 1/f noise, but they exhibit larger dark currents, and their quantization only along the growth direction prevents them from absorbing photons at normal incidence, thereby limiting their quantum efficiencies. Like QWIPs, QDIPs offer the advantages of greater ease of operation, greater uniformity, and lower 1/f noise, but without the disadvantages: QDIPs exhibit lower dark currents, and quantum efficiencies of QDIPs are greater because the three-dimensional quantization of QDIPs is favorable to the absorption of photons at normal or oblique incidence. Moreover, QDIPs can be operated at higher temperatures (around 200 K) than are required for operation of QWIPs. The main problem in the development of QDIP imagers is to fabricate quantum dots with the requisite uniformity of size and spacing. A promising approach to be tested soon involves the use of electron-beam lithography to define the locations and sizes of quantum dots. A photoresist-covered GaAs substrate would be exposed to the beam generated by an advanced, high-precision electron beam apparatus. The exposure pattern would consist of spots typically having a diameter of 4 nm and typically spaced 20 nm apart. The exposed photoresist would be developed by either a high-contrast or a low-contrast method. In the high-contrast method, the spots would be etched in such a way as to form steep-wall holes all the way down to the substrate. The holes would be wider than the electron beam spots perhaps as

  13. NeuroSeek dual-color image processing infrared focal plane array

    NASA Astrophysics Data System (ADS)

    McCarley, Paul L.; Massie, Mark A.; Baxter, Christopher R.; Huynh, Buu L.

    1998-09-01

    Several technologies have been developed in recent years to advance the state of the art of IR sensor systems including dual color affordable focal planes, on-focal plane array biologically inspired image and signal processing techniques and spectral sensing techniques. Pacific Advanced Technology (PAT) and the Air Force Research Lab Munitions Directorate have developed a system which incorporates the best of these capabilities into a single device. The 'NeuroSeek' device integrates these technologies into an IR focal plane array (FPA) which combines multicolor Midwave IR/Longwave IR radiometric response with on-focal plane 'smart' neuromorphic analog image processing. The readout and processing integrated circuit very large scale integration chip which was developed under this effort will be hybridized to a dual color detector array to produce the NeuroSeek FPA, which will have the capability to fuse multiple pixel-based sensor inputs directly on the focal plane. Great advantages are afforded by application of massively parallel processing algorithms to image data in the analog domain; the high speed and low power consumption of this device mimic operations performed in the human retina.

  14. Integration of IR focal plane arrays with massively parallel processor

    NASA Astrophysics Data System (ADS)

    Esfandiari, P.; Koskey, P.; Vaccaro, K.; Buchwald, W.; Clark, F.; Krejca, B.; Rekeczky, C.; Zarandy, A.

    2008-04-01

    The intent of this investigation is to replace the low fill factor visible sensor of a Cellular Neural Network (CNN) processor with an InGaAs Focal Plane Array (FPA) using both bump bonding and epitaxial layer transfer techniques for use in the Ballistic Missile Defense System (BMDS) interceptor seekers. The goal is to fabricate a massively parallel digital processor with a local as well as a global interconnect architecture. Currently, this unique CNN processor is capable of processing a target scene in excess of 10,000 frames per second with its visible sensor. What makes the CNN processor so unique is that each processing element includes memory, local data storage, local and global communication devices and a visible sensor supported by a programmable analog or digital computer program.

  15. Thin active region, type II superlattice photodiode arrays: Single-pixel and focal plane array characterization

    NASA Astrophysics Data System (ADS)

    Little, J. W.; Svensson, S. P.; Beck, W. A.; Goldberg, A. C.; Kennerly, S. W.; Hongsmatip, T.; Winn, M.; Uppal, P.

    2007-02-01

    We have measured the radiometric properties of two midwave infrared photodiode arrays (320×256pixel2 format) fabricated from the same wafer comprising a thin (0.24μm), not intentionally doped InAs /GaSb superlattice between a p-doped GaSb layer and a n-doped InAs layer. One of the arrays was indium bump bonded to a silicon fanout chip to allow for the measurement of properties of individual pixels, and one was bonded to a readout integrated circuit to enable array-scale measurements and infrared imaging. The superlattice layer is thin enough that it is fully depleted at zero bias, and the collection efficiency of photogenerated carriers in the intrinsic region is close to unity. This simplifies the interpretation of photocurrent data as compared with previous measurements made on thick superlattices with complex doping profiles. Superlattice absorption coefficient curves, obtained from measurements of the external quantum efficiency using two different assumptions for optical coupling into the chip, bracket values calculated using an eight-band k •p model. Measurements of the quantum efficiency map of the focal plane array were in good agreement with the single-pixel measurements. Imagery obtained with this focal plane array demonstrates the high uniformity and crystal quality of the type II superlattice material.

  16. Design of a focal plane array with analog neural preprocessing

    NASA Astrophysics Data System (ADS)

    Koren, Ivo; Dohndorf, Juergen; Schluessler, Jens-Uwe; Werner, Joerg; Kroenig, Arndt; Ramacher, Ulrich

    1996-12-01

    The design of a CMOS focal plane array with 128 by 128 pixels and analog neural preprocessing is presented. Optical input to the array is provided by substrate-well photodiodes. A two-dimensional neural grid wIth next- neighbor connectivity, implemented as differential current- mode circuit, is capable of spatial low-pass filtering combined with contrast enhancement or binarization. The gain, spatial filter and nonlinearity parameters of the neural network are controlled externally using analog currents. This allows the multipliers and sigmoid transducers to be operated in weak inversion for a wide parameter sweep range as well as in moderate or strong inversion for a larger signal to pattern-noise ratio. The cell outputs are sequentially read out by an offset compensated differential switched-capacitor multiplexer with column preamplifiers. The analog output buffer is designed for pixel rates up to 1 pixel/microsecond and 2 by 100 pF load capacitance. All digital clocks controlling the analog data path are generated on-chip. The clock timing is programmable via a serial computer interface. Using 1 micrometer double-poly double-metal CMOS process, one pixel cell occupies 96 by 96 micrometer2 and the total chip size is about 2.3 cm2. Operating the neural network in weak inversion, the power dissipation of the analog circuitry is less than 100 mW.

  17. Multi-Color Megapixel QWIP focal plane arrays for remote sensing

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Bandara, S. V.; Liu, J. K.; Hill, C. J.; Rafol, S. B.; Mumolo, J. M.; Trinh, J. T.; Tidrow, M. Z.; LeVan, P. D.

    2005-01-01

    In this paper, we will discuss the performance in terms of quantum efficiency, NEAT, uniformity, operability, and modulation transfer functions of the 1024x1024 pixel arrays and the progress of dualband QWIP focal plane array development work.

  18. Development of a 2K x 2K GaAs QWIP Focal Plane Array

    NASA Technical Reports Server (NTRS)

    Jhabvala, M.; Choi, K.; Jhabvala, C.; Kelly, D.; Hess, L.; Ewin, A.; La, A.; Wacynski, A.; Sun, J.; Adachi, T.; Costen, N.; Ni, Q.; Snodgrass, Stephen; Foltz, Roger

    2013-01-01

    We are developing the next generation of GaAs Quantum Well Infrared Photodetector (QWIP) focal plane arrays (FPAs) in preparation for future NASA space-borne Earth observing missions. It is anticipated that these missions will require both wider ground spatial coverage as well as higher ground imaging resolution. In order to demonstrate our capability in meeting these future goals we have taken a two-tiered approach in the next stage of advanced QWIP focal plane array development. We will describe our progress in the development of a 512 x 3,200 (512 x 3K) array format for this next generation thermal imaging array for the NASA Landsat project. However, there currently is no existing readout integrated circuit (ROIC) for this format array.so to demonstrate the ability to scale-up an existing ROIC we developed a 1,920 x 2,048 (2K x 2K) array and it hybridized to a Raytheon SB419 CTIA readout integrated circuit that was scaled up from their existing 512 x 640 SB339 ROIC. Two versions of the 512 x 3K QWIP array were fabricated to accommodate a future design scale-up of both the Indigo 9803 ROIC based on a 25 micron pixel dimension and a scale up of the Indigo 9705 ROIC based on a 30 micron pixel dimension. Neither readout for the 512 x 3K has yet to be developed but we have fabricated both versions of the array. We describe the design, development and test results of this effort as well as the specific applications these FPAs are intended to address.

  19. Modulation Transfer Function Measurement of Infrared Focal-Plane Arrays with Small Fill Factors

    NASA Astrophysics Data System (ADS)

    de la Barrière, Florence; Druart, Guillaume; Guérineau, Nicolas; Rommeluère, Sylvain; Mugnier, Laurent; Gravrand, Olivier; Baier, Nicolas; Lhermet, Nicolas; Destefanis, Gérard; Derelle, Sophie

    2012-10-01

    This paper describes an original method to measure the modulation transfer function (MTF) of an infrared focal-plane array (IRFPA), based on a diffraction grating called a continuously self-imaging grating (CSIG). We give a general methodology to design the test bench, and we describe the data processing approach which has been developed to extract relevant information about the size of the photodiodes and filtering effects. The MTF measurement capability of this method is illustrated with a cooled IRFPA.

  20. Solar-Driven Background Intensity Variations in a Focal Plane Array

    SciTech Connect

    Eyer, H.H.; Guillen, J.L.L.; Vittitoe, C.N.

    1998-12-03

    Portions of a series of end-of-life tests are described for a Sandia National Li~boratories- designed space-based sensor that utilizes a mercury-cadmium-telluride focal plane array. Variations in background intensity are consistent with the hypothesis that seasonal variations in solar position cause changes in the pattern of shadows falling across the compartment containing the optical elements, filter-band components, and focal plane array. When the sensor compartment is most fully illuminated by the sun, background intensities are large and their standard deviations tend to be large. During the winter season, when the compartment is most fully shadowed by surrounding structure, backgrounci intensities are small and standard deviations tend to be small. Details in the surrounding structure are speculated to produce transient shadows that complicate background intensifies as a function of time or of sensor position in orbit.

  1. InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

    NASA Astrophysics Data System (ADS)

    Rehm, R.; Walther, M.; Schmitz, J.; Fleißner, J.; Fuchs, F.; Ziegler, J.; Cabanski, W.

    2006-03-01

    The first fully operational mid-IR (3-5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement.

  2. Advancement in 17-micron pixel pitch uncooled focal plane arrays

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Skidmore, George; Howard, Christopher; Clarke, Elwood; Han, C. J.

    2009-05-01

    This paper provides an update of 17 micron pixel pitch uncooled microbolometer development at DRS. Since the introduction of 17 micron pitch 640x480 focal plane arrays (FPAs) in 2006, significant progress has been made in sensor performance and manufacturing processes. The FPAs are now in initial production with an FPA noise equivalent temperature difference (NETD), detector thermal time constant, and pixel operability equivalent or better than that of the current 25 micron pixel pitch production FPAs. NETD improvement was achieved without compromising detector thermal response or thermal time constant by simultaneous reduction in bolometer heat capacity and thermal conductance. In addition, the DRS unique "umbrella" microbolometer cavities were optically tuned to optimize detector radiation absorption for specific spectral band applications. The 17 micron pixel pitch FPAs are currently being considered for the next generation soldier systems such as thermal weapon sights (TWS), vehicle driver vision enhancers (DVE), digitally fused enhanced night vision goggles (DENVG) and unmanned air vehicle (UAV) surveillance sensors, because of overall thermal imaging system size, weight and power advantages.

  3. Method of fabricating multiwavelength infrared focal plane array detector

    NASA Technical Reports Server (NTRS)

    Forrest, Stephen R. (Inventor); Olsen, Gregory H. (Inventor); Kim, Dong-Su (Inventor); Lange, Michael J. (Inventor)

    1996-01-01

    A multiwavelength local plane array infrared detector is included on a common substrate having formed on its top face a plurality of In.sub.x Ga.sub.1-x As (x.ltoreq.0.53) absorption layers, between each pair of which a plurality of InAs.sub.y P.sub.1-y (y.ltoreq.1) buffer layers are formed having substantially increasing lattice parameters, respectively, relative to said substrate, for preventing lattice mismatch dislocations from propagating through successive ones of the absorption layers of decreasing bandgap relative to said substrate, whereby a plurality of detectors for detecting different wavelengths of light for a given pixel are provided by removing material above given areas of successive ones of the absorption layers, which areas are doped to form a pn junction with the surrounding unexposed portions of associated absorption layers, respectively, with metal contacts being formed on a portion of each of the exposed areas, and on the bottom of the substrate for facilitating electrical connections thereto.

  4. Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results

    NASA Technical Reports Server (NTRS)

    Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

    1999-01-01

    The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

  5. 1024x1024 Pixel MWIR and LWIR QWIP Focal Plane Arrays and 320x256 MWIR:LWIR Pixel Colocated Simultaneous Dualband QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Bandara, Sumith V.; Liu, John K.; Hill, Cory J.; Rafol, S. B.; Mumolo, Jason M.; Trinh, Joseph T.; Tidrow, M. Z.; Le Van, P. D.

    2005-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NE(Delta)T) of 17 mK at a 95K operating temperature with f/2.5 optics at 300K background and the LWIR detector array has demonstrated a NE(Delta)T of 13 mK at a 70K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90K and 70K operating-temperatures respectively, with similar optical and background conditions. In addition, we are in the process of developing MWIR and LWIR pixel collocated simultaneously readable dualband QWIP focal plane arrays.

  6. Validating Phasing and Geometry of Large Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Standley, Shaun P.; Gautier, Thomas N.; Caldwell, Douglas A.; Rabbette, Maura

    2011-01-01

    The Kepler Mission is designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-sized and smaller planets in or near the habitable zone. The Kepler photometer is an array of 42 CCDs (charge-coupled devices) in the focal plane of a 95-cm Schmidt camera onboard the Kepler spacecraft. Each 50x25-mm CCD has 2,200 x 1,024 pixels. The CCDs accumulate photons and are read out every six seconds to prevent saturation. The data is integrated for 30 minutes, and then the pixel data is transferred to onboard storage. The data is subsequently encoded and transmitted to the ground. During End-to-End Information System (EEIS) testing of the Kepler Mission System (KMS), there was a need to verify that the pixels requested by the science team operationally were correctly collected, encoded, compressed, stored, and transmitted by the FS, and subsequently received, decoded, uncompressed, and displayed by the Ground Segment (GS) without the outputs of any CCD modules being flipped, mirrored, or otherwise corrupted during the extensive FS and GS processing. This would normally be done by projecting an image on the focal plane array (FPA), collecting the data in a flight-like way, and making a comparison between the original data and the data reconstructed by the science data system. Projecting a focused image onto the FPA through the telescope would normally involve using a collimator suspended over the telescope opening. There were several problems with this approach: the collimation equipment is elaborate and expensive; as conceived, it could only illuminate a limited section of the FPA (.25 percent) during a given test; the telescope cover would have to be deployed during testing to allow the image to be projected into the telescope; the equipment was bulky and difficult to situate in temperature-controlled environments; and given all the above, test setup, execution, and repeatability were significant concerns. Instead of using this complicated approach of

  7. Development of high performance SWIR InGaAs focal plane array

    NASA Astrophysics Data System (ADS)

    Nagi, Richie; Bregman, Jeremy; Mizuno, Genki; Oduor, Patrick; Olah, Robert; Dutta, Achyut K.; Dhar, Nibir K.

    2015-05-01

    Banpil Photonics has developed a novel InGaAs based photodetector array for Short-Wave Infrared (SWIR) imaging, for the most demanding security, defense, and machine vision applications. These applications require low noise from both the detector and the readout integrated circuit arrays. In order to achieve high sensitivity, it is crucial to minimize the dark current generated by the photodiode array. This enables the sensor to function in extremely low light situations, which enables it to successfully exploit the benefits of the SWIR band. In addition to minimal dark current generation, it is essential to develop photodiode arrays with higher operating temperatures. This is critical for reducing the power consumption of the device, as less energy is spent in cooling down the focal plane array (in order to reduce the dark current). We at Banpil Photonics are designing, simulating, fabricating and testing SWIR InGaAs arrays, and have achieved low dark current density at room temperature. This paper describes Banpil's development of the photodetector array. We also highlight the fabrication technique used to reduce the amount of dark current generated by the photodiode array, in particular the surface leakage current. This technique involves the deposition of strongly negatively doped semiconductor material in the area between the pixels. This process reduces the number of dangling bonds present on the edges of each pixel, which prevents electrons from being swept across the surface of the pixels. This in turn drastically reduces the amount of surface leakage current at each pixel, which is a major contributor towards the total dark current. We present the optical and electrical characterization data, as well as the analysis that illustrates the dark current mechanisms. Also highlighted are the challenges and potential opportunities for further reduction of dark current, while maintaining other parameters of the photodiode array, such as size, weight, temperature

  8. Test plane uniformity analysis for the MSFC solar simulator lamp array

    NASA Technical Reports Server (NTRS)

    Griner, D. B.

    1976-01-01

    A preliminary analysis was made on the solar simulator lamp array. It is an array of 405 tungsten halogen lamps with Fresnel lenses to achieve the required spectral distribution and collimation. A computer program was developed to analyze lamp array performance at the test plane. Measurements were made on individual lamp lens combinations to obtain data for the computer analysis. The analysis indicated that the performance of the lamp array was about as expected, except for a need to position the test plane within 2.7 m of the lamp array to achieve the desired 7 percent uniformity of illumination tolerance.

  9. The fabrication of out of plane aspherical microlens arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Wang, Wanjun

    2013-03-01

    MOEMS (Micro-Opto-Elecro-Mechanical Systems) has brought new inspirations to the traditional optics design and manufacturing, due to their advantages such as micro sizes, low cost, good performance, easy to integrate, and mass production. From the microfabrication technology perspective, microlens is among the most difficult components to make, and it is also the most important component of all free space micro-optic components. In recent years, the aspherical lens with controllable curvature has become one of the most popular research subjects since it is helpful in eliminating aberration. In this paper, we report a new method of fabricating and replicating aspherical microlens array with primary optic axis in parallel with the substrate surface. The technology was based on ultra-violet (UV) lithography of SU-8 thick resist. A novel water bath oblique lithography technique was adopted. Diameter of the prototype microlenses fabricated is about 200 μm. By changing the pattern of mask and other process parameters, aspherical microlenses with different sizes and surface curvatures can be obtained. The microlens made using this technique has its main optical axis in parallel with the substrate, this makes it much easier to be integrated with other components into on-chip optical platforms such as optical switch and the imaging systems. This kind of micro-lens arrays will also be incorporated to microfluidic systems such as micro flow cytometry for fluorescence detections.

  10. Optically coupled focal plane arrays using lenslets and multiplexers

    DOEpatents

    Veldkamp, Wilfrid B.

    1991-01-01

    A detector array including a substrate having an array of diffractive lenses formed on the top side of the substrate and an array of sensor elements formed on the backside of the substrate. The sensor elements within the sensor array are oriented on the backside so that each sensor is aligned to receive light from a corresponding diffractive lens of the lens array. The detector array may also include a second substrate having an array of diffractive elements formed on one of its surfaces, the second substrate being disposed above and in proximity to the top side of the other substrate so that the elements on the second substrate are substantially aligned with corresponding sensor elements and diffractive lenses on the other substrate.

  11. Performance of focal plane arrays for the photon counting arrays (PCAR) program

    NASA Astrophysics Data System (ADS)

    Blessinger, Michael A.; Enriquez, Marlon; Groppe, Joseph V.; Flynn, Kevin; Sudol, Thomas M.; Onat, Bora M.; Kleinhans, William E.

    2007-04-01

    The DARPA PCAR program is sponsoring the development of low noise, near infrared (1.5 μm wavelength) focal plane arrays (FPAs) for night vision applications. The first phase of this work has produced a collection of 640 x 512 pixel, 20 μm pitch FPAs with low noise. The approach was to design four different read out integrated circuits (ROICs), all compatible with the same bump-bonded InGaAs photodiode detector array. Two of the designs have capacitive transimpedance amplifier (CTIA) pixels, each with a somewhat different amplifier design and with two different sizes of small integration capacitors. The third design is a source follower per detector (SFD) pixel, integrating on the detector capacitance. The fourth design also integrates on the detector capacitance, but uses a moderate gain, in-pixel amplifier to boost the signal level, and also has a differential pixel output. All four designs require off-chip correlated sampling to achieve the desired noise level. The correlated sampling is performed digitally in the data acquisition software. Each design is capable of 30 frames per second read out rate, and has a dynamic range of 1000:1 using a rolling, non-snapshot integration. The designs were fabricated in a standard CMOS foundry process, and were bump-bonded to InGaAs detector arrays. All four designs are working without any significant design errors, and are producing low noise imaging, with less than 50 electrons rms noise per pixel after correlated double sampling.

  12. Combined real-time ultrasound plane wave compounding and linear array optoacoustics

    NASA Astrophysics Data System (ADS)

    Fournelle, Marc; Bost, Wolfgang; Tretbar, Steffen

    2015-07-01

    In optoacoustic imaging, the high optical contrast between different tissue types is combined with the high resolution and low scattering of ultrasound. Using adapted reconstruction algorithms, images of the distribution of light absorption in tissue can be obtained. Such as in any emerging modality, there is limited experience regarding the interpretation of optoacoustic images. For this reason, we developed a flexible hardware platform combining ultrasound imaging with optoacoustics. The system is based on the software processing of channel data and different types of reconstruction algorithms are implemented. It combines optoacoustic imaging based on linear arrays for detection with plane wave compounding ultrasound. Our system further includes a custom made probe based on a 7,5 MHz array, custom made fibre bundles for targeted light delivery and an acoustic coupling pad. The system was characterized on phantoms and first in-vivo datasets from subcutaneous vasculature were acquired.

  13. Fast iterative adaptive nonuniformity correction with gradient minimization for infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Jufeng; Gao, Xiumin; Chen, Yueting; Feng, Huajun; Xu, Zhihai; Li, Qi

    2014-07-01

    A fast scene-based nonuniformity correction algorithm is proposed for fixed-pattern noise removal in infrared focal plane array imagery. Based on minimization of L0 gradient of the estimated irradiance, the correction function is optimized through correction parameters estimation via iterative optimization strategy. When applied to different real IR data, the proposed method provides enhanced results with good visual effect, making a good balance between nonuniformity correction and details preservation. Comparing with other excellent approaches, this algorithm can accurately estimate the irradiance rapidly with fewer ghosting artifacts.

  14. Plane-wave decomposition by spherical-convolution microphone array

    NASA Astrophysics Data System (ADS)

    Rafaely, Boaz; Park, Munhum

    2001-05-01

    Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.

  15. QWIP focal plane arrays performances from MWIR up to VLWIR

    NASA Astrophysics Data System (ADS)

    Robo, J. A.; Costard, E.; Truffer, J. P.; Nedelcu, A.; Marcadet, X.; Bois, P.

    2009-05-01

    Since 2002, the THALES Group has been manufacturing sensitive arrays using QWIP technology based on GaAs and related III-V compounds, at the Alcatel-Thales-III-V Lab (formerly part of THALES Research and Technology Laboratory). In the past researchers claimed many advantages of QWIPs. Uniformity was one of these and has been the key parameter for the production to start. Another widely claimed advantage for QWIPs was the so-called band-gap engineering and versatility of the III-V processing allowing the custom design of quantum structures at various wavelengths in MWIR, LWIR and VLWIR. An overview of the available performances of QWIPs in the whole infrared spectrum is presented here. We also discuss about the under-development products such as dual band and polarimetric structures.

  16. Status of uncooled focal plane detector arrays for smart IR sensors

    NASA Astrophysics Data System (ADS)

    Liddiard, Kevin C.; Ringh, Ulf; Jansson, Christer

    1996-06-01

    A cooperative research project between the Defense Science and Technology Organization, Australia, and the National Defense Research Establishment, Sweden, seeks to investigate concepts for smart IR focal plane detector arrays, whereby a monolithic Semiconductor Film Bolometer detector array is integrated with a CMOS signal conditioning circuit, analog- to-digital conversion and signal processing functions on the same silicon chip. Novel signal conditioning and on-chip digital readout techniques have been successfully demonstrated, and the supporting signal processing electronic design is being developed. This paper discusses the status of detector materials research and staring focal plane array development. The first experimental array has been delivered and is undergoing evaluation.

  17. Signal processing and compensation electronics for junction field-effect transistor /JFET/ focal plane arrays

    NASA Astrophysics Data System (ADS)

    Wittig, K. R.

    1982-06-01

    A signal processing system has been designed and constructed for a pyroelectric infrared area detector which uses a matrix-addressable JFET array for readout and for on-focal plane preamplification. The system compensates for all offset and gain nonuniformities in and after the array. Both compensations are performed in real time at standard television rates, so that changes in the response characteristics of the array are automatically corrected for. Two-point compensation is achieved without the need for two separate temperature references. The focal plane circuitry used to read out the array, the offset and gain compensation algorithms, the architecture of the signal processor, and the system hardware are described.

  18. WISE-Heritage Megapixel BIB Focal Plane Arrays for Astronomy

    NASA Astrophysics Data System (ADS)

    Hogue, Henry; Mainzer, A.; Molyneux, D.; Reynolds, D.; Masterjohn, S.; Muzilla, M.

    2009-01-01

    The most significant design features of the low-noise 1024x1024 cryogenic FPA readout developed by DRS for the Wide-field Infrared Survey Explorer (WISE) have been transferred to a new high-flux FPA readout design for terrestrial and airborne astronomy with warm telescopes. The development of the new readout and the first 1024x1024 arsenic-doped silicon (Si:As) BIB FPA based on it was a joint effort between DRS and NASA JPL. This FPA is called the MegaMIR FPA, since it will be initially utilized in the MegaMIR camera being developed by JPL. New high-flux Si:As detector arrays were fabricated by DRS for use in the MegaMIR FPA, and the first two engineering FPAs have been prepared and delivered to JPL for evaluation. . In parallel DRS is applying the same high-flux readout for development of a 512x512 antimony-doped silicon (Si:Sb) having twice the pixel size and pitch as the MegaMIR FPA. The 4 times larger pixel size is better matched to the diffraction-limited resolution of the longer-wavelength Si:Sb detectors ( 40 µm cut-off vs 28 µm of Si:As).

  19. Characterization of type II SLS n-CBIRD focal plane array

    NASA Astrophysics Data System (ADS)

    Rafol, S. B.; Gunapala, S. D.; Ting, D. Z.; Soibel, A.; Khoshakhlagh, A.; Nguyen, J.; Höglund, L.; Liu, J. K.; Mumolo, J. M.; Keo, S. A.; Luong, E. M.

    2012-10-01

    New generation of focal plane arrays (FPAs) based on type II SLS, which are hybrids of detector array and Read Out Integrated Circuits (ROIC), present extraordinary challenge to characterize. The standard performance metrics are: temporal NEΔT, noise equivalent irradiance (NEI), quantum efficiency, dark current and modulation transfer function (MTF). Imaging system modulation Transfer Function (MTF) is an important quantitative metric of performance in spatial domain, but it is rarely reported in the literature especially for type II SLS. MTF measurement is believed to be a good metric of performance for camera systems in addition to standard performance parameters. The paper will report on the characterization of complimentary barrier infrared detector n-CBIRD FPA.

  20. Progress in DRS production line for uncooled focal plane arrays

    NASA Astrophysics Data System (ADS)

    Han, Chien J.; Howard, Christopher G.; Howard, Philip E.; Ionescu, Adrian C.; Li, Chuan C.; Monson, John C.; Naranjo, Robert L.; Scholten, Myron J.; Sweeney, R. Michael; Strong, Roger L.; Sullivan, William; Teherani, Towfik H.

    2004-08-01

    To improve its capacity to meet customer needs, DRS Infrared Technologies began technology transfer of the VOx uncooled FPA process from its Anaheim facility to its Dallas facility in the Fall of 2002. The new facility delivered its first U3000 arrays (320x240, 51μm pitch) three months after the VOx deposition system was installed, and produced over 300 units of U3000 per month just twelve months after beginning the transfer. Process enhancements and tool upgrades have enabled excellent control of the microbolometer process. Today, this line selectively fabricates arrays with NETD varying from 30mK to 80mK in 15mK bins with less than 30 ms time constant. The same arrays also have low defect density of less than 2% dead pixels and no more than one row and one column out. The arrays are packaged in imager or radiometer (F/1.4) packages. DRS also transferred small and large format arrays with 25μm pitch under the PEO-Soldier Sensor Producibility to the Dallas facility. Production of the 25μm pitch devices is currently more that 100 units per month and is ramping up to meet customer demand. This paper reports on production progress on the U3000s and the status of U3500 and U6000 25μm pitch array.

  1. Study on 512×128 pixels InGaAs near infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Li, Xue; Tang, Hengjing; Huang, Songlei; Shao, Xiumei; Li, Tao; Huang, Zhangcheng; Gong, Haimei

    2014-10-01

    It is well known that In0.53Ga0.47As epitaxial material is lattice-matched to InP substrate corresponding to the wavelength from 0.9μm to 1.7μm, which results to high quality material and good device characteristics at room temperature. In order to develop the near infrared multi-spectral imaging, 512×128 pixels InGaAs Near Infrared Focal Plane Arrays (FPAs) were studied. The n-InP/i-InGaAs/n-InP double hereto-structure epitaxial material was grown by MBE. The 512×128 back-illuminated planar InGaAs detector arrays were fabricated, including the improvement of passivation film, by grooving the diffusion masking layer, the P type electrode layer, In bump condition and so on. The photo-sensitive region has the diffusion area of 23×23μm2 and pixel pitch of 30×30μm2 . The 512×128 detector arrays were individually hybridized on readout integrated circuit(ROIC) by Indium bump based on flip-chip process to make focal plane arrays (FPAs). The ROIC is based on a capacitive trans-impedance amplifier with correlated double sampling and integrated while readout (IWR) mode with high readout velocity of every pixel resulting in low readout noise and high frame frequency. The average peak detectivity and the response non-uniformity of the FPAs are 1.63×1012 cmHz1/2/W and 5.9%, respectively. The power dissipation and frame frequency of the FPAs are about 180mW and 400Hz, respectively.

  2. Concurrent array-based queue

    SciTech Connect

    Heidelberger, Philip; Steinmacher-Burow, Burkhard

    2015-01-06

    According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.

  3. Mechanical design of mounts for IGRINS focal plane arrays and field flattening lenses

    NASA Astrophysics Data System (ADS)

    Oh, Jae Sok; Park, Chan; Cha, Sang-Mok; Yuk, In-Soo; Kim, Kang-Min; Chun, Moo-Young; Ko, Kyeongyeon; Oh, Heeyeong; Jeong, Ueejeong; Nah, Jakyoung; Lee, Hanshin; Pavel, Michael; Jaffe, Daniel T.

    2014-07-01

    IGRINS, the Immersion GRating INfrared Spectrometer, is a near-infrared wide-band high-resolution spectrograph jointly developed by the Korea Astronomy and Space Science Institute and the University of Texas at Austin. IGRINS employs three HAWAII-2RG focal plane array (FPA) detectors. The mechanical mounts for these detectors and for the final (field-flattening) lens in the optical train serve a critical function in the overall instrument design: Optically, they permit the only positional compensation in the otherwise "build to print" design. Thermally, they permit setting and control of the detector operating temperature independently of the cryostat bench. We present the design and fabrication of the mechanical mount as a single module. The detector mount includes the array housing, housing for the SIDECAR ASIC, a field flattener lens holder, and a support base. The detector and ASIC housing will be kept at 65 K and the support base at 130 K. G10 supports thermally isolate the detector and ASIC housing from the support base. The field flattening lens holder attaches directly to the FPA array housing and holds the lens with a six-point kinematic mount. Fine adjustment features permit changes in axial position and in yaw and pitch angles. We optimized the structural stability and thermal characteristics of the mount design using computer-aided 3D modeling and finite element analysis. Based on the computer simulation, the designed detector mount meets the optical and thermal requirements very well.

  4. Focal Plane Arrays of Voltage-Biased Superconducting Bolometers

    NASA Technical Reports Server (NTRS)

    Myers, Michael J.; Clarke, John; Gildemeister, J. M.; Lee, Adrian T.; Richards, P. L.; Schwan, Dan; Skidmore, J. T.; Spieler, Helmuth; Yoon, Jongsoo

    2001-01-01

    The 200-micrometer to 3-mm wavelength range has great astronomical and cosmological significance. Science goals include characterization of the cosmic microwave background, measurement of the Sunyaev-Zel'dovich effect in galaxy clusters, and observations of forming galaxies. Cryogenic bolometers are the most sensitive broadband detectors in this frequency range. Because single bolometer pixels are reaching the photon noise limit for many observations, the development of large arrays will be critical for future science progress. Voltage-biased superconducting bolometers (VSBs) have several advantages compared to other cryogenic bolometers. Their strong negative electrothermal feedback enhances their linearity, speed, and stability. The large noise margin of the SQUID readout enables multiplexed readout schemes, which are necessary for developing large arrays. In this paper, we discuss the development of a large absorber-coupled array, a frequency-domain SQUID readout multiplexer, and an antenna-coupled VSB design.

  5. Demonstration of a bias tunable quantum dots-in-a-well focal plane array

    NASA Astrophysics Data System (ADS)

    Andrews, Jonathan; Jang, Woo-Yong; Pezoa, Jorge E.; Sharma, Yagya D.; Lee, Sang Jun; Noh, Sam Kyu; Hayat, Majeed M.; Restaino, Sergio; Teare, Scott W.; Krishna, Sanjay

    2009-11-01

    Infrared detectors based on quantum wells and quantum dots have attracted a lot of attention in the past few years. Our previous research has reported on the development of the first generation of quantum dots-in-a-well (DWELL) focal plane arrays, which are based on InAs quantum dots embedded in an InGaAs well having GaAs barriers. This focal plane array has successfully generated a two-color imagery in the mid-wave infrared (i.e. 3-5 μm) and the long-wave infrared (i.e. 8-12 μm) at a fixed bias voltage. Recently, the DWELL device has been further modified by embedding InAs quantum dots in InGaAs and GaAs double wells with AlGaAs barriers, leading to a less strained InAs/InGaAs/GaAs/AlGaAs heterostructure. This is expected to improve the operating temperature while maintaining a low dark current level. This paper examines 320 × 256 double DWELL based focal plane arrays that have been fabricated and hybridized with an Indigo 9705 read-out integrated circuit using Indium-bump (flip-chip) technology. The spectral tunability is quantified by examining images and determining the transmittance ratio (equivalent to the photocurrent ratio) between mid-wave and long-way infrared filter targets. Calculations were performed for a bias range from 0.3 to 1.0 V. The results demonstrate that the mid-wave transmittance dominates at these low bias voltages, and the transmittance ratio continuously varies over different applied biases. Additionally, radiometric characterization, including array uniformity and measured noise equivalent temperature difference for the double DWELL devices is computed and compared to the same results from the original first generation DWELL. Finally, higher temperature operation is explored. Overall, the double DWELL devices had lower noise equivalent temperature difference and higher uniformity, and worked at higher temperature (70 K and 80 K) than the first generation DWELL device.

  6. Hemispherical infrared focal plane arrays: a new design parameter for the instruments

    NASA Astrophysics Data System (ADS)

    Fendler, M.; Dumas, D.; Chemla, F.; Cohen, M.; Laporte, P.; Tekaya, K.; Le Coarer, E.; Primot, J.; Ribot, H.

    2012-07-01

    In ground based astronomy, mainly all designs of sky survey telescopes are limited by the requirement that the detecting surface is flat whereas the focal surface is curved. Two kinds of solution have been investigated up to now. The first one consists in adding optical systems to flatten the image surface; however this solution complicates the design and increases the system size. Somehow, this solution increases, in the same time, the weight and price of the instrument. The second solution consists in curving artificially the focal surface by using a mosaic of several detectors, which are positioned in a spherical shape. However, this attempt is dedicated to low curvature and is limited by the technical difficulty to control the detectors alignment and tilt between each others. Today we would like to propose an ideal solution which is to curve the focal plane array in a spherical shape, thanks to our monolithic process developed at CEA-LETI based on thinned silicon substrates which allows a 100% optical fill factor. Two infrared uncooled cameras have been performed, using 320 x 256 pixels and 25 μm pitch micro-bolometer arrays curved at a bending radius of 80 mm. These two micro-cameras illustrate the optical system simplification and miniaturization involved by curved focal plane arrays. Moreover, the advantages of curved detectors on the optical performances (Point Spreading Function), as well as on volume and cost savings have been highlighted by the simulation of the opto-mechanical architecture of the spectrometer OptiMOS-EVE for the European Extremely Large Telescope (E-ELT).

  7. Materials, devices, techniques, and applications for Z-plane focal plane array technology II; Proceedings of the Meeting, San Diego, CA, July 12, 13, 1990

    NASA Astrophysics Data System (ADS)

    Carson, John C.

    1990-11-01

    Various papers on materials, devices, techniques, and applications for X-plane focal plane array technology are presented. Individual topics addressed include: application of Z-plane technology to the remote sensing of the earth from GEO, applications of smart neuromorphic focal planes, image-processing of Z-plane technology, neural network Z-plane implementation with very high interconnection rates, using a small IR surveillance satellite for tactical applications, establishing requirements for homing applications, Z-plane technology. Also discussed are: on-array spike suppression signal processing, algorithms for on-focal-plane gamma circumvention and time-delay integration, current HYMOSS Z-technology, packaging of electrons for on- and off-FPA signal processing, space/performance qualification of tape automated bonded devices, automation in tape automated bonding, high-speed/high-volume radiometric testing of Z-technology focal planes, 128-layer HYMOSS-module fabrication issues, automation of IRFPA production processes.

  8. Guided torsional wave generation of a linear in-plane shear piezoelectric array in metallic pipes.

    PubMed

    Zhou, Wensong; Yuan, Fuh-Gwo; Shi, Tonglu

    2016-02-01

    Cylindrical guided waves based techniques are effective and promising tools for damage detection in long pipes. The essential operations are generation and reception of guided waves in the structures utilizing transducers. A novel in-plane shear (d36 type) PMNT wafer is proposed to generate and receive the guided wave, especially the torsional waves, in metallic pipes. In contrast to the traditional wafer, this wafer will directly introduce in-plane shear deformation when electrical field is conveniently applied through its thickness direction. A single square d36 PMNT wafer is bonded on the surface of the pipe positioned collinearly with its axis, when actuated can predominantly generate torsional (T) waves along the axial direction, circumferential shear horizontal (C-SH) waves along circumferential direction, and other complex cylindrical Lamb-like wave modes along other helical directions simultaneously. While a linear array of finite square size d36 PMNT wafers was equally spaced circumferentially, when actuated simultaneously can nearly uniform axisymmetric torsional waves generate in pipes and non-symmetric wave modes can be suppressed greatly if the number of the d36 PMNT wafer is sufficiently large. This paper first presents the working mechanism of the linear d36 PMNT array from finite element analysis (FEA) by examining the constructive and destructive displacement wavefield phenomena in metallic pipes. Furthermore, since the amplitude of the received fundamental torsional wave signal strongly depends on frequency, a series of experiments are conducted to determine the frequency tuning curve for the torsional wave mode. All results indicate the linear d36 PMNT array has potential for efficiently generating uniform torsional wavefield of the fundamental torsional wave mode, which is more effective in monitoring structural health in metallic pipes. PMID:26548525

  9. Recent Developments and Applications of Quantum Well Infrared Photodetector Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.

    2000-01-01

    There are many applications that require long wavelength, large, uniform, reproducible, low cost, stable, and radiation-hard infrared (IR) focal plane arrays (FPAs). For example, the absorption lines of many gas molecules, such as ozone, water, carbon monoxide, carbon dioxide, and nitrous oxide occur in the wavelength region from 3 to 18 micron. Thus, IR imaging systems that operate in the long wavelength IR (LWIR) region (6 - 18 micron) are required in many space borne applications such as monitoring the global atmospheric temperature profiles, relative humidity profiles, cloud characteristics, and the distribution of minor constituents in the atmosphere which are being planned for future NASA Earth and planetary remote sensing systems. Due to higher radiation hardness, lower 1/f noise, and larger array size the GaAs based Quantum Well Infrared Photodetector (QWIP) FPAs are very attractive for such space borne applications compared to intrinsic narrow band gap detector arrays. In this presentation we will discuss the optimization of the detector design, material growth and processing that has culminated in realization of large format long-wavelength QWIP FPAs, portable and miniature LWIR cameras, holding forth great promise for myriad applications in 6-18 micron wavelength range in science, medicine, defense and industry. In addition, we will present some system demonstrations using broadband, two-color, and high quantum efficiency long-wavelength QWIP FPAs.

  10. A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics.

    PubMed

    Mazin, Benjamin A; Bumble, Bruce; Meeker, Seth R; O'Brien, Kieran; McHugh, Sean; Langman, Eric

    2012-01-16

    Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging. PMID:22274494

  11. Estimation of Thickness and Cadmium Composition Distributions in HgCdTe Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Mouzali, S.; Lefebvre, S.; Rommeluère, S.; Ferrec, Y.; Primot, J.

    2016-09-01

    Mercury cadmium telluride (HgCdTe) is one of the most commonly used material systems for infrared detection. The performance of infrared focal-plane arrays (IRFPAs) based on this material is limited by several noise sources. In this paper, we focus on the fixed pattern noise, which is related to disparities between the spectral responses of pixels. In our previous work, we showed that spectral nonuniformities in a HgCdTe IRFPA were caused by inhomogeneities of thickness and cadmium composition in the HgCdTe layer, using an optical description of the pixel structure. We propose to use this bidimensional dependence combined with experimental spectral responses to estimate disparities of thickness and cadmium composition in a specific HgCdTe-based IRFPA. The estimation methods and the resulting maps are presented, highlighting the accuracy of this nondestructive method.

  12. Estimation of Thickness and Cadmium Composition Distributions in HgCdTe Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Mouzali, S.; Lefebvre, S.; Rommeluère, S.; Ferrec, Y.; Primot, J.

    2016-05-01

    Mercury cadmium telluride (HgCdTe) is one of the most commonly used material systems for infrared detection. The performance of infrared focal-plane arrays (IRFPAs) based on this material is limited by several noise sources. In this paper, we focus on the fixed pattern noise, which is related to disparities between the spectral responses of pixels. In our previous work, we showed that spectral nonuniformities in a HgCdTe IRFPA were caused by inhomogeneities of thickness and cadmium composition in the HgCdTe layer, using an optical description of the pixel structure. We propose to use this bidimensional dependence combined with experimental spectral responses to estimate disparities of thickness and cadmium composition in a specific HgCdTe-based IRFPA. The estimation methods and the resulting maps are presented, highlighting the accuracy of this nondestructive method.

  13. A comparison of deghosting techniques in adaptive nonuniformity correction for IR focal-plane array systems

    NASA Astrophysics Data System (ADS)

    Rossi, Alessandro; Diani, Marco; Corsini, Giovanni

    2010-10-01

    Focal-plane array (FPA) IR systems are affected by fixed-pattern noise (FPN) which is caused by the nonuniformity of the responses of the detectors that compose the array. Due to the slow temporal drift of FPN, several scene-based nonuniformity correction (NUC) techniques have been developed that operate calibration during the acquisition only by means of the collected data. Unfortunately, such algorithms are affected by a collateral damaging problem: ghosting-like artifacts are generated by the edges in the scene and appear as a reverse image in the original position. In this paper, we compare the performance of representative methods for reducing ghosting. Such methods relate to the least mean square (LMS)-based NUC algorithm proposed by D.A. Scribner. In particular, attention is focused on a recently proposed technique which is based on the computation of the temporal statistics of the error signal in the aforementioned LMS-NUC algorithm. In this work, the performances of the deghosting techniques have been investigated by means of IR data corrupted with simulated nonuniformity noise over the detectors of the FPA. Finally, we have made some considerations on the computational aspect which is a challenging task for the employment of such techniques in real-time systems.

  14. InGaAs focal plane array developments and perspectives

    NASA Astrophysics Data System (ADS)

    Rouvié, A.; Coussement, Jérome; Huet, O.; Truffer, JP.; Pozzi, Maxime; Oubensaid, E. H.; Hamard, S.; Maillart, P.; Costard, E.

    2014-10-01

    Thanks to the various developments presently available, SWIR technology presents a growing interest and gives the opportunity to address a large spectrum of applications such as defense and security (night vision, active imaging), space (earth observation), transport (automotive safety) or industry (non destructive process control). InGaAs material, initially developed for telecommunications detectors, appears as a good candidate to satisfy SWIR detection needs. The lattice matching with InP constitutes a double advantage to this material: attractive production capacity and uncooled operation thanks to low dark current level induced by high quality material. In the context of this evolving domain, the InGaAs imagery activities from III-VLab were transferred to Sofradir, which provides a framework for the production activity with the manufacturing of high performances products: CACTUS320 and CACTUS640. The developments towards VGA format with 15μm pixel pitch, lead today to the industrialization of a new product: SNAKE SW. On one side, the InGaAs detection array presents high performances in terms of dark current and quantum efficiency. On the other side, the low noise ROIC has different additional functionalities. Then this 640x512 @ 15μm module appears as well suited to answer the needs of a wide range of applications. In this paper, we will present the Sofradir InGaAs technology, the performances of our last product SNAKE SW and the perspectives of InGaAs new developments.

  15. New developments on InGaAs focal plane array

    NASA Astrophysics Data System (ADS)

    Coussement, J.; Rouvié, A.; Oubensaid, E. H.; Huet, O.; Hamard, S.; Truffer, J.-P.; Pozzi, M.; Maillart, P.; Reibel, Y.; Costard, E.; Billon-Lanfrey, D.

    2014-06-01

    SWIR detection band benefits from natural (sun, night glow, thermal radiation) or artificial (eye safe lasers) photons sources combined to low atmospheric absorption and specific contrast compared to visible wavelengths. It gives the opportunity to address a large spectrum of applications such as defense and security (night vision, active imaging), space (earth observation), transport (automotive safety) or industry (non destructive process control). InGaAs material appears as a good candidate to satisfy SWIR detection needs. The lattice matching with InP constitutes a double advantage to this material: attractive production capacity and uncooled operation thanks to low dark current level induced by high quality material. The recent transfer of imagery activities from III-VLab to Sofradir provides a framework for the production activity with the manufacturing of high performances products: CACTUS320 SW and CACTUS640 SW. The developments, begun at III-Vlab towards VGA format with 15μm pixel pitch, lead today to the industrialization of a new product: SNAKE SW. On one side, the InGaAs detection array presents high performances in terms of dark current and quantum efficiency. On the other side, the low noise ROIC has different additional functionalities. Then this 640×512 @ 15μm module appears as well suited to answer the needs of a wide range of applications. In this paper, we will present the Sofradir InGaAs technology, some performances optimization and the last developments leading to SNAKE SW.

  16. Research in the modulation transfer function (MTF) measurement of InGaAs focal plane arrays

    NASA Astrophysics Data System (ADS)

    Xu, Zhonghua; Fang, Jiaxiong

    2012-10-01

    The Modulation Transfer Function (MTF) of an opto-electrical device is defined as the ratio of the system output modulation to the input modulation, which describes the performance of the imaging system in the Fourier domain. Accurate measurement of the MTF is often obtained by analyzing the high-quality image of a special target reproduced by the optical system with known MTF. To evaluate the MTF of short-wave infrared InGaAs focal plane arrays (FPAs), we develop a laboratory system with high precision and automation based on the slit scan method. An 8*1 linear InGaAs FPAs is then measured by this test set-up for the first time to evaluate the MTF of each pixel at room temperature. The results show a good MTF repeatability and uniformity of the 8*1 InGaAs FPAs. The relationship between the MTF and illumination is also discussed.

  17. Advanced planar LWIR and VLWIR HgCdTe focal plane arrays

    NASA Astrophysics Data System (ADS)

    Chu, Muren; Gurgenian, Ray H.; Mesropian, Shoghig; Terterian, Sevag; Becker, Latika; Walsh, D.; Kokoroski, S. A.; Goodnough, Mark A.; Rosner, Brett D.

    2004-01-01

    The advanced planar ion-implantation-isolated heterojunction process, which utilizes the benefits of both the boron implantation and the heterojunction epitaxy techniques, has been developed and used to produce longwave and very longwave HgCdTe focal plane arrays in the 320v256 format. The wavelength of these arrays ranges from 10.0-17.0μm. The operability of the longwave HgCdTe arrays is typically over 97%. Without anti-reflection coating and with a 60° FOV cold shield, the D* of the 10.0μm array is 9.4x1010cm x (Hz)1/2 x W-1 at 77K. The 14.7μm and 17.0μm very longwave HgCdTe array diodes have excellent reverse characteristics. The detailed characteristics of these arrays are presented.

  18. Performance of the QWIP focal plane arrays for NASA's Landsat Data Continuity Mission

    NASA Astrophysics Data System (ADS)

    Jhabvala, M.; Choi, K.; Waczynski, A.; La, A.; Sundaram, M.; Costard, E.; Jhabvala, C.; Kan, E.; Kahle, D.; Foltz, R.; Boehm, N.; Hickey, M.; Sun, J.; Adachi, T.; Costen, N.; Hess, L.; Facoetti, H.; Montanaro, M.

    2011-06-01

    The focal plane assembly for the Thermal Infrared Sensor (TIRS) instrument on NASA's Landsat Data Continuity Mission (LDCM) consists of three 512 x 640 GaAs Quantum Well Infrared Photodetector (QWIP) arrays. The three arrays are precisely mounted and aligned on a silicon carrier substrate to provide a continuous viewing swath of 1850 pixels in two spectral bands defined by filters placed in close proximity to the detector surfaces. The QWIP arrays are hybridized to Indigo ISC9803 readout integrated circuits (ROICs). QWIP arrays were evaluated from four laboratories; QmagiQ, (Nashua, NH), Army Research Laboratory, (Adelphi, MD), NASA/ Goddard Space Flight Center, (Greenbelt, MD) and Thales, (Palaiseau, France). All were found to be suitable. The final discriminating parameter was the spectral uniformity of individual pixels relative to each other. The performance of the QWIP arrays and the fully assembled, NASA flight-qualified, focal plane assembly will be reviewed. An overview of the focal plane assembly including the construction and test requirements of the focal plane will also be described.

  19. InGaAs focal plane array developments and perspectives

    NASA Astrophysics Data System (ADS)

    Rouvié, A.; Coussement, J.; Huet, O.; Truffer, J. P.; Pozzi, M.; Oubensaid, E. H.; Hamard, S.; Chaffraix, V.; Costard, E.

    2015-05-01

    SWIR spectral band is an attractive domain thanks to its intrinsic properties. Close to visible wavelengths, SWIR images interpretation is made easier for field actors. Besides complementary information can be extracted from SWIR band and bring significant added value in several fields of applications such as defense and security (night vision, active imaging), space (earth observation), transport (automotive safety) or industry (non destructive process control). Among the various new technologies able to detect SWIR wavelengths, InGaAs appears as a key technology. Initially developed for optical telecommunications, this material guaranties performances, stability and reliability and is compatible with attractive production capacity. Thanks to high quality material, very low dark current levels can be achieved at ambient temperature. Then uncooled operation can be set up, allowing compact and low power systems. Since the recent transfer of InGaAs imaging activities from III-Vlab, Sofradir provides a framework for the production activity with the manufacturing of high performances products: CACTUS320 SW. The developments towards VGA format with 15μm pixel pitch, lead today to the industrialization of a new product: SNAKE. On one side, the InGaAs detection array presents high performances in terms of dark current and quantum efficiency. On the other side, the low noise ROIC has different additional functionalities. Then this 640x512 @ 15μm sensor appears as well suited to answer the needs of a wide range of applications. In this paper, we will present the Sofradir InGaAs technology, the performances of our last product SNAKE and the perspectives of InGaAs new developments.

  20. Modeling of HgCdTe focal plane array spectral inhomogeneities

    NASA Astrophysics Data System (ADS)

    Mouzali, Salima; Lefebvre, Sidonie; Rommeluère, Sylvain; Ferrec, Yann; Primot, Jérôme

    2015-06-01

    Infrared focal plane arrays (IRFPA) are widely used to perform high quality measurements such as spectrum acquisition at high rate, ballistic missile defense, gas detection, and hyperspectral imaging. For these applications, the fixed pattern noise represents one of the major limiting factors of the array performance. This sensor imperfection refers to the nonuniformity between pixels, and is partially caused by disparities of the cut-off wavenumbers. In this work, we focus particularly on mercury cadmium telluride (HgCdTe), which is the most important material of IR cooled detector applications. Among the many advantages of this ternary alloy is the tunability of the bandgap energy with Cadmium composition, as well as the high quantum efficiency. In order to predict and understand spectral inhomogeneities of HgCdTe-based IRFPA, we propose a modeling approach based on the description of optical phenomena inside the pixels. The model considers the p-n junctions as a unique absorbent bulk layer, and derives the sensitivity of the global structure to both Cadmium composition and HgCdTe layer thickness. For this purpose, HgCdTe optical and material properties were necessary to be known at low temperature (80K), in our operating conditions. We therefore achieved the calculation of the real part of the refractive index using subtracti

  1. Quantum Well Infrared Photodetector (QWIP) Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Gunapala, S.; Bandara, S.

    1998-01-01

    Intrinsic infrared detectors in the long-wavelength range (6 - 20 ??are based on interband transition which promotes an electron across the band gap (E(sub g)) from the valence band to the conduction band.

  2. Long-Wavelength Infrared (LWIR) Quantum Dot Infrared Photodetector (QDIP) Focal Plane Array

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Bandara, S. V.; Liu, J. K.; Hill, C. J.; Rafol, S. B.; Mumolo, J. M.; Shott, C. A.

    2006-01-01

    We have exploited the artificial atomlike properties of epitaxially self-assembled quantum dots for the development of high operating temperature long wavelength infrared (LWIR) focal plane arrays. Quantum dots are nanometer-scale islands that form spontaneously on a semiconductor substrate due to lattice mismatch. QDIPs are expected to outperform quantum well infrared detectors (QWIPs) and are expected to offer significant advantages over II-VI material based focal plane arrays. QDIPs are fabricated using robust wide bandgap III-V materials which are well suited to the production of highly uniform LWIR arrays. We have used molecular beam epitaxy (MBE) technology to grow multi-layer LWIR quantum dot structures based on the InAs/InGaAs/GaAs material system. JPL is building on its significant QWIP experience and is basically building a Dot-in-the-Well (DWELL) device design by embedding InAs quantum dots in a QWIP structure. This hybrid quantum dot/quantum well device offers additional control in wavelength tuning via control of dot-size and/or quantum well sizes. In addition the quantum wells can trap electrons and aide in ground state refilling. Recent measurements have shown a 10 times higher photoconductive gain than the typical QWIP device, which indirectly confirms the lower relaxation rate of excited electrons (photon bottleneck) in QDPs. Subsequent material and device improvements have demonstrated an absorption quantum efficiency (QE) of approx. 3%. Dot-in-the-well (DWELL) QDIPs were also experimentally shown to absorb both 45 deg. and normally incident light. Thus we have employed a reflection grating structure to further enhance the quantum efficiency. JPL has demonstrated wavelength control by progressively growing material and fabricating devices structures that have continuously increased in LWIR response. The most recent devices exhibit peak responsivity out to 8.1 microns. Peak detectivity of the 8.1 micrometer devices has reached approx. 1 x 10(exp 10

  3. Mercury cadmium telluride short- and medium-wavelength infrared staring focal plane arrays

    NASA Technical Reports Server (NTRS)

    Vural, Kadri

    1987-01-01

    Short and medium IR wavelength 64 x 64 hybrid focal plane arrays (FPAs) have been developed using sapphire-grown HgCdTe. The short wavelength arrays were developed for a prototype airborne imaging spectrometer, while those of medium wavelength are suitable for tactical missile seekers and strategic surveillance systems. Attention is presently given to results obtained for these FPAs' current-voltage characteristics, as well as for their characterization at different temperatures. The detector arrays were also mated to a multiplexer and characterized under different operating conditions. The unit cell size used is 52 x 52 microns.

  4. Development of uncooled focal plane detector arrays for smart IR sensors

    NASA Astrophysics Data System (ADS)

    Liddiard, Kevin C.; Reinhold, Olaf; Ringh, Ulf; Jansson, Christer

    1997-11-01

    This paper reports on the development of silicon microbolometer uncooled IR focal plane detector arrays at the Defence Science and Technology Organization (DSTO), in collaboration with the National Defence Research Establishment (FOA). The detector arrays were designed by Electro-optic Sensor Design, which also provided specialist scientific advice on array fabrication. Detector arrays are prepared by monolithic processing at DSTO, using surface micromachining to achieve thermal isolation, and are integrated on-chip with a CMOS signal conditioning and readout microcircuit designed by FOA. The CMOS circuit incorporates 16-bit analog-to-digital conversion, and is described in more detail in an accompanying paper presented. The ultimate objective is to develop 'smart' focal plane arrays which have on-chip signal processing functions, giving a capability for decision making such as automatic target detection. The silicon microbolometer technology described in the paper was invented at DSTO, and is representative of core technology employed in many initiatives world-wide. A brief overview will be given of theoretical considerations which influence detector array design, followed by an outline of recent developments in array processing.

  5. Measurement of modulation transfer function of focal plane arrays and imaging systems

    NASA Astrophysics Data System (ADS)

    Boreman, Glenn D.

    1994-05-01

    A method for measuring the modulation transfer function (MTF) of focal-plane arrays (FPA's) has been developed which uses the statistical properties of laser speckle. The entire area of the focal plane is characterized, and no optics are required for target projection. The random nature of the test pattern avoids phasing effects between the target and the detector-array structure, which greatly relaxes alignment tolerances as compared to other methods. The technique is applicable to arrays that have intentional nonlinearity of response, as well as to those arrays that are inherently linear. The test can be performed on any focal-plane configuration, either one dimensional (1D) or two dimensional (2D). The data processing is usually performed by an off-line computer. However, the test is also useful for real-time diagnostics, to facilitate adjustment of focal-plane operating parameters. In the real-time case, the necessary signal processing can be performed on a digital oscilloscope.

  6. Chemical imaging of cotton fibers using an infrared microscope and a focal-plane array detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this presentation, the chemical imaging of cotton fibers with an infrared microscope and a Focal-Plane Array (FPA) detector will be discussed. Infrared spectroscopy can provide us with information on the structure and quality of cotton fibers. In addition, FPA detectors allow for simultaneous spe...

  7. Status of very long infrared-wave focal plane array development at DEFIR

    NASA Astrophysics Data System (ADS)

    Gravrand, O.; Chorier, Ph.

    2009-05-01

    The very long infrared wavelength (>14μm) is a very challenging range for the design of large HgCdTe focal plane arrays. As the wavelength gets longer (ie the semiconductor gap gets smaller), the physic of photodiodes asks for numerous technological improvements to keep a high level of detection performance. DEFIR (LETI-Sofradir common research team) has been highly active in this field during the last few years. The need (mainly expressed by the space industry ESA and CNES) of very long wave focal plane arrays appears very demanding in terms of dark current, defect density and of course quantum efficiency. This paper aims at presenting a status of long and very long wave focal plane array development at DEFIR for three different ion implanted technologies: n on p mercury vacancies doped technology, n on p extrinsic doped technology, and p on n arsenic on indium technology. Special focus is done to 15μm cut off n/p focal plane array fabricated in our laboratory demonstrating high uniformity, diffusion and shot noise limited photodiodes at 50K.

  8. Characterization of post-correction uniformity on infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    O'Neill, John J.; Costanzo, Christopher R.; Kaplan, David R.

    1995-05-01

    With increased requirements for better performance being placed on thermal imaging systems, new characterization figures of merit are being developed to assess infrared focal plane array (IRFPA) attributes. Post correction uniformity (PCU) is a parameter that determines how successfully a thermal imaging system can eliminate spatial noise from scanning and staring focal plane arrays. Requirements on PCU, particularly for the more sensitive IRFPAs and applications, are quite rigorous. Test issues of l/f noise, drift, and repeatability become critical and require a rethinking of accepted methods. As infrared sensors have become more sensitive, the need to characterize these focal plane arrays under more controlled and realistic test conditions has emerged. The U.S. Army Night Vision and Electronic SEnsors Directorate (NVESD) has attempted to address these issues by developing a unique capability to measure the PCU of IR focal plane arrays using software algorithms and a specialized mechanical modulator. The modulator is a two foot diameter, two toothed (one reflective and one emissive) blade, which is used to facilitate the real-time collection of test, gain, and offset flux levels. This paper addresses (1) the significance of PCU from a system perspective, (2) discuss the limitations of various PCU measurement techniques, (3) present the NVESD approach for measuring PCU, and (4) report PCU data collected using these techniques.

  9. Radiation-Induced Transient Effects in Near Infrared Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Pickel, J.; Marshall, P.; Waczynski, A.; McMurray, R.; Gee, G.; Polidan, E.; Johnson, S.; McKeivey, M.; Ennico, K.; Johnson, R.

    2004-01-01

    This viewgraph presentation describes a test simulate the transient effects of cosmic ray impacts on near infrared focal plane arrays. The objectives of the test are to: 1) Characterize proton single events as function of energy and angle of incidence; 2) Measure charge spread (crosstalk) to adjacent pixels; 3) Assess transient recovery time.

  10. A novel design of infrared focal plane array with digital read out interface

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoyang; Ding, Ruijun; Lu, Wei; Zhou, Chun

    2010-10-01

    Infrared focal plane array (IRFPA) with digital read out interface is a key sign of the third generation IRFPA, which plays an important role in the reliability and miniaturization of infrared systems. A readout integrated circuit (ROIC) of IRFPA with digital readout interface based on dual ramp single slope (DRSS) analog to digital converter (ADC) architecture is presented in the paper. The design is realized using shared ADCs in column-wise and these ADCs are consisted of simplified DRSS architecture and shared units. Sample, conversion and readout are proceeded simultaneously in order to adapt large scale and high readout frame rate application. This circuit also shows many advantages, including small area and low power consumption. Simulation result shows that this architecture can be expand to 320×256 pixel array with a frame rate of 100 frames per second or a larger size whit lower frame rate, the quantized resolution of this circuit is 12 bit, and the analog power consumption is only 17μw per ADC.

  11. Pixelated spectral filter for integrated focal plane array in the long-wave IR.

    SciTech Connect

    Kemme, Shanalyn A.; Cruz-Cabrera, Alvaro Augusto; Boye, Robert R.; Samora, Sally; Carter, Tony Ray; Briggs, Ronald D.

    2010-03-01

    We present the design, fabrication, and characterization of a pixelated, hyperspectral arrayed component for Focal Plane Array (FPA) integration in the Long-Wave IR. This device contains tens of pixels within a single super-pixel which is tiled across the extent of the FPA. Each spectral pixel maps to a single FPA pixel with a spectral FWHM of 200nm. With this arrayed approach, remote sensing data may be accumulated with a non-scanning, 'snapshot' imaging system. This technology is flexible with respect to individual pixel center wavelength and to pixel position within the array. Moreover, the entire pixel area has a single wavelength response, not the integrated linear response of a graded cavity thickness design. These requirements bar tilted, linear array technologies where the cavity length monotonically increases across the device.

  12. Dual-band technology on indium gallium arsenide focal plane arrays

    NASA Astrophysics Data System (ADS)

    Dixon, Peter; Hess, Cory D.; Li, Chuan; Ettenberg, Martin; Trezza, John

    2011-06-01

    While InGaAs-based SWIR imaging technology has been improved dramatically over the past 10 years, the motivation remains to reduce Size Weight and Power (SWaP) for applications in Intelligence Surveillance and Reconnaissance (ISR). Goodrich ISR Systems, Princeton (Sensors Unlimited, Inc.) has continued to improve detector sensitivity. Additionally, SUI is working jointly with DRS-RSTA to develop innovative techniques for manufacturing dual-band focal planes to provide next generation technology for not only reducing SWaP for SWIR imagers, but also to combine imaging solutions for providing a single imager for Visible Near-SWIR (VNS) + LW imaging solutions. Such developments are targeted at reducing system SWaP, cost and complexity for imaging payloads on board UASs as well as soldier deployed systems like weapon sights. Our motivation is to demonstrate capability in providing superior image quality in fused LWIR and SWIR imaging systems, while reducing the total system SWaP and cost by enabling Short Wave and Thermal imaging in a single uncooled imager. Under DARPA MTO awarded programs, a LW bolometer (DRS-RSTA) is fabricated on a Short Wave (SW) InGaAs Vis-SWIR (SUI-Goodrich) Imager. The combined imager is a dual-band Sensor-Chip Assembly which is capable of imaging in VIS-SWIR + LW. Both DRS and Goodrich have developed materials and process enhancements to support these dual-band platform investigations. The two imagers are confocal and coaxial with respect to the incident image plane. Initial work has completed a single Read Out Integrated Circuit (ROIC) capable of running both imagers. The team has hybridized InGaAs Focal planes to 6" full ROIC wafers to support bolometer fabrication onto the SW array.

  13. Focal plane resolution and overlapped array time delay and integrate imaging

    NASA Astrophysics Data System (ADS)

    Grycewicz, Thomas J.; Cota, Stephen A.; Lomheim, Terrence S.; Kalman, Linda S.

    2010-06-01

    In this paper we model sub-pixel image registration for a generic earth-observing satellite system with a focal plane using two offset time delay and integrate (TDI) arrays in the focal plane to improve the achievable ground resolution over the resolution achievable with a single array. The modeling process starts with a high-resolution image as ground truth. The Parameterized Image Chain Analysis & Simulation Software (PICASSO) modeling tool is used to degrade the images to match the optical transfer function, sampling, and noise characteristics of the target system. The model outputs a pair of images with a separation close to the nominal half-pixel separation between the overlapped arrays. A registration estimation algorithm is used to measure the offset for image reconstruction. The two images are aligned and summed on a grid with twice the capture resolution. We compare the resolution in images between the inputs before overlap, the reconstructed image, and a simulation for the image which would have been captured on a focal plane with twice the resolution. We find the performance to always be better than the lower resolution baseline, and to approach the performance of the high-resolution array in the ideal case. We show that the overlapped array imager significantly outperforms both the conventional high- and low-resolution imagers in conditions with high image smear.

  14. Type II superlattice infrared focal plane arrays: Optical, electrical, and mid-wave infrared imaging characterization.

    NASA Astrophysics Data System (ADS)

    Little, John; Svensson, Stefan; Goldberg, Arnie; Kennerly, Steve; Olver, Kim; Hongsmatip, Trirat; Winn, Michael; Uppal, Parvez

    2006-03-01

    We have studied the infrared optical and temperature dependent electrical properties of 320 x 256 arrays of GaSb/InAs type II superlattice infrared photodiodes. Good agreement between single-pixel and focal plane array measurements of the photon-to- electron/hole conversion efficiency was obtained, and the infrared absorption coefficient extracted from these measurements was found to be comparable to that of HgCdTe with the same bandgap as the type II superlattice. Temperature and voltage dependent dark current measurements and the voltage dependent photocurrent generated by a 300 K background scene were described well using a semi-empirical model of the photodiode. We will show high-quality images obtained from the mid-infrared focal plane array operating at 78 K.

  15. Large format focal plane array integration with precision alignment, metrology and accuracy capabilities

    NASA Astrophysics Data System (ADS)

    Neumann, Jay; Parlato, Russell; Tracy, Gregory; Randolph, Max

    2015-09-01

    Focal plane alignment for large format arrays and faster optical systems require enhanced precision methodology and stability over temperature. The increase in focal plane array size continues to drive the alignment capability. Depending on the optical system, the focal plane flatness of less than 25μm (.001") is required over transition temperatures from ambient to cooled operating temperatures. The focal plane flatness requirement must also be maintained in airborne or launch vibration environments. This paper addresses the challenge of the detector integration into the focal plane module and housing assemblies, the methodology to reduce error terms during integration and the evaluation of thermal effects. The driving factors influencing the alignment accuracy include: datum transfers, material effects over temperature, alignment stability over test, adjustment precision and traceability to NIST standard. The FPA module design and alignment methodology reduces the error terms by minimizing the measurement transfers to the housing. In the design, the proper material selection requires matched coefficient of expansion materials minimizes both the physical shift over temperature as well as lowering the stress induced into the detector. When required, the co-registration of focal planes and filters can achieve submicron relative positioning by applying precision equipment, interferometry and piezoelectric positioning stages. All measurements and characterizations maintain traceability to NIST standards. The metrology characterizes the equipment's accuracy, repeatability and precision of the measurements.

  16. Numerical analysis of InSb parameters and InSb 2D infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolei; Zhang, Hongfei; Sun, Weiguo; Zhang, Lei; Meng, Chao; Lu, Zhengxiong

    2012-10-01

    Accurate and reliable numerical simulation tools are necessary for the development of advanced semiconductor devices. InSb is using the MATLAB and TCAD simulation tool to calculatet the InSb body bandstructure, blackbody's radiant emittance and simultaneously solve the Poisson, Continuity and transport equations for 2D detector structures. In this work the material complexities of InSb, such as non-parabolicity, degenergcy, mobility and Auger recombination/generation are explained, and physics based models are developed. The Empirical Tight Binding Method (ETBM) was been using to calculate the bandstructure for InSb at 77 K by Matlab. We describe a set of systematic experiments performed in order to calibrate the simulation to semiconductor devices backside illuminated InSb focal plane arrays realized with planar technology. The spectral photoresponse and crosstalk characteristic for mid-wavelength InSb infrared focal plane arrays have been numerically studied.

  17. 256 x 256 hybrid HgCdTe infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Bailey, Robert B.; Kozlowski, Lester J.; Chen, Jenkon; Bui, Duc Q.; Vural, Kadri

    1991-05-01

    Hybrid HgCdTe 256 x 256 focal plane arrays have been developed to meet the sensitivity, resolution, and field-of-view requirements of high-performance medium-wavelength infrared (MWIR) imaging systems. The detector arrays for these hybrids are fabricated on substrates that reduce or eliminate the thermal expansion mismatch to the silicon readout circuit. The readouts are foundry-processed CMOS switched-FET circuits that have charge capacities greater than 107 electrons and a single video output capable of 10-MHz data rates. The high quantum efficiency, tunable absorption wavelength, and broad operating temperature range of these large HgCdTe staring focal plane arrays give them significant advantages over competing sensors. The mature Producible Alternative to CdTe for Epitaxy-1 (PACE-1) technology, using sapphire detector substrates, has demonstrated 256 x 256 MWIR arrays with mean laboratory noise equivalent temperature difference (NETO) of 9 mK for a 4.9-micron cutoff wavelength, 40-micron pixel size, and 80-K operating temperature. RMS detector response nonuniformities are less than 4 percent, and pixel yields are greater than 99 percent. The newly developed PACE-3 process uses silicon for the detector substrate to eliminate completely the thermal mismatch with the silicon readout circuit. It has the potential for similar performance in even larger array sizes. A 640 x 480 hybrid array is under development.

  18. Terahertz 3D printed diffractive lens matrices for field-effect transistor detector focal plane arrays.

    PubMed

    Szkudlarek, Krzesimir; Sypek, Maciej; Cywiński, Grzegorz; Suszek, Jarosław; Zagrajek, Przemysław; Feduniewicz-Żmuda, Anna; Yahniuk, Ivan; Yatsunenko, Sergey; Nowakowska-Siwińska, Anna; Coquillat, Dominique; But, Dmytro B; Rachoń, Martyna; Węgrzyńska, Karolina; Skierbiszewski, Czesław; Knap, Wojciech

    2016-09-01

    We present the concept, the fabrication processes and the experimental results for materials and optics that can be used for terahertz field-effect transistor detector focal plane arrays. More specifically, we propose 3D printed arrays of a new type - diffractive multi-zone lenses of which the performance is superior to that of previously used mono-zone diffractive or refractive elements and evaluate them with GaN/AlGaN field-effect transistor terahertz detectors. Experiments performed in the 300-GHz atmospheric window show that the lens arrays offer both a good efficiency and good uniformity, and may improve the signal-to-noise ratio of the terahertz field-effect transistor detectors by more than one order of magnitude. In practice, we tested 3 × 12 lens linear arrays with printed circuit board THz detector arrays used in postal security scanners and observed significant signal-to-noise improvements. Our results clearly show that the proposed technology provides a way to produce cost-effective, reproducible, flat optics for large-size field-effect transistor THz-detector focal plane arrays. PMID:27607620

  19. Collection of photogenerated charge carriers in small-pitched infrared photovoltaic focal plane arrays

    NASA Astrophysics Data System (ADS)

    Chekanova, Galina V.; Drugova, Albina A.; Kholodnov, Viacheslav; Nikitin, Mikhail S.

    2010-10-01

    Technology of infrared (IR) photovoltaic (PV) focal plane arrays (FPA) covering spectral range from 1.6 to 14 μm gradually moves from simple quasi-matrix (linear) arrays like as 4×288 pixels to large format high definition arrays 1280×1024 pixels and more. Major infrared detector materials for PV technology are InSb and its alloys and ternary alloys Hg1-xCdxTe. Progress in IR PV technology was provided in last decade by serious improvement in material growing techniques. Increasing of PV array format is related always to decreasing of pixel size and spacing between neighbor pixels to minimal size reasonable from point of view of infrared physics. So pitch is small (15-25 μm) in large format arrays. Ambipolar diffusion length of photogenerated charge carriers can exceed pitch many times in high quality absorption layers of PV arrays. It means that each pixel can collect excess charge carriers generated far from n+-p junction border. Optimization of resolution, filling factor and cross-talking level of small-pitched PV FPA requires comprehensive estimation of photodiode's (PD) pixel performance depending on pixel and array design, material properties and operating conditions. Objective of the present work was to develop general approach to estimate collection of photogenerated charge carriers in small-pitched arrays.

  20. Modulation Transfer Function Consequences of Planar Dense Array Geometries in Infrared Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Pinkie, Benjamin; Wichman, Adam R.; Bellotti, Enrico

    2015-09-01

    Finite-difference time-domain and finite element method simulations are used to evaluate two-dimensional spot-scan profiles of p-on- n double-layer planar heterostructure (DLPH) detector arrays with abrupt p-type diffusions. The modulation transfer function (MTF) is calculated from the spot-scan profiles. An asymmetric dark and photo current collection mechanism is identified and explained as a result of electric field bunching through the corners of polygonal diffusions in DLPH arrays. The MTF consequences of the asymmetric collection are studied for triangular, square, and hexagonal diffusions in square and hexagonal arrays. We show that the placement and shape of the diffusion relative to the pixel can modify the MTF by several percent. The magnitude of the effect is largest for diffusions with fewer degrees of rotational symmetry.

  1. Accounting for uncertainty in location when detecting point sources using infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Nichols, J. M.; Waterman, J. R.

    2016-07-01

    This work derives the modeling and detection theory required to predict the performance of an infrared focal plane array in detecting point source targets. Specifically, we focus on modeling the uncertainty associated with the location of the point source on the array. In the process we derive several new expressions related to pixel-averaged detection performance under a variety of problem assumptions. The resulting predictions are compared to standard approaches where the location is assumed fixed and known. It is further shown how to incorporate these predictions into multi-frame detection strategies.

  2. Self-correction of telescope surface errors using a correlating focal plane array

    NASA Astrophysics Data System (ADS)

    Cornwell, T. J.; Napier, P. J.

    The effects on the performance of a large radio telescope of aberrations such as reflector surface errors, defocussing, coma and pointing errors can be removed if the telesocpe is equipped with an array feed in its focal plane. If the cross correlations between all possible pairs of array elements are measured, then aberration-free images of radio sources can be obtained. Because of the great cost of building very precise large structures in space, in the future this concept may offer the possibility of a more economical design for a large, high frequency, space-born radio telescope.

  3. Object tracking based on bit-planes

    NASA Astrophysics Data System (ADS)

    Li, Na; Zhao, Xiangmo; Liu, Ying; Li, Daxiang; Wu, Shiqian; Zhao, Feng

    2016-01-01

    Visual object tracking is one of the most important components in computer vision. The main challenge for robust tracking is to handle illumination change, appearance modification, occlusion, motion blur, and pose variation. But in surveillance videos, factors such as low resolution, high levels of noise, and uneven illumination further increase the difficulty of tracking. To tackle this problem, an object tracking algorithm based on bit-planes is proposed. First, intensity and local binary pattern features represented by bit-planes are used to build two appearance models, respectively. Second, in the neighborhood of the estimated object location, a region that is most similar to the models is detected as the tracked object in the current frame. In the last step, the appearance models are updated with new tracking results in order to deal with environmental and object changes. Experimental results on several challenging video sequences demonstrate the superior performance of our tracker compared with six state-of-the-art tracking algorithms. Additionally, our tracker is more robust to low resolution, uneven illumination, and noisy video sequences.

  4. Two-color HgCdTe infrared staring focal plane arrays

    NASA Astrophysics Data System (ADS)

    Smith, Edward P.; Pham, Le T.; Venzor, Gregory M.; Norton, Elyse; Newton, Michael; Goetz, Paul; Randall, Valerie; Pierce, Gregory; Patten, Elizabeth A.; Coussa, Raymond A.; Kosai, Ken; Radford, William A.; Edwards, John; Johnson, Scott M.; Baur, Stefan T.; Roth, John A.; Nosho, Brett; Jensen, John E.; Longshore, Randolph E.

    2003-12-01

    Raytheon Vision Systems (RVS) in collaboration with HRL Laboratories is contributing to the maturation and manufacturing readiness of third-generation two-color HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256x256 30μm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) spectral regions. FPAs configured for MWIR/MWIR, MWIR/LWIR and LWIR/LWIR detection are used for target identification, signature recognition and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer-heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all two-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single mesa, single indium bump, and sequential mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.

  5. An improved retina-like nonuniformity correction for infrared focal-plane array

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Zhang, Zhi-jie; Wang, Chen-sheng

    2015-11-01

    The non-uniform response in infrared focal plane array (IRFPA) detectors produces corrupted images with nonuniformity noise. This paper mainly proposes an improved adaptive nonuniformity correction (NUC) method based on the retina-like neural network approach. The main purpose of NUC method is to obtain reliable estimations of gain and offset parameters. In this paper the two correction parameters are updated with two different learning rates respectively for the purpose of updating these two parameters synchronously. And then more accurate estimations of the two correction parameters can be obtained. Again, in order to reduce the ghost artifacts normally introduced by the strong edge effectively, the proposed algorithm employs the non-local means (NLM) method to estimate the desired target value of each detector. The proposed NUC method has been tested by applying it to the IR sequence of frames with simulated nonuniformity noise and real nonuniformity noise, respectively. The performance comparisons are implemented with the well-established scene-based NUC techniques. And the experimental results show the efficiency of the proposed method.

  6. Submillisecond measurements of system optical modulation functions in mosaic focal plane arrays

    NASA Technical Reports Server (NTRS)

    Thurlow, P. E.

    1981-01-01

    Measurements of system optical modulation functions (MTF, SWR) may be distorted by time-dependent environmental effects (thermal, vibration, flexure) and by electronics drift. Fast data collection may therefore be advantageous by minimizing drift time. The problem of fast data collection is accentuated when modulation data must be taken on a large number of detectors in a focal plane array. A method has been developed for the generation and storage of knife edge data from focal plane arrays, where data collection time per detector is in the submillisecond range. Once knife edge collects are completed, MTF response is found using conventional convolution techniques. SWR is obtained directly from knife edge response using a computerized simulation algorithm which bypasses use of MTF harmonics. Requirements for detector electronics speed, damping, and dynamic range are considered.

  7. InAs/GaSb superlattices for advanced infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Rehm, Robert; Walther, Martin; Schmitz, Johannes; Rutz, Frank; Fleißner, Joachim; Scheibner, Ralf; Ziegler, Johann

    2009-11-01

    We report on the development of high performance focal plane arrays for the mid-wavelength infrared spectral range from 3-5 μm (MWIR) on the basis of InAs/GaSb superlattice photodiodes. An investigation on the minority electron diffusion length with a set of six sample ranging from 190 to 1000 superlattice periods confirms that InAs/GaSb superlattice focal plane arrays achieve very high external quantum efficiency. This enabled the fabrication of a range of monospectral MWIR imagers with high spatial and excellent thermal resolution at short integration times. Furthermore, novel dual-color imagers have been developed, which offer advanced functionality due to a simultaneous, pixel-registered detection of two separate spectral channels in the MWIR.

  8. Modulation transfer function measurements of QWIP and superlattice focal plane arrays

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Ting, D. Z.; Rafol, S. B.; Soibel, A.; Khoshakhlagh, A.; Hill, C.; Liu, J. K.; Mumolo, J. M.; Keo, S. A.

    2013-01-01

    Modulation transfer function (MTF) is the ability of an imaging system to faithfully image a given object. The MTF of an imaging system quantifies the ability of the system to resolve or transfer spatial frequencies. In this presentation we will discuss the detail MTF measurements of 1024x1024 pixels multi-band quantum well infrared photodetector and 320x256 pixels long-wavelength InAs/GaSb superlattice infrared focal plane arrays.

  9. Focal Plane Array Shutter Mechanism of the JWST NIRSpec Detector System

    NASA Technical Reports Server (NTRS)

    Hale, Kathleen; Sharma, Rajeev

    2006-01-01

    This viewgraph presentation reviews the requirements, chamber location, shutter system design, stepper motor specifications, dry lubrication, control system, the environmental cryogenic function testing and the test results of the Focal Plane Array Shutter mechanism for the James Webb Space Telescope Near Infrared Spectrum Detector system. Included are design views of the location for the Shutter Mechanism, lubricant (lubricated with Molybdenum Di Sulfide) thickness, and information gained from the cryogenic testing.

  10. Vacuum packaging of InGaAs focal plane array with four-stage thermoelectric cooler

    NASA Astrophysics Data System (ADS)

    Mo, De-feng; Liu, Da-fu; Yang, Li-yi; Xu, Qin-fei; Li, Xue

    2013-09-01

    The InGaAs focal plane array (FPA) detectors, covering the near-infrared 1~2.4 μm wavelength range, have been developed for application in space-based spectroscopy of the Earth atmosphere. This paper shows an all-metal vacuum package design for area array InGaAs detector of 1024×64 pixels, and its architecture will be given. Four-stage thermoelectric cooler (TEC) is used to cool down the FPA chip. To acquire high heat dissipation for TEC's Joule-heat, tungsten copper (CuW80) and kovar (4J29) is used as motherboard and cavity material respectively which joined by brazing. The heat loss including conduction, convection and radiation is analyzed. Finite element model is established to analyze the temperature uniformity of the chip substrate which is made of aluminum nitride (AlN). The performance of The TEC with and without heat load in vacuum condition is tested. The results show that the heat load has little influence to current-voltage relationship of TEC. The temperature difference (ΔT) increases as the input current increases. A linear relationship exists between heat load and ΔT of the TEC. Theoretical analysis and calculation show that the heat loss of radiation and conduction is about 187 mW and 82 mW respectively. Considering the Joule-heat of readout circuit and the heat loss of radiation and conduction, the FPA for a 220 K operation at room temperature can be achieved. As the thickness of AlN chip substrate is thicker than 1 millimeter, the temperature difference can be less than 0.3 K.

  11. Microwave assisted magnetization reversal in cylindrical antidot arrays with in-plane and perpendicular anisotropy

    NASA Astrophysics Data System (ADS)

    Yumak, Mehmet; Ture, Kerim; Aktas, Gulen; Vega, Victor; Prida, Victor; Garcia, Carlos

    2012-02-01

    Porous anodic alumina is a particularly attractive self-ordered system used as template to fabricate nanostructures. The anodic film contains a self-ordered hexagonal array of parallel pores with tunable pore size and interpore distance, and whose pore locations can be templated. Deposition of magnetic films onto porous alumina leads to the formation of porous magnetic films, whose properties differ significantly from those of unpatterned films. The study of antidot arrays has both technological and fundamental importance. Although porous alumina films are typically synthesized in a planar geometry, in this work we deposited NiFe and Ti/CoCrPt magnetic films with in-plane and out-of-plane anisotropy onto cylindrical-geometry porous anodic alumina substrates to achieve cylindrical antidot arrays. The effect of both, the magnitude of the AC current and the circular magnetic field on the magnetization reversal has been studied for in-plane and perpendicular anisotropies. The level of reduction in the switching field was found to be dependent on the power, the frequency of the microwave pulses and the circular applied magnetic field. Such a reduction is associate with the competition between pumping and damping processes.

  12. Low power, highly linear output buffer. [for infrared focal plane arrays

    NASA Technical Reports Server (NTRS)

    Foley, D.; Butler, N.; Stobie, J.

    1992-01-01

    A class AB CMOS output buffer has been designed for use on an IR focal plane array. Given the requirements for power dissipation and load capacitance a class A output, such as a source follower, would be unsuitable. The approach taken uses a class AB amplifier configured as a charge integrator. Thus it converts a charge packet in the focal plane multiplexer to a voltage which is then the output of the focal plane. With a quiescent current of 18 micro-a and a load capacitance of 100 pf, the amplifier has an open loop unity gain bandwidth of 900 khz. Integral nonlinearity is better than .03 percent over 5.5 volts when run with VDD-VSS = 6v.

  13. [Research on the neas infrared focal plane array detector imaging technology used in the laser warning].

    PubMed

    Wang, Zhi-Bin; Huang, Yan-Fei; Wang, Yao-Li; Zhang, Rui; Wang, Yan-Chao

    2014-04-01

    In order to achieve the incoming laser's accurate position, it is necessary to improve the detected laser's direction resolution. The InGaAs focal plane array detector with the type of FPA-320 x 256-C was selected as the core component of the diffraction grating laser warning device. The detection theory of laser wavelength and direction based on diffraction grating was introduced. The drive circuit was designed through the analysis of the detector's performance and parameters. Under the FPGA' s timing control, the detector's analog output was sampled by the high-speed AD. The data was cached to FPGA's extended SRAM, and then transferred to a PC through USB. Labview on a PC collects the raw data for processing and displaying. The imaging experiments were completed with the above method. With the wavelength of 1550 nm and 980 nm laser from different directions the diffraction images were detected. Through analysis the location of the zero order and one order can be determined. According to the grating diffraction theory, the wavelength and the direction of the two-dimensional angle can be calculated. It indicates that the wavelength error is less than 10 nm, and the angle error is less than 1 degrees. PMID:25007645

  14. Absolute temperature measurements using a two-color QWIP focal plane array

    NASA Astrophysics Data System (ADS)

    Bundas, Jason; Dennis, Richard; Patnaude, Kelly; Burrows, Douglas; Faska, Ross; Sundaram, Mani; Reisinger, Axel; Manitakos, Dan

    2010-04-01

    The infrared photon flux emitted by an object depends not only on its temperature but also on a proportionality factor referred to as its emissivity. Since the latter parameter is usually not known quantitatively a priori, any temperature determination based on single-band radiometric measurements suffers from an inherent uncertainty. Recording photon fluxes in two separate spectral bands can in principle circumvent this limitation. The technique amounts to solving a system of two equations in two unknowns, namely, temperature and emissivity. The temperature derived in this manner can be considered absolute in the sense that it is independent of the emissivity, as long as that emissivity is the same in both bands. QmagiQ has previously developed a 320x256 midwave/longwave staring focal plane array which has been packaged into a dual-band laboratory camera. The camera in question constitutes a natural tool to generate simultaneous and independent emissivity maps and temperature maps of entire two-dimensional scenes, rather than at a single point on an object of interest. We describe a series of measurements we have performed on a variety of targets of different emissivities and temperatures. We examine various factors that affect the accuracy of the technique. They include the influence of the ambient radiation reflected off the target, which must be properly accounted for and subtracted from the collected signal in order to lead to the true target temperature. We also quantify the consequences of spectrally varying emissivities.

  15. Optical sensitivity non-uniformity analysis and optimization of a tilt optical readout focal plane array

    NASA Astrophysics Data System (ADS)

    Fu, Jianyu; Shang, Haiping; Shi, Haitao; Li, Zhigang; Ou, Yi; Chen, Dapeng; Zhang, Qingchuan

    2016-02-01

    An optical readout focal plane array (FPA) usually has a differently tilted reflector/absorber at the initial state due to the micromachining technique. The angular deviation of the reflector/absorber has a strong impact on the optical sensitivity non-uniformity, which is a key factor which affects the imaging uniformity. In this study, a theoretical analysis has been developed, and it is found that the stress matching in SiO2-Aluminum (Al) bilayer leg could make a contribution towards reducing the optical sensitivity non-uniformity. Ion implantation of phosphorus (P) has been utilized to control the stress in SiO2 film. By controlling the implantation energy and dose, the stress and stress stability are modified. The optical readout FPA has been successfully fabricated with the stress-control technique based on P+ implantation. It is demonstrated that the gray response non-uniformity of optical readout FPA has decreased from 25.69% to 10.7%.

  16. Solid-state image sensor with focal-plane digital photon-counting pixel array

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Pain, Bedabrata (Inventor)

    1995-01-01

    A photosensitive layer such as a-Si for a UV/visible wavelength band is provided for low light level imaging with at least a separate CMOS amplifier directly connected to each PIN photodetector diode to provide a focal-plane array of NxN pixels, and preferably a separate photon-counting CMOS circuit directly connected to each CMOS amplifier, although one row of counters may be time shared for reading out the photon flux rate of each diode in the array, together with a buffer memory for storing all rows of the NxN image frame before transfer to suitable storage. All CMOS circuitry is preferably fabricated in the same silicon layer as the PIN photodetector diode for a monolithic structure, but when the wavelength band of interest requires photosensitive material different from silicon, the focal-plane array may be fabricated separately on a different semiconductor layer bump-bonded or otherwise bonded for a virtually monolithic structure with one free terminal of each diode directly connected to the input terminal of its CMOS amplifier and digital counter for integration of the photon flux rate at each photodetector of the array.

  17. Producibility of Vertically Integrated Photodiode (VIP)tm scanning focal plane arrays

    NASA Astrophysics Data System (ADS)

    Turner, Arthur M.; Teherani, Towfik; Ehmke, John C.; Pettitt, Cindy; Conlon, Peggy; Beck, Jeffrey D.; McCormack, Kent; Colombo, Luigi; Lahutsky, Tom; Murphy, Terry; Williams, Robert L.

    1994-07-01

    Vertically integrated photodiode, VIPTM, technology is now being used to produce second generation infrared focal plane arrays with high yields and performance. The VIPTM process employs planar, ion implanted, n on p diodes in HgCdTe which is epoxy hybridized directly to the read out integrated circuits on 100 mm Si wafers. The process parameters that are critical for high performance and yield include: HgCdTe dislocation density and thickness, backside passivation, frontside passivation, and junction formation. Producibility of infrared focal plane arrays (IRFPAs) is also significantly enhanced by read out integrated circuits (ROICs) which have the ability to deselect defective pixels. Cold probe screening before lab dewar assembly reduces costs and improves cycle times. The 240 X 1 and 240 X 2 scanning array formats are used to demonstrate the effect of process optimization, deselect, and cold probe screening on yield and cycle time. The versatility of the VIPTM technology and its extension to large area arrays is demonstrated using 240/288 X 4 and 480 X 5 TDI formats. Finally, the high performance of VIPTM IRFPAs is demonstrated by comparing data from a 480 X 5 to the SADA-II specification.

  18. 58 X 62 InSb focal plane array for infrared astronomy

    NASA Astrophysics Data System (ADS)

    Orias, G.; Hoffman, A. W.; Casselman, M. F.

    1986-01-01

    Santa Barbara Research Center has developed a 58 x 62 staring mosaic focal plane array (FPA) consisting of an indium antimonide detector array hybridized to a silicon direct readout (DRO) multiplexer for use in IR astronomy. The detectors are sensitive to radiation from 1 to 5 microns. Each detector in the array is connected to the DRO via an indium bump contact and has its own high-impedance, low-capacitance buffer amplifier. The requirements of infrared astronomy include low dark-current and readout noise for near-BLIP performance and full-frame readout times from 32 ms to more than 20s. Both modeling and measurements of the FPA performance are presented. Results include responsivity, noise, NEP, linearity, and dark current.

  19. High-resolution digital readout for uncooled smart IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Ringh, Ulf; Jansson, Christer; Liddiard, Kevin C.; Reinhold, Olaf

    1997-11-01

    This paper discusses the development of a high resolution digital readout from a 2D array of uncooled IR detectors. The need for a high resolution analogue to digital converter (ADC) is described and anew concept is presented. Experimental VLSI arrays have been designed using 0.8 micrometers CMOS technology and the pixel size is 40 micrometers X 40 micrometers . The concept has been demonstrated by using 320 parallel 16 bit ADCs in a 320 X 240 readout array with a frame rate of 30 Hz. High linearity and low noise is obtained and the power consumption for each ADC is 0.5 mW. The high digital resolution allows for digital offset correction off the local plane. A 16 X 16 version of the readout circuit has been postprocessed with uncooled IR detectors. These are currently under evaluation.

  20. Dual-Color InAs/GaSb Superlattice Focal-Plane Array Technology

    NASA Astrophysics Data System (ADS)

    Rehm, Robert; Walther, Martin; Rutz, Frank; Schmitz, Johannes; Wörl, Andreas; Masur, Jan-Michael; Scheibner, Ralf; Wendler, Joachim; Ziegler, Johann

    2011-08-01

    Within a very few years, InAs/GaSb superlattice technology has proven its suitability for high-performance infrared imaging detector arrays. At the Fraunhofer Institute for Applied Solid State Physics (IAF) and AIM Infrarot-Module GmbH, efforts have been focused on developing mature fabrication technology for dual-color InAs/GaSb superlattice focal-plane arrays for simultaneous, colocated detection at 3 μm to 4 μm and 4 μm to 5 μm in the mid-wavelength infrared atmospheric transmission window. Integrated into a wide-field-of-view missile approach warning system for an airborne platform, a very low number of pixel outages and cluster defects is mandatory for bispectral detector arrays. Process refinements, intense root-cause analysis, and specific test methodologies employed at various stages during the process have proven to be the key for yield enhancements.

  1. Transport in arrays of submicron Josephson junctions over a ground plane

    SciTech Connect

    Ho, Teressa Rae

    1997-12-01

    One-dimensional (1D) and two-dimensional (2D) arrays of Al islands linked by submicron Al/Al{sub x}O{sub y}/Al tunnel junctions were fabricated on an insulating layer grown on a ground plane. The arrays were cooled to temperatures as low as 20 mK where the Josephson coupling energy E{sub J} of each junction and the charging energy E{sub C} of each island were much greater than the thermal energy k{sub B}T. The capacitance C{sub g} between each island and the ground plane was much greater than the junction capacitance C. Two classes of arrays were studied. In the first class, the normal state tunneling resistance of the junctions was much larger than the resistance quantum for single electrons, R{sub N}{much_gt} R{sub Q{sub e}}{identical_to} h/e{sup 2} {approx} 25.8 k{Omega}, and the islands were driven normal by an applied magnetic field such that E{sub J} = 0 and the array was in the Coulomb blockade regime. The arrays were made on degenerately-doped Si, thermally oxidized to a thickness of approximately 100 nm. The current-voltage (I - V) characteristics of a 1D and a 2D array were measured and found to display a threshold voltage V{sub T} below which little current flows. In the second class of arrays, the normal state tunneling resistance of the junctions was close to the resistance quantum for Cooper pairs, R{sub N}{approx}R{sub Q}{equivalent_to}h/4e{sup 4}{approx}6.45k{Omega}, such that E{sub J}/E{sub C}{approx}1. The arrays were made on GaAs/Al{sub 0.3}Ga{sub 0.7}As heterostructures with a two-dimensional electron gas approximately 100 nm below the surface. One array displayed superconducting behavior at low temperature. Two arrays displayed insulating behavior at low temperature, and the size of the Coulomb gap increased with increasing R{sub g}.

  2. Low-power 12-bit superconducting analog-to-digital converter for cryogenic focal plane array readouts

    NASA Astrophysics Data System (ADS)

    Rylov, Sergey V.; Robertazzi, R. P.

    1996-06-01

    Superconducting Analog-to-Digital Converters (ADCs) are attractive for use on cryogenic focal plane arrays because of their ultra-low power consumption and their ability to operate at cryogenic temperatures. We have developed a 12 bit ADC based on Nb thin film superconducting integrated circuit technology which dissipates less than 0.44 mW while in operation at 4.2 K. Extensions of this deign to lower junction critical currents would allow the production of an ADC which dissipates less than 0.1 mW when fully biased. The ADC had at least 9.75 effective bits of resolution for 20 kHz input signals, limited by the harmonic distortions of the signal source. We estimate that the ultimate resolution of this ADC can be greater than 20 bits at 10 MHz bandwidth with our current 2.5 micron fabrication process. Potential applications for this device include focal plane array read out electronics for low temperature (4.2 K and below) imaging arrays, such as those being used on the SIRTF mission being planned by NASA. Other applications include high precision instrumentation for metrology uses.

  3. Design trade-offs in ADC architectures dedicated to uncooled focal plane arrays

    NASA Astrophysics Data System (ADS)

    Robert, P.; Dupont, B.; Pochic, D.

    2008-04-01

    This paper presents two different architectures for the design of Analog to Digital Converters specifically adapted to infrared bolometric image sensors. Indeed, the increasing demand for integrated functions in uncooled readout circuits leads to on-chip ADC design as an interface between the internal analog core and the digital processing electronics. However specifying an on-chip ADC dedicated to focal plane array raises many questions about its architecture and its performance requirements. We will show that two architecture approaches are needed to cover the different sensor features in terms of array size and frame speed. A monolithic 14 bits ADC with a pipeline architecture, and a column 13 bits ADC with an original dual-ramp architecture, will be described. Finally, we will show measurement results to confirm the monolithic ADC is suitable for small array, as 160 x 120 with low frame speed, while a column ADC is more compliant for higher array, as 640 x 480 with a 60 Hz frame speed or 1024 x 768 arrays.

  4. Review of Concepts and Applications for Multispectral/Hyperspectral Focal Plane Array (FPA) Technology

    NASA Technical Reports Server (NTRS)

    McAdoo, James A.

    2001-01-01

    Multispectral, and ultimately hyperspectral, focal plane arrays (FPAs) represent the logical extension of two-color FPA technology, which has already shown its utility in military applications. Incorporating the spectral discrimination function directly in the FPA would offer the potential for orders-of-magnitude increase in remote sensor system performance. It would allow reduction or even elimination of optical components currently required to provide spectral discrimination in atmospheric remote sensors. The result would be smaller, simpler instruments with higher performance than exist today.

  5. Optimization of indium bump preparation in infrared focal plane array fabrication

    NASA Astrophysics Data System (ADS)

    Hou, Zhijin; Si, Junjie; Wang, Wei; Wang, Haizhen; Wang, Liwen

    2014-11-01

    Optimization of indium bump preparation in infrared focal plane array (IRFPA) fabrication is presented. Reasons of bringing defective pixels during conventional lift-off and cleanout process in fabrication of indium bump are discussed. IRFPAs are characterized by IRFPA test-bench. Results show that defective pixels of InSb IRFPA are owing to indium bumps connecting through indium residue on the surface of wafer. The characteristic and configuration of defective pixels of InSb IRFPA are given and analyzed. A method of reducing defective pixels through optimizing liftoff and cleanout process in InSb IRFPA is proposed. Results prove that this method is effective.

  6. Mid-wave infrared metasurface microlensed focal plane array for optical crosstalk suppression.

    PubMed

    Akın, Onur; Demir, Hilmi Volkan

    2015-10-19

    Spatial crosstalk is one of the fundamental drawbacks of diminishing pixel size in mid-wave infrared focal plane arrays (IR-FPAs). We proposed an IR-FPA using the concept of optical phase discontinuities for substantial optical crosstalk suppression. This IR-FPA consists of asymmetrically tailored V-shaped optical antennas. Full-wave simulations confirmed major improvements in narrowing the intensity distribution of incident light beam by over 30-folds and concentrating these distributions in the central pixel of IR-FPA by achieving optical crosstalks of <1%. PMID:26480363

  7. Quantum Well and Quantum Dot Modeling for Advanced Infrared Detectors and Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Ting, David; Gunapala, S. D.; Bandara, S. V.; Hill, C. J.

    2006-01-01

    This viewgraph presentation reviews the modeling of Quantum Well Infrared Detectors (QWIP) and Quantum Dot Infrared Detectors (QDIP) in the development of Focal Plane Arrays (FPA). The QWIP Detector being developed is a dual band detector. It is capable of running on two bands Long-Wave Infrared (LWIR) and Medium Wavelength Infrared (MWIR). The same large-format dual-band FPA technology can be applied to Quantum Dot Infrared Photodetector (QDIP) with no modification, once QDIP exceeds QWIP in single device performance. Details of the devices are reviewed.

  8. Analysis of characteristics of plane microwave antennas with a linearly expanding aperture for disk antenna arrays

    NASA Astrophysics Data System (ADS)

    Zayarnyi, V. P.; Parpula, A. A.; Girich, V. S.

    2014-11-01

    Mathematical models constructed for plane symmetric microwave antennas with a linearly expanding aperture make it possible to calculate the directional patterns depending on the aperture configuration. The directional patterns for analogous antennas operating in the range 5.9-12.5 GHz are measured experimentally; good agreement between the theoretical and experimental results is observed. The regularities in the influence of the aperture configuration of the antennas under investigation on the shape of the principal lobe of their directional patterns are established; these regularities are used for designing disk antenna arrays of circular and sector scan on their basis.

  9. Advanced III/V quantum-structure devices for high performance infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Rehm, Robert; Walther, Martin; Schmitz, Johannes; Rutz, Frank; Fleissner, Joachim; Scheibner, Ralf; Ziegler, Johann

    2009-09-01

    A mature production technology for Quantum Well Infrared Photodetector (QWIP) focal plane arrays (FPAs) and InAs/GaSb superlattice (SL) FPAs has been developed. Dual-band and dual-color QWIP- and SL-imagers are demonstrated for the 3-5 μm and 8-12 μm atmospheric windows in the infrared. The simultaneous, co-located detection of both spectral channels resolves the temporal and spatial registration problems common to existing bispectral IRimagers. The ability for a reliable remote detection of hot CO2 signatures makes tailored dual-color superlattice imagers ideally suited for missile warning systems for airborne platforms.

  10. Fiber optically coupled infrared focal plane array system for use in missile warning receiver applications

    NASA Astrophysics Data System (ADS)

    Daniels, Arnold; Liepmann, Till W.

    1999-07-01

    The location and installation of mid-infrared missile warning receiver sensors is limited by the mechanical constraints of the detector/dewar assembly and the associated cryogenic cooler assembly. The size, shape, and weight of these assemblies limit the installation alternatives, and prevent placing the missile warning receiver system in the optimum locations. Hence, their coverage and detection performance is limited. A micro-lens array coupled to a coherent fiber optic bundle and an infrared focal plane array were designed and experimentally implemented, to allow the mid-wave sensor and cryogenic devices to be located remotely from the receiver aperture. This eliminates the receiver aperture placement restrictions while easing the integration and maintenance of the sensor/dewar and cooler. Modulation transfer function and noise equivalent temperature difference measurements were performed to determine the performance of the imaging system.

  11. Strained-layer superlattice focal plane array having a planar structure

    DOEpatents

    Kim, Jin K.; Carroll, Malcolm S.; Gin, Aaron; Marsh, Phillip F.; Young, Erik W.; Cich, Michael J.

    2010-07-13

    An infrared focal plane array (FPA) is disclosed which utilizes a strained-layer superlattice (SLS) formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5 epitaxially grown on a GaSb substrate. The FPA avoids the use of a mesa structure to isolate each photodetector element and instead uses impurity-doped regions formed in or about each photodetector for electrical isolation. This results in a substantially-planar structure in which the SLS is unbroken across the entire width of a 2-D array of the photodetector elements which are capped with an epitaxially-grown passivation layer to reduce or eliminate surface recombination. The FPA has applications for use in the wavelength range of 3-25 .mu.m.

  12. Folded multiple-capture: an architecture for high dynamic range disturbance-tolerant focal plane array

    NASA Astrophysics Data System (ADS)

    Kavusi, Sam; El Gamal, Abbas

    2004-08-01

    Earlier studies have shown that multiple capture can achieve high SNR, but cannot satisfy the high dynamic range (HDR) and high speed requirements of the Vertically-Integrated-Sensor-Array (VISA) project. Synchronous self-reset, on the other hand, can achieve these requirements, but suffers from poor SNR. Extended counting can achieve high dynamic range at high frame rate and with good SNR, but at the expense of high power consumption. The paper proposes a new HDR focal plane array architecture, denoted by folded-multiple capture (FMC), which by combining features of the synchronous self-reset and multiple capture schemes, can satisfy the VISA requirements at a fraction of the power dissipation and with more robustness to device variations than extended counting. The architecture is also capable of detecting subframe disturbances, e.g., due to laser jamming, and correcting for it.

  13. Multiple detector focal plane array ultraviolet spectrometer for the AMPS laboratory

    NASA Technical Reports Server (NTRS)

    Feldman, P. D.

    1975-01-01

    The possibility of meeting the requirements of the amps spectroscopic instrumentation by using a multi-element focal plane detector array in a conventional spectrograph mount was examined. The requirements of the detector array were determined from the optical design of the spectrometer which in turn depends on the desired level of resolution and sensitivity required. The choice of available detectors and their associated electronics and controls was surveyed, bearing in mind that the data collection rate from this system is so great that on-board processing and reduction of data are absolutely essential. Finally, parallel developments in instrumentation for imaging in astronomy were examined, both in the ultraviolet (for the Large Space Telescope as well as other rocket and satellite programs) and in the visible, to determine what progress in that area can have direct bearing on atmospheric spectroscopy.

  14. Low dark current LWIR HgCdTe focal plane arrays at AIM

    NASA Astrophysics Data System (ADS)

    Haiml, M.; Eich, D.; Fick, W.; Figgemeier, H.; Hanna, S.; Mahlein, M.; Schirmacher, W.; Thöt, R.

    2016-05-01

    Cryogenically cooled HgCdTe (MCT) quantum detectors are unequalled for applications requiring high imaging as well as high radiometric performance in the infrared spectral range. Compared with other technologies, they provide several advantages, such as the highest quantum efficiency, lower power dissipation compared to photoconductive devices, and fast response times, hence outperforming micro-bolometer arrays. AIM will present its latest results on n-on-p as well as p-on-n low dark current planar MCT photodiode focal plane detector arrays at cut-off wavelengths >11 μm at 80 K. Dark current densities below the Rule'07 have been demonstrated for n-on-p devices. Slightly higher dark current densities and excellent cosmetics with very low cluster and point defect densities have been demonstrated for p-on-n devices.

  15. Coherent Optical Focal Plane Array Receiver for PPM Signals: Investigation and Applications

    NASA Technical Reports Server (NTRS)

    Fernandez, Michela Munoz

    2006-01-01

    The performance of a coherent optical focal plane array receiver for PPM signals under atmospheric turbulence is investigated and applications of this system are addressed. The experimental demonstration of this project has already been explained in previous publications [1]. This article shows a more exhaustive analysis of the expressions needed to obtain the Bit Error Rate (BER) for the real system under study in the laboratory. Selected experimental results of this system are described and compared with theoretical BER expressions, and array combining gains are presented. Receiver sensitivity in terms of photons per bit (PPB) is examined; BER results are shown as a function of signal to noise ratios, (SNR), as well as a function of photons per symbol, and photons per bit.

  16. Experimental characterization, evaluation, and diagnosis of advanced hybrid infrared focal plane array electro-optical performance

    NASA Astrophysics Data System (ADS)

    Lomheim, Terrence S.; Schumann, Lee W.; Kohn, Stanley E.

    1998-07-01

    High performance scanning time-delay-and-integration and staring hybrid focal plane devices with very large formats, small pixel sizes, formidable frame and line rates, on-chip digital programmability, and high dynamic ranges, are being developed for a myriad of defense, civil, and commercial applications that span the spectral range from shortwave infrared (SWIR) to longwave infrared (LWIR). An essential part in the development of such new advanced hybrid infrared focal planes is empirical validation of their electro-optical (EO) performance. Many high-reliability, high-performance applications demand stringent and near flawless EO performance over a wide variety of operating conditions and environments. Verification of focal plane performance compliance over this wide range of parametric conditions requires the development and use of accurate, flexible, and statistically complete test methods and associated equipment. In this paper we review typical focal plane requirements, the ensuing measurement requirements (quantity, accuracy, repeatability, etc.), test methodologies, test equipment requirements, electronics and computer-based data acquisition requirements, statistical data analysis and display requirements, and associated issues. We also discuss special test requirements for verifying the performance of panchromatic thermal and multispectral imaging focal planes where characterization of dynamic modulation transfer function (MTF), and point-image response and optical overload is generally required. We briefly overview focal plane radiation testing. We conclude with a discussion of the technical challenges of characterizing future advanced hybrid focal plane testing where it is anticipated that analog-to- digital conversion will be included directly on focal plane devices, thus creating the scenario of 'photons-in-to-bits- out' within the focal plane itself.

  17. Modeling and deformation analyzing of InSb focal plane arrays detector under thermal shock

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoling; Meng, Qingduan; Zhang, Liwen; Lv, Yanqiu

    2014-03-01

    A higher fracture probability appearing in indium antimonide (InSb) infrared focal plane arrays (IRFPAs) subjected to the thermal shock test, restricts its final yield. In light of the proposed equivalent method, where a 32 × 32 array is employed to replace the real 128 × 128 array, a three-dimensional modeling of InSb IRFPAs is developed to explore its deformation rules. To research the damage degree to the mechanical properties of InSb chip from the back surface thinning process, the elastic modulus of InSb chip along the normal direction is lessened. Simulation results show when the out-of-plane elastic modulus of InSb chip is set with 30% of its Young's modulus, the simulated Z-components of strain distribution agrees well with the top surface deformation features in 128 × 128 InSb IRFPAs fracture photographs, especially with the crack origination sites, the crack distribution and the global square checkerboard buckling pattern. Thus the Z-components of strain are selected to explore the deformation rules in the layered structure of InSb IRFPAs. Analyzing results show the top surface deformation of InSb IRFPAs originates from the thermal mismatch between the silicon readout integrated circuits (ROIC) and the intermediate layer above, made up of the alternating indium bump array and the reticular underfill. After passing through both the intermediate layer and the InSb chip, the deformation amplitude is reduced firstly from 2.23 μm to 0.24 μm, finally to 0.09 μm. Finally, von Mises stress criterion is employed to explain the causes that cracks always appear in the InSb chip.

  18. 320 x 256 Complementary Barrier Infrared Detector Focal Plane Array for Long-Wave Infrared Imaging

    NASA Technical Reports Server (NTRS)

    Nguyen, Jean; Rafol, Sir B.; Soibel, Alexander; Khoskhlagh, Arezou; Ting, David Z.-Y.; Liu, John K.; Mumolo, Jason M.; Gunapala, Sarath D.

    2012-01-01

    A 320 x 256 Complementary Barrier Infrared (CBIRD) focal plane array for long-wavelength infrared (LWIR) imaging is reported. The arrays were grown by molecular beam expitaxy (MBE) with a 300 period 1.9 um thick absorber. The mean dark current density of 2.2 x 10-4 A/cm2 was measured at an operating bias of 128 mV with a long wavelength cutoff of 8.8 ?m observed at 50% of the peak. The maximum quantum efficiency was 54% measured at 5.6 ?m. Operating at T = 80K, the array yielded an 81% fill factor with 97% operability. Good imagery with a mean noise equivalent different temperature (NE?T) of 18.6 mK and a mean detectivity of D* = 1.3 x 1011 cm-Hz1/2/W was achieved. The substrate was thinned using mechanical lapping and neither an AR coating nor a passivation layer was applied. This article provides the details of the fabrication process for achieving low-dark current LWIR CBIRD arrays. Discussion for an effective hard mask for excellent pattern transfer is given and appropriate mounting techniques for good thermal contact during the dry etching process is described. The challenges and differences between etching large 200 ?m test diodes and small 28 ?m FPA pixels are given.

  19. 320 x 256 complementary barrier infrared detector focal plane array for long-wave infrared imaging

    NASA Astrophysics Data System (ADS)

    Nguyen, Jean; Rafol, B., , Sir; Soibel, Alexander; Khoskhlagh, Arezou; Ting, David Z.-Y.; Liu, John K.; Mumolo, Jason M.; Gunapala, Sarath D.

    2012-06-01

    A 320 x 256 Complementary Barrier Infrared (CBIRD) focal plane array for long-wavelength infrared (LWIR) imaging is reported. The arrays were grown by molecular beam expitaxy (MBE) with a 300 period 1.9 um thick absorber. The mean dark current density of 2.2 x 10-4 A/cm2 was measured at an operating bias of 128 mV with a long wavelength cutoff of 8.8 μm observed at 50% of the peak. The maximum quantum efficiency was 54% measured at 5.6 μm. Operating at T = 80K, the array yielded an 81% fill factor with 97% operability. Good imagery with a mean noise equivalent different temperature (NE▵T) of 18.6 mK and a mean detectivity of D* = 1.3 x 1011 cm-Hz1/2/W was achieved. The substrate was thinned using mechanical lapping and neither an AR coating nor a passivation layer was applied. This article provides the details of the fabrication process for achieving low-dark current LWIR CBIRD arrays. Discussion for an effective hard mask for excellent pattern transfer is given and appropriate mounting techniques for good thermal contact during the dry etching process is described. The challenges and differences between etching large 200 μm test diodes and small 28 μm FPA pixels are given.

  20. Performance enhancement of uncooled infrared focal plane array by integrating metamaterial absorber

    SciTech Connect

    Ma, Wei; Wen, Yongzheng; Yu, Xiaomei

    2015-03-16

    This letter presents an infrared (IR) focal plane array (FPA) with metamaterial absorber (MMA) integrated to enhance its performance. A glass substrate, on which arrays of bimaterial cantilevers are fabricated as the thermal-sensitive pixels by a polyimide surface sacrificial process, is employed to allow the optical readout from the back side of the substrate. Whereas the IR wave radiates onto the FPA from the front side, which consequently avoids the energy loss caused by the silicon substrate compared with the previous works. This structure also facilitates the integration of MMA by introducing a layer of periodic square resonators atop the SiN{sub x} structural layer to form a metal/dielectric/metal stack with the gold mirror functioning as the ground plane. A comparative experiment was carried out on the FPAs that use MMA and ordinary SiN{sub x} as the absorbers, respectively. The performance improvement was verified by the evaluation of the absorbers as well as the imaging results of both FPAs.

  1. Infrared focal plane array producibility and related materials; Proceedings of the Meeting, Orlando, FL, Apr. 20, 21, 1992

    NASA Astrophysics Data System (ADS)

    Balcerak, Ray; Pellegrini, Paul W.; Scribner, Dean A.

    The present conference discusses the commercial diversification of the U.S. IR detector industry's commercial diversification, HgCdTe focal-plane array (FPAs) manufacture, LPE of (Hg,Cd)Te FPAs, uncooled IR FPA detector producibility, a high performance staring IR camera, and novel technologies for FPA dewars. Also discussed are hybridizing FPAs, cryoprober test development, HgCdTe on Si for monolithic focal plane arrays, popcorn noise in linear InGaAs detector arrays, and the use of narrowband laser speckle for MTF characterization of CCDs. (No individual items are abstracted in this volume)

  2. Optical MEMS-based arrays

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul B.

    2003-07-01

    Industrial Micro Electro Mechanical Systems (MEMS) developers are rapidly bringing to demonstration inertial radio frequency, and optical MEMS devices and components. The Army has a requirement for compact, highly reliable, and inexpensive laser beam steering components for missile seekers and unmanned aerial vehicles remote sensing components to provide a fast scanning capability for pointing, acquisition, tracking, and data communication. The coupling of this requirement with recent developments in the micro-optics area, has led scientists and engineers at the Army Aviation and Missile Command (AMCOM) to consider optical MEMS-based phased arrays, which have potential applications in the commercial industry as well as in the military, as a replacement for gimbals. Laser beam steering in commercial applications such as free space communicataion, scanning display, bar-code reading, and gimbaled seekers; require relatively large monolithic micro-mirrors to accomplish the required optical resolution. The Army will benefit from phased arrays composed of relatively small micro-mirrors that can be actuated through large deflection angles with substantially reduced volume times. The AMCOM Aviation and Missile Research, Development, and Engineering Center (AMRDEC) has initiated a research project to develop MEMS-based phased arrays for use in a small volume, inexpensive Laser Detection and Ranging (LADAR) seeker that is particularly attractive because of its ability to provide large field-of-regard and autonomous target acquisition for reconnaissance mission applications. The primary objective of the collaborative project with the Defence Advanced Research Projects Agency (DARPA) is to develop a rugged, MEMS-based phased arrays for incorporation into the 2-D scanner of a LADAR seeker. Design challenges and approach to achieving performance requirements will be discussed.

  3. Design and testing of an all-digital readout integrated circuit for infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Kelly, Michael; Berger, Robert; Colonero, Curtis; Gregg, Mark; Model, Joshua; Mooney, Daniel; Ringdahl, Eric

    2005-08-01

    The digital focal plane array (DFPA) project demonstrates the enabling technologies necessary to build readout integrated circuits for very large infrared focal plane arrays (IR FPAs). Large and fast FPAs are needed for a new class of spectrally diverse sensors. Because of the requirement for high-resolution (low noise) sampling, and because of the sample rate needed for rapid acquisition of high-resolution spectra, it is highly desirable to perform analog-to-digital (A/D) conversion right at the pixel level. A dedicated A/D converter located under every pixel in a one-million-plus element array, and all-digital readout integrated circuits will enable multi- and hyper-spectral imaging systems with unprecedented spatial and spectral resolution and wide area coverage. DFPAs provide similar benefits to standard IR imaging systems as well. We have addressed the key enabling technologies for realizing the DFPA architecture in this work. Our effort concentrated on demonstrating a 60-micron footprint, 14-bit A/D converter and 2.5 Gbps, 16:1 digital multiplexer, the most basic components of the sensor. The silicon test chip was fabricated in a 0.18-micron CMOS process, and was designed to operate with HgxCd1-xTe detectors at cryogenic temperatures. Two A/D designs, one using static logic and one using dynamic logic, were built and tested for performance and power dissipation. Structures for evaluating the bit-error-rate of the multiplexer on-chip and through a differential output driver were implemented for a complete performance assessment. A unique IC probe card with fixtures to mount into an evacuated, closed-cycle helium dewar were also designed for testing up to 2.5 Gbps at temperatures as low as 50 K.

  4. High-performance uncooled amorphous silicon video graphics array and extended graphics array infrared focal plane arrays with 17-μm pixel pitch

    NASA Astrophysics Data System (ADS)

    Tissot, Jean-Luc; Tinnes, Sébastien; Durand, Alain; Minassian, Christophe; Robert, Patrick; Vilain, Michel; Yon, Jean-Jacques

    2011-06-01

    The high level of accumulated expertise by ULIS and CEA/LETI on uncooled microbolometers made from amorphous silicon with 45, 35, and 25 μm enables ULIS to develop video graphics array (VGA) and extended graphics array (XGA) infrared focal plane array (IRFPA) formats with 17-μm pixel pitch to fulfill every application. These detectors keep all the recent innovations developed on the 25-μm pixel-pitch read out integrated circuit (ROIC) (detector configuration by serial link, low power consumption, and wide electrical dynamic range). The specific appeal of these units lies in the high spatial resolution it provides while keeping the small thermal time constant. The reduction of the pixel pitch turns the VGA array into a product well adapted for high-resolution and compact systems and the XGA a product well adapted for high-resolution imaging systems. High electro-optical performances have been demonstrated with noise equivalent temperature difference (NETD) < 50 mK. We insist on NETD and wide thermal dynamic range trade-off, and on the high characteristics uniformity achieved thanks to the mastering of the amorphous silicon technology as well as the ROIC design. This technology node paves the way to high-end products as well as low-end, compact, smaller formats, such as 320 × 240 and 160 × 120 or smaller.

  5. Demonstration of 1024x1024 pixel dual-band QWIP focal plane array

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Ting, D. Z.; Hill, C. J.; Nguyen, J.; Rafol, S. B.

    2010-04-01

    QWIPs are well known for their stability, high pixel-pixel uniformity and high pixel operability which are quintessential parameters for large area imaging arrays. In this paper we report the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP focal plane array (FPA). The dual-band QWIP device was developed by stacking two multi-quantum-well stacks tuned to absorb two different infrared wavelengths. The full width at half maximum (FWHM) of the mid-wave infrared (MWIR) band extends from 4.4 - 5.1 μm and FWHM of the long-wave infrared (LWIR) band extends from 7.8 - 8.8 μm. Dual-band QWIP detector arrays were hybridized with direct injection 30 μm pixel pitch megapixel dual-band simultaneously readable CMOS read out integrated circuits using the indium bump hybridization technique. The initial dual-band megapixel QWIP FPAs were cooled to 68K operating temperature. The preliminary data taken from the first megapixel QWIP FPA has shown system NE▵T of 27 and 40 mK for MWIR and LWIR bands respectively.

  6. Polymer films as planarization and sacrificial layers for uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Liu, Weiguo; Cai, Changlong; Zhou, Shun

    2010-10-01

    This paper presents a planarization procedure using polymer films to achieve a flat CMOS surface of Readout Integrated Circuit (ROIC) for the integration between uncooled infrared focal plane arrays and ROIC. At the same time, the polymer film is also used as the sacrificial layers. After amorphous Silicon (a-Si) film was deposited using plasma enhanced chemical vapor deposition (PECVD), and patterned using inductively coupled plasma (ICP), the polymer sacrificial layer should be removed to form a-Si self-supporting micro-bridge structure. So the thickness of polymer film determine the height of the micro-bridge; the soft curing temperature determines if the contact hole can be etched by developer during the first photolithography; and the rate of dry etching determines whether the sacrificial layers of the structure can be released successfully. In this paper, the curing temperature, surface roughness, etching process of polymer films are systematically researched. On this basis, polymer film as planarization successfully reduces the 2μm height of the bumps on ROIC to less than 83 nm, over the planarized polymer mesas, bolometer arrays are fabricated. Then the polymer film as sacrificial are removed by ICP and 160x120 self-supporting micro-bridge structure arrays are successfully fabricated.

  7. Polymer films as planarization and sacrificial layers for uncooled infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Liu, Weiguo; Cai, Changlong; Zhou, Shun

    2011-02-01

    This paper presents a planarization procedure using polymer films to achieve a flat CMOS surface of Readout Integrated Circuit (ROIC) for the integration between uncooled infrared focal plane arrays and ROIC. At the same time, the polymer film is also used as the sacrificial layers. After amorphous Silicon (a-Si) film was deposited using plasma enhanced chemical vapor deposition (PECVD), and patterned using inductively coupled plasma (ICP), the polymer sacrificial layer should be removed to form a-Si self-supporting micro-bridge structure. So the thickness of polymer film determine the height of the micro-bridge; the soft curing temperature determines if the contact hole can be etched by developer during the first photolithography; and the rate of dry etching determines whether the sacrificial layers of the structure can be released successfully. In this paper, the curing temperature, surface roughness, etching process of polymer films are systematically researched. On this basis, polymer film as planarization successfully reduces the 2μm height of the bumps on ROIC to less than 83 nm, over the planarized polymer mesas, bolometer arrays are fabricated. Then the polymer film as sacrificial are removed by ICP and 160x120 self-supporting micro-bridge structure arrays are successfully fabricated.

  8. CMOS focal-plane-array for analysis of enzymatic reaction in system-on-chip spectrophotometer

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Ha, Chanki; Park, Chan B.; Joo, Youngjoong

    2004-06-01

    A CMOS focal-plane-array is designed for the high-throughput analysis of enzymatic reaction in on-chip spectrophotometer system. One of potential applications of the presented prototype system is to perform enzymatic analysis of biocompounds contained in blood. This function normally requires an expensive diode-array spectrophotometer, but it is possible to perform high throughput analysis with low budget if the spectrophotometer system is scaled down to a chip. The CMOS active pixel sensor array can cover a layer of polydimethylsiloxane (PDMS) forming the microfluidic channels and the substrate solution for enzymatic reaction can be injected into the channels by capillary force. Under room light, the underneath CMOS active pixel sensor with 40 x 40 pixels detect the gray levels of the fluid"s color. Inside the image sensor chip (size: 3mm x 3mm), the pixels of the same column share the same sample and hold circuits. The analog signals from 40 columns are multiplexed into one input feeding an on-chip 8 bits dual-slope analog to digital converter. The color change can be displayed on the external monitor by using a data acquisition card and personal computer.

  9. Performance bounds for passive sensor arrays operating in a turbulent medium: Plane-wave analysis

    NASA Astrophysics Data System (ADS)

    Collier, S. L.; Wilson, D. K.

    2003-05-01

    The performance bounds of a passive acoustic array operating in a turbulent medium with fluctuations described by a von Kármán spectrum are investigated. This treatment considers a single, monochromatic, plane-wave source at near-normal incidence. A line-of-sight propagation path is assumed. The primary interests are in calculating the Cramer-Rao lower bounds of the azimuthal and elevational angles of arrival and in observing how these bounds change with the introduction of additional unknowns, such as the propagation distance, turbulence parameters, and signal-to-noise ratio. In both two and three dimensions, it is found that for large values of the index-of-refraction variance, the Cramer-Rao lower bounds of the angles of arrival increase significantly at large values of the normalized propagation distance. For small values of the index-of-refraction variance and normalized propagation distance, the signal-to-noise ratio is found to be the limiting factor. In the two-dimensional treatment, it is found that the estimate of the angle of arrival will decouple from the estimates of the other parameters with the appropriate choice of array geometry. In three dimensions, again with an appropriate choice of array geometry, the estimates of the azimuth and elevation will decouple from the estimates of the other parameters, but due to the constraints of the model, will remain coupled to one another.

  10. Performance bounds for passive sensor arrays operating in a turbulent medium: plane-wave analysis.

    PubMed

    Collier, S L; Wilson, D K

    2003-05-01

    The performance bounds of a passive acoustic array operating in a turbulent medium with fluctuations described by a von Kármán spectrum are investigated. This treatment considers a single, monochromatic, plane-wave source at near-normal incidence. A line-of-sight propagation path is assumed. The primary interests are in calculating the Cramer-Rao lower bounds of the azimuthal and elevational angles of arrival and in observing how these bounds change with the introduction of additional unknowns, such as the propagation distance, turbulence parameters, and signal-to-noise ratio. In both two and three dimensions, it is found that for large values of the index-of-refraction variance, the Cramer-Rao lower bounds of the angles of arrival increase significantly at large values of the normalized propagation distance. For small values of the index-of-refraction variance and normalized propagation distance, the signal-to-noise ratio is found to be the limiting factor. In the two-dimensional treatment, it is found that the estimate of the angle of arrival will decouple from the estimates of the other parameters with the appropriate choice of array geometry. In three dimensions, again with an appropriate choice of array geometry, the estimates of the azimuth and elevation will decouple from the estimates of the other parameters, but due to the constraints of the model, will remain coupled to one another. PMID:12765389

  11. Progress in development of H4RG-10 infrared focal plane arrays for WFIRST-AFTA

    NASA Astrophysics Data System (ADS)

    Piquette, Eric C.; McLevige, William; Auyeung, John; Wong, Andre

    2014-07-01

    We describe progress in the development and demonstration of Teledyne's new high resolution large format FPA for astronomy, the H4RG-10 IR. The H4RG-10 is the latest in Teledyne's H×RG line of sensors, in a 4096×4096 format using 10 micron pixels. It is offered as a hybrid sensor using either a silicon p-i-n detector array (HyViSI) or a HgCdTe photodiode array with standard infrared cutoff wavelength of 1.75μm, 2.5μm, or 5.3μm (with custom cutoff wavelengths also available). The HgCdTe sensor arrays are fully substrate removed to provide high quantum efficiency, response to visible wavelengths, and minimize cosmic ray and fringing mitigation. Packaging using either CE6 or SiC bases is available. Teledyne is currently fabricating H4RG-10 SWIR FPAs for NASA's WFIRST space telescope instrument. Initial array performance has been tested and will be presented. Key results include the demonstration of low dark current (array mean dark current of <0.01e-/s/pixel at 100K), low noise (<10 e-/CDS read noise), and high array operability (>99% pixels). The paper discusses the sensor configuration and features, the performance achieved to date including QE, dark current, noise maps and histograms, and the remaining challenges.

  12. Coaxial Dual-wavelength Interferometric Method for a Thermal Infrared Focal-plane-array with Integrated Gratings.

    PubMed

    Shang, Yuanfang; Ye, Xiongying; Cao, Liangcai; Song, Pengfei; Feng, Jinyang

    2016-01-01

    Uncooled infrared (IR) focal-plane-array (FPA) with both large sensing range and high sensitivity is a great challenge due to the limited dynamic range of the detected signals. A coaxial dual-wavelength interferometric system was proposed here to detect thermal-induced displacements of an ultrasensitive FPA based on polyvinyl-chloride(PVC)/gold bimorph cantilevers and carbon nanotube (CNT)-based IR absorbing films. By alternately selecting the two displacement measurements performed by λ1 (=640 nm) and λ2 (=660 nm), the temperature measuring range with greater than 50% maximum sensitivity can be extended by eight-fold in comparison with the traditional single-wavelength mode. Meanwhile, the relative measurement error over the full measuring range is below 0.4%. In addition, it offers a feasible approach for on-line and on-wafer FPA characterization with great convenience and high efficiency. PMID:27193803

  13. Coaxial Dual-wavelength Interferometric Method for a Thermal Infrared Focal-plane-array with Integrated Gratings

    NASA Astrophysics Data System (ADS)

    Shang, Yuanfang; Ye, Xiongying; Cao, Liangcai; Song, Pengfei; Feng, Jinyang

    2016-05-01

    Uncooled infrared (IR) focal-plane-array (FPA) with both large sensing range and high sensitivity is a great challenge due to the limited dynamic range of the detected signals. A coaxial dual-wavelength interferometric system was proposed here to detect thermal-induced displacements of an ultrasensitive FPA based on polyvinyl-chloride(PVC)/gold bimorph cantilevers and carbon nanotube (CNT)-based IR absorbing films. By alternately selecting the two displacement measurements performed by λ1 (=640 nm) and λ2 (=660 nm), the temperature measuring range with greater than 50% maximum sensitivity can be extended by eight-fold in comparison with the traditional single-wavelength mode. Meanwhile, the relative measurement error over the full measuring range is below 0.4%. In addition, it offers a feasible approach for on-line and on-wafer FPA characterization with great convenience and high efficiency.

  14. Coaxial Dual-wavelength Interferometric Method for a Thermal Infrared Focal-plane-array with Integrated Gratings

    PubMed Central

    Shang, Yuanfang; Ye, Xiongying; Cao, Liangcai; Song, Pengfei; Feng, Jinyang

    2016-01-01

    Uncooled infrared (IR) focal-plane-array (FPA) with both large sensing range and high sensitivity is a great challenge due to the limited dynamic range of the detected signals. A coaxial dual-wavelength interferometric system was proposed here to detect thermal-induced displacements of an ultrasensitive FPA based on polyvinyl-chloride(PVC)/gold bimorph cantilevers and carbon nanotube (CNT)-based IR absorbing films. By alternately selecting the two displacement measurements performed by λ1 (=640 nm) and λ2 (=660 nm), the temperature measuring range with greater than 50% maximum sensitivity can be extended by eight-fold in comparison with the traditional single-wavelength mode. Meanwhile, the relative measurement error over the full measuring range is below 0.4%. In addition, it offers a feasible approach for on-line and on-wafer FPA characterization with great convenience and high efficiency. PMID:27193803

  15. Analysis and simulation of a new kind of noise at the input stage of infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Huang, Zhangcheng; Chen, Yu; Huang, Songlei; Fang, Jiaxiong

    2014-05-01

    Noise is a primary characteristic of an infrared focal plane array (FPA) that contributes to detection performance at low light level. In a capacitive-feedback trans-impedance amplifier (CTIA)-based readout integrated circuit (ROIC), reset noise can be removed by correlated double sampling (CDS). There is an exotic experimental phenomenon that FPA noise will increase greatly if the first sampling time of CDS is less than a threshold value. A noise model at FPA interface is presented in this paper which explains that this new kind of noise originates from incompletely settling of CTIA preamplifier. As this noise is performed in time domains, we use transient noise simulation technique to describe the dependence of this noise on detector pixel capacitance, integration capacitor, and some other design parameters. Based on the theoretical model analysis and simulation results, effective design method is obtained to reduce this kind of noise.

  16. A substrate-free optical readout focal plane array with a heat sink structure

    NASA Astrophysics Data System (ADS)

    Rmwen, Liu; Yanmei, Kong; Binbin, Jiao; Zhigang, Li; Haiping, Shang; Dike, Lu; Chaoqun, Gao; Dapeng, Chen; Qingchuan, Zhang

    2013-02-01

    A substrate-free optical readout focal plane array (FPA) operating in 8-12 μm with a heat sink structure (HSS) was fabricated and its performance was tested. The temperature distribution of the FPA with an HSS investigated by using a commercial FLIR IR camera shows excellent uniformity. The thermal cross-talk effect existing in traditional substrate-free FPAs was eliminated effectively. The heat sink is fabricated successfully by electroplating copper, which provides high thermal capacity and high thermal conductivity, on the frame of substrate-free FPA. The FPA was tested in the optical-readout system, the results show that the response and NETD are 13.6 grey/K (F / # = 0.8) and 588 mK, respectively.

  17. A micropillar array for sample concentration via in-plane evaporation

    PubMed Central

    Choi, Jae-Woo; Hosseini Hashemi, Seyyed Mohammad; Erickson, David; Psaltis, Demetri

    2014-01-01

    We present a method to perform sample concentration within a lab-on-a-chip using a microfluidic structure which controls the liquid-gas interface through a micropillar array fabricated in polydimethylsiloxane between microfluidic channels. The microstructure confines the liquid flow and a thermal gradient is used to drive evaporation at the liquid-gas-interface. The evaporation occurs in-plane to the microfluidic device, allowing for precise control of the ambient environment. This method is demonstrated with a sample containing 1 μm, 100 nm fluorescent beads and SYTO-9 labelled Escherichia coli bacteria. Over 100 s, the fluorescent beads and bacteria are concentrated by a factor of 10. PMID:25379093

  18. Measurement of optical modulation functions in sparsely sampled mosaic focal plane arrays

    NASA Technical Reports Server (NTRS)

    Young, J. B.; Thurlow, P. E.

    1982-01-01

    It is pointed out that the measurement of optical modulation functions for detectors in focal plane arrays may be somewhat more difficult under 'full-up' systems conditions as compared to ideal laboratory conditions. An idealized optical modulation test arrangement is considered along with a full-up scanned system involving an earth mapper in polar orbit. In testing the system in full-up condition, a problem arises with respect to the acquisition of knife edge response data. In order to overcome this problem, a preferred method is developed for obtaining KER data on a single scan. A special 'phased edge' reticle is developed for use in the test set-up. Attention is given to aspects of knife edge reconstruction.

  19. Visualization of Subsurface Defects in Composites using a Focal Plane Array Infrared Camera

    NASA Technical Reports Server (NTRS)

    Plotnikov, Yuri A.; Winfree, William P.

    1999-01-01

    A technique for enhanced defect visualization in composites via transient thermography is presented in this paper. The effort targets automated defect map construction for multiple defects located in the observed area. Experimental data were collected on composite panels of different thickness with square inclusions and flat bottom holes of different depth and orientation. The time evolution of the thermal response and spatial thermal profiles are analyzed. The pattern generated by carbon fibers and the vignetting effect of the focal plane array camera make defect visualization difficult. An improvement of the defect visibility is made by the pulse phase technique and the spatial background treatment. The relationship between a size of a defect and its reconstructed image is analyzed as well. The image processing technique for noise reduction is discussed.

  20. Time resolved photo-luminescent decay characterization of mercury cadmium telluride focal plane arrays

    DOE PAGESBeta

    Soehnel, Grant

    2015-01-20

    The minority carrier lifetime is a measurable material property that is an indication of infrared detector device performance. To study the utility of measuring the carrier lifetime, an experiment has been constructed that can time resolve the photo-luminescent decay of a detector or wafer sample housed inside a liquid nitrogen cooled Dewar. Motorized stages allow the measurement to be scanned over the sample surface, and spatial resolutions as low as 50µm have been demonstrated. A carrier recombination simulation was developed to analyze the experimental data. Results from measurements performed on 4 mercury cadmium telluride focal plane arrays show strong correlationmore » between spatial maps of the lifetime, dark current, and relative response.« less

  1. The study of selective heating of indium bump in MCT infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Zhang, Haiyan; Cao, Lan; Zhuang, Fulong; Hu, Xiaoning; Gong, Haimei

    2012-10-01

    Generally the electrical interconnectivity between The Mercury Cadmium Telluride (MCT) infrared focal plane array (IRFPA) device and circuit takes the flip chip technology using indium bump as a connection medium. In order to improve the reliability of the interconnectivity indium melting is a common packaging technique at present. This technique is called reflow soldering. The heating is transferred to the indium bump by heating the device and circuit. This heating process will persist about 10 minutes resulting in the MCT material going through a 10 minutes high temperature baking course. This baking process will strongly degenerate the characteristic of the MCT device. Under this circumstance this article gives a new heating technique for indium bump which is call induction heating melting technique. This method realizes the selective heating. While the indium bump is melted by the conduction heating the semiconductor material such as MCT can't be heated.

  2. Methodology for testing infrared focal plane arrays in simulated nuclear radiation environments

    NASA Astrophysics Data System (ADS)

    Divita, E. L.; Mills, R. E.; Koch, T. L.; Gordon, M. J.; Wilcox, R. A.; Williams, R. E.

    1992-07-01

    This paper summarizes test methodology for focal plane array (FPA) testing that can be used for benign (clear) and radiation environments, and describes the use of custom dewars and integrated test equipment in an example environment. The test methodology, consistent with American Society for Testing Materials (ASTM) standards, is presented for the total accumulated gamma dose, transient dose rate, gamma flux, and neutron fluence environments. The merits and limitations of using Cobalt 60 for gamma environment simulations and of using various fast-neutron reactors and neutron sources for neutron simulations are presented. Test result examples are presented to demonstrate test data acquisition and FPA parameter performance under different measurement conditions and environmental simulations.

  3. Fabrication of resonator-quantum well infrared photodetector focal plane array by inductively coupled plasma etching

    NASA Astrophysics Data System (ADS)

    Sun, Jason; Choi, Kwong-Kit

    2016-02-01

    Inductively coupled plasma (ICP) etching has distinct advantages over reactive ion etching in that the etching rates are considerably higher, the uniformity is much better, and the sidewalls of the etched material are highly anisotropic due to the higher plasma density and lower operating pressure. Therefore, ICP etching is a promising process for pattern transfer required during microelectronic and optoelectronic fabrication. Resonator-quantum well infrared photodetectors (R-QWIPs) are the next generation of QWIP detectors that use resonances to increase the quantum efficiency (QE). To fabricate R-QWIP focal plane arrays (FPAs), two optimized ICP etching processes are developed. Using these etching techniques, we have fabricated R-QWIP FPAs of several different formats and pixel sizes with the required dimensions and completely removed the substrates of the FPAs. Their QE spectra were tested to be 30 to 40%. The operability and spectral nonuniformity of the FPA is ˜99.5 and 3%, respectively.

  4. Characterization of an advanced focal plane for multispectral linear array (MLA) application

    NASA Technical Reports Server (NTRS)

    King, P.; Botts, S.; Orias, G.; Yang, H. B.

    1984-01-01

    It is pointed out that the MLA instrument represents the next generation in the Landsat series of earth resources satellites. The MLA sensor concept utilizes a pushbroom scan mode to eliminate electromechanical scan mirrors, and the lower reliabililty and higher power dissipation which accompany their employment. The pushbroom scanner makes use of a linear array which consists generally of thousands of detectors oriented perpendicular to the along-track direction of the satellite. Test techniques have been developed for the measurement of the module parameters which are critical to MLA focal plane performance. These measurements include the determination of infrared responsivity, linearity over the dynamic range, temporal noise, and fixed pattern effects on each detector element of each module tested. Tests related to spectral response, crosstalk, and spot scan profiles are also conducted. A description is provided of the test equipment involved.

  5. Time resolved photo-luminescent decay characterization of mercury cadmium telluride focal plane arrays

    SciTech Connect

    Soehnel, Grant

    2015-01-20

    The minority carrier lifetime is a measurable material property that is an indication of infrared detector device performance. To study the utility of measuring the carrier lifetime, an experiment has been constructed that can time resolve the photo-luminescent decay of a detector or wafer sample housed inside a liquid nitrogen cooled Dewar. Motorized stages allow the measurement to be scanned over the sample surface, and spatial resolutions as low as 50µm have been demonstrated. A carrier recombination simulation was developed to analyze the experimental data. Results from measurements performed on 4 mercury cadmium telluride focal plane arrays show strong correlation between spatial maps of the lifetime, dark current, and relative response.

  6. Evolution of large format impurity band conductor focal plane arrays for astronomy applications

    NASA Astrophysics Data System (ADS)

    Mills, Robert; Beuville, Eric; Corrales, Elizabeth; Hoffman, Alan; Finger, Gert; Ives, Derek

    2011-09-01

    Raytheon Vision Systems (RVS) has developed a family of high performance large format infrared (IR) detector arrays whose detectors are most effective for the detection of long and very long wavelength IR energy. This paper describes the evolution of the present state of the art one mega-pixel Si: As Impurity Band Conduction (IBC) arrays toward a four mega-pixel array that is desired by the astronomy community. Raytheon's Aquarius-1k, developed in collaboration with ESO, is a 1024 × 1024 pixel high performance array with a 30 μm pitch that features high quantum efficiency IBC detectors, low noise, low dark current, and on-chip clocking for ease of operation. Since the Aquarius-1k array was designed primarily for ground-based astronomy applications, it incorporates selectable gains and a large well capacity among its other features. Raytheon, in collaboration with JAXA (Japan Aerospace Exploration Agency), is also designing a 2048 × 2048 pixel high performance array with a 25 μm pitch. This 2k × 2k readout circuit will be based on the successful design used for the on the Mid-Infrared Instrument (MIRI) aboard the James Webb Space Telescope (JWST). It will feature high quantum efficiency IBC detectors, low noise, low dark current, and on-chip clocking for ease of operation. This version will also incorporate flight qualified packaging to support space-based astronomy applications. Previous generations of RVS IBC detectors have flown on several platforms, including NASA's Spitzer Space Telescope and Japan's Akari Space Telescope.

  7. Control and acquisition system for SWIR focal plane arrays from SOFRADIR

    NASA Astrophysics Data System (ADS)

    Beaufort, T.; Duvet, L.

    2009-07-01

    We report on the design, testing and characterization of a control and acquisition system developed for SWIR detectors from SOFRADIR. These detectors are MCT arrays developed for SWIR (Short Wavelength Infra Red) and hyperspectral applications;. The ROIC (Readout integrated circuitry) of each FPA (Focal Plane Array) delivers multiple analog outputs buffered and converted in the digital domain by dedicated board designed by SOFRADIR. These boards perform a time multiplexing of the digitized signals, leading to high data throughputs. Each FPA has its own dedicated Stirling micro-cooler. The control and acquisition system developed by our team is able to handle the high data throughput (up to 1.6 Gbit/s) thanks to a high speed acquisition board from National Instruments embedded in a PXI system. A standard DAQ card is used to acquire the house-keepings, control the different power supplies and clock generators while an SPI adapter enables the configuration of the FPA. The overall system is managed under the Labview environment with a flexible and comprehensive interface to the user with extensive logging of all operational parameters. The purpose of this paper is to describe the architecture of the overall system and to detail its performances.

  8. WSPEC: A Waveguide Filter-Bank Focal Plane Array Spectrometer for Millimeter Wave Astronomy and Cosmology

    NASA Astrophysics Data System (ADS)

    Bryan, Sean; Aguirre, James; Che, George; Doyle, Simon; Flanigan, Daniel; Groppi, Christopher; Johnson, Bradley; Jones, Glenn; Mauskopf, Philip; McCarrick, Heather; Monfardini, Alessandro; Mroczkowski, Tony

    2016-07-01

    Imaging and spectroscopy at (sub-)millimeter wavelengths are key frontiers in astronomy and cosmology. Large area spectral surveys with moderate spectral resolution (R=50-200) will be used to characterize large-scale structure and star formation through intensity mapping surveys in emission lines such as the CO rotational transitions. Such surveys will also be used to study the the Sunyaev Zeldovich (SZ) effect, and will detect the emission lines and continuum spectrum of individual objects. WSPEC is an instrument proposed to target these science goals. It is a channelizing spectrometer realized in rectangular waveguide, fabricated using conventional high-precision metal machining. Each spectrometer is coupled to free space with a machined feed horn, and the devices are tiled into a 2D array to fill the focal plane of the telescope. The detectors will be aluminum lumped-element kinetic inductance detectors (LEKIDs). To target the CO lines and SZ effect, we will have bands at 135-175 and 190-250 GHz, each Nyquist-sampled at R≈ 200 resolution. Here, we discuss the instrument concept and design, and successful initial testing of a WR10 (i.e., 90 GHz) prototype spectrometer. We recently tested a WR5 (180 GHz) prototype to verify that the concept works at higher frequencies, and also designed a resonant backshort structure that may further increase the optical efficiency. We are making progress towards integrating a spectrometer with a LEKID array and deploying a prototype device to a telescope for first light.

  9. WSPEC: A Waveguide Filter-Bank Focal Plane Array Spectrometer for Millimeter Wave Astronomy and Cosmology

    NASA Astrophysics Data System (ADS)

    Bryan, Sean; Aguirre, James; Che, George; Doyle, Simon; Flanigan, Daniel; Groppi, Christopher; Johnson, Bradley; Jones, Glenn; Mauskopf, Philip; McCarrick, Heather; Monfardini, Alessandro; Mroczkowski, Tony

    2015-12-01

    Imaging and spectroscopy at (sub-)millimeter wavelengths are key frontiers in astronomy and cosmology. Large area spectral surveys with moderate spectral resolution (R=50 -200) will be used to characterize large-scale structure and star formation through intensity mapping surveys in emission lines such as the CO rotational transitions. Such surveys will also be used to study the the Sunyaev Zeldovich (SZ) effect, and will detect the emission lines and continuum spectrum of individual objects. WSPEC is an instrument proposed to target these science goals. It is a channelizing spectrometer realized in rectangular waveguide, fabricated using conventional high-precision metal machining. Each spectrometer is coupled to free space with a machined feed horn, and the devices are tiled into a 2D array to fill the focal plane of the telescope. The detectors will be aluminum lumped-element kinetic inductance detectors (LEKIDs). To target the CO lines and SZ effect, we will have bands at 135-175 and 190-250 GHz, each Nyquist-sampled at R≈ 200 resolution. Here, we discuss the instrument concept and design, and successful initial testing of a WR10 (i.e., 90 GHz) prototype spectrometer. We recently tested a WR5 (180 GHz) prototype to verify that the concept works at higher frequencies, and also designed a resonant backshort structure that may further increase the optical efficiency. We are making progress towards integrating a spectrometer with a LEKID array and deploying a prototype device to a telescope for first light.

  10. Evaluation and display of polarimetric image data using long-wave cooled microgrid focal plane arrays

    NASA Astrophysics Data System (ADS)

    Bowers, David L.; Boger, James K.; Wellems, L. David; Black, Wiley T.; Ortega, Steve E.; Ratliff, Bradley M.; Fetrow, Matthew P.; Hubbs, John E.; Tyo, J. Scott

    2006-05-01

    Recent developments for Long Wave InfraRed (LWIR) imaging polarimeters include incorporating a microgrid polarizer array onto the focal plane array (FPA). Inherent advantages over typical polarimeters include packaging and instantaneous acquisition of thermal and polarimetric information. This allows for real time video of thermal and polarimetric products. The microgrid approach has inherent polarization measurement error due to the spatial sampling of a non-uniform scene, residual pixel to pixel variations in the gain corrected responsivity and in the noise equivalent input (NEI), and variations in the pixel to pixel micro-polarizer performance. The Degree of Linear Polarization (DoLP) is highly sensitive to these parameters and is consequently used as a metric to explore instrument sensitivities. Image processing and fusion techniques are used to take advantage of the inherent thermal and polarimetric sensing capability of this FPA, providing additional scene information in real time. Optimal operating conditions are employed to improve FPA uniformity and sensitivity. Data from two DRS Infrared Technologies, L.P. (DRS) microgrid polarizer HgCdTe FPAs are presented. One FPA resides in a liquid nitrogen (LN2) pour filled dewar with a 80°K nominal operating temperature. The other FPA resides in a cryogenic (cryo) dewar with a 60° K nominal operating temperature.

  11. SWIR HgCdTe 256x256 focal plane array technology at BAE Systems

    NASA Astrophysics Data System (ADS)

    Hairston, A.; Tobin, S. P.; Hutchins, M.; Marciniec, J.; Mullarkey, J.; Norton, P.; Gurnee, M.; Reine, M. B.

    2006-08-01

    This paper reports new performance data for SWIR HgCdTe 256x256 hybrid Focal Plane Arrays with cutoff wavelengths of 2.6-2.7 μm, operating at temperatures of 190 K to 220 K. The unit cell size is 30x30 μm2. Back-illuminated SWIR HgCdTe P-on-n photodiode arrays were fabricated from two-layer LPE films grown on CdZnTe substrates. Response uniformity is excellent, with σ/μ=3-4%, and response operabilities are better than 99.9%. At a temperature of 190 K and a background photon flux of 6.8x10 11 ph/cm2-s, the median NEI is 1.1x10 9 ph/cm2-s, which is 1.4 times the BLIP NEI. NEI operabilities are better than 98.8%. Quantum efficiencies for large-area test diodes are 69% to 78%, close to the 79% upper limit imposed by reflection from the non-antireflection-coated CdZnTe substrate.

  12. Solid-state Image Sensor with Focal-plane Digital Photon-counting Pixel Array

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R.; Pain, Bedabrata

    1997-01-01

    A solid-state focal-plane imaging system comprises an NxN array of high gain. low-noise unit cells. each unit cell being connected to a different one of photovoltaic detector diodes, one for each unit cell, interspersed in the array for ultra low level image detection and a plurality of digital counters coupled to the outputs of the unit cell by a multiplexer(either a separate counter for each unit cell or a row of N of counters time shared with N rows of digital counters). Each unit cell includes two self-biasing cascode amplifiers in cascade for a high charge-to-voltage conversion gain (greater than 1mV/e(-)) and an electronic switch to reset input capacitance to a reference potential in order to be able to discriminate detection of an incident photon by the photoelectron (e(-))generated in the detector diode at the input of the first cascode amplifier in order to count incident photons individually in a digital counter connected to the output of the second cascade amplifier. Reseting the input capacitance and initiating self-biasing of the amplifiers occurs every clock cycle of an integratng period to enable ultralow light level image detection by the may of photovoltaic detector diodes under such ultralow light level conditions that the photon flux will statistically provide only a single photon at a time incident on anyone detector diode during any clock cycle.

  13. Design rule of indium bump in infrared focal plane array for longer cycling life

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoling; Meng, Chao; Zhang, Wei; Lv, Yanqiu; Si, Junjie; Meng, Qingduan

    2016-05-01

    In light of the proposed equivalent method, a three-dimensional structural modeling of InSb infrared focal plane arrays (IRFPAs) is created, and the simulated strain distribution is identical to the deformation distribution on the top surface of InSb IRFPAs. After comparing the deformation features at different regions with the structural characteristics of IRFPAs, we infer that the flatness of InSb IRFPAs will be improved with a thinner indium bump array, and this inference is verified by subsequent simulation results. That is, when the diameter of indium bump is smaller than 20 μm, the simulated Z-components of strain on the whole top surface of InSb IRFPAs is uniform, and the deformation amplitude is small. When the diameter of indium bump is larger than 28 μm, the simulated Z-components of strain increases rapidly with the thicker indium bump, and the flatness of InSb IRFPAs is worsened rapidly. According to the changing trend of deformation amplitude with diameters of indium bump, and employing element pitches normalization method, a design rule of indium bump is proposed. That is, when the diameter of indium bump is shorter than 0.4 times the element pitch, the flatness of InSb IRFPAs is in an acceptable range. This design rule was supported by different IRFPAs with different formats delivered by several main research groups for achieving a longer cycling life.

  14. Dark current measurement of Type-II superlattice infrared focal plane array detector

    NASA Astrophysics Data System (ADS)

    Sakai, Michito; Katayama, Haruyoshi; Murooka, Junpei; Kimata, Masafumi; Iguchi, Yasuhiro

    2014-06-01

    We report the result of a dark current measurement of a Type-II superlattice (T2SL) infrared focal plane array (FPA), which consists of a 6 μm cutoff T2SL detector array and the readout integration circuit (ROIC) ISC0903 of FLIR Systems. In order to measure the dark current of the FPA, we obtained images with different exposure times in a fully closed cold shield of 77 K. Using the temporal change rate of the output and considering the charge conversion efficiency of the ROIC, we obtained a dark current density with an average value of 4 × 10-5 A/cm2 at a bias of -100 mV. We also compare the result of the FPA dark current measurement with that of a test element group (TEG), which was a single pixel detector, fabricated by the same process as the FPA. The dark current density of the TEG was 3 × 10-6 A/cm2 at a bias of -100 mV, lower than that of the FPA. We discuss the discrepancy between the dark current densities of the FPA and the TEG.

  15. Embedded nonuniformity correction in infrared focal plane arrays using the Constant Range algorithm

    NASA Astrophysics Data System (ADS)

    Redlich, Rodolfo; Figueroa, Miguel; Torres, Sergio N.; Pezoa, Jorge E.

    2015-03-01

    We present a digital fixed-point architecture that performs real-time nonuniformity correction in infrared (IR) focal plane arrays using the Constant Range algorithm. The circuit estimates and compensates online the gains and offsets of a first-order nonuniformity model using pixel statistics from the video stream. We demonstrate our architecture with a prototype built on a Xilinx Spartan-6 XC6SLX45T field-programmable gate array (FPGA), which can process an IR video stream from a FLIR Tau 2 long-wave IR camera with a resolution of 640 × 480 14-bit pixels at up to 238 frames per second (fps) with low resource utilization and adds only 13 mW to the FPGA power. Post-layout simulations of a custom integrated circuit implementation of the architecture on a 32 nm CMOS process show that the circuit can operate at up to 900 fps at the same resolution, and consume less than 4.5 mW.

  16. Carbon nanotube array based sensor

    DOEpatents

    Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

    2005-09-20

    A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

  17. Large format high-operability SWIR and MWIR focal plane array performance and capabilities

    NASA Astrophysics Data System (ADS)

    Bangs, James; Langell, Mark; Reddy, Madhu; Melkonian, Leon; Johnson, Scott; Elizondo, Lee; Rybnicek, Kimon; Norton, Elyse; Jaworski, Frank; Asbrock, James; Baur, Stefan

    2011-06-01

    High-performance large-format detector arrays responsive to the 1-5μm wavelength range of the infrared spectrum fabricated using large area HgCdTe layers grown on 6-inch diameter (211) silicon substrates are available for advanced imaging applications. This paper reviews performance and capabilities of Raytheon Vision Systems (RVS) HgCdTe/Si Focal Plane Arrays (FPA) and shows 2k x 2k format MWIR HgCdTe/Si FPA performance with NEdT operabilities better than 99.9%. SWIR and MWIR detector performance for HgCdTe/Si is comparable to established performance of HgCdTe/CdZnTe wafers. HgCdTe devices fabricated on both types of substrates have demonstrated very low dark current, high quantum efficiency and full spectral band fill factor characteristic of HgCdTe. HgCdTe has the advantage of being able to precisely tune the detector cutoff via adjustment of the Cd composition in the MBE growth. The HgCdTe/Si detectors described in this paper are p-on-n mesa delineated architecture and fabricated using the same mature etch, passivation, and metallization processes as our HgCdTe/CdZnTe line. Uniform device quality HgCdTe epitaxial layers and application of detector fabrication processes across the full area of 6-inch wafers routinely produces high performing detector pixels from edge to edge of the photolithographic limits across the wafer, offering 5 times the printable area as costly 6×6cm CdZnTe substrates. This 6-inch HgCdTe detector wafer technology can provide applications demanding very wide FOV high resolution coverage the capability to produce a very large single piece infrared detector array, up to a continuous image plane 10×10 cm in size. Alternatively, significant detector cost reduction through allowing more die of a given size to be printed on each wafer is possible, with further cost reduction achieved through transition towards automated detector fabrication and photolithographic processes for both increased yields and reduced touch labor costs. RVS continues

  18. InSb photovoltaic infrared detector array with quasi-plane structure

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Wang, L.; Chen, X.; Shen; Shouzhen

    1984-12-01

    A quasi-plane technology is developed, which is based on a mesa photosensitive unit with SiO2 medium as mask, using a metal film as expanding electrode and a supersonic technique for welding the electrode wire on the substrate. The detectors made with this technology have good electrical and photoelectrical performance, such as high junction impedance, high reverse breakdown voltage, good stability of performance and no crosstalk. The mechanism yielding high performance is briefly discussed.

  19. An uncooled 1280 x 1024 InGaAs focal plane array for small platform, shortwave infrared imaging

    NASA Astrophysics Data System (ADS)

    Battaglia, J.; Blessinger, M.; Enriquez, M.; Ettenberg, M.; Evans, M.; Flynn, K.; Lin, M.; Passe, J.; Stern, M.; Sudol, T.

    2009-05-01

    The increasing demand for short wave infrared (SWIR) imaging technology for soldier-based and unmanned platforms requires camera systems where size, weight and power consumption are minimized without loss of performance. Goodrich, Sensors Unlimited Inc. reports on the development of a novel focal plane (FPA) array for DARPA's MISI (Micro-Sensors for Imaging) Program. This large format (1280 x 1024) array is optimized for day/night imaging in the wavelength region from 0.4 μm to 1.7 μm and consists of an InGaAs detector bump bonded to a capacitance transimpedance amplifier (CTIA)-based readout integrated circuit (ROIC) on a compact 15 μm pixel pitch. Two selectable integration capacitors provide for high dynamic range with low (< 50 electrons) noise, and expanded onchip ROIC functionality includes analog-to-digital conversion and temperature sensing. The combination of high quality, low dark current InGaAs with temperature-parameterized non-uniformity correction allows operation at ambient temperatures while eliminating the need for thermoelectric cooling. The resulting lightweight, low power implementation is suitable for man-portable and UAV-mounted applications.

  20. Antennas for Terahertz Applications: Focal Plane Arrays and On-chip Non-contact Measurement Probes

    NASA Astrophysics Data System (ADS)

    Trichopoulos, Georgios C.

    The terahertz (THz) band provides unique sensing opportunities that enable several important applications such as biomedical imaging, remote non-destructive inspection of packaged goods, and security screening. THz waves can penetrate most materials and can provide unique spectral information in the 0.1--10 THz band with high resolution. In contrast, other imaging modalities, like infrared (IR), suffer from low penetration depths and are thus not attractive for non-destructive evaluation. However, state-of-the-art THz imaging systems typically employ mechanical raster scans using a single detector to acquire two-dimensional images. Such devices tend to be bulky and complicated due to the mechanical parts, and are thus rather expensive to develop and operate. Thus, large-format (e.g. 100x100 pixels) and all-electronics based THz imaging systems are badly needed to alleviate the space, weight and power (SWAP) factors and enable cost effective utilization of THz waves for sensing and high-data-rate communications. In contrast, photonic sensors are very compact because light can couple directly to the photodiode without residing to radiation coupling topologies. However, in the THz band, due to the longer wavelengths and much lower photon energies, highly efficient antennas with optimized input impedance have to be integrated with THz sensors. Here, we implement novel antenna engineering techniques that are optimized to take advantage of recent technological advances in solid-state THz sensing devices. For example, large-format focal plane arrays (FPAs) have been the Achilles' heel of THz imaging systems. Typically, optical components (lenses, mirrors) are employed in order to improve the optical performance of FPAs, however, antenna sensors suffer from degraded performance when they are far from the optical axis, thus minimizing the number of useful FPA elements. By modifying the radiation pattern of FPA antennas we manage to alleviate the off-axis aberration

  1. Mercury-Cadmium-Telluride Focal Plane Array Performance Under Non-Standard Operating Conditions

    NASA Technical Reports Server (NTRS)

    Richardson, Brandon S.; Eastwood, Michael L.; Bruce, Carl F.; Green, Robert O.; Coles, J. B.

    2011-01-01

    This paper highlights a new technique that allows the Teledyne Scientific & Imaging LLC TCM6604A Mercury-Cadmium-Telluride (MCT) Focal Plane Array (FPA) to operate at room temperature. The Teledyne MCT FPA has been a standard in Imaging Spectroscopy since its creation in the 1980's. This FPA has been used in applications ranging from space instruments such as CRISM, M3 and ARTEMIS to airborne instruments such as MaRS and the Next Generation AVIRIS Instruments1. Precise focal plane alignment is always a challenge for such instruments. The current FPA alignment process results in multiple cold cycles requiring week-long durations, thereby increasing the risk and cost of a project. These alignment cycles are necessary because optimal alignment is approached incrementally and can only be measured with the FPA and Optics at standard operating conditions, requiring a cold instrument. Instruments using this FPA are normally cooled to temperatures below 150K for the MCT FPA to properly function. When the FPA is run at higher temperatures the dark current increases saturating the output. This paper covers the prospect of warm MCT FPA operation from a theoretical and experimental perspective. We discuss the empirical models and physical laws that govern MCT material properties and predict the optimal settings that will result in the best MCT PA performance at 300K. Theoretical results are then calculated for the proposed settings. We finally present the images and data obtained using the actual system with the warm MCT FPA settings. The paper concludes by emphasizing the strong positive correlation between the measured values and the theoretical results.

  2. Examination of cotton fibers and common contaminants using an infrared microscope and a focal-plane array detector

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemical imaging of cotton fibers and common contaminants in fibers is presented. Chemical imaging was performed with an infrared microscope equipped with a Focal-Plane Array (FPA) detector. Infrared spectroscopy can provide us with information on the structure and quality of cotton fibers. In a...

  3. Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane substrate

    SciTech Connect

    Chou, Namsun; Lee, Jongho; Kim, Sohee

    2014-12-15

    This paper describes a reliable fabrication method of stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate. The electrode traces and pads were formed in out-of-plane structures to improve the flexibility and stretchability of the electrode array. The suspended traces and pads were attached to the PDMS substrate via parylene posts that were located nearby the traces and under the pads. As only conventional micro-electro-mechanical systems techniques were used, the out-of-plane electrode arrays were clearly fabricated at wafer level with high yield and reliability. Also, bi-layer out-of-plane electrodes were formed through additional fabrication steps in addition to mono-layer out-of-plane electrodes. The mechanical characteristics such as the stretchability, flexibility, and foldability of the fabricated electrodes were evaluated, resulting in stable electrical connection of the metal traces with up to 32.4% strain and up to 360° twist angle over 25 mm. The durability in stretched condition was validated by cyclic stretch test with 10% and 20% strain, resulting in electrical disconnection at 8600 cycles when subjected to 20% strain. From these results, it is concluded that the proposed fabrication method produced highly reliable, out-of-plane and stretchable electrodes, which would be used in various flexible and stretchable electronics applications.

  4. High performance type II superlattice focal plane array with 6μm cutoff wavelength

    NASA Astrophysics Data System (ADS)

    Miura, Kouhei; Machinaga, Ken-ichi; Balasekaran, Sundararajan; Kawahara, Takahiko; Migita, Masaki; Inada, Hiroshi; Iguchi, Yasuhiro; Sakai, Michito; Murooka, Junpei; Katayama, Haruyoshi; Kimata, Masafumi

    2016-05-01

    The cutoff wavelength of 6μm is preferable for the full usage of the atmospheric window in the mid-wavelength region. An InAs/GaSb type-II superlattice (T2SL) is the only known infrared material that has a theoretically predicted high performance and also the cutoff wavelength can be easily controlled by changing the thickness of InAs and GaSb. In this study, we used a p-i-n structure with InAs/GaSb T2SL absorber and also barrier layers which was grown on a Tedoped GaSb substrate by molecular beam epitaxy. A mesa-type focal plane array (FPA) with 320×256 pixels and 30μm pixel pitch was fabricated. Mesa structures were formed by inductively coupled plasma reactive ion etching with halogen gas mixture. Prior to the deposition of the SiO2 passivation film, N2 plasma treatment was applied for reducing the dark currents. Measured dark current of the sensor was 4x10-7A/cm2 at temperature of 77K and reverse bias of -20mV. The quantum efficiency was 0.35 and the detectivity was 4.1x1012cm/Hz1/2W. The sensor array was hybridized with the commercially available readout integrated circuit using indium bumps. The noise equivalent differential temperature measured with F/2.3 optics was 31mK at 77K. The operability was over 99%. This FPA is suitable for full usage of the atmospheric window in the mid-wavelength region.

  5. Numerical Simulation of Refractive-Microlensed HgCdTe Infrared Focal Plane Arrays Operating in Optical Systems

    NASA Astrophysics Data System (ADS)

    Li, Yang; Ye, Zhen-Hua; Hu, Wei-Da; Lei, Wen; Gao, Yan-Lin; He, Kai; Hua, Hua; Zhang, Peng; Chen, Yi-Yu; Lin, Chun; Hu, Xiao-Ning; Ding, Rui-Jun; He, Li

    2014-08-01

    The optoelectronic performance of the mid-wavelength HgCdTe infrared focal plane array (IRFPA) with refractive microlenses integrated on its CdZnTe substrate has been numerically simulated. A reduced light-distribution model based on scalar Kirchhoff diffraction theory was adopted to reveal the true behavior of IRFPAs operating in an optical system under imaging conditions. The pixel crosstalk obtained and the energy-gathering characteristics demonstrated that the microlenses can delay the rise in crosstalk when the image point shifts toward pixel boundaries, and can restrict the major optical absorption process in any case within a narrow region around the pixel center. The dependence of the microlenses' effects on the system's properties was also analyzed; this showed that intermediate relative aperture and small microlens radius are required for optimized device performance. Simulation results also indicated that for detectors farther from the center of the field of view, the efficacy of microlenses in crosstalk suppression and energy gathering is still maintained, except for a negligible difference in the lateral magnification from an ordinary array without microlenses.

  6. Very large scale heterogeneous integration (VLSHI) and wafer-level vacuum packaging for infrared bolometer focal plane arrays

    NASA Astrophysics Data System (ADS)

    Forsberg, Fredrik; Roxhed, Niclas; Fischer, Andreas C.; Samel, Björn; Ericsson, Per; Hoivik, Nils; Lapadatu, Adriana; Bring, Martin; Kittilsland, Gjermund; Stemme, Göran; Niklaus, Frank

    2013-09-01

    Imaging in the long wavelength infrared (LWIR) range from 8 to 14 μm is an extremely useful tool for non-contact measurement and imaging of temperature in many industrial, automotive and security applications. However, the cost of the infrared (IR) imaging components has to be significantly reduced to make IR imaging a viable technology for many cost-sensitive applications. This paper demonstrates new and improved fabrication and packaging technologies for next-generation IR imaging detectors based on uncooled IR bolometer focal plane arrays. The proposed technologies include very large scale heterogeneous integration for combining high-performance, SiGe quantum-well bolometers with electronic integrated read-out circuits and CMOS compatible wafer-level vacuum packing. The fabrication and characterization of bolometers with a pitch of 25 μm × 25 μm that are arranged on read-out-wafers in arrays with 320 × 240 pixels are presented. The bolometers contain a multi-layer quantum well SiGe thermistor with a temperature coefficient of resistance of -3.0%/K. The proposed CMOS compatible wafer-level vacuum packaging technology uses Cu-Sn solid-liquid interdiffusion (SLID) bonding. The presented technologies are suitable for implementation in cost-efficient fabless business models with the potential to bring about the cost reduction needed to enable low-cost IR imaging products for industrial, security and automotive applications.

  7. Microbolometer Terahertz Focal Plane Array and Camera with Improved Sensitivity in the Sub-Terahertz Region

    NASA Astrophysics Data System (ADS)

    Oda, Naoki; Kurashina, Seiji; Miyoshi, Masaru; Doi, Kohei; Ishi, Tsutomu; Sudou, Takayuki; Morimoto, Takao; Goto, Hideki; Sasaki, Tokuhito

    2015-10-01

    A pixel in an uncooled microbolometer terahertz (THz) focal plane array (FPA) has a suspended structure above read-out integrated circuit (ROIC) substrate. An optical cavity structure is formed between a thin metallic layer deposited on the suspended structure and a thick metallic layer deposited on the ROIC surface. The geometrical optical cavity length for our previous pixel structure, 3-4 μm, is extended three times, so that responsivity can be increased in the sub-THz region. This modification is carried out by depositing a thick SiN layer on the thick metallic layer. The modified pixel structure is applied to 640 × 480 and 320 × 240 THz-FPAs with 23.5 μm pixel pitch. Minimum detectable powers per pixel (MDP) are evaluated for these FPAs at 4.3, 2.5, 0.6, and 0.5 THz, and the MDP values are found to be improved by a factor of ten at 0.6 and 0.5 THz. The MDP values of the THz-FPAs developed in this work are compared with those of other THz detectors, such as uncooled antenna-coupled CMOS (complimentary metal-oxide semiconductor) THz-FPAs and cooled bolometer arrays. It is found that our THz-FPAs are more sensitive in the sub-THz region than the CMOS THz-FPAs, while they are much less sensitive than the cooled bolometer arrays. These THz-FPAs are incorporated into a 640 × 480 THz camera and 320 × 240 THz camera, and imaging equipment is developed. The equipment consists of a linearly polarized sub-THz source, a collimator lens, a beam homogenizer, two wire grids, a quarter-wave plate, and two THz cameras, and sub-THz images are demonstrated. It should be mentioned for the equipment that imaging of transmission and reflection is realized by moving only the quarter-wave plate, and the reflection image is taken along a direction normal to a sample surface so that the reflection image is hardly deformed.

  8. 1024 x 1024 pixel mid-wavelength and long-wavelength infrared QWIP focal plane arrays for imaging applications

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Hill, C. J.; Rafol, S. B.; Mumolo, J. M.; Trinh, J. T.; Tidrow, M. Z.; LeVan, P. D.

    2005-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 10(24) x 10(24) pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NEAT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEAT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In this paper, we will discuss the performance in terms of quantum efficiency, NE(delta)T, uniformity, operability and modulation transfer functions.

  9. Plane wave scattering from a plasmonic nanowire array spacer-separated from a plasmonic film

    NASA Astrophysics Data System (ADS)

    Thomas, Arun; Trivedi, Rahul; Dhawan, Anuj

    2016-06-01

    In this paper, we present a theoretical analysis of the electromagnetic response of a plasmonic nanowire–spacer–plasmonic film system. The analytical solution presented in this paper is a full-wave solution, which is used to compute the fields scattered by the plasmonic nanostructure system on illumination by a plane electromagnetic wave. The physical structure comprises of an array of plasmonic nanowires made of a plasmonic metal such as gold or silver placed over a plasmonic film of the same material and separated from it by a dielectric spacer such as silica or alumina. Such a nanostructure exhibits a spectrum that is extremely sensitive to various geometric and electromagnetic parameters such as spacer thickness and spacer refractive index, which makes it favourable for various sensing applications such as chemical and biological sensing, strain sensing, position sensing, vibration sensing, and thickness sensing. We report a comparison of our analytical solution with a numerical rigorous coupled wave analysis of the same structure with the plasmonic medium being treated as local in nature.

  10. Evolution of miniature detectors and focal plane arrays for infrared sensors

    NASA Technical Reports Server (NTRS)

    Watts, Louis A.

    1993-01-01

    Sensors that are sensitive in the infrared spectral region have been under continuous development since the WW2 era. A quest for the military advantage of 'seeing in the dark' has pushed thermal imaging technology toward high spatial and temporal resolution for night vision equipment, fire control, search track, and seeker 'homing' guidance sensing devices. Similarly, scientific applications have pushed spectral resolution for chemical analysis, remote sensing of earth resources, and astronomical exploration applications. As a result of these developments, focal plane arrays (FPA) are now available with sufficient sensitivity for both high spatial and narrow bandwidth spectral resolution imaging over large fields of view. Such devices combined with emerging opto-electronic developments in integrated FPA data processing techniques can yield miniature sensors capable of imaging reflected sunlight in the near IR and emitted thermal energy in the Mid-wave (MWIR) and longwave (LWIR) IR spectral regions. Robotic space sensors equipped with advanced versions of these FPA's will provide high resolution 'pictures' of their surroundings, perform remote analysis of solid, liquid, and gas matter, or selectively look for 'signatures' of specific objects. Evolutionary trends and projections of future low power micro detector FPA developments for day/night operation or use in adverse viewing conditions are presented in the following test.

  11. Analysis and quantification of laser-dazzling effects on IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Hueber, N.,; Vincent, D.,; Morin, A.,; Dieterlen, A.,; Raymond, P.,

    2010-04-01

    Today Optronic Countermeasure (OCM) concerns imply an IR Focal-Plane Array (FPA) facing an in-band laser irradiation. In order to evaluate the efficiency of new countermeasure concepts or the robustness of FPAs, it is necessary to quantify the whole interaction effects. Even though some studies in the open literature show the vulnerability of imaging systems to laser dazzling, the diversity of analysis criteria employed does not allow the results of these studies to be correlated. Therefore, we focus our effort on the definition of common sensor figures of merit adapted to laser OCM studies. In this paper, two investigation levels are presented: the first one for analyzing the local nonlinear photocell response and the second one for quantifying the whole dazzling impact on image. The first study gives interesting results on InSb photocell behaviors when irradiated by a picosecond MWIR laser. With an increasing irradiance, four different successive responses appear: from linear, logarithmic, decreasing ones to permanent linear offset response. In the second study, our quantifying tools are described and their successful implementation through the picosecond laser-dazzling characterization of an InSb FPA is assessed.

  12. High-speed infrared imaging by an uncooled optomechanical focal plane array.

    PubMed

    Feng, Yun; Zhao, Yuejin; Dong, Liquan; Liu, Ming; Li, Xueyan; Ma, Wei; Yu, Xiaomei; Kong, Lingqin; Liu, Xiaohua

    2015-12-01

    In this paper, we theoretically and experimentally demonstrate that the imaging speed of the optomechanical focal plane array infrared imaging system can be significantly improved by changing the pressure in the vacuum chamber. The decrease in the thermal time constant is attributed to the additional thermal conductance caused by air. The response time will be greatly shortened to about 1/3 time in low vacuum (around ∼10(2)  Pa) compared with that in high vacuum. At a chamber pressure of 50 Pa, the "trailing" in the IR image of a moving hot iron is eliminated with negligible deterioration in the image quality. Moreover, infrared images on rapid occurrence events, such as ignition of an alcohol blast burner, lighting and fusion of a tungsten filament, are captured at a frame rate up to 200 Hz. The above results show that the proposed pressure-dependent performance provides a way to improve the system imaging speed and helps to slow down a dynamic event, which is of great value to the uncooled IR imaging systems in practical applications. PMID:26836676

  13. Epitaxial InSb for elevated temperature operation of large IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Ashley, Tim; Burke, Theresa M.; Emeny, Martin T.; Gordon, Neil T.; Hall, David J.; Lees, David J.; Little, J. Chris; Milner, Daniel

    2003-09-01

    The use of epitaxially grown indium antimonide (InSb) has previously been demonstrated for the production of large 2D focal plane arrays. It confers several advantages over conventional, bulk InSb photo-voltaic detectors, such as reduced cross-talk, however here we focus on the improvement in operating temperature that can be achieved because more complex structures can be grown. Diode resistance, imaging, NETD and operability results are presented for a progression of structures that reduce the diode leakage current as the temperature is raised above 80K, compared with a basic p+-n-n+ structure presented previously. These include addition of a thin region of InAlSb to reduce p-contact leakage current, and construction of the whole device from InAlSb to reduce thermal generation in the active region of the detector. An increase in temperature to 110K, whilst maintaining full 80K performance, is achieved, and imaging up to 130K is demonstrated. This gives the prospect of significant benefits for the cooling systems, including, for example, use of argon in Joule-Thomson coolers or an increase in the life and/or decrease in the cost; power consumption and cool-down time of Stirling engines by several tens of per cent.

  14. Advances in three-dimensional integration technologies in support of infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Temple, D. S.; Vick, E. P.; Malta, D.; Lueck, M. R.; Skokan, M. R.; Masterjohn, C. M.; Muzilla, M. S.

    2015-01-01

    Staring infrared focal plane arrays (FPAs) require pixel-level, three-dimensional (3D) integration with silicon readout integrated circuits (ROICs) that provide detector bias, integrate detector current, and may further process the signals. There is an increased interest in ROIC technology as a result of two trends in the evolution of infrared FPAs. The first trend involves decreasing the FPA pixel size, which leads to the increased information content within the same FPA die size. The second trend involves the desire to enhance signal processing capability at the FPA level, which opens the door to the detector behaving like a smart peripheral rather than a passive component—with complex signal processing functions being executed on, rather than off, the FPA chip. In this paper, we review recent advances in 3D integration process technologies that support these key trends in the development of infrared FPAs. Specifically, we discuss approaches in which the infrared sensor is integrated with 3D ROIC stacks composed of multiple layers of silicon circuitry interconnected using metal-filled through-silicon vias. We describe the continued development of the 3D integration technology and summarize key demonstrations that show its viability for pixels as small as 5 microns.

  15. Evolution of miniature detectors and focal plane arrays for infrared sensors

    NASA Astrophysics Data System (ADS)

    Watts, Louis A.

    1993-06-01

    Sensors that are sensitive in the infrared spectral region have been under continuous development since the WW2 era. A quest for the military advantage of 'seeing in the dark' has pushed thermal imaging technology toward high spatial and temporal resolution for night vision equipment, fire control, search track, and seeker 'homing' guidance sensing devices. Similarly, scientific applications have pushed spectral resolution for chemical analysis, remote sensing of earth resources, and astronomical exploration applications. As a result of these developments, focal plane arrays (FPA) are now available with sufficient sensitivity for both high spatial and narrow bandwidth spectral resolution imaging over large fields of view. Such devices combined with emerging opto-electronic developments in integrated FPA data processing techniques can yield miniature sensors capable of imaging reflected sunlight in the near IR and emitted thermal energy in the Mid-wave (MWIR) and longwave (LWIR) IR spectral regions. Robotic space sensors equipped with advanced versions of these FPA's will provide high resolution 'pictures' of their surroundings, perform remote analysis of solid, liquid, and gas matter, or selectively look for 'signatures' of specific objects. Evolutionary trends and projections of future low power micro detector FPA developments for day/night operation or use in adverse viewing conditions are presented in the following test.

  16. Colloidal quantum dot Vis-SWIR imaging: demonstration of a focal plane array and camera prototype (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Klem, Ethan J. D.; Gregory, Christopher W.; Temple, Dorota S.; Lewis, Jay S.

    2015-08-01

    RTI has developed a photodiode technology based on solution-processed PbS colloidal quantum dots (CQD). These devices are capable of providing low-cost, high performance detection across the Vis-SWIR spectral range. At the core of this technology is a heterojunction diode structure fabricated using techniques well suited to wafer-scale fabrication, such as spin coating and thermal evaporation. This enables RTI's CQD diodes to be processed at room temperature directly on top of read-out integrated circuits (ROIC), without the need for the hybridization step required by traditional SWIR detectors. Additionally, the CQD diodes can be fabricated on ROICs designed for other detector material systems, effectively allowing rapid prototype demonstrations of CQD focal plane arrays at low cost and on a wide range of pixel pitches and array sizes. We will show the results of fabricating CQD arrays directly on top of commercially available ROICs. Specifically, the ROICs are a 640 x 512 pixel format with 15 µm pitch, originally developed for InGaAs detectors. We will show that minor modifications to the surface of these ROICs make them suitable for use with our CQD detectors. Once completed, these FPAs are then assembled into a demonstration camera and their imaging performance is evaluated. In addition, we will discuss recent advances in device architecture and processing resulting in devices with room temperature dark currents of 2-5 nA/cm^2 and sensitivity from 350 nm to 1.7 μm. This combination of high performance, dramatic cost reduction, and multi-band sensitivity is ideally suited to expand the use of SWIR imaging in current applications, as well as to address applications which require a multispectral sensitivity not met by existing technologies.

  17. Modeling and stress analysis of large format InSb focal plane arrays detector under thermal shock

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Wen; Meng, Qing-Duan; Zhang, Xiao-Ling; Yu, Qian; Lv, Yan-Qiu; Si, Jun-Jie

    2013-09-01

    Higher fracture probability, appearing in large format InSb infrared focal plane arrays detector under thermal shock loadings, limits its applicability and suitability for large format equipment, and has been an urgent problem to be solved. In order to understand the fracture mechanism and improve the reliability, three dimensional modeling and stress analysis of large format InSb detector is necessary. However, there are few reports on three dimensional modeling and simulation of large format InSb detector, due to huge meshing numbers and time-consuming operation to solve. To solve the problems, basing on the thermal mismatch displacement formula, an equivalent modeling method is proposed in this paper. With the proposed equivalent modeling method, employing the ANSYS software, three dimensional large format InSb detector is modeled, and the maximum Von Mises stress appearing in InSb chip dependent on array format is researched. According to the maximum Von Mises stress location shift and stress increasing tendency, the adaptability range of the proposed equivalent method is also derived, that is, for 16 × 16, 32 × 32 and 64 × 64 format, its adaptability ranges are not larger than 64 × 64, 256 × 256 and 1024 × 1024 format, respectively. Taking 1024 × 1024 InSb detector as an example, the Von Mises stress distribution appearing in InSb chip, Si readout integrated circuits and indium bump arrays are described, and the causes are discussed in detail. All these will provide a feasible research plan to identify the fracture origins of InSb chip and reduce fracture probability for large format InSb detector.

  18. Automated optical testing of LWIR objective lenses using focal plane array sensors

    NASA Astrophysics Data System (ADS)

    Winters, Daniel; Erichsen, Patrik; Domagalski, Christian; Peter, Frank; Heinisch, Josef; Dumitrescu, Eugen

    2012-10-01

    The image quality of today's state-of-the-art IR objective lenses is constantly improving while at the same time the market for thermography and vision grows strongly. Because of increasing demands on the quality of IR optics and increasing production volumes, the standards for image quality testing increase and tests need to be performed in shorter time. Most high-precision MTF testing equipment for the IR spectral bands in use today relies on the scanning slit method that scans a 1D detector over a pattern in the image generated by the lens under test, followed by image analysis to extract performance parameters. The disadvantages of this approach are that it is relatively slow, it requires highly trained operators for aligning the sample and the number of parameters that can be extracted is limited. In this paper we present lessons learned from the R and D process on using focal plane array (FPA) sensors for testing of long-wave IR (LWIR, 8-12 m) optics. Factors that need to be taken into account when switching from scanning slit to FPAs are e.g.: the thermal background from the environment, the low scene contrast in the LWIR, the need for advanced image processing algorithms to pre-process camera images for analysis and camera artifacts. Finally, we discuss 2 measurement systems for LWIR lens characterization that we recently developed with different target applications: 1) A fully automated system suitable for production testing and metrology that uses uncooled microbolometer cameras to automatically measure MTF (on-axis and at several o-axis positions) and parameters like EFL, FFL, autofocus curves, image plane tilt, etc. for LWIR objectives with an EFL between 1 and 12mm. The measurement cycle time for one sample is typically between 6 and 8s. 2) A high-precision research-grade system using again an uncooled LWIR camera as detector, that is very simple to align and operate. A wide range of lens parameters (MTF, EFL, astigmatism, distortion, etc.) can be

  19. Theory and design of compact hybrid microphone arrays on two-dimensional planes for three-dimensional soundfield analysis.

    PubMed

    Chen, Hanchi; Abhayapala, Thushara D; Zhang, Wen

    2015-11-01

    Soundfield analysis based on spherical harmonic decomposition has been widely used in various applications; however, a drawback is the three-dimensional geometry of the microphone arrays. In this paper, a method to design two-dimensional planar microphone arrays that are capable of capturing three-dimensional (3D) spatial soundfields is proposed. Through the utilization of both omni-directional and first order microphones, the proposed microphone array is capable of measuring soundfield components that are undetectable to conventional planar omni-directional microphone arrays, thus providing the same functionality as 3D arrays designed for the same purpose. Simulations show that the accuracy of the planar microphone array is comparable to traditional spherical microphone arrays. Due to its compact shape, the proposed microphone array greatly increases the feasibility of 3D soundfield analysis techniques in real-world applications. PMID:26627782

  20. Camera array based light field microscopy.

    PubMed

    Lin, Xing; Wu, Jiamin; Zheng, Guoan; Dai, Qionghai

    2015-09-01

    This paper proposes a novel approach for high-resolution light field microscopy imaging by using a camera array. In this approach, we apply a two-stage relay system for expanding the aperture plane of the microscope into the size of an imaging lens array, and utilize a sensor array for acquiring different sub-apertures images formed by corresponding imaging lenses. By combining the rectified and synchronized images from 5 × 5 viewpoints with our prototype system, we successfully recovered color light field videos for various fast-moving microscopic specimens with a spatial resolution of 0.79 megapixels at 30 frames per second, corresponding to an unprecedented data throughput of 562.5 MB/s for light field microscopy. We also demonstrated the use of the reported platform for different applications, including post-capture refocusing, phase reconstruction, 3D imaging, and optical metrology. PMID:26417490

  1. Camera array based light field microscopy

    PubMed Central

    Lin, Xing; Wu, Jiamin; Zheng, Guoan; Dai, Qionghai

    2015-01-01

    This paper proposes a novel approach for high-resolution light field microscopy imaging by using a camera array. In this approach, we apply a two-stage relay system for expanding the aperture plane of the microscope into the size of an imaging lens array, and utilize a sensor array for acquiring different sub-apertures images formed by corresponding imaging lenses. By combining the rectified and synchronized images from 5 × 5 viewpoints with our prototype system, we successfully recovered color light field videos for various fast-moving microscopic specimens with a spatial resolution of 0.79 megapixels at 30 frames per second, corresponding to an unprecedented data throughput of 562.5 MB/s for light field microscopy. We also demonstrated the use of the reported platform for different applications, including post-capture refocusing, phase reconstruction, 3D imaging, and optical metrology. PMID:26417490

  2. Hemispherical curved monolithic cooled and uncooled infrared focal plane arrays for compact cameras

    NASA Astrophysics Data System (ADS)

    Tekaya, Kevin; Fendler, Manuel; Dumas, Delphine; Inal, Karim; Massoni, Elisabeth; Gaeremynck, Yann; Druart, Guillaume; Henry, David

    2014-06-01

    InfraRed (IR) sensor systems like night vision goggles, missile approach warning systems and telescopes have an increasing interest in decreasing their size and weight. At the same time optical aberrations are always more difficult to optimize with larger Focal Plane Arrays (FPAs) and larger field of view. Both challenges can now take advantage of a new optical parameter thanks to flexible microelectronics technologies: the FPA spherical curvature. This bio-inspired approach can correct optical aberrations and reduce the number of lenses in camera conception. Firstly, a new process to curve thin monolithic devices has been applied to uncooled microbolometers FPAs. A functional 256×320 25μm pitch (roughly 1cm2) uncooled FPA has been thinned and curved. Its electrical response showed no degradation after our process (variation of less than 2.3% on the response). Then a two lenses camera with a curved FPA is designed and characterized in comparison with a two lenses camera with a flat FPA. Their Modulation Transfer Functions (MTFs) show clearly an improvement in terms of beams dispersion. Secondly, a new process to fabricate monolithic cooled flip-chip MCT-IRCMOS FPAs was developed leading to the first spherical cooled IR FPA: with a radius of 550 mm. Other radii are achieved. A standard opto-electrical characterization at 80 K of the imager shows no additional short circuit and no mean response alteration compared to a standard IRCMOS shown in reference. Noise is also studied with a black body between 20 and 30°C.

  3. Differentiation of group I and group II strains of Clostridium botulinum by focal plane array Fourier transform infrared spectroscopy.

    PubMed

    Kirkwood, Jonah; Ghetler, Andrew; Sedman, Jacqueline; Leclair, Daniel; Pagotto, Franco; Austin, John W; Ismail, Ashraf A

    2006-10-01

    A method was developed for whole-organism fingerprinting of Clostridium botulinum isolates by focal plane array Fourier transform infrared (FPA-FTIR) spectroscopy. A database of 150,000 infrared spectra of 44 strains of C. botulinum was acquired using a FPA-FTIR imaging spectrometer equipped with a 16 x 16 array detector to evaluate the ability of FTIR spectroscopy to differentiate the 44 strains. The database contained strains from C. botulinum groups I and II producing botulinum neurotoxin of serotypes A, B, E, and F. All strains were grown on each of three agar media (brain heart infusion, McClung Toabe agar base, and universal) prior to spectral acquisition. Given the dependence of the infrared spectra of microorganisms on the composition of the growth medium, the spectra were initially separated into three subsets corresponding to the three growth media employed. However, the replicate spectra of all strains, regardless of growth medium, were properly clustered by hierarchical cluster analysis based on differences in their infrared spectral profiles in three narrow spectral regions (1,428 to 1,412, 1,296 to 1,284, and 1,112 to 1,100 cm(-1)). The dendrogram generated from the FTIR data revealed complete separation between group I and group II strains. The spectral differences between group I and group II strains allowed accurate classification of C. botulinum strains at the group level in two blind validation studies (n = 40). These results demonstrate that FPA-FTIR spectroscopy has the potential for rapid discrimination of group I and group II C. botulinum strains in less than 3 min per sample. PMID:17066916

  4. Demonstration of a two-color 320×256 quantum dots-in-a-well focal plane array

    NASA Astrophysics Data System (ADS)

    Varley, Eric S.; Ramirez, David A.; Brown, Jay S.; Lee, Sang Jun; Stintz, Andreas; Lenz, Michael; Krishna, Sanjay; Reisinger, Axel; Sundaram, Mani

    2007-09-01

    In our research group, we develop novel dots-in-a-well (DWELL) photodetectors that are a hybrid of the quantum dot infrared photodetector (QDIP). The DWELL detector consists of an active region composed of InAs quantum dots embedded in InGaAs quantum wells. By adjusting the InGaAs well thickness, our structure allows for the manipulation of the operating wavelength and the nature of the transitions (bound-to-bound, bound-to-quasibound and bound-to-continuum) of the detector. Based on these principles, DWELL samples were grown using molecular beam epitaxy and fabricated into 320 x 256 focal plane arrays (FPAs) with Indium bumps using standard lithography at the University of New Mexico. The FPA evaluated was hybridized to an Indigo 9705 readout integrated circuit (ROIC) in collaboration with QmagiQ LLC and tested with a CamIRa TM system manufactured by SE-IR Corp. From this evaluation, we report the first two-color, co-located quantum dot based imaging system that can be used to take multicolor images using a single FPA. We demonstrated that we can operate the device at an intermediate bias (V b=-1.25 V) and obtain two color response from the FPA at 77K. Using filter lenses, both MWIR and LWIR responses were obtained from the array at the same bias voltage. The MWIR and LWIR responses are thought to be from bound states in the dot to higher and lower lying states in the quantum well respectively. Temporal NEDT for the DWELL FPA was measured to be 80mK at 77K.

  5. Focal plane arrays for submillimeter waves using two-dimensional electron gas elements: A grant under the Innovative Research Program

    NASA Technical Reports Server (NTRS)

    Yngvesson, K. Sigfrid; Lau, Kei-May

    1992-01-01

    This final report describes a three-year research effort, aimed at developing new types of THz low noise receivers, based on bulk effect ('hot electron') nonlinearities in the Two-Dimensional Electron Gas (2DEG) Medium, and the inclusion of such receivers in focal plane arrays. 2DEG hot electron mixers have been demonstrated at 35 and 94 GHz with three orders of magnitude wider bandwidth than previous hot electron mixers, which use bulk InSb. The 2DEG mixers employ a new mode of operation, which was invented during this program. Only moderate cooling is required for this mode, to temperatures in the range 20-77 K. Based on the results of this research, it is now possible to design a hot electron mixer focal plane array for the THz range, which is anticipated to have a DSB receiver noise temperature of 500-1000K. In our work on this grant, we have found similar results the the Cronin group (resident at the University of Bath, UK). Neither group has so far demonstrated heterodyne detection in this mode, however. We discovered and explored some new effects in the magnetic field mode, and these are described in the report. In particular, detection of 94 GHz and 238 GHz, respectively, by a new effect, 'Shubnikov de Haas detection', was found to be considerably stronger in our materials than the cyclotron resonance detection. All experiments utilized devices with an active 2DEG region of size of the order of 10-40 micrometers long, and 20-200 micrometers wide, formed at the heterojunction between AlGaAs and GaAs. All device fabrication was performed in-house. The materials for the devices were also grown in-house, utilizing OMCVD (Organo Metallic Chemical Vapor Deposition). In the course of this grant, we developed new techniques for growing AlGaAs/GaAs with mobilities equalling the highest values published by any laboratory. We believe that the field of hot electron mixers and detectors will grow substantially in importance in the next few years, partly as a result of

  6. Enchanced interference cancellation and telemetry reception in multipath environments with a single paraboic dish antenna using a focal plane array

    NASA Technical Reports Server (NTRS)

    Mukai, Ryan (Inventor); Vilnrotter, Victor A. (Inventor)

    2011-01-01

    An Advanced Focal Plane Array ("AFPA") for parabolic dish antennas that exploits spatial diversity to achieve better channel equalization performance in the presence of multipath (better than temporal equalization alone), and which is capable of receiving from two or more sources within a field-of-view in the presence of multipath. The AFPA uses a focal plane array of receiving elements plus a spatio-temporal filter that keeps information on the adaptive FIR filter weights, relative amplitudes and phases of the incoming signals, and which employs an Interference Cancelling Constant Modulus Algorithm (IC-CMA) that resolves multiple telemetry streams simultaneously from the respective aero-nautical platforms. This data is sent to an angle estimator to calculate the target's angular position, and then on to Kalman filters FOR smoothing and time series prediction. The resulting velocity and acceleration estimates from the time series data are sent to an antenna control unit (ACU) to be used for pointing control.

  7. Uncooled SWIR InGaAs/GaAsSb type-II quantum well focal plane array

    NASA Astrophysics Data System (ADS)

    Inada, H.; Miura, K.; Mori, H.; Nagai, Y.; Iguchi, Y.; Kawamura, Y.

    2010-04-01

    Low dark current photodiodes (PDs) in the short wavelength infrared (SWIR) upto 2.5μm region, are expected for many applications. HgCdTe (MCT) is predominantly used for infrared imaging applications. However, because of high dark current, MCT device requires a refrigerator such as stirling cooler, which increases power consumption, size and cost of the sensing system. Recently, InGaAs/GaAsSb type II quantum well structures were considered as attractive material system for realizing low dark current PDs owing to lattice-matching to InP substrate. Planar type PIN-PDs were successfully fabricated. The absorption layer with 250 pair-InGaAs(5nm)/GaAsSb(5nm) quantum well structures was grown on S-doped (100) InP substrates by solid source molecular beam epitaxy method. InP and InGaAs were used for cap layer and buffer layer, respectively. The p-n junctions were formed in the absorption layer by the selective diffusion of zinc. Diameter of light-receiving region was 140μm. Low dark current was obtained by improving GaAsSb crystalline quality. Dark current density was 0.92mA/cm2 which was smaller than that of a conventional MCT. Based on the same process as the discrete device, a 320x256 planar type focal plane array was also fabricated. Each PD has 15μm diameter and 30μm pitch and it was bonded to read-out IC by using indium bump flip chip process. Finally, we have successfully demonstrated the 320 x256 SWIR image at room temperature. This result means that planer type PD array with the type II InGaAs/GaAsSb quantum well structure is a promising candidate for uncooled applications.

  8. Modelling ultrasonic array signals in multilayer anisotropic materials using the angular spectrum decomposition of plane wave responses

    NASA Astrophysics Data System (ADS)

    Humeida, Yousif; Pinfield, Valerie J.; Challis, Richard E.

    2013-08-01

    Ultrasonic arrays have seen increasing use for the characterisation of composite materials. In this paper, ultrasonic wave propagation in multilayer anisotropic materials has been modelled using plane wave and angular spectrum decomposition techniques. Different matrix techniques, such as the stiffness matrix method and the transfer matrix method, are used to calculate the reflection and transmission coefficients of ultrasonic plane waves in the considered media. Then, an angular decomposition technique is used to derive the bounded beams from finite-width ultrasonic array elements from the plane wave responses calculated earlier. This model is considered to be an analytical exact solution for the problem; hence the diffraction of waves in such composite materials can be calculated for different incident angles for a very wide range of frequencies. This model is validated against experimental measurements using the Full-Matrix Capture (FMC) of array data in both a homogeneous isotropic material, i.e. aluminium, and an inhomogeneous multilayer anisotropic material, i.e. a carbon fibre reinforced composite.

  9. Linear mode photon counting from visible to MWIR with HgCdTe avalanche photodiode focal plane arrays

    NASA Astrophysics Data System (ADS)

    Sullivan, William; Beck, Jeffrey; Scritchfield, Richard; Skokan, Mark; Mitra, Pradip; Sun, Xiaoli; Abshire, James; Carpenter, Darren; Lane, Barry

    2015-05-01

    Results of characterization data on linear mode photon counting (LMPC) HgCdTe electron-initiated avalanche photodiode (e-APD)focal plane arrays (FPA) are presented that reveal an improved understanding and the growing maturity of the technology. The first successful 2x8 LMPC FPA was fabricated in 2010 [1]. Since then a process validation lot of 2x8 arrays was fabricated. Five arrays from this lot were characterized that replicated the previous 2x8 LMPC array performance. In addition, it was unambiguously verified that readout integrated circuit (ROIC) glow was responsible for most of the false event rate (FER) of the 2010 array. The application of a single layer metal blocking layer between the ROIC and the detector array and optimization of the ROIC biases reduced the FER by an order of magnitude. Photon detection efficiencies (PDEs) of greater than 50% were routinely demonstrated across 5 arrays, with one array reaching a PDE of 70%. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 μm to 25 μm resulting in a 2x increase in E-APD gain from 470 on the 2010 array to 1100 on one of the 2013 FPAs. Mean single photon signal to noise ratios of >12 were demonstrated at excess noise factors of 1.2-1.3. NASA Goddard Space Flight Center (GSFC) performed measurements on the delivered FPA that verified the PDE and FER data.

  10. Array-based photoacoustic spectroscopy

    DOEpatents

    Autrey, S. Thomas; Posakony, Gerald J.; Chen, Yu

    2005-03-22

    Methods and apparatus for simultaneous or sequential, rapid analysis of multiple samples by photoacoustic spectroscopy are disclosed. A photoacoustic spectroscopy sample array including a body having at least three recesses or affinity masses connected thereto is used in conjunction with a photoacoustic spectroscopy system. At least one acoustic detector is positioned near the recesses or affinity masses for detection of acoustic waves emitted from species of interest within the recesses or affinity masses.

  11. Effects of crystallographic plane and co-deposited element on the growth of ion-sputter induced Si nano-cone arrays: a mechanism study

    NASA Astrophysics Data System (ADS)

    Song, Sheng-Chi; Qiu, Ying; Hao, Hong-Chen; Lu, Ming

    2015-06-01

    Self-organized Si nano-cone arrays induced by Ar+ ion sputtering on different Si crystallographic planes with different co-deposited alien atoms are investigated. The Si planes are (100), (110), and (111) ones, and the alien elements are Ta, Mo, Fe, and C, respectively. It is found that the growth of Si nano-cone arrays is insensitive to the initial crystallographic plane, but depends strongly on the co-deposited element. For the same Ar+ ion dose and sample temperature, the smaller the activation energy between the co-deposited element and Si is, the larger the average cone height and base diameter are. It is found that the preferential sputtering does not play an important role in the nano-cone formation. A model based on the concepts of classical surface-curvature-dependent sputtering yield and the formation of stationary silicide is proposed, which explains the observed results. The results of microstructural and compositional analysis support the proposed model.

  12. Shutterless solution for simultaneous focal plane array temperature estimation and nonuniformity correction in uncooled long-wave infrared camera.

    PubMed

    Cao, Yanpeng; Tisse, Christel-Loic

    2013-09-01

    In uncooled long-wave infrared (LWIR) microbolometer imaging systems, temperature fluctuations of the focal plane array (FPA) result in thermal drift and spatial nonuniformity. In this paper, we present a novel approach based on single-image processing to simultaneously estimate temperature variances of FPAs and compensate the resulting temperature-dependent nonuniformity. Through well-controlled thermal calibrations, empirical behavioral models are derived to characterize the relationship between the responses of microbolometer and FPA temperature variations. Then, under the assumption that strong dependency exists between spatially adjacent pixels, we estimate the optimal FPA temperature so as to minimize the global intensity variance across the entire thermal infrared image. We make use of the estimated FPA temperature to infer an appropriate nonuniformity correction (NUC) profile. The performance and robustness of the proposed temperature-adaptive NUC method are evaluated on realistic IR images obtained by a 640 × 512 pixels uncooled LWIR microbolometer imaging system operating in a significantly changed temperature environment. PMID:24085086

  13. Design, fabrication and testing of 17um pitch 640x480 uncooled infrared focal plane array detector

    NASA Astrophysics Data System (ADS)

    Jiang, Lijun; Liu, Haitao; Chi, Jiguang; Qian, Liangshan; Pan, Feng; Liu, Xiang

    2015-10-01

    Uncooled infrared focal plane array (UIRFPA) detectors are widely used in industrial thermography cameras, night vision goggles, thermal weapon sights, as well as automotive night vision systems. To meet the market requirement for smaller pixel pitch and higher resolution, we have developed a 17um pitch 640x480 UIRFPA detector. The detector is based on amorphous silicon (a-Si) microbolometer technology, the readout integrated circuit (ROIC) is designed and manufactured with 0.35um standard CMOS technology on 8 inch wafer, the microbolometer is fabricated monolithically on the ROIC using an unique surface micromachining process developed inside the company, the fabricated detector is vacuum packaged with hermetic metal package and tested. In this paper we present the design, fabrication and testing of the 17um 640x480 detector. The design trade-off of the detector ROIC and pixel micro-bridge structure will be discussed, by comparison the calculation and simulation to the testing results. The novel surface micromachining process using silicon sacrificial layer will be presented, which is more compatible with the CMOS process than the traditional process with polyimide sacrificial layer, and resulted in good processing stability and high fabrication yield. The performance of the detector is tested, with temperature equivalent temperature difference (NETD) less than 60mK at F/1 aperture, operability better than 99.5%. The results demonstrate that the detector can meet the requirements of most thermography and night vision applications.

  14. Effect of the out-of-plane stress on the properties of epitaxial SrTiO{sub 3} films with nano-pillar array on Si-substrate

    SciTech Connect

    Bai, Gang; Xie, Qiyun; Liu, Zhiguo; Wu, Dongmei

    2015-08-21

    A nonlinear thermodynamic formalism has been proposed to calculate the physical properties of the epitaxial SrTiO{sub 3} films containing vertical nano-pillar array on Si-substrate. The out-of-plane stress induced by the mismatch between film and nano-pillars provides an effective way to tune the physical properties of ferroelectric SrTiO{sub 3} films. Tensile out-of-plane stress raises the phase transition temperature and increases the out-of-plane polarization, but decreases the out-of-plane dielectric constant below Curie temperature, pyroelectric coefficient, and piezoelectric coefficient. These results showed that by properly controlling the out-of-plane stress, the out-of-plane stress induced paraelectric-ferroelectric phase transformation will appear near room temperature. Excellent dielectric, pyroelectric, piezoelectric properties of these SrTiO{sub 3} films similar to PZT and other lead-based ferroelectrics can be expected.

  15. 15-micro-m 128 x 128 GaAs/Al(x)Ga(1-x) As Quantum Well Infrared Photodetector Focal Plane Array Camera

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Park, Jin S.; Sarusi, Gabby; Lin, True-Lon; Liu, John K.; Maker, Paul D.; Muller, Richard E.; Shott, Craig A.; Hoelter, Ted

    1997-01-01

    In this paper, we discuss the development of very sensitive, very long wavelength infrared GaAs/Al(x)Ga(1-x)As quantum well infrared photodetectors (QWIP's) based on bound-to-quasi-bound intersubband transition, fabrication of random reflectors for efficient light coupling, and the demonstration of a 15 micro-m cutoff 128 x 128 focal plane array imaging camera. Excellent imagery, with a noise equivalent differential temperature (N E(delta T)) of 30 mK has been achieved.

  16. Enhancing the Bipolar Redox Cycling Efficiency of Plane-Recessed Microelectrode Arrays by Adding a Chemically Irreversible Interferent.

    PubMed

    He, Dingwen; Yan, Jiawei; Zhu, Feng; Zhou, Yongliang; Mao, Bingwei; Oleinick, Alexander; Svir, Irina; Amatore, Christian

    2016-09-01

    The individual electrochemical anodic responses of dopamine (DA), epinephrine (EP), and pyrocatechol (CT) were investigated at arrays of recessed gold disk-microelectrodes arrays (MEAs) covered by a gold plane electrode and compared to those of their binary mixture (CT and EP) when the top-plane electrode was operated as a bipolar electrode or as a collector. The interferent species (EP) displays a chemically irreversible wave over the same potential range as the chemically reversible ones of DA or CT. As expected, in the generator-collector (GC) mode, EP did not contribute to the redox cycling amplification that occurred only for DA or CT. Conversely, in the bipolar mode, the presence of EP drastically increased the bipolar redox cycling efficiency of DA and CT. This evidenced that the chemically irreversible oxidation of EP at the anodic poles of the top plane floating electrode provided additional electron fluxes that were used to more efficiently reduce the oxidized DA or CT species at the cathodic poles. This suggests an easy experimental strategy for enhancing the bipolar efficiency of MEAs up to reach a performance identical to that achieved when the same MEAs are operated in a GC mode. PMID:27490270

  17. Ultra-low dark current InGaAs technology for focal plane arrays for low-light level visible-shortwave infrared imaging

    NASA Astrophysics Data System (ADS)

    Onat, Bora M.; Huang, Wei; Masaun, Navneet; Lange, Michael; Ettenberg, Martin H.; Dries, Christopher

    2007-04-01

    Under the DARPA Photon Counting Arrays (PCAR) program we have investigated technologies to reduce the overall noise level in InGaAs based imagers for identifying a man at 100m under low-light level imaging conditions. We report the results of our experiments comprising of 15 InGaAs wafers that were utilized to investigate lowering dark current in photodiode arrays. As a result of these experiments, we have achieved an ultra low dark current of 2nA/cm2 through technological advances in InGaAs detector design, epitaxial growth, and processing at a temperature of +12.3 degrees C. The InGaAs photodiode array was hybridized to a low noise readout integrated circuit, also developed under this program. The focal plane array (FPA) achieves very high sensitivity in the shortwave infrared bands in addition to the visible response added via substrate removal process post hybridization. Based on our current room-temperature stabilized SWIR camera platform, these imagers enable a full day-night imaging capability and are responsive to currently fielded covert laser designators, illuminators, and rangefinders. In addition, improved haze penetration in the SWIR compared to the visible provides enhanced clarity in the imagery of a scene. In this paper we show the results of our dark current studies as well as FPA characterization of the camera built under this program.

  18. A method for synthesis of small arrays of printed dipole antennas backed by a ground plane

    NASA Astrophysics Data System (ADS)

    Popovic, Branko D.

    1987-11-01

    A method is proposed for synthesis of antenna arrays consisting of narrow strip-dipole antennas printed on a thin dielectric substrate. Approximately antiresonant dipoles (i.e., dipoles about one wavelength long) are considered, because by moderate variation of their width and length their impedance can be varied in a wide range. A method for analysis of such arrays is described first, in which the printed strip dipoles are replaced by approximately equivalent circular-cylindrical dipoles with coaxial magnetic coating, using recently proposed generalization of equivalent radius of thin cylindrical antennas. An interactive optimization procedure is next applied for synthesis, which enables arrays to be obtained having array radiation pattern and, particularly, dipole impedances close to the desired.

  19. Non-redundant hexagonal array configurations for optical interferometric systems compactly covering central domains in the spatial-frequency plane

    NASA Astrophysics Data System (ADS)

    Kopilovich, L. E.

    2005-07-01

    Two-dimensional non-redundant arrays are used in many applications, in particular as pupil masks in imaging contexts. The problem of arranging a mask with a given element number on a hexagonal grid, providing the complete coverage of central domain of maximum radius in the spatial-frequency plane is considered here. Diagrams show optimum configurations having third-order symmetry which were found for 12, 15, 18 and 21 elements. Their autocorrelations illustrate the extent to which the central domain of the spatial-frequency plane is covered. The case of a greater element number is also discussed. Optimum configurations with 24 and 30 elements are found using Baumert's tables of cyclic difference sets.

  20. Spatial modeling of optical crosstalk in InGaAsP Geiger-mode APD focal plane arrays.

    PubMed

    Piccione, Brian; Jiang, Xudong; Itzler, Mark A

    2016-05-16

    We report a spatial model of optical crosstalk in InGaAsP Geiger-mode APD focal plane arrays created via non-sequential ray tracing. Using twenty-four equivalent experimental data sets as a baseline, we show that experimental results can be reproduced to a high degree of accuracy by incorporating secondary crosstalk effects, with reasonable assumptions of material and emission source properties. We use this model to categorize crosstalk according to source and path, showing that the majority of crosstalk in the immediate neighborhood of avalanching pixels in the present devices can be attributed to direct line-of-sight emissions. PMID:27409885

  1. Infrared hyperspectral imaging using a broadly tunable external cavity quantum cascade laser and microbolometer focal plane array

    SciTech Connect

    Phillips, Mark C.; Ho, Nicolas

    2008-02-04

    A versatile mid-infrared hyperspectral imaging system is demonstrated by combining a broadly tunable external cavity quantum cascade laser and a microbolometer focal plane array. The tunable mid-infrared laser provided high brightness illumination over a tuning range from 985 cm-1 to 1075 cm-1 (9.30-10.15 μm). Hypercubes containing images at 300 wavelengths separated by 0.3 cm 1 were obtained in 12 s. High spectral resolution chemical imaging of methanol vapor was demonstrated for both static and dynamic systems. The system was also used to image and characterize multiple component liquid and solid samples.

  2. Experimental implementations of 2D IR spectroscopy through a horizontal pulse shaper design and a focal plane array detector.

    PubMed

    Ghosh, Ayanjeet; Serrano, Arnaldo L; Oudenhoven, Tracey A; Ostrander, Joshua S; Eklund, Elliot C; Blair, Alexander F; Zanni, Martin T

    2016-02-01

    Aided by advances in optical engineering, two-dimensional infrared spectroscopy (2D IR) has developed into a promising method for probing structural dynamics in biophysics and material science. We report two new advances for 2D IR spectrometers. First, we report a fully reflective and totally horizontal pulse shaper, which significantly simplifies alignment. Second, we demonstrate the applicability of mid-IR focal plane arrays (FPAs) as suitable detectors in 2D IR experiments. FPAs have more pixels than conventional linear arrays and can be used to multiplex optical detection. We simultaneously measure the spectra of a reference beam, which improves the signal-to-noise by a factor of 4; and two additional beams that are orthogonally polarized probe pulses for 2D IR anisotropy experiments. PMID:26907414

  3. The CHROMA focal plane array: a large-format, low-noise detector optimized for imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Demers, Richard T.; Bailey, Robert; Beletic, James W.; Bernd, Steve; Bhargava, Sidharth; Herring, Jason; Kobrin, Paul; Lee, Donald; Pan, Jianmei; Petersen, Anders; Piquette, Eric; Starr, Brian; Yamamoto, Matthew; Zandian, Majid

    2013-09-01

    The CHROMA (Configurable Hyperspectral Readout for Multiple Applications) is an advanced Focal Plane Array (FPA) designed for visible-infrared imaging spectroscopy. Using Teledyne's latest substrateremoved HgCdTe detector, the CHROMA FPA has very low dark current, low readout noise and high, stable quantum efficiency from the deep blue (390nm) to the cutoff wavelength. CHROMA has a pixel pitch of 30 microns and is available in array formats ranging from 320×480 to 1600×480 pixels. Users generally disperse spectra over the 480 pixel-length columns and image spatially over the n×160 pixellength rows, where n=2, 4, 8, 10. The CHROMA Readout Integrated Circuit (ROIC) has Correlated Double Sampling (CDS) in pixel and generates its own internal bias signals and clocks. This paper presents the measured performance of the CHROMA FPA with 2.5 micron cutoff wavelength including the characterization of noise versus pixel gain, power dissipation and quantum efficiency.

  4. A novel 512×8 ROIC with time-delayed-integration for MW infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-ling; Feng, Qi; Chen, Hong-lei; Huang, Ai-bo; Ding, Rui-jun; Ni, Yun-zhi

    2011-08-01

    In this paper a novel 512×8 readout circuit (ROIC) with time delayed integration (TDI) for middle wave (MW) infrared focal plane array (IRFPA) is present. As we known TDI is delicately devised and used in readout circuit to effectively increase the integration time and reduce the photon noise. At the same time, the bucket-brigade device (BBD) structure is commonly used in TDI implementation due to its simplicity and small size in integration. We adopt eight-stage BBD structure to get higher Signal-to-Noise ratio (SNR) and achieve faster image scanning speed for linear IRFPA in the 3μm -5μm spectral band. Because the center distance between each pixel is 28μm×56μm, an input stage based on direct injection (DI) which has high injection ratio and small layout area is proved to be suitable in this design. The detector consists of two segments in a staggered format that reads out synchronously. In order to achieve high flexibility, integration time can be controlled and the defective pixels can be de-selection manually. Some other features such as bidirectional operation, integration time, readout mode, an adaptive charge capacity control method and power consumption are also discussed in this article. The novel 512×8 ROIC is fabricated with 0.6μm double poly double metal CMOS technology and interconnected with MW IRFPA using indium bump. The experiments show that our method can achieve good performance of integration of MW signal both at room temperature and at 77K low temperature. The power consumption of the circuit is about 30mW at 5V supply and the readout clock frequency is up to 4MHz.

  5. Stray light reduction in testing of NIRSpec subsystems: the focal plane array and micro-shutter assembly

    NASA Astrophysics Data System (ADS)

    Connelly, Joseph A.; Hadjimichael, Theo J.; Boucarut, Rene A.; Tveekrem, June L.; Mott, D. Brent

    2006-08-01

    The James Webb Space Telescope (JWST) is an infrared, space-based telescope scheduled for launch in 2013. JWST will hold four scientific instruments, including the Near Infrared Spectrograph (NIRSpec). NIRSpec operates in the wavelength range from 0.6 to 5 microns, and will be assembled by the European Space Agency. NASA/Goddard Space Flight Center (GSFC) is responsible for two NIRSpec subsystems: the detector subsystem, with the focal plane array (FPA), and the micro-shutter subsystem, with the micro-shutter assembly (MSA). The FPA consists of two side-by-side Rockwell Scientific HgCdTe 2Kx2K detectors, with the detectors and readout electronics optimized for low noise. The MSA is a GSFC developed micro-electro-mechanical system (MEMS) that serves as a programmable slit mask, allowing NIRSpec to obtain simultaneous spectra of >100 objects in a single field of view. We present the optical characterization test plan of the FPA. The test plan is driven by many requirements: cryogenic operating temperature, a flight-like beam shape, and multi-wavelength flux from 1 to 10,000 photons per second, thus low stray light is critical. We use commercial optical modeling software to predict stray light effects at the FPA. We also present the optical contrast test plan of the MSA. Each individual shutter element operates in an on/off state, and the most important optical metric is contrast. The MSA is designed to minimize stray and scattered light, and the test setup reduces stray light such that the optical contrast is measurable.

  6. The vertical photoconductor: A novel device structure suitable for HgCdTe two-dimensional infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Siliquini, J. F.; Faraone, L.

    1997-06-01

    A novel photoconductive device structure is proposed and described that has been designed specifically as a sensing element for high density two-dimensional infrared focal plane array (IRFPA) applications. Although the design concept can be applied to a variety of epitaxially grown HgCdTe material, optimum performance can be achieved using n-type HgCdTe semiconductor material consisting of epitaxially grown heterostructure layers in which a two-dimensional mosaic of vertical design photoconductors are fabricated. The heterostructure layers provide high performance devices at greatly reduced power dissipation levels, while the vertical design allows for the high density integration of photoconductors in a two-dimensional array geometry with high fill factor. The salient feature of the proposed device structure is that the bias field is applied in the vertical direction such that it is parallel to the impinging infrared radiation. A comprehensive one-dimensional model is presented for the vertical design photoconductor, which is subsequently used to determine the optimum design parameters in order to achieve maximum responsivity at the lowest possible power dissipation level. It is found that the proposed device structure has the potential to be used in the fabrication of long wavelength IRFPAs approaching 10 6 pixels using 25 × 25 μm 2 detector elements. Furthermore, this is achieved with individual device detectivities that are background limited and for a total array power dissipation of less than 0.1 W using a pulsed biasing scheme. Performance issues such as response uniformity, pixel yield, fill factor, crosstalk, power dissipation, detector impedance, array architecture, and maximum array size are discussed in relation to the suitability of the proposed vertical photoconductor structure for use in IRFPA modules. When considering IRFPA operability, it is found that in many cases the proposed technology has the potential to deliver significant advantages, such

  7. Real-time, continuous-wave terahertz imaging using a microbolometer focal-plane array

    NASA Technical Reports Server (NTRS)

    Hu, Qing (Inventor); Min Lee, Alan W. (Inventor)

    2010-01-01

    The present invention generally provides a terahertz (THz) imaging system that includes a source for generating radiation (e.g., a quantum cascade laser) having one or more frequencies in a range of about 0.1 THz to about 10 THz, and a two-dimensional detector array comprising a plurality of radiation detecting elements that are capable of detecting radiation in that frequency range. An optical system directs radiation from the source to an object to be imaged. The detector array detects at least a portion of the radiation transmitted through the object (or reflected by the object) so as to form a THz image of that object.

  8. The Constellation-X Focal Plane Microcalorimeter Array: An NTD-Germanium Solution

    NASA Technical Reports Server (NTRS)

    Beeman, J.; Silver, E.; Bandler, S.; Schnopper, H.; Murray, S.; Madden, N.; Landis, D.; Haller, E. E.; Barbera, M.

    2001-01-01

    The hallmarks of Neutron Transmutation Doped (NTD) germanium cryogenic thermistors include high reliability, reproducibility, and long term stability of bulk carrier transport properties. Using micro-machined NTD Ge thermistors with integral 'flying' leads, we can now fabricate two-dimensional arrays that are built up from a series of stacked linear arrays. We believe that this modular approach of building, assembling, and perhaps replacing individual modules of detectors is essential to the successful fabrication and testing of large multi-element instruments. Details of construction are presented.

  9. An IR focal plane array employing superconducting Josephson junction thermal detectors

    NASA Astrophysics Data System (ADS)

    Osterman, D. P.; Yao, C.-T.; Dang, H.; Cohen, C.; Radparvar, M.

    1990-07-01

    Thin-film superconductors invite the single-process/single-substrate fabrication of IR detector arrays and their associated processing circuitry. In place of the bolometric thermal-detection principle typical of previous superconductor-employing schemes, the temperature-dependence of the current-voltage relation in a current-biased Josephson tunnel junction is used in the present device; this yields very low intrinsic detector noise, as well as clearly-defined 'on' and 'off' states. Superconducting processing circuitry encompassing addressing and decoding circuits, analog amplifiers, and ADC has been tested for an 8 x 8 prototype array.

  10. Microfabrication and Device Parameter Testing of the Focal Plane Arrays for the Spider and BICEP2/Keck CMB Polarimeters

    NASA Astrophysics Data System (ADS)

    Bonetti, J. A.; Turner, A. D.; Kenyon, M.; Orlando, A.; Brevik, J. A.; Trangsrud, A.; Sudiwala, R.; Leduc, H. G.; Nguyen, H. T.; Day, P. K.; Bock, J. J.; Golwala, S. R.; Sayers, J.; Kovac, J. M.; Lange, A. E.; Jones, W. C.; Kuo, C. L.

    2009-12-01

    Spider and BICEP2/Keck are projects to study the polarization of the cosmic microwave background (CMB). The focal planes for both require large format arrays of superconducting transition edge sensors (TES's). A major challenge for these projects is fabricating arrays with high uniformity in device parameters. A microfabrication process is described that meets this challenge. The results from device testing are discussed. Each focal plane is composed of 4 square wafers (tiles), and each wafer contains 128 membrane-isolated, polarization-sensitive, antenna-coupled TES's. After processing, selected wafers are pre-screened in a quick-turn-around, cryogen-free, 3He fridge. The pre-screening is performed with a commercial resistance bridge and measures transition temperatures (Tc) and normal state resistances (Rn). After pre-screening, 4 tiles at a time are fully characterized in a testbed employing a SQUID readout and SQUID mulitplexing. The tests demonstrate the values of Tc, Rn, thermal conductance, g, and the standard deviations of each, across a wafer and from wafer to wafer, are within design specifications.

  11. Pyroelectric infrared linear arrays based on PIMNT

    NASA Astrophysics Data System (ADS)

    Ma, Xueliang; Shao, Xiumei; Yu, Yuehua; Luo, Haosu; Liu, Linhua; Xia, Wang; Li, Yanjin

    2012-10-01

    Pyroelectric infrared linear arrays can work at ambient temperature without cryogenic system and have the merits of comparatively homogenous spectral response in wide spectrum range, compact structure, long-time stability and low cost for many applications. xPb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)O3-(1-x-y)PbTiO3 (PIMNT) single crystal is a kind of novel pyroelectric material, which possesses superior pyroelectric performances and is appraised as a candidate for high performance pyroelectric infrared linear arrays. This paper describes the layout and essential properties of the pyroelectric infrared linear arrays based on PIMNT with 128 responsive elements. The transmittance measurement of PIMNT indicates that an absorption layer is needed when the PIMNT based linear arrays work at room temperature in 0.8 - 12.0 μm wave range due to the low absorption ratio especially in 0.8 - 10.0 μm wave band. The arrays employ a hybrid structure consisting of the PIMNT pyroelectric chip and CMOS read-out circuit. They are electrically bonded by ultrasonic bonding process. Also some details of the process technologies of the PIMNT pyroelectric chip are depicted in this paper.

  12. Solar-blind AlGaN 256x256 p-i-n detectors and focal plane arrays

    NASA Astrophysics Data System (ADS)

    Reine, M. B.; Hairston, A.; Lamarre, P.; Wong, K. K.; Tobin, S. P.; Sood, A. K.; Cooke, C.; Pophristic, M.; Guo, S.; Peres, B.; Singh, R.; Eddy, C. R., Jr.; Chowdhury, U.; Wong, M. M.; Dupuis, R. D.; Li, T.; DenBaars, S. P.

    2006-02-01

    This paper reports the development of aluminum-gallium nitride (AlGaN or Al xGa 1-xN) photodiode technology for high-operability 256×256 hybrid Focal Plane Arrays (FPAs) for solar-blind ultraviolet (UV) detection in the 260-280 nm spectral region. These hybrid UV FPAs consist of a 256×256 back-illuminated AlGaN p-i-n photodiode array, operating at zero bias voltage, bump-mounted to a matching 256×256 silicon CMOS readout integrated circuit (ROIC) chip. The unit cell size is 30×30 μm2. The photodiode arrays were fabricated from multilayer AlGaN films grown by MOCVD on 2" dia. UV-transparent sapphire substrates. Improvements in AlGaN material growth and device design enabled high quantum efficiency and extremely low leakage current to be achieved in high-operability 256×256 p-i-n photodiode arrays with cuton and cutoff wavelengths of 260 and 280 nm, placing the response in the solar-blind wavelength region (less than about 280 nm) where solar radiation is heavily absorbed by the ozone layer. External quantum efficiencies (at V=0, 270 nm, no antireflection coating) as high as 58% were measured in backilluminated devices. A number of 256×256 FPAs, with the AlGaN arrays fabricated from films grown at three different facilities, achieved response operabilities as high as 99.8%, response nonuniformities (σ/μ) as low as 2.5%, and zero-bias resistance median values as high as 1×10 16 ohm, corresponding to R 0A products of 7×10 10 ohm-cm2. Noise Equivalent Irradiance (NEI) data were measured on these FPAs. Median NEI values at 1 Hz are 250-500 photons/pixel-s, with best-element values as low as 90 photons/pixel-s at 1 Hz.

  13. Plane wave based selfconsistent solution of the GW Dyson equation

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Wang; Cao, Huawei

    We have developed a selfconsistent procedure to calculate the full Dyson equation based on plane wave basis set. The whole formalism is based on the Greens function matrix of the plane wave G-vector. There is no truncation of the conduction band when the dielectric function is calculated. The Dyson equation is the variational minimum solution of the total energy in terms of the Greens function. The calculation uses the ''space-time'' method, with special algorithm for imaginary time integration and Fourier transformation. We have tested isolated molecules and periodic systems. The effects of selfconsistency compared to the G0W0 results will be presented. We will also discuss some special techniques used in the k-point summation for the periodic system. Massive parallelization is used to carry out such calculations. This work is supported by the Director, SC/BES/MSED of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, through the Material Theory program at Lawrence Berkeley National Laboratory.

  14. Commercial and industrial applications of indium gallium arsenide near-infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Cohen, Marshall J.; Ettenberg, Martin H.; Lange, Michael J.; Olsen, Gregory H.

    1999-07-01

    Sensors Unlimited, Inc. has developed focal pane arrays (FPAs) fabricated with indium gallium arsenide (InGaAs) photodiode arrays and silicon CMOS readout integrated circuits. These devices are readily available in a wide variety of formats suitable for commercial and industrial applications. InGaAs FPAs are sensitive to the near IR, operate without cooling, and come in both 2D formats and 1D formats. 1D InGaAs FPAs are used as both spectroscopic detectors and line scan imagers. Key applications include miniature spectrometers used for wavelength control and monitoring of WDM laser sources, octane determination, the sorting o plastics during recycling, and web process control. 2D InGaAs FPAs find use in applications such as laser beam profiling, visualization of 'clear' ice on aircraft and roadways, and industrial thermal imaging.

  15. An abuttable CCD imager for visible and X-ray focal plane arrays

    NASA Technical Reports Server (NTRS)

    Burke, Barry E.; Mountain, Robert W.; Harrison, David C.; Bautz, Marshall W.; Doty, John P.

    1991-01-01

    A frame-transfer silicon charge-coupled-device (CCD) imager has been developed that can be closely abutted to other imagers on three sides of the imaging array. It is intended for use in multichip arrays. The device has 420 x 420 pixels in the imaging and frame-store regions and is constructed using a three-phase triple-polysilicon process. Particular emphasis has been placed on achieving low-noise charge detection for low-light-level imaging in the visible and maximum energy resolution for X-ray spectroscopic applications. Noise levels of 6 electrons at 1-MHz and less than 3 electrons at 100-kHz data rates have been achieved. Imagers have been fabricated on 1000-Ohm-cm material to maximize quantum efficiency and minimize split events in the soft X-ray regime.

  16. Digital pixel CMOS focal plane array with on-chip multiply accumulate units for low-latency image processing

    NASA Astrophysics Data System (ADS)

    Little, Jeffrey W.; Tyrrell, Brian M.; D'Onofrio, Richard; Berger, Paul J.; Fernandez-Cull, Christy

    2014-06-01

    A digital pixel CMOS focal plane array has been developed to enable low latency implementations of image processing systems such as centroid trackers, Shack-Hartman wavefront sensors, and Fitts correlation trackers through the use of in-pixel digital signal processing (DSP) and generic parallel pipelined multiply accumulate (MAC) units. Light intensity digitization occurs at the pixel level, enabling in-pixel DSP and noiseless data transfer from the pixel array to the peripheral processing units. The pipelined processing of row and column image data prior to off chip readout reduces the required output bandwidth of the image sensor, thus reducing the latency of computations necessary to implement various image processing systems. Data volume reductions of over 80% lead to sub 10μs latency for completing various tracking and sensor algorithms. This paper details the architecture of the pixel-processing imager (PPI) and presents some initial results from a prototype device fabricated in a standard 65nm CMOS process hybridized to a commercial off-the-shelf short-wave infrared (SWIR) detector array.

  17. 256 x 256 PACE-1 PV HgCdTe focal plane arrays for medium and short wavelength infrared applications

    NASA Technical Reports Server (NTRS)

    Kozlowski, L. J.; Vural, K.; Johnson, V. H.; Chen, J. K.; Bailey, R. B.

    1990-01-01

    The development of two 256 by 256 hybrid HgCdTe focal plane array (FPA) families is described, and their performance is discussed. The hybrid FPAs employ a PV HgCdTe detector array and custom Si CMOS readouts. The PACE-1 process was used to fabricate the detectors, whereby the liquid phase epitaxial growth of HgCdTe occurs on sapphire substrates buffered by a layer of CdTe. The performance characteristics of the detector arrays are given. A tactical 256 by 256 CMOS readout is tested, in which a high functional yield was achieved. Updated test results are given for a 256 by 256 readout circuit developed for use in an orbital replacement instrument for the Hubble Space Telescope. The characterizations of several MWIR and SWIR FPAs were thorough and shown to be reliable. The pixel yield, maximum FPA responsivity nonuniformity, and SWIR FPA read noise for the tests are given. The high contrast and insignificant fixed pattern noise of the imagery from the MWIR 256 by 256 FPA are emphasized. These qualities were obtained when the device was operating at 80 k and utilizing f/2 optics with an 8-in. focal length and a 4.4 micron high pass filter.

  18. 256 X 256 PACE-1 PV HgCdTe focal plane arrays for medium and short wavelength infrared applications

    NASA Astrophysics Data System (ADS)

    Kozlowski, L. J.; Vural, K.; Johnson, V. H.; Chen, J. K.; Bailey, R. B.

    1990-09-01

    The development of two 256 by 256 hybrid HgCdTe focal plane array (FPA) families is described, and their performance is discussed. The hybrid FPAs employ a PV HgCdTe detector array and custom Si CMOS readouts. The PACE-1 process was used to fabricate the detectors, whereby the liquid phase epitaxial growth of HgCdTe occurs on sapphire substrates buffered by a layer of CdTe. The performance characteristics of the detector arrays are given. A tactical 256 by 256 CMOS readout is tested, in which a high functional yield was achieved. Updated test results are given for a 256 by 256 readout circuit developed for use in an orbital replacement instrument for the Hubble Space Telescope. The characterizations of several MWIR and SWIR FPAs were thorough and shown to be reliable. The pixel yield, maximum FPA responsivity nonuniformity, and SWIR FPA read noise for the tests are given. The high contrast and insignificant fixed pattern noise of the imagery from the MWIR 256 by 256 FPA are emphasized. These qualities were obtained when the device was operating at 80 k and utilizing f/2 optics with an 8-in. focal length and a 4.4 micron high pass filter.

  19. A 25μm pitch LWIR staring focal plane array with pixel-level 15-bit ADC ROIC achieving 2mK NETD

    NASA Astrophysics Data System (ADS)

    Bisotto, Sylvette; de Borniol, Eric; Mollard, Laurent; Guellec, Fabrice; Peizerat, Arnaud; Tchagaspanian, Micha"l.; Castelein, Pierre; Maillart, Patrick

    2010-10-01

    CEA-Leti MINATEC has been involved in infrared focal plane array (IRFPA) development since many years, with performing HgCdTe in-house process from SWIR to LWIR and more recently in focusing its work on new ROIC architectures. The trend is to integrate advanced functions into the CMOS design for the purpose of applications demanding a breakthrough in Noise Equivalent Temperature Difference (NETD) performances (reaching the mK in LWIR band) or a high dynamic range (HDR) with high-gain APDs. In this paper, we present a mid-TV format focal plane array (FPA) operating in LWIR with 25μm pixel pitch, including a new readout IC (ROIC) architecture based on pixel-level charge packets counting. The ROIC has been designed in a standard 0.18μm 6-metal CMOS process, LWIR n/p HgCdTe detectors were fabricated with CEA-Leti in-house process. The FPA operates at 50Hz frame rate in a snapshot integrate-while-read (IWR) mode, allowing a large integration time. While classical pixel architectures are limited by the charge well capacity, this architecture exhibits a large well capacity (near 3Ge-) and the 15-bit pixel level ADC preserves an excellent signal-to-noise ratio (SNR) at full well. These characteristics are essential for LWIR FPAs as broad intra-scene dynamic range imaging requires high sensitivity. The main design challenges for this digital pixel array (SNR, power consumption and layout density) are discussed. The electro-optical results demonstrating a peak NETD value of 2mK and images taken with the FPA are presented. They validate both the pixel-level ADC concept and its circuit implementation. A previously unreleased SNR of 90dB is achieved.

  20. Plane-wise sensitivity based inhomogeneous excitation fields for magnetorelaxometry imaging of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Baumgarten, Daniel; Braune, Friedemann; Supriyanto, Eko; Haueisen, Jens

    2015-04-01

    Promising biomedical applications of magnetic nanoparticles share the need for a quantitative knowledge of their in vivo distribution. From multichannel magnetorelaxometry measurements with sequential activation of inhomogeneous excitation fields, the distribution can be quantitatively determined. In first studies, single excitation coils were consecutively activated. We aim at further advancing this imaging technology by suitable activation patterns involving multiple excitation coils. In this work, we propose the estimation of these patterns based on the spatial sensitivity in order to reduce the number of required measurements. The sensitivity of a voxel carrying magnetic nanoparticles is determined by its position relative to the sensors and the excitation field. Whereas the position is fixed within a given setup, the excitation is controlled by the currents in the coils. The currents required for a defined target sensitivity are estimated by solving an inverse problem. In our work, two target sensitivity paradigms are presented: (a) plane-wise activation, where only one plane with high sensitivities is sought and moved through the source space and (b) plane-wise non-activation, where all voxels except for one plane should receive high sensitivity. Our approach is investigated in simulation studies using a setup with a cubic region of interest and a planar sensor array. The imaging quality of both activation paradigms is evaluated. Our results demonstrate the principal applicability of this spatial sensitivity based approach for defining inhomogeneous activation patterns. The obtained patterns allow for a similar imaging quality using a lower number of activation sequences compared to the conventional single coil activation.

  1. A 25μm pitch LWIR focal plane array with pixel-level 15-bit ADC providing high well capacity and targeting 2mK NETD

    NASA Astrophysics Data System (ADS)

    Guellec, Fabrice; Peizerat, Arnaud; Tchagaspanian, Michael; de Borniol, Eric; Bisotto, Sylvette; Mollard, Laurent; Castelein, Pierre; Zanatta, Jean-Paul; Maillart, Patrick; Zecri, Michel; Peyrard, Jean-Christophe

    2010-04-01

    CEA Leti has recently developed a new readout IC (ROIC) with pixel-level ADC for cooled infrared focal plane arrays (FPAs). It operates at 50Hz frame rate in a snapshot Integrate-While-Read (IWR) mode. It targets applications that provide a large amount of integrated charge thanks to a long integration time. The pixel-level analog-to-digital conversion is based on charge packets counting. This technique offers a large well capacity that paves the way for a breakthrough in NETD performances. The 15 bits ADC resolution preserves the excellent detector SNR at full well (3Ge-). These characteristics are essential for LWIR FPAs as broad intra-scene dynamic range imaging requires high sensitivity. The ROIC, featuring a 320x256 array with 25μm pixel pitch, has been designed in a standard 0.18μm CMOS technology. The main design challenges for this digital pixel array (SNR, power consumption and layout density) are discussed. The IC has been hybridized to a LWIR detector fabricated using our in-house HgCdTe process. The first electro-optical test results of the detector dewar assembly are presented. They validate both the pixel-level ADC concept and its circuit implementation. Finally, the benefit of this LWIR FPA in terms of NETD performance is demonstrated.

  2. Joint FDTD-Optical/FEM-Electrical Numerical Simulation of Reflection-Type Subwavelength-Microstructure InSb Infrared Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    He, J. L.; Hu, W. D.; Ye, Z. H.; Lv, Y. Q.; Chen, X. S.; Lu, W.

    2016-09-01

    The design of a reflection-type subwavelength microstructure has been numerically investigated to concentrate incident light onto pixels for improved photoresponse of InSb infrared focal-plane arrays. Compared with traditional microlenses placed on top of the detector substrate, this reflection-type microstructure is better suited for extremely small pixel pitches. The structure is simulated using a joint numerical method combining the finite-difference time-domain method based on Maxwell's curl equations and the finite-element method based on the Poisson and continuity equations. The results show that this advanced design could effectively improve device response without sacrificing crosstalk. The optimal structure parameters are obtained theoretically, with response increase of approximately 100%.

  3. Joint FDTD-Optical/FEM-Electrical Numerical Simulation of Reflection-Type Subwavelength-Microstructure InSb Infrared Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    He, J. L.; Hu, W. D.; Ye, Z. H.; Lv, Y. Q.; Chen, X. S.; Lu, W.

    2016-05-01

    The design of a reflection-type subwavelength microstructure has been numerically investigated to concentrate incident light onto pixels for improved photoresponse of InSb infrared focal-plane arrays. Compared with traditional microlenses placed on top of the detector substrate, this reflection-type microstructure is better suited for extremely small pixel pitches. The structure is simulated using a joint numerical method combining the finite-difference time-domain method based on Maxwell's curl equations and the finite-element method based on the Poisson and continuity equations. The results show that this advanced design could effectively improve device response without sacrificing crosstalk. The optimal structure parameters are obtained theoretically, with response increase of approximately 100%.

  4. Stretchable and transparent electrodes based on in-plane structures

    NASA Astrophysics Data System (ADS)

    Kim, Kukjoo; Kim, Joohee; Hyun, Byung Gwan; Ji, Sangyoon; Kim, So-Yun; Kim, Sungwon; An, Byeong Wan; Park, Jang-Ung

    2015-08-01

    Stretchable electronics has attracted great interest with compelling potential applications that require reliable operation under mechanical deformation. Achieving stretchability in devices, however, requires a deeper understanding of nanoscale materials and mechanics beyond the success of flexible electronics. In this regard, tremendous research efforts have been dedicated toward developing stretchable electrodes, which are one of the most important building blocks for stretchable electronics. Stretchable transparent thin-film electrodes, which retain their electrical conductivity and optical transparency under mechanical deformation, are particularly important for the favourable application of stretchable devices. This minireview summarizes recent advances in stretchable transparent thin-film electrodes, especially employing strategies based on in-plane structures. Various approaches using metal nanomaterials, carbon nanomaterials, and their hybrids are described in terms of preparation processes and their optoelectronic/mechanical properties. Some challenges and perspectives for further advances in stretchable transparent electrodes are also discussed.

  5. Stretchable and transparent electrodes based on in-plane structures.

    PubMed

    Kim, Kukjoo; Kim, Joohee; Hyun, Byung Gwan; Ji, Sangyoon; Kim, So-Yun; Kim, Sungwon; An, Byeong Wan; Park, Jang-Ung

    2015-09-21

    Stretchable electronics has attracted great interest with compelling potential applications that require reliable operation under mechanical deformation. Achieving stretchability in devices, however, requires a deeper understanding of nanoscale materials and mechanics beyond the success of flexible electronics. In this regard, tremendous research efforts have been dedicated toward developing stretchable electrodes, which are one of the most important building blocks for stretchable electronics. Stretchable transparent thin-film electrodes, which retain their electrical conductivity and optical transparency under mechanical deformation, are particularly important for the favourable application of stretchable devices. This minireview summarizes recent advances in stretchable transparent thin-film electrodes, especially employing strategies based on in-plane structures. Various approaches using metal nanomaterials, carbon nanomaterials, and their hybrids are described in terms of preparation processes and their optoelectronic/mechanical properties. Some challenges and perspectives for further advances in stretchable transparent electrodes are also discussed. PMID:26287668

  6. World's first demonstration of type-II superlattice dual band 640x512 LWIR focal plane array

    NASA Astrophysics Data System (ADS)

    Huang, Edward Kwei-wei; Razeghi, Manijeh

    2012-01-01

    High resolution multi-band infrared detection of terrestrial objects is useful in applications such as long range and high altitude surveillance. In this paper, we present a 640 by 512 type-II superlattice focal plane array (FPA) in the long-wave infrared (LWIR) suitable for such purposes, featuring 100% cutoff wavelengths at 9.5μm (blue channel) and 13μm (red). The dual band camera is single-bump hybridized to an Indigo 30μm pitch ISC0905 read-out integrated circuit. Test pixels revealed background limited behavior with specific detectivities as high as ~5x1011 Jones at 7.9μm (blue) and ~1x1011 Jones at 10.2μm (red) at 77K.

  7. InGaAs focal plane arrays and cameras for man-portable near-infrared imaging

    NASA Astrophysics Data System (ADS)

    Ettenberg, Martin H.; Cohen, Marshall J.; Olsen, Gregory H.; Kennedy, James J.

    1999-07-01

    During this presentation, the status of the technology will be described and prototype applications will be demonstrated and discussed. Included in the discussion will be: (1) the ability to distinguish camouflage from the surrounding environment, (2) the ability to see through fog that is opaque to visible imagers, (3) the ability to image eye-safe lasers for range-finding and target-acquisition, and (4) the use in conjunction with NIR flood lights for both covert surveillance and search and rescue operations. The high room-temperature D* makes indium gallium arsenide focal plane arrays excellent candidates for inclusion in small, light-weight, low-power, and low-cost NIR imaging modules. This type of development will enable additional applications such as the use in gun sights and micro-unmanned aerial vehicle surveillance. The presentation will conclude with the discussion of ongoing development activities.

  8. Evaluation of global horizontal irradiance to plane-of-array irradiance models at locations across the United States

    SciTech Connect

    Lave, Matthew; Hayes, William; Pohl, Andrew; Hansen, Clifford W.

    2015-02-02

    We report an evaluation of the accuracy of combinations of models that estimate plane-of-array (POA) irradiance from measured global horizontal irradiance (GHI). This estimation involves two steps: 1) decomposition of GHI into direct and diffuse horizontal components and 2) transposition of direct and diffuse horizontal irradiance (DHI) to POA irradiance. Measured GHI and coincident measured POA irradiance from a variety of climates within the United States were used to evaluate combinations of decomposition and transposition models. A few locations also had DHI measurements, allowing for decoupled analysis of either the decomposition or the transposition models alone. Results suggest that decomposition models had mean bias differences (modeled versus measured) that vary with climate. Transposition model mean bias differences depended more on the model than the location. Lastly, when only GHI measurements were available and combinations of decomposition and transposition models were considered, the smallest mean bias differences were typically found for combinations which included the Hay/Davies transposition model.

  9. Analysis and design of low noise column stage in CMOS ROIC for UV GaN focal plane array

    NASA Astrophysics Data System (ADS)

    Li, Xiaojuan; Yuan, Yonggang; Xie, Jing; Wang, Jiqiang; Ma, Ding; Wang, Ling; Li, Xiangyang

    2015-03-01

    A novel column-stage structure of readout integrated circuit (ROIC) for GaN ultraviolet (UV) focal plane array (FPA) working in "solar-blind" band is proposed. The column stage has better drive capability, higher dynamic range, stable bias current and low impedance. The noise voltage of the column readout stage is discussed, which has been reduced by small-current driving, column-stage sample and hold and the technology of divided-output-bus. This research on low-noise ROIC is designed for weak-current UV FPA. It is designed, simulated and laid out using the 0.35um 2P4M CMOS 5V process. The clock rate operates at 8MHz. The simulation input current sets 0.01nA. The output swing is 2.6V and power consumption is 40 mW according to the measurement results.

  10. 640 x 512 Pixels Long-Wavelength Infrared (LWIR) Quantum-Dot Infrared Photodetector (QDIP) Imaging Focal Plane Array

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D.; Bandara, Sumith V.; Hill, Cory J.; Ting, David Z.; Liu, John K.; Rafol, Sir B.; Blazejewski, Edward R.; Mumolo, Jason M.; Keo, Sam A.; Krishna, Sanjay; Chang, Y. -C.; Shott, Craig A.

    2007-01-01

    Epitaxially grown self-assembled. InAs-InGaAs-GaAs quantum dots (QDs) are exploited for the development of large-format long-wavelength infrared focal plane arrays (FPAs). The dot-in-a-well (DWELL) structures were experimentally shown to absorb both 45 degrees and normal incident light, therefore, a reflection grating structure was used to enhance the quantum efficiency. The devices exhibit peak responsivity out to 8.1 micrometers, with peak detectivity reaching approximately 1 X 10(exp 10) Jones at 77 K. The devices were fabricated into the first long-wavelength 640 x 512 pixel QD infrared photodetector imaging FPA, which has produced excellent infrared imagery with noise equivalent temperature difference of 40 mK at 60-K operating temperature.

  11. PtSi Schottky-barrier focal plane arrays for multispectral imaging in ultraviolet, visible, and infrared spectral bands

    NASA Astrophysics Data System (ADS)

    Tsaur, Bor-Yeu; Chen, C. K.; Mattia, John-Paul

    1990-04-01

    PtSi Schottky-barrier detectors, which are conventionally used in the back-illumination mode for thermal imaging in the 3-5 micron infrared (IR) spectral band, are shown to exhibit excellent photoresponse in the near-ultraviolet and visible regions when operated in the front-illumination mode. For devices without antireflection coatings, external quantum efficiency in excess of 60 percent has been obtained for wavelengths between 400 and 800 nm. The efficiency decreases below 400 nm but is still about 35 percent at 290 nm. High-quality imaging has been demonstrated in both the visible and 3-5 micron spectral bands for front-illuminated 160- x 244-element PtSi focal plane arrays integrated with monolithic CCD readout circuitry.

  12. Electromagnetic analysis of the IR sensor focal plane arrays of micro-optics

    NASA Astrophysics Data System (ADS)

    Sikorski, Zbigniew

    2000-04-01

    Matrices of binary micro-lenses monolithically integrated with the focal-place-arrays (FPA) of longwave IR uncooled detectors can significantly improve sensor's parameters. Surface relief of the binary micro-lenses is built of annular stair step structures of heights and widths smaller than the radiation length. Scalar diffraction theory cannot correctly describe diffraction on these micro-structures and therefore the rigorous electromagnetic theory should be applied. In this aper, we have applied the electromagnetic eignemode method to study binary micro-optics for the longwave IR FPA of 50 micrometers pixel width. We have shown that binary refractive micro-lenses outperform their diffractive counterparts allowing for detectors of 10 micrometers width. The effective refractive micro-lenses require the 8-level surface relief. Geometrical optics predictions of the focal position agree quite well width electromagnetic calculations.

  13. InAs/GaSb superlattice focal plane array infrared detectors: manufacturing aspects

    NASA Astrophysics Data System (ADS)

    Rutz, Frank; Rehm, Robert; Schmitz, Johannes; Fleissner, Joachim; Walther, Martin; Scheibner, Ralf; Ziegler, Johann

    2009-05-01

    InAs/GaSb type-II short-period superlattice (SL) photodiodes have been shown to be very promising for 2nd and 3rd generation thermal imaging systems with excellent detector performance. A multi-wafer molecular beam epitaxy (MBE) growth process on 3"-GaSb substrates, which allows simultaneous growth on five substrates with excellent homogeneity has been developed. A reliable III/V-process technology for badge processing of single-color and dual-color FPAs has been set up to facilitate fabrication of mono- and bi-spectral InAs/GaSb SL detector arrays for the mid-IR spectral range. Mono- and bispectral SL camera systems with different pitch and number of pixels have been fabricated. Those imaging systems show excellent electro-optical performance data with a noise equivalent temperature difference (NETD) around 10 mK.

  14. Integrated array of 2-μm antimonide-based single-photon counting devices.

    PubMed

    Diagne, M A; Greszik, M; Duerr, E K; Zayhowski, J J; Manfra, M J; Bailey, R J; Donnelly, J P; Turner, G W

    2011-02-28

    A 32x32 Sb-based Geiger-mode (GM) avalanche photodiode array, operating at 2 μm with three-dimensional imaging capability, is presented. The array is interfaced with a ROIC (readout integrated circuit) in which each pixel can detect a photon and record the arrival time. The hybridized unit for the 1000-element focal plane array, when operated at 77K with 1 V overbias range, shows an average dark count rate of 1.5 kHz. Three-dimensional range images of objects were acquired. PMID:21369250

  15. Analysis of high frame rate readout circuit for near-infrared InGaAs focal plane array

    NASA Astrophysics Data System (ADS)

    Huang, Zhangcheng; Chen, Yu; Huang, Songlei; Fang, Jiaxiong

    2013-09-01

    High frame rate imaging for applications such as meteorological forecast, motion target tracking require high-speed Read-Out Integrated Circuit (ROIC). In order to achieve 10 KHz of frame rate, this paper analyzes the bandwidth of Capacitive-feedback Trans-Impedance Amplifier (CTIA) in ROIC which is the dominant bandwidth-limiting node when interfaced with large InGaAs detector pixel capacitance of about 10pF. A small-signal model is presented to study the relationship between integration capacitance, detector capacitance, transconductance and CTIA bandwidth. Calculation and simulation results show explicitly how the series resistance at the interface restricts the frame rate of Focal Plane Arrays (FPA). In order to achieve low-noise performance at a high frame rate, this paper describes an optimal solution in ROIC design. A prototype ROIC chip (DL7) has been fabricated with 0.5-μm mixed signal CMOS process and interfaced with InGaAs detector arrays. Test results show that frame rate is above 10 KHz and ROIC noise is around 270 e-, near identical to the design value.

  16. High-Performance M/LWIR Dual-Band HgCdTe/Si Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    Vilela, M. F.; Olsson, K. R.; Norton, E. M.; Peterson, J. M.; Rybnicek, K.; Rhiger, D. R.; Fulk, C. W.; Bangs, J. W.; Lofgreen, D. D.; Johnson, S. M.

    2013-11-01

    Mercury cadmium telluride (HgCdTe) grown on large-area silicon (Si) substrates allows for larger array formats and potentially reduced focal-plane array (FPA) cost compared with smaller, more expensive cadmium zinc telluride (CdZnTe) substrates. In this work, the use of HgCdTe/Si for mid- wavelength/long-wavelength infrared (M/LWIR) dual-band FPAs is evaluated for tactical applications. A number of M/LWIR dual-band HgCdTe triple-layer n- P- n heterojunction device structures were grown by molecular-beam epitaxy (MBE) on 100-mm (211)Si substrates. Wafers exhibited low macrodefect densities (< 300 cm-2). Die from these wafers were mated to dual-band readout integrated circuits to produce FPAs. The measured 81-K cutoff wavelengths were 5.1 μm for band 1 (MWIR) and 9.6 μm for band 2 (LWIR). The FPAs exhibited high pixel operability in each band with noise-equivalent differential temperature operability of 99.98% for the MWIR band and 98.7% for the LWIR band at 81 K. The results from this series are compared with M/LWIR FPAs from 2009 to address possible methods for improvement. Results obtained in this work suggest that MBE growth defects and dislocations present in devices are not the limiting factor for detector operability, with regards to infrared detection for tactical applications.

  17. Solar-blind AlGaN 256×256 p-i-n detectors and focal plane arrays

    NASA Astrophysics Data System (ADS)

    Reine, M. B.; Hairston, A.; Lamarre, P.; Wong, K. K.; Tobin, S. P.; Sood, A. K.; Cooke, C.; Pophristic, M.; Guo, S.; Peres, B.; Singh, R.; Eddy, C. R. _Jr., Jr.; Chowdhury, U.; Wong, M. M.; Dupuis, R. D.; Li, T.; DenBaars, S. P.

    2006-02-01

    This paper reports the development of aluminum-gallium nitride (AlGaN or Al xGa 1-xN) photodiode technology for high-operability 256×256 hybrid Focal Plane Arrays (FPAs) for solar-blind ultraviolet (UV) detection in the 260-280 nm spectral region. These hybrid UV FPAs consist of a 256×256 back-illuminated AlGaN p-i-n photodiode array, operating at zero bias voltage, bump-mounted to a matching 256×256 silicon CMOS readout integrated circuit (ROIC) chip. The unit cell size is 30×30 μm2. The photodiode arrays were fabricated from multilayer AlGaN films grown by MOCVD on 2" dia. UV-transparent sapphire substrates. Improvements in AlGaN material growth and device design enabled high quantum efficiency and extremely low leakage current to be achieved in high-operability 256×256 p-i-n photodiode arrays with cuton and cutoff wavelengths of 260 and 280 nm, placing the response in the solar-blind wavelength region (less than about 280 nm) where solar radiation is heavily absorbed by the ozone layer. External quantum efficiencies (at V=0, 270 nm, no antireflection coating) as high as 58% were measured in back-illuminated devices. A number of 256×256 FPAs, with the AlGaN arrays fabricated from films grown at three different facilities, achieved response operabilities as high as 99.8%, response nonuniformities (σ/μ) as low as 2.5%, and zero-bias resistance median values as high as 1×10 16 ohm, corresponding to R0A products of 7×10 10 ohm-cm2. Noise Equivalent Irradiance (NEI) data were measured on these FPAs. Median NEI values at 1 Hz are 250-500 photons/pixel-s, with best-element values as low as 90 photons/pixel-s at 1 Hz.

  18. Defect density reduction in InAs/GaSb type II superlattice focal plane array infrared detectors

    NASA Astrophysics Data System (ADS)

    Walther, Martin; Rehm, Robert; Schmitz, Johannes; Niemasz, Jasmin; Rutz, Frank; Wörl, Andreas; Kirste, Lutz; Scheibner, Ralf; Wendler, Joachim; Ziegler, Johann

    2011-01-01

    InAs/GaSb short-period superlattices (SL) have proven their large potential for high performance focal plane array infrared detectors. Lots of interest is focused on the development of short-period InAs/GaSb SLs for mono- and bispectral infrared detectors between 3 - 30 μm. InAs/GaSb short-period superlattices can be fabricated with up to 1000 periods in the intrinsic region without revealing diffusion limited behavior. This enables the fabrication of InAs/GaSb SL camera systems with very high responsivity, comparable to state of the art CdHgTe and InSb detectors. The material system is also well suited for the fabrication of dual-color mid-wavelength infrared InAs/GaSb SL camera systems. These systems exhibit high quantum efficiency and offer simultaneous and spatially coincident detection in both spectral channels. An essential point for the performance of two-dimensional focal plane infrared detectors in camera systems is the number of defective pixel on the matrix detector. Sources for pixel outages are manifold and might be caused by the dislocation in the substrate, the epitaxial growth process or by imperfections during the focal plane array fabrication process. The goal is to grow defect-free epitaxial layers on a dislocation free large area GaSb substrate. Permanent improvement of the substrate quality and the development of techniques to monitor the substrate quality are of particular importance. To examine the crystalline quality of 3" and 4" GaSb substrates, synchrotron white beam X-ray topography (SWBXRT) was employed. In a comparative defect study of different 3" GaSb and 4" GaSb substrates, a significant reduction of the dislocation density caused by improvements in bulk crystal growth has been obtained. Optical characterization techniques for defect characterization after MBE growth are employed to correlate epitaxially grown defects with the detector performance after hybridization with the read-out integrated circuit.

  19. Terahertz Absorption Characteristics of NiCr Film and Enhanced Absorption by Reactive Ion Etching in a Microbolometer Focal Plane Array

    NASA Astrophysics Data System (ADS)

    Gou, Jun; Wang, Jun; Li, Weizhi; Tai, Huiling; Gu, Deen; Jiang, Yadong

    2013-08-01

    Nano - scale metallic films have been proven to be an effective terahertz (THz) absorption layer in uncooled infrared (IR) microbolometers operated in THz spectral range. Optimized absorption can be achieved by adjusting the thickness of metallic film. Nickel - chromium (NiCr) thin films are deposited on the diaphragms of 320 × 240 VOx - based infrared focal plane arrays (IRFPA). Absorption measurements of the diaphragms with different thicknesses of NiCr (5 to 40 nm) agree reasonably well with the predicted absorption. To improve THz absorption further, a reactive ion etching (RIE) process applied to the dielectric support layer is first suggested, which generates nano - scale surface structures and increases the effective surface area of NiCr absorption film. This provides an effective way which is easy to accomplish and compatible with the manufacturing process of microbolometer IRFPAs to improve THz absorption and detection sensitivity.

  20. Numerical modeling of extended short wave infrared InGaAs focal plane arrays

    NASA Astrophysics Data System (ADS)

    Glasmann, Andreu; Wen, Hanqing; Bellotti, Enrico

    2016-05-01

    Indium gallium arsenide (In1-xGaxAs) is an ideal material choice for short wave infrared (SWIR) imaging due to its low dark current and excellent collection efficiency. By increasing the indium composition from 53% to 83%, it is possible to decrease the energy gap from 0.74 eV to 0.47 eV and consequently increase the cutoff wavelength from 1.7 μm to 2.63 μm for extended short wavelength (ESWIR) sensing. In this work, we apply our well-established numerical modeling methodology to the ESWIR InGaAs system to determine the intrinsic performance of pixel detectors. Furthermore, we investigate the effects of different buffer/cap materials. To accomplish this, we have developed composition-dependent models for In1-xGaxAs, In1-xAlxAs, and InAs1-y Py. Using a Green's function formalism, we calculate the intrinsic recombination coefficients (Auger, radiative) to model the diffusion-limited behavior of the absorbing layer under ideal conditions. Our simulations indicate that, for a given total thickness of the buffer and absorbing layer, structures utilizing a linearly graded small-gap InGaAs buffer will produce two orders of magnitude more dark current than those with a wide gap, such as InAlAs or InAsP. Furthermore, when compared with experimental results for ESWIR photodiodes and arrays, we estimate that there is still a 1.5x magnitude of reduction in dark current before reaching diffusion-limited behavior.

  1. Flagging and Correction of Pattern Noise in the Kepler Focal Plane Array

    NASA Technical Reports Server (NTRS)

    Kolodziejczak, Jeffery J.; Caldwell, Douglas A.; VanCleve, Jeffrey E.; Clarke, Bruce D.; Jenkins, Jon M.; Cote, Miles T.; Klaus, Todd C.; Argabright, Vic S.

    2010-01-01

    In order for Kepler to achieve its required less than 20 PPM photometric precision for magnitude 12 and brighter stars, instrument-induced variations in the CCD readout bias pattern (our "2D black image"), which are either fixed or slowly varying in time, must be identified and the corresponding pixels either corrected or removed from further data processing. The two principle sources of these readout bias variations are crosstalk between the 84 science CCDs and the 4 fine guidance sensor (FGS) CCDs and a high frequency amplifier oscillation on less than 40% of the CCD readout channels. The crosstalk produces a synchronous pattern in the 2D black image with time-variation observed in less than 10% of individual pixel bias histories. We will describe a method of removing the crosstalk signal using continuously-collected data from masked and over-clocked image regions (our "collateral data"), and occasionally-collected full-frame images and reverse-clocked readout signals. We use this same set to detect regions affected by the oscillating amplifiers. The oscillations manifest as time-varying moir pattern and rolling bands in the affected channels. Because this effect reduces the performance in only a small fraction of the array at any given time, we have developed an approach for flagging suspect data. The flags will provide the necessary means to resolve any potential ambiguity between instrument-induced variations and real photometric variations in a target time series. We will also evaluate the effectiveness of these techniques using flight data from background and selected target pixels.

  2. Cavity-based linear polarizer immune to the polarization direction of an incident plane wave.

    PubMed

    Wang, Jiang; Shen, Zhongxiang; Gao, Xiang; Wu, Wen

    2016-01-15

    We herein report a linear polarizer based on a 2D array of substrate integrated waveguide cavities, which can convert an arbitrary linearly polarized (LP) incident wave into an outgoing LP wave in a specified polarization direction with constant transmittance. Two orthogonal slots etched on the front surface of the cavity are utilized to couple a wave of arbitrary polarization into the cavity, while another slot on the back side helps to couple the field out along a desired polarization direction. Microwave experiments are performed as a proof of concept. The proposed polarizer exhibits very good performance with stable transmittance as 50% and a polarization extinction ratio over 45 dB. The new polarizer is potentially useful in novel polarization-selective devices that are immune to the polarization direction of an incident plane wave. PMID:26766730

  3. Development of Biosensors Based on Carbon Nanotube Nanoelectrode Arrays

    SciTech Connect

    Lin, Yuehe; Tu, Yi; Lu, Fang; Ren, Zhifeng

    2004-12-28

    The fabrication, electrochemical characterization, and sensing applications of low-site density carbon nanotubes based nanoelectrode arrays (CNT-NEAs) are reported in this work. Spin-coating of an epoxy resin provides a new way to create the electrode passivation layer that effectively reduces the current leakage and eliminates the electrode capacitance by sealing the side-wall of CNTs. The CNT-NEAs fabricated in our work effectively use the open ends of CNTs for electrochemical sensing. The open ends of the CNTs have fast electron transfer rates similar to a graphite edge-plane electrode, while the side-walls present very slow electron transfer rates similar to the graphitic basal plane. Cyclic voltammetry showed the sigmoidal shape curves with low capacitive current and scan-rate-independent limiting current. The successful development of a glucose biosensor based on CNT-NEAs for the selective detection of glucose is also described. Glucose oxidase was covalently immobilized on the CNTs tips via carbodiimide chemistry by forming amide linkages between the amine residues and carboxylic acid groups on the open ends of CNTs. The biosensor effectively performs selective electrochemical detections of glucose in the presence of common interferences.

  4. Linear Microbolometric Array Based on VOx Thin Film

    NASA Astrophysics Data System (ADS)

    Chen, Xi-Qu

    2010-05-01

    In this paper, a linear microbolometric array based on VOx thin film is proposed. The linear microbolometric array is fabricated by using micromachining technology, and its thermo-sensitive VOx thin film has excellent infrared response spectrum and TCR characteristics. Integrated with CMOS circuit, an experimentally prototypical monolithic linear microbolometric array is designed and fabricated. The testing results of the experimental linear array show that the responsivity of linear array can approach 18KV/W and is potential for infrared image systems.

  5. Microfabricated Cell-based Biosensor Arrays.

    PubMed

    Pishko, Michael

    2005-01-01

    Here, we described the fabrication using photolithography of poly(ethylene glycol) (PEG)-based hydrogel microstructures encapsulating viable mammalian cells on glass and silicon substrates. Substrates were treated with 3-(trichlorosilyl) propyl methacrylate to form pendant acrylate group to covalent link the hydrogel microstructure. Cells were encapsulated in arrays of cylindrical hydrogel microstructures 600 and 50 μm in diameter and viability assays demonstrated that encapsulated cells remained viable after photoencapsulation. These microstructures had clearly defined, three-dimensional structure without any residual cells remaining surface and no delamination of hydrogel elements from functionalized substrate occurred in aqueous environment for over a week. By changing spin-coating rates and feature sizes of photomasks, we could create cell-containing microstructures with aspect ratios ranging from 0.12 to 1.4. In case of 50 μm hydrogel microstructure, number of cells could be limited to 1 or 2 cells per element and array consisting of 400 elements could be fabricated in a square of 2 mm2. These cell-containinghydrogel microstructures were also successfully fabricated in poly(dimethylsiloxane) microchannels to create optical biosensor arrays of individually addressable single or multiple cell- containing hydrogel microstructures with potential applications in drug screening or pathogen detection. PMID:17282370

  6. Lenticular arrays based on liquid crystals

    NASA Astrophysics Data System (ADS)

    Urruchi Del Pozo, V.; Algorri Genaro, J. F.; Sánchez-Pena, J. M.; Geday, M. A.; Arregui, X. Q.; Bennis, N.

    2012-09-01

    Lenticular array products have experienced a growing interest in the last decade due to the very wide range of applications they can cover. Indeed, this kind of lenses can create different effects on a viewing image such as 3D, flips, zoom, etc. In this sense, lenticular based on liquid crystals (LC) technology is being developed with the aim of tuning the lens profiles simply by controlling the birefringence electrically. In this work, a LC lenticular lens array has been proposed to mimic a GRIN lenticular lens array but adding the capability of tuning their lens profiles. Comb control electrodes have been designed as pattern masks for the ITO on the upper substrate. Suitable high resistivity layers have been chosen to be deposited on the control electrode generating an electric field gradient between teeth of the same electrode. Test measurements have allowed us to demonstrate that values of phase retardations and focal lengths, for an optimal driving waveform, are fairly in agreement. In addition, results of focusing power of tuneable lenses were compared to those of conventional lenses. The behaviour of both kinds of lenses has revealed to be mutually similar for focusing collimated light and for refracting images.

  7. Short wave infrared InGaAs focal plane arrays detector: the performance optimization of photosensitive element

    NASA Astrophysics Data System (ADS)

    Gao, Xin-jiang; Tang, Zun-lie; Zhang, Xiu-chuan; Chen, Yang; Jiang, Li-qun; Cheng, Hong-bing

    2009-07-01

    Significant progress has been achieved in technology of the InGaAs focal plane arrays (FPA) detector operating in short wave infrared (SWIR) last two decades. The no cryogenic cooling, low manufacturing cost, low power, high sensitivity and maneuverability features inherent of InGaAs FPA make it as a mainstream SWIR FPA in a variety of critical military, national security, aerospace, telecommunications and industrial applications. These various types of passive image sensing or active illumination image detecting systems included range-gated imaging, 3-Dimensional Ladar, covert surveillance, pulsed laser beam profiling, machine vision, semiconductor inspection, free space optical communications beam tracker, hyperspectroscopy imaging and many others. In this paper the status and perspectives of hybrid InGaAs FPA which is composed of detector array (PDA) and CMOS readout integrate circuit (ROIC) are reviewed briefly. For various low light levels applications such as starlight or night sky illumination, we have made use of the interface circuit of capacitive feedback transimpedance amplifier (CTIA) in which the integration capacitor was adjustable, therefore implements of the physical and electrical characteristics matches between detector arrays and readout intergrate circuit was achieved excellently. Taking into account the influences of InGaAs detector arrays' optoelectronic characteristics on performance of the FPA, we discussed the key parameters of the photodiode in detailed, and the tradeoff between the responsivity, dark current, impedance at zero bias and junction capacitance of photosensitive element has been made to root out the impact factors. As a result of the educed approach of the photodiode's characteristics optimizing which involve with InGaAs PDA design and process, a high performance InGaAs FPA of 30um pixel pitch and 320×256 format has been developed of which the response spectrum range over 0.9um to 1.7um, the mean peak detectivity (λ=1.55

  8. Neuroelectronic device based on nanocoax arrays

    NASA Astrophysics Data System (ADS)

    Naughton, Jeffrey R.; Lundberg, Jaclyn N.; Varela, Juan A.; Burns, Michael J.; Chiles, Thomas C.; Christianson, John P.; Naughton, Michael J.

    2015-03-01

    We report on development of a nanocoax-based neuroelectronic array. The device has been used in real time to noninvasively couple to a ganglion sac located along the main nerve cord of the leech Hirudo medicinalis. This allowed for extracellular recording of synaptic activity in the form of spontaneous synapse firing in pre- and post-synaptic somata, with the next target being recording of local field potentials from rat hippocampal cells. We also discuss an alteration of the architecture to facilitate optical integration of the nanoarray, toward utilizing the so-modified device to elicit / inhibit action potentials in optogenetically-modified cells.

  9. Spin scan tomographic array-based imager.

    PubMed

    Hovland, Harald

    2014-12-29

    This work presents a novel imaging device based on tomographic reconstruction. Similar in certain aspects to the earlier presented tomographic scanning (TOSCA) principle, it provides several important enhancements. The device described generates a stream of one-dimensional projections from a linear array of thin stripe detectors onto which the (circular) image of the scene is rotated. A two-dimensional image is then reproduced from the one-dimensional signals using tomographic processing techniques. A demonstrator is presented. Various aspects of the design and construction are discussed, and resulting images and movies are presented. PMID:25607168

  10. A Flexible Base Electrode Array for Intraspinal Microstimulation

    PubMed Central

    Khaled, I.; Elmallah, S.; Cheng, C.; Moussa, W.A.; Mushahwar, V.K.; Elias, A.L.

    2013-01-01

    In this paper, we report the development of a flexible base array of penetrating electrodes which can be used to interface with the spinal cord. A customizable and feasible fabrication protocol is described. The flexible base arrays were fabricated and implanted into surrogate cords which were elongated by 12%. The resulting strains were optically measured across the cord and compared to those associated with two types of electrodes arrays (one without a base and one with a rigid base connecting the electrodes). The deformation behavior of cords implanted with the flexible base arrays resembled the behavior of cords implanted with individual microwires that were not connected through a base. The results of the strain test were used to validate a 2D finite element model. The validated model was used to assess the stresses induced by the electrodes of the 3 types of arrays on the cord, and to examine how various design parameters (thickness, base modulus, etc.) impact the mechanical behavior of the electrode array. Rigid base arrays induced higher stresses on the cord than the flexible base arrays which in turn imposed higher stresses than the individual microwire implants. The developed flexible base array showed improvement over the rigid base array; however, its stiffness needs to be further reduced to emulate the mechanical behavior of individual microwire arrays without a base. PMID:23744656

  11. Uncooled long-wave infrared small pixel focal plane array and system challenges

    NASA Astrophysics Data System (ADS)

    Lohrmann, Dieter; Littleton, Roy; Reese, Colin; Murphy, Dan; Vizgaitis, Jay

    2013-06-01

    There is a strong motivation for smaller pixels based on end-user demand for lower-cost, higher-resolution camera systems both for military and commercial applications. Uncooled detector technology fits the need for a low size, weight, and power system. We explore the tradeoffs and challenges to achieving pixel designs smaller than the current 17-μm state-of-the-art detectors without loss in sensitivity or resolution. For illustration we consider a 12-μm design. We also address modulation transfer function issues as the pixel size shrinks, and examine the difference between the performance of present devices and the theoretical performance limit for uncooled detectors.

  12. Third-generation focal plane array IR detection modules at AIM

    NASA Astrophysics Data System (ADS)

    Cabanski, Wolfgang A.; Breiter, Rainer; Koch, R.; Mauk, Karl-Heinz; Rode, Werner; Ziegler, Johann; Schneider, Harald; Walther, Martin; Oelmaier, Reinhard

    2001-10-01

    According to the common understanding, the 3rd generation of infrared (IR) detection modules is expected to provide advanced functionalities like more pixels, multicolor or multiband capability, higher frame rates and better thermal resolution. This paper is intended to present the present status at AIM on such technologies. A high speed device with 256 X 256 pixels in a 40 micrometer pitch is designed to provide up to 800 Hz full frame rate with pixel rates as high as 80 Mpixels/s. The read out circuit is designed to stare while scan in a flash integration mode to allow nearly full frame integration for even 800 Hz frame rate. A miniaturized command and control electronics with 14 Bit deep digital output and a non uniformity correction board capable to take into account non linear self learning scene based correction models are developed together with the integrated detector cooler assembly (IDCA). As working horse for dual color/band capabilities, AIM has developed a sequential multi color module to provide customers with a flexible tool to analyze the pros and cons of spectral selective detection. The module is based on a 384 X 288 mercury cadmium telluride (MCT) detector available in the mid wave (MWIR) or long wave spectral band (LWIR). A rotating wheel with 4 facets for filters or microscanner plates provides spectral selectivity. AIM's programmable MVIP image processing is used for controlling the detector and for non uniformity correction. The MVIP allows set the integration time and NUC coefficients individually for each filter position for comparable performance to accurately evaluate the pay off of spectral selectivity in the IR. In parallel, a dual color detector FPA is under development. The FPA is realized as a MCT MWIR device, LWIR, however, is also doable. Dual color macro cells are realized with 192 X 192 pixels in a pitch of effectively 56 micrometer. The cell design provides, that both colors detect radiation from target points identical within

  13. HgCdTe heterostructures on Si (310) substrates for midinfrared focal plane arrays

    SciTech Connect

    Yakushev, M. V. Brunev, D. V.; Varavin, V. S.; Vasilyev, V. V.; Dvoretskii, S. A.; Marchishin, I. V.; Predein, A. V.; Sabinina, I. V.; Sidorov, Yu. G.; Sorochkin, A. V.

    2011-03-15

    Results of studies of the molecular beam epitaxial growth of HgCdTe alloys on Si substrates as large as 100 mm in diameter are presented. Optimum conditions for obtaining HgCdTe/Si(310) heterostructures of the device quality for the spectral range of 3-5 {mu}m are determined. The results of measurements and discussion of photoelectric parameters of an infrared photodetector of a format of 320 Multiplication-Sign 256 elements with a step of 30 {mu}m based on a hybrid assembly of a matrix photosensitive cell with a Si multiplexer are presented. A high stability of photodetector parameters to thermocycling from room temperature to liquid-nitrogen temperature is shown.

  14. Third generation focal plane array IR detection modules and applications (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Cabanski, W.; Munzberg, M.; Rode, W.; Wendler, J.; Ziegler, J.; Fleissner, J.; Fuchs, F.; Rehm, R.; Schmitz, J.; Schneider, H.; Walther, M.

    2005-05-01

    The 3rd generation of infrared (IR) detection modules is expected to provide advanced features like higher resolution 1024x1024 or 1280x720 pixels and/or new functions like multicolor or multi band capability, higher frame rates and better thermal resolution. This paper is intended to present the current status at AIM on quantum well (QWIP) and antimonide superlattices (SL) detection modules for ground and airborne applications in the high performance range. For spectral selective detection, a QWIP detector combining 3-5μm (MWIR) and 8-10μm (LWIR) detection in each pixel with coincident integration has been developed in a 384x288x2 format with 40 μm pitch. Excellent thermal resolution with NETD < 30mK @ F/2, 6.8 ms for both peak wavelengths (4.8 μm and 8.0 μm) has been achieved. Thanks to the well established QWIP technology, the pixel outage rates even in these complex structures are below 0.5% in both bands. QWIP dual band or dual color detectors provide good resolution as long as integration times in the order of 5-10ms can be tolerated. This is acceptable for all applications where no fast motions of the platform or the targets are to be expected. For rapidly changing scenes-like e.g. in case of missile warning applications for airborne platforms-a material system with higher quantum efficiency is required to limit integration times to typically 1ms. AIM and IAF selected antimonide based type II superlattices (SL) for such kind of applications. The SL technology provides-similar to QWIP's-an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. While promising results on single SL pixels have been reported since many years, so far no SL based detection module could be realized. IAF and AIM last year managed to realize first most promising SL based detectors. Fully integrated IDCA's with a MWIR SL device with 256x256 pixels in 40μm pitch have been integrated and tested. The modules exhibit excellent thermal resolution of

  15. Toward 17µm pitch heterogeneously integrated Si/SiGe quantum well bolometer focal plane arrays

    NASA Astrophysics Data System (ADS)

    Ericsson, Per; Fischer, Andreas C.; Forsberg, Fredrik; Roxhed, Niclas; Samel, Björn; Savage, Susan; Stemme, Göran; Wissmar, Stanley; Öberg, Olof; Niklaus, Frank

    2011-06-01

    Most of today's commercial solutions for un-cooled IR imaging sensors are based on resistive bolometers using either Vanadium oxide (VOx) or amorphous Silicon (a-Si) as the thermistor material. Despite the long history for both concepts, market penetration outside high-end applications is still limited. By allowing actors in adjacent fields, such as those from the MEMS industry, to enter the market, this situation could change. This requires, however, that technologies fitting their tools and processes are developed. Heterogeneous integration of Si/SiGe quantum well bolometers on standard CMOS read out circuits is one approach that could easily be adopted by the MEMS industry. Due to its mono crystalline nature, the Si/SiGe thermistor material has excellent noise properties that result in a state-ofthe- art signal-to-noise ratio. The material is also stable at temperatures well above 450°C which offers great flexibility for both sensor integration and novel vacuum packaging concepts. We have previously reported on heterogeneous integration of Si/SiGe quantum well bolometers with pitches of 40μm x 40μm and 25μm x 25μm. The technology scales well to smaller pixel pitches and in this paper, we will report on our work on developing heterogeneous integration for Si/SiGe QW bolometers with a pixel pitch of 17μm x 17μm.

  16. Crack-free AlGaN for solar-blind focal plane arrays through reduced area epitaxy

    NASA Astrophysics Data System (ADS)

    Cicek, E.; McClintock, R.; Vashaei, Z.; Zhang, Y.; Gautier, S.; Cho, C. Y.; Razeghi, M.

    2013-02-01

    We report on crack reduction for solar-blind ultraviolet detectors via the use of a reduced area epitaxy (RAE) method to regrow on patterned AlN templates. With the RAE method, a pre-deposited AlN template is patterned into isolated mesas in order to reduce the formation of cracks in the subsequently grown high Al-content AlxGa1-xN structure. By restricting the lateral dimensions of the epitaxial growth area, the biaxial strain is relaxed by the edges of the patterned squares, which resulted in ˜97% of the pixels being crack-free. After successful implementation of RAE method, we studied the optical characteristics, the external quantum efficiency, and responsivity of average pixel-sized detectors of the patterned sample increased from 38% and 86.2 mA/W to 57% and 129.4 mA/W, respectively, as the reverse bias is increased from 0 V to 5 V. Finally, we discussed the possibility of extending this approach for focal plane array, where crack-free large area material is necessary for high quality imaging.

  17. Large-Format HgCdTe Dual-Band Long-Wavelength Infrared Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    Smith, E. P. G.; Venzor, G. M.; Gallagher, A. M.; Reddy, M.; Peterson, J. M.; Lofgreen, D. D.; Randolph, J. E.

    2011-08-01

    Raytheon Vision Systems (RVS) continues to further its capability to deliver state-of-the-art high-performance, large-format, HgCdTe focal-plane arrays (FPAs) for dual-band long-wavelength infrared (L/LWIR) detection. Specific improvements have recently been implemented at RVS in molecular-beam epitaxy (MBE) growth and wafer fabrication and are reported in this paper. The aim of the improvements is to establish producible processes for 512 × 512 30- μm-unit-cell L/LWIR FPAs, which has resulted in: the growth of triple-layer heterojunction (TLHJ) HgCdTe back-to-back photodiode detector designs on 6 cm × 6 cm CdZnTe substrates with 300-K Fourier-transform infrared (FTIR) cutoff wavelength uniformity of ±0.1 μm across the entire wafer; demonstration of detector dark-current performance for the longer-wavelength detector band approaching that of single-color liquid-phase epitaxy (LPE) LWIR detectors; and uniform, high-operability, 512 × 512 30- μm-unit-cell FPA performance in both LWIR bands.

  18. Evaluation of global horizontal irradiance to plane-of-array irradiance models at locations across the United States

    DOE PAGESBeta

    Lave, Matthew; Hayes, William; Pohl, Andrew; Hansen, Clifford W.

    2015-02-02

    We report an evaluation of the accuracy of combinations of models that estimate plane-of-array (POA) irradiance from measured global horizontal irradiance (GHI). This estimation involves two steps: 1) decomposition of GHI into direct and diffuse horizontal components and 2) transposition of direct and diffuse horizontal irradiance (DHI) to POA irradiance. Measured GHI and coincident measured POA irradiance from a variety of climates within the United States were used to evaluate combinations of decomposition and transposition models. A few locations also had DHI measurements, allowing for decoupled analysis of either the decomposition or the transposition models alone. Results suggest that decompositionmore » models had mean bias differences (modeled versus measured) that vary with climate. Transposition model mean bias differences depended more on the model than the location. Lastly, when only GHI measurements were available and combinations of decomposition and transposition models were considered, the smallest mean bias differences were typically found for combinations which included the Hay/Davies transposition model.« less

  19. Time-resolved Fourier transform infrared spectroscopy of chemical reactions in solution using a focal plane array detector.

    PubMed

    Kaun, N; Vellekoop, M J; Lendl, B

    2006-11-01

    A Fourier transform infrared (FT-IR) microscope equipped with a single as well as a 64 x 64 element focal plane array MCT detector was used to measure chemical reaction taking place in a microstructured flow cell designed for time-resolved FT-IR spectroscopy. The flow cell allows transmission measurements through aqueous solutions and incorporates a microstructured mixing unit. This unit achieves lamination of the two input streams with a cross-section of 300 x 5 microm each, resulting in fast diffusion-controlled mixing of the two input streams. Microscopic measurement at defined positions along the outlet channel allows time-resolved information of the reaction taking place in the flow cell to be obtained. In this paper we show experimental results on the model reaction between formaldehyde and sulfite. Using the single-point MCT detector, high-quality FT-IR spectra could be obtained from a spot size of 80 x 200 microm whereas the FPA detector allowed recording light from an area of 260 x 260 microm focused on its 64 x 64 detector elements. Therefore, more closely spaced features could be discerned at the expense of a significantly lower signal-to-noise (S/N) ratio per spectrum. Multivariate curve resolution-alternating least squares was used to extract concentration profiles of the reacting species along the outlet channel axis. PMID:17132444

  20. Research progress on a focal plane array ladar system using a laser diode transmitter and FM/cw radar principles

    NASA Astrophysics Data System (ADS)

    Stann, Barry L.; Abou-Auf, Ahmed; Aliberti, Keith; Giza, Mark M.; Ovrebo, Greg; Ruff, William C.; Simon, Deborah R.; Stead, Michael R.

    2002-07-01

    The Army Research Laboratory is developing scannerless ladar systems for smart munition and reconnaissance applications. Here we report on progress attained over the past year related to the construction of a 32x32 pixel ladar. The 32x32 pixel architecture achieves ranging based on a frequency modulation/continuous wave (FM/cw) technique implemented by directly amplitude modulating a near-IR diode laser transmitter with a radio frequency (rf) subcarrier that is linearly frequency modulated. The diode's output is collected and projected to form an illumination field in the downrange image area. The returned signal is focused onto an array of metal-semiconductor-metal (MSM) detectors where it is detected and mixed with a delayed replica of the laser modulation signal that modulates the responsivity of each detector. The output of each detector is an intermediate frequency (IF) signal (a product of the mixing process) whose frequency is proportional to the target range. This IF signal is continuously sampled over each period of the rf modulation. Following this, a N channel signal processor based-on field-programmable gate arrays calculates the discrete Fourier transform over the IF waveform in each pixel to establish the ranges to all the scatterers and their respective amplitudes. Over the past year, we have built one and two-dimensional self-mixing MSM detector arrays at .8 and 1.55 micrometers , designed and built circuit boards for reading data out of a 32x32 pixel array, and designed an N channel FPGA signal processor for high-speed formation of range gates. In this paper we report on the development and performance of these components and the results of system tests conducted in the laboratory.

  1. Microfluidic System for Solution Array Based Bioassays

    SciTech Connect

    Dougherty, G M; Tok, J B; Pannu, S S; Rose, K A

    2006-02-10

    The objective of this project is to demonstrate new enabling technology for multiplex biodetection systems that are flexible, miniaturizable, highly automated, low cost, and high performance. It builds on prior successes at LLNL with particle-based solution arrays, such as those used in the Autonomous Pathogen Detection System (APDS) successfully field deployed to multiple locations nationwide. We report the development of a multiplex solution array immunoassay based upon engineered metallic nanorod particles. Nanobarcodes{reg_sign} particles are fabricated by sequential electrodeposition of dissimilar metals within porous alumina templates, yielding optically encoded striping patterns that can be read using standard laboratory microscope optics and PC-based image processing software. The addition of self-assembled monolayer (SAM) coatings and target-specific antibodies allows each encoded class of nanorod particles to be directed against a different antigen target. A prototype assay panel directed against bacterial, viral, and soluble protein targets demonstrates simultaneous detection at sensitivities comparable to state of the art immunoassays, with minimal cross-reactivity. Studies have been performed to characterize the colloidal properties (zeta potential) of the suspended nanorod particles as a function of pH, the ionic strength of the suspending solution, and surface functionalization state. Additional studies have produced means for the non-contact manipulation of the particles, including the insertion of magnetic nickel stripes within the encoding pattern, and control via externally applied electromagnetic fields. Using the results of these studies, the novel Nanobarcodes{reg_sign} based assay was implemented in a prototype automated system with the sample processing functions and optical readout performed on a microfluidic card. The unique physical properties of the nanorod particles enable the development of integrated microfluidic systems for

  2. The development of ground-based infrared multi-object spectrograph based on the microshutter array

    NASA Astrophysics Data System (ADS)

    Moon, Dae-Sik; Sivanandam, Suresh; Kutyrev, Alexander S.; Moseley, Samuel H.; Graham, James R.; Roy, Aishwarya

    2014-07-01

    We report on our development of a near-infrared multi-object spectrograph for ground-based applications using the micro-shutter array, which was originally developed for the Near Infrared Spectrograph of the James Webb Space Telescope. The micro-shutter array in this case acts as a source selector at a reimaged telescope focal plane. The developed spectrograph will be implemented either with ground-layer adaptive optics system or multi-conjugate adaptive optics system on a large telescope. This will enable for the first time fully reconfigurable infrared multi-object spectroscopy with adaptive optics systems. We envision studying diverse astronomical objects with our spectrograph, including high-redshift galaxies, galaxy clusters and super star clusters.

  3. Confirmation of Auger-1 Minority-Carrier Lifetimes in Hg0.77Cd0.23Te and Prediction of Dark Current for Long-Wave Infrared Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    Destefanis, V.; Kerlain, A.

    2016-05-01

    Minority-carrier lifetime measurements have been carried out on Hg0.77Cd0.23Te (111)B materials with gap suitable for detection in the Long-Wave Infrared (LWIR) band. The materials were grown on top of CdZnTe substrates using a liquid-phase epitaxy (LPE) process. From measurements done at 80 K, a clear difference in terms of minority-carrier lifetimes was obtained, as expected, between p-intrinsic (≤5 ns) and n-extrinsic doped samples (420 ns). Minority-carrier lifetimes were also measured as a function of temperature for the n-type samples. Auger-1-limited lifetimes were demonstrated over a wide temperature range (from 80 K to 300 K) with negligible Radiative or Shockley-Read-Hall lifetime contributions. Predictions of dark current densities are made from those lifetime measurements, assuming an Auger-1-limited lifetime. The agreement is very good between the predictions and dark current densities measured from p-on-n 640 × 512 pixels LWIR HgCdTe focal-plane arrays with 15-μm pitch from SOFRADIR, Agreement between predicted and measured dark currents and Rule'07 for LWIR is also demonstrated herein. Finally, minority-carrier lifetime measurements are demonstrated as a predictive method for focal-plane array performance. State-of-the-art dark currents from SOFRADIR p-on-n LWIR focal-plane arrays based upon high-quality HgCdTe materials are also illustrated.

  4. Confirmation of Auger-1 Minority-Carrier Lifetimes in Hg0.77Cd0.23Te and Prediction of Dark Current for Long-Wave Infrared Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    Destefanis, V.; Kerlain, A.

    2016-09-01

    Minority-carrier lifetime measurements have been carried out on Hg0.77Cd0.23Te (111)B materials with gap suitable for detection in the Long-Wave Infrared (LWIR) band. The materials were grown on top of CdZnTe substrates using a liquid-phase epitaxy (LPE) process. From measurements done at 80 K, a clear difference in terms of minority-carrier lifetimes was obtained, as expected, between p-intrinsic (≤5 ns) and n-extrinsic doped samples (420 ns). Minority-carrier lifetimes were also measured as a function of temperature for the n-type samples. Auger-1-limited lifetimes were demonstrated over a wide temperature range (from 80 K to 300 K) with negligible Radiative or Shockley-Read-Hall lifetime contributions. Predictions of dark current densities are made from those lifetime measurements, assuming an Auger-1-limited lifetime. The agreement is very good between the predictions and dark current densities measured from p-on- n 640 × 512 pixels LWIR HgCdTe focal-plane arrays with 15- μm pitch from SOFRADIR, Agreement between predicted and measured dark currents and Rule'07 for LWIR is also demonstrated herein. Finally, minority-carrier lifetime measurements are demonstrated as a predictive method for focal-plane array performance. State-of-the-art dark currents from SOFRADIR p-on- n LWIR focal-plane arrays based upon high-quality HgCdTe materials are also illustrated.

  5. Graphene-based liquid crystal microlens arrays

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Chen, Cheng; Wu, Yong; Luo, Jun; Lei, Yu; Tong, Qing; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2015-12-01

    In this paper, we design and fabricate a kind of liquid crystal microlens arrays (LCMAs) with patterned electrodes made of monolayer graphene, which is grown on copper sheet by chemical vapor deposition (CVD). Graphene is the first two-dimensional atomic crystal. It uniquely combines extreme mechanical strength, high optically transmittance from visible light to infrared spectrum, and excellent electrical conductivity. These properties make it highly attractive for various applications in photonic devices that require conductive but transparent thin films. The graphene-based LCMAs have shown excellent optical performances in the tests. By adjusting the voltage signal loaded over the graphene-based LCMAs, the point spread functions (PSF) and focusing images of incident laser beams with different wavelengths, could be obtained. At the same time, we also get the focusing images of the common ITO-based LCMAs under the same experimental conditions to discuss the advantages and disadvantages between them. Further, the graphene-based LCMAs are also used in visible imaging. During the imaging tests, the graphene electrodes in the LCMAs work well.

  6. Observation of the launch of the Atlas 5 EELV with a dual-band QWIP focal plane array

    NASA Astrophysics Data System (ADS)

    Goldberg, Arnold C.

    2003-12-01

    We present imagery taken with a quantum well infrared photodetector (QWIP) dual-band infrared (IR) focal plane array (FPA) of the inaugural launch of the Atlas 5 launch vehicle. The FPA was developed under the Army Research Laboratory's Advanced Sensors Federated Laboratory program and used a read-out integrated circuit produced under the Air Force Research Laboratory's Advanced Multi-Quantum Well Technology program. The detectors are able to sense light in both the 3-5 micron (MWIR) and 8-12 micron (LWIR) atmospheric transmission windows such that the resulting LWIR and MIWR images are pixel registered and simultaneous. The FPA was installed in a camera system that used a closed-cycle cooler to operate at 60 K. The camera was placed at the prime focus of an all-reflective telescope on a computer-controlled tracking mount at the Innovative Sensor Technology Evaluation Facility (ISTEF) at the Kennedy Space Center. The launch was observed from ISTEF at a distance of 15 km from the pad. Before and after the launch, The FPA/camera system was calibrated using standard blackbody sources. The launch vehicle was observed from about 30 s after launch until approximately 4 minutes after launch. This corresponded to ranges between 15 km and more than 300 km and altitudes from just over 1 km to more than 100 km. Several interesting differences in the structure of the plume were observed. In addition, the hardbody of the rocket was seen in the LWIR imagery but was undetectable in the MWIR imagery. The imagery was unsaturated in both bands allowing us to obtain good measurements of the radiance of the plume in both the MWIR and LWIR bands.

  7. Recent development of SWIR focal plane array with InGaAs/GaAsSb type-II quantum wells

    NASA Astrophysics Data System (ADS)

    Inada, Hiroshi; Machinaga, Kenichi; Balasekaran, Sundararajan; Miura, Kouhei; Kawahara, Takahiko; Migita, Masaki; Akita, Katsushi; Iguchi, Yasuhiro

    2016-05-01

    HgCdTe (MCT) is predominantly used for infrared imaging applications even in SWIR region. However, MCT is expensive and contains environmentally hazardous substances. Therefore, its application has been restricted mainly military and scientific use and was not spread to commercial use. InGaAs/GaAsSb type-II quantum well structures are considered as an attractive material for realizing low dark current PDs owing to lattice-matching to InP substrate. Moreover, III-V compound material systems are suitable for commercial use. In this report, we describe successful operation of focal plane array (FPA) with InGaAs/GaAsSb quantum wells and mention improvement of optical characteristics. Planar type pin-PDs with 250-pairs InGaAs(5nm)/GaAsSb(5nm) quantum well absorption layer were fabricated. The p-n junction was formed in the absorption layer by the selective diffusion of zinc. Electrical and optical characteristics of FPA or pin-PDs were investigated. Dark current of 1μA/cm2 at 210K, which showed good uniformity and led to good S/N ratio in SWIR region, was obtained. Further, we could successfully reduce of stray light in the cavity of FPA with epoxy resin. As a result, the clear image was taken with 320x256 format and 7% contrast improvement was achieved. Reliability test of 10,000 heat cycles was carried out. No degradations were found in FPA characteristics of the epoxy coated sample. This result means FPA using InGaAs/GaAsSb type-II quantum wells is a promising candidate for commercial applications.

  8. DEPFET based x-ray detectors for the MIXS focal plane on BepiColombo

    NASA Astrophysics Data System (ADS)

    Treis, J.; Hälker, O.; Andricek, L.; Herrmann, S.; Heinzinger, K.; Lauf, T.; Lechner, P.; Lutz, G.; Mas-Hesse, J. M.; Porro, M.; Richter, R. H.; San Juan, J. L.; Schaller, G.; Schnecke, M.; Schopper, F.; Segneri, G.; Soltau, H.; Stevenson, T.; Strüder, L.; Whitford, C.

    2008-07-01

    DEPFET Macropixel detectors, based on the fusion of the combined Detector-Amplifier structure DEPFET with a silicon drift chamber (SDD) like drift ring structure, combine the excellent properties of the DEPFETs with the advantages of the drift detectors. As both device concepts rely on the principle of sideways depletion, a device entrance window with excellent properties is obtained at full depletion of the detector volume. DEPFET based focal plane arrays have been proposed for the Focal Plane Detectors for the MIXS (Mercury Imaging X-ray Spectrometer) instrument on BepiColombo, ESAs fifth cornerstone mission, with destination Mercury. MIXS uses a lightweight Wolter Type 1 mirror system to focus fluorescent radiation from the Mercury surface on the FPA detector, which yields the spatially resolved relative element abundance in Mercurys crust. In combination with the reference information from the Solar Intensity X-ray Spectrometer (SIXS), the element abundance can be measured quantitatively as well. The FPA needs to have an energy resolution better than 200 eV FWHM @ 1 keV and is required to cover an energy range from 0.5 keV to 10 keV, for a pixel size of 300 x 300 μm2. Main challenges for the instrument are the increase in leakage current due to a high level of radiation damage, and the limited cooling resources due to the difficult thermal environment in the mercury orbit. By applying an advanced cooling concept, using all available cooling power for the detector itself, and very high speed readout, the energy resolution requirement can be kept during the entire mission lifetime up to an end-of-life dose of ~ 3 × 1010 10 MeV p / cm2. The production of the first batch of flight devices has been finished at the MPI semiconductor laboratory, and first prototype modules have been built. The results of the first tests will be presented here.

  9. Derivatization technique to increase the spectral selectivity of two-dimensional Fourier transform infrared focal plane array imaging: analysis of binder composition in aged oil and tempera paint.

    PubMed

    Zumbühl, Stefan; Scherrer, Nadim C; Eggenberger, Urs

    2014-01-01

    The interpretation of standard Fourier transform infrared spectra (FT-IR) on oil-based paint samples often suffers from interfering bands of the different compounds, namely, binder, oxidative aging products, carboxylates formed during aging, and several pigments and fillers. The distinction of the aging products such as ketone and carboxylic acid functional groups pose the next problem, as these interfere with the triglyceride esters of the oil. A sample preparation and derivatization technique using gaseous sulfur tetrafluoride (SF4), was thus developed with the aim to discriminate overlapping signals and achieve a signal enhancement on superposed compounds. Of particular interest in this context is the signal elimination of the broad carboxylate bands of the typical reaction products developing during the aging processes in oil-based paints, as well as signal interference originating from several typical pigments in this spectral range. Furthermore, it is possible to distinguish the different carbonyl-containing functional groups upon selective alteration. The derivatization treatment can be applied to both microsamples and polished cross sections. It increases the selectivity of the infrared spectroscopy technique in a fundamental manner and permits the identification and two-dimensional (2D) localization of binder components in aged paint samples at the micrometer scale. The combination of SF4 derivatization with high-resolution 2D FT-IR focal plane array (FPA) imaging delivers considerable advances to the study of micro-morphological processes involving organic compounds. PMID:24694702

  10. Synchrotron Infrared Confocal Microspectroscopic Spatial Resolution or a Customized Synchrotron/focal Plane Array System Enhances Chemical Imaging of Biological Tissue or Cells

    SciTech Connect

    D Wetzel; M Nasse; =

    2011-12-31

    Spectroscopy and spatially resolved chemical imaging of biological materials using an infrared microscope is greatly enhanced with confocal image plane masking to 5-6 {mu} with a third generation microspectrometer and illumination with a synchrotron radiation source compared to globar illuminated and array detection or singly masked system. Steps toward this instrumental achievement are illustrated with spectra and images of biological tissue sections, including single cells, brain, aorta, and grain specimens. A recent, customized synchrotron infrared microspectrometer installation enables focal plane array detection to achieve both rapid and high definition chemical imaging. Localization of the ester carbonyl population in single modified starch granules was used to provide direct comparison of the two advanced imaging capabilities.

  11. Evaluation of in-plane local stress distribution in stacked IC chip using dynamic random access memory cell array for highly reliable three-dimensional IC

    NASA Astrophysics Data System (ADS)

    Tanikawa, Seiya; Kino, Hisashi; Fukushima, Takafumi; Koyanagi, Mitsumasa; Tanaka, Tetsu

    2016-04-01

    As three-dimensional (3D) ICs have many advantages, IC performances can be enhanced without scaling down of transistor size. However, 3D IC has mechanical stresses inside Si substrates owing to its 3D stacking structure, which induces negative effects on transistor performances such as carrier mobility changes. One of the mechanical stresses is local bending stress due to organic adhesive shrinkage among stacked IC chips. In this paper, we have proposed an evaluation method for in-plane local stress distribution in the stacked IC chips using retention time modulation of a dynamic random access memory (DRAM) cell array. We fabricated a test structure composed of a DRAM chip bonded on a Si interposer with dummy Cu/Sn microbumps. As a result, we clarified that the DRAM cell array can precisely evaluate the in-plane local stress distribution in the stacked IC chips.

  12. Synchrotron infrared confocal microspectroscopic spatial resolution or a customized synchrotron/focal plane array system enhances chemical imaging of biological tissue or cells

    NASA Astrophysics Data System (ADS)

    Wetzel, David L.; Nasse, Michael J.

    2011-09-01

    Spectroscopy and spatially resolved chemical imaging of biological materials using an infrared microscope is greatly enhanced with confocal image plane masking to 5-6 μm with a third generation microspectrometer and illumination with a synchrotron radiation source compared to globar illuminated and array detection or singly masked system. Steps toward this instrumental achievement are illustrated with spectra and images of biological tissue sections, including single cells, brain, aorta, and grain specimens. A recent, customized synchrotron infrared microspectrometer installation enables focal plane array detection to achieve both rapid and high definition chemical imaging. Localization of the ester carbonyl population in single modified starch granules was used to provide direct comparison of the two advanced imaging capabilities.

  13. Silicon-based wire electrode array for neural interfaces

    NASA Astrophysics Data System (ADS)

    Pei, Weihua; Zhao, Hui; Zhao, Shanshan; Fang, Xiaolei; Chen, Sanyuan; Gui, Qiang; Tang, Rongyu; Chen, Yuanfang; Hong, Bo; Gao, Xiaorong; Chen, Hongda

    2014-09-01

    Objectives. Metal-wire electrode arrays are widely used to record and stimulate neurons. Commonly, these devices are fabricated from a long insulated metal wire by cutting it into the proper length and using the cross-section as the electrode site. The assembly of a micro-wire electrode array with regular spacing is difficult. With the help of micro-machine technology, a silicon-based wire electrode array (SWEA) is proposed to simplify the assembling process and provide a wire-type electrode with tapered tips. Approach. Silicon wires with regular spacing coated with metal are generated from a silicon wafer through micro-fabrication and are ordered into a 3D array. A silicon wafer is cut into a comb-like structure with hexagonal teeth on both sides by anisotropic etching. To establish an array of silicon-based linear needles through isotropic wet etching, the diameters of these hexagonal teeth are reduced; their sharp edges are smoothed out and their tips are sharpened. The needle array is coated with a layer of parylene after metallization. The tips of the needles are then exposed to form an array of linear neural electrodes. With these linear electrode arrays, an array of area electrodes can be fabricated. Main results. A 6  ×  6 array of wire-type electrodes based on silicon is developed using this method. The time required to manually assemble the 3D array decreases significantly with the introduction of micro-fabricated 2D array. Meanwhile, the tip intervals in the 2D array are accurate and are controlled at no more than 1%. The SWEA is effective both in vitro and in vivo. Significance. Using this method, the SWEA can be batch-prepared in advance along with its parameters, such as spacing, length, and diameter. Thus, neural scientists can assemble proper electrode arrays in a short time.

  14. The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.

    PubMed

    Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

    2013-04-01

    Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 μs or lower. PMID:23571955

  15. Bionic ommatidia based on microlens array

    NASA Astrophysics Data System (ADS)

    Hao, Liu; Sihai, Chen; Shan, Dong; Xinjian, Yi

    2009-06-01

    A simple method is reported to manufacture a planar compound eye using a microlens array. The compound eye, inspired by insects, consists of a microlens array and a waveguide coupled with it. A microlens array with lenses of 50 μm in diameter is fabricated by melting AZ1500 photoresist and then transferring it onto SU-8. With the self-focus method applied, a waveguide array is formed, and each is exactly coupled to a lens. The formation of the waveguide is simulated using finite difference time domain (FDTD) arithmetic, resembling the ommatidia produced in our experiment. The ommatidia is also testified to astrict beam, just as the natural compound eyes do.

  16. Determination of charge-carrier diffusion length in the photosensing layer of HgCdTe n-on-p photovoltaic infrared focal plane array detectors

    SciTech Connect

    Vishnyakov, A. V.; Stuchinsky, V. A. Brunev, D. V.; Zverev, A. V.; Dvoretsky, S. A.

    2014-03-03

    In the present paper, we propose a method for evaluating the bulk diffusion length of minority charge carriers in the photosensing layer of photovoltaic focal plane array (FPA) photodetectors. The method is based on scanning a strip-shaped illumination spot with one of the detector diodes at a low level of photocurrents j{sub ph} being registered; such scanning provides data for subsequent analysis of measured spot-scan profiles within a simple diffusion model. The asymptotic behavior of the effective (at j{sub ph} ≠ 0) charge-carrier diffusion length l{sub d} {sub eff} as a function of j{sub ph} for j{sub ph} → 0 inferred from our experimental data proved to be consistent with the behavior of l{sub d} {sub eff} vs j{sub ph} as predicted by the model, while the obtained values of the bulk diffusion length of minority carriers (electrons) in the p-HgCdTe film of investigated HgCdTe n-on-p FPA photodetectors were found to be in a good agreement with the previously reported carrier diffusion-length values for HgCdTe.

  17. Simulation and experimental characterization of the point spread function, pixel saturation, and blooming of a mercury cadmium telluride focal plane array.

    PubMed

    Soehnel, Grant; Tanbakuchi, Anthony

    2012-11-20

    A custom IR spot scanning experiment was constructed to project subpixel spots on a mercury cadmium telluride focal plane array (FPA). The hardware consists of an FPA in a liquid nitrogen cooled Dewar, high precision motorized stages, a custom aspheric lens, and a 1.55 and 3.39 μm laser source. By controlling the position and intensity of the spot, characterizations of cross talk, saturation, blooming, and (indirectly) the minority carrier lifetime were performed. In addition, a Monte-Carlo-based charge diffusion model was developed to validate experimental data and make predictions. Results show very good agreement between the model and experimental data. Parameters such as wavelength, reverse bias, and operating temperature were found to have little effect on pixel crosstalk in the absorber layer of the detector. Saturation characterizations show that these FPAs, which do not have antiblooming circuitry, exhibit an increase in cross talk due to blooming at ∼39% beyond the flux required for analog saturation. PMID:23207309

  18. Growth of InAs/GaSb short-period superlattices for high-resolution mid-wavelength infrared focal plane array detectors

    NASA Astrophysics Data System (ADS)

    Walther, M.; Schmitz, J.; Rehm, R.; Kopta, S.; Fuchs, F.; Fleißner, J.; Cabanski, W.; Ziegler, J.

    2005-05-01

    InAs/GaSb short-period superlattices (SLs) with a broken gap type-II band alignment are investigated for the fabrication of photovoltaic pin-photodetectors on GaSb substrates. The structures were grown by molecular beam epitaxy using valved cracker cells for arsenic and antimony. Effective bandgap and strain in the SL were adjusted by varying the thickness of the InAs and GaSb layers in the SL and the controlled formation of InSb-like or GaAs-like bonds at the interfaces. MBE growth conditions were investigated and optimized in order to achieve good morphological, electrical and optical properties. IR-photodiodes with a cut-off wavelength of 5.4 μm reveal quantum efficiencies around 30% and detectivity values exceeding 10 13 Jones at 77 K. A focal plane array camera with 256×256 detector elements and 40 μm pitch based on InAs/GaSb short-period SLs was fabricated for the first time. The camera system reveals an excellent thermal resolution with a noise equivalent temperature difference below 12 mK for an integration time of 5 ms using f/2 optics. The detector performance, comparable with state of the art mercury-cadmium-telluride IR detectors, makes this material system very interesting for the fabrication of advanced thermal imaging systems.

  19. Crystallographic plane-orientation dependent atomic force microscopy-based local oxidation of silicon carbide.

    PubMed

    Ahn, Jung-Joon; Jo, Yeong-Deuk; Kim, Sang-Cheol; Lee, Ji-Hoon; Koo, Sang-Mo

    2011-01-01

    The effect of crystalline plane orientations of Silicon carbide (SiC) (a-, m-, and c-planes) on the local oxidation on 4H-SiC using atomic force microscopy (AFM) was investigated. It has been found that the AFM-based local oxidation (AFM-LO) rate on SiC is closely correlated to the atomic planar density values of different crystalline planes (a-plane, 7.45 cm-2; c-plane, 12.17 cm-2; and m-plane, 6.44 cm-2). Specifically, at room temperature and under about 40% humidity with a scan speed of 0.5 μm/s, the height of oxides on a- and m-planes 4H-SiC is 6.5 and 13 nm, respectively, whereas the height of oxides on the c-plane increased up to 30 nm. In addition, the results of AFM-LO with thermally grown oxides on the different plane orientations in SiC are compared. PMID:21711752

  20. Crystallographic plane-orientation dependent atomic force microscopy-based local oxidation of silicon carbide

    PubMed Central

    2011-01-01

    The effect of crystalline plane orientations of Silicon carbide (SiC) (a-, m-, and c-planes) on the local oxidation on 4H-SiC using atomic force microscopy (AFM) was investigated. It has been found that the AFM-based local oxidation (AFM-LO) rate on SiC is closely correlated to the atomic planar density values of different crystalline planes (a-plane, 7.45 cm-2; c-plane, 12.17 cm-2; and m-plane, 6.44 cm-2). Specifically, at room temperature and under about 40% humidity with a scan speed of 0.5 μm/s, the height of oxides on a- and m-planes 4H-SiC is 6.5 and 13 nm, respectively, whereas the height of oxides on the c-plane increased up to 30 nm. In addition, the results of AFM-LO with thermally grown oxides on the different plane orientations in SiC are compared. PMID:21711752

  1. GPU-based beamformer: fast realization of plane wave compounding and synthetic aperture imaging.

    PubMed

    Yiu, Billy Y S; Tsang, Ivan K H; Yu, Alfred C H

    2011-08-01

    Although they show potential to improve ultrasound image quality, plane wave (PW) compounding and synthetic aperture (SA) imaging are computationally demanding and are known to be challenging to implement in real-time. In this work, we have developed a novel beamformer architecture with the real-time parallel processing capacity needed to enable fast realization of PW compounding and SA imaging. The beamformer hardware comprises an array of graphics processing units (GPUs) that are hosted within the same computer workstation. Their parallel computational resources are controlled by a pixel-based software processor that includes the operations of analytic signal conversion, delay-and-sum beamforming, and recursive compounding as required to generate images from the channel-domain data samples acquired using PW compounding and SA imaging principles. When using two GTX-480 GPUs for beamforming and one GTX-470 GPU for recursive compounding, the beamformer can compute compounded 512 x 255 pixel PW and SA images at throughputs of over 4700 fps and 3000 fps, respectively, for imaging depths of 5 cm and 15 cm (32 receive channels, 40 MHz sampling rate). Its processing capacity can be further increased if additional GPUs or more advanced models of GPU are used. PMID:21859591

  2. 15-{micro}m 128 x 128 GaAs/Al{sub x}Ga{sub 1{minus}x}As quantum well infrared photodetector focal plane array camera

    SciTech Connect

    Gunapala, S.D.; Park, J.S.; Sarusi, G.; Lin, T.L.; Liu, J.K.; Maker, P.D.; Muller, R.E.; Shott, C.A.; Hoelter, T.

    1997-01-01

    In this paper, the authors discuss the development of very sensitive, very long wavelength infrared GaAs/Al{sub x}Ga{sub 1{minus}x}As quantum well infrared photodetectors (QWIP`s) based on bound-to-quasi-bound intersubband transition, fabrication of random reflectors for efficient light coupling, and the demonstration of a 15-{micro}m cutoff 128 x 128 focal plane array imaging camera. Excellent imagery, with a noise equivalent differential temperature (NE{Delta}T) of 30 mK has been achieved.

  3. Genetic optimisation of a plane array geometry for beamforming. Application to source localisation in a high speed train

    NASA Astrophysics Data System (ADS)

    Le Courtois, Florent; Thomas, Jean-Hugh; Poisson, Franck; Pascal, Jean-Claude

    2016-06-01

    Thanks to its easy implementation and robust performance, beamforming is applied for source localisation in several fields. Its effectiveness depends greatly on the array sensor configuration. This paper introduces a criterion to improve the array beampattern and increase the accuracy of sound source localisation. The beamwidth and the maximum sidelobe level are used to quantify the spatial variation of the beampattern through a new criterion. This criterion is shown to be useful, especially for the localisation of moving sources. A genetic algorithm is proposed for the optimisation of microphone placement. Statistical analysis of the optimised arrays provides original results on the algorithm performance and on the optimal microphone placement. An optimised array is tested to localise the sound sources of a high speed train. The results show an accurate separation.

  4. A cantilever array-based artificial nose

    PubMed

    Baller; Lang; Fritz; Gerber; Gimzewsk; Drechsler; Rothuizen; Despont; Vettiger; Battiston; Ramseyer; Fornaro; Meyer; Guntherodt

    2000-02-01

    We present quantitative and qualitative detection of analyte vapors using a microfabricated silicon cantilever array. To observe transduction of physical and chemical processes into nanomechanical motion of the cantilever, swelling of a polymer layer on the cantilever is monitored during exposure to the analyte. This motion is tracked by a beam-deflection technique using a time multiplexing scheme. The response pattern of eight cantilevers is analyzed via principal component analysis (PCA) and artificial neural network (ANN) techniques, which facilitates the application of the device as an artificial chemical nose. Analytes tested comprise chemical solvents, a homologous series of primary alcohols, and natural flavors. First differential measurements of surface stress change due to protein adsorption on a cantilever array are shown using a liquid cell. PMID:10741645

  5. Low-noise InGaAs infrared 1.0- to 2.4-μm focal plane arrays for SCIAMACHY

    NASA Astrophysics Data System (ADS)

    van der A, Ronald J.; Hoogeveen, Ruud W. M.; Spruijt, Hugo J.; Goede, Albert P. H.

    1997-01-01

    SCIAMACHY has been selected for the ESA environmental satellite ENVISAT with the objective to carry out atmospheric research in the UV, VIS, and IR spectral range. The most innovative parts of the instrument are the low- noise InGaAs semiconductor focal plane arrays covering the 1.0-2.4 micrometers wavelength range. For the first time InGaAs focal plane arrays with an extended wavelength range have become space qualified. In this paper theory and measurement of the dark current and noise behavior of these detectors is presented. Each InGaAs focal plane array consists of a 1024 pixel linear photo-detecting sliver and two 512 pixel multiplexing read-out chips. Each multiplexer contains 512 individual charge transimpedance amplifier and correlated double sampling circuits. A cylindrical lens, integrated in the detector housing, focuses the light on detector in the cross-dispersion direction. The InGaAs composition of the detectors is tuned to match the required wavelength range. Measurements have been performed of the dark current and noise as function of temperature and bias voltage in order to relate their performance to theory presented in this paper. InGaAs detectors sensitive to 2400 nm wavelength achieve dark current levels as low as 20-100 fA per detector pixel area of 1.25 (DOT) 10-4 cm2 at an operating temperature of 150 K and a bias voltage of 2 mV. Lower temperatures further reduce the dark current but also decrease the quantum efficiency at long wavelengths, yielding no net gain in performance. The development programme of these SCIAMACHY detectors has been carried out by Epitaxx Inc., for and in cooperation with the Space Research Organization Netherlands.

  6. Postwall waveguide slot array with cosecant radiation pattern and null filling for base station antennas in local multidistributed systems

    NASA Astrophysics Data System (ADS)

    Hirokawa, J.; Yamazaki, C.; Ando, M.

    2002-04-01

    The authors propose to use planar antennas of waveguide slots with the simple structure of postwall waveguide for base station antennas in Local Multipoint Distribution Systems (LMDS). The array has a cosecant radiation pattern with null filling in the vertical plane for uniform illumination in a sector area. The slots are paired as an element to achieve traveling wave excitation because the phase, as well as the amplitude, has to be controlled for null filling in a cosecant pattern. It is the first time to design an array of reflection-canceling slot pairs to get a tapered distribution both in amplitude and phase. This paper extends the designability of the reflection-canceling slot arrays. A 16-element array is designed at 25-26 GHz band. The model array has a cosecant pattern with 3-dB deviations and a peak gain of 17.1 dBi in measurements.

  7. Modulation transfer function measurement of an infrared focal plane array by use of the self-imaging property of a canted periodic target.

    PubMed

    Guérineau, N; Primot, J; Tauvy, M; Caes, M

    1999-02-01

    We present a new technique for measuring the modulation transfer function (MTF) of a focal plane array (FPA). The main idea is to project a periodic pattern of thin lines that are canted with respect to the sensor's columns. Practically, one aims the projection by using the self-imaging property of a periodic target. The technique, called the canted periodic target test, has been validated experimentally on a specific infrared FPA, leading to MTF evaluation to as great as five times the Nyquist frequency. PMID:18305656

  8. Enabling more capability within smaller pixels: advanced wafer-level process technologies for integration of focal plane arrays with readout electronics

    NASA Astrophysics Data System (ADS)

    Temple, Dorota S.; Vick, Erik P.; Lueck, Matthew R.; Malta, Dean; Skokan, Mark R.; Masterjohn, Christopher M.; Muzilla, Mark S.

    2014-05-01

    Over the past decade, the development of infrared focal plane arrays (FPAs) has seen two trends: decreasing of the pixel size and increasing of signal-processing capability at the device level. Enabling more capability within smaller pixels can be achieved through the use of advanced wafer-level processes for the integration of FPAs with silicon (Si) readout integrated circuits (ROICs). In this paper, we review the development of these wafer-level integration technologies, highlighting approaches in which the infrared sensor is integrated with three-dimensional ROIC stacks composed of multiple layers of Si circuitry interconnected using metal-filled through-silicon vias.

  9. PdSi focal-plane array detectors for short-wave infrared Raman spectroscopy of biological tissue: a feasibility study

    NASA Astrophysics Data System (ADS)

    Brennan, James F., III; Beattie, Mark E.; Wang, Yang; Cantella, Michael J.; Tsaur, Bor-Yeu; Dasari, Ramachandra R.; Feld, Michael S.

    1996-10-01

    We have used a PdSi focal-plane array detector to measure short-wave infrared Raman spectra of pure compounds and human tissue. Raman bands of the pure compounds are clearly visible in the spectra, and a calcification feature at 960 cm -1 is readily identifiable in the spectra of diseased human aorta. The performance characteristics of our detection device were good; dark noise contributed approximately 60 (electrons/s)/pixel, and the read noise was approximately 50 rms electrons/pixel. The primary noise in the spectra was due to fixed-pattern noise, which is the variation in measured signal across a detector when it is uniformly illuminated.

  10. A study of near source effects in array-based (SPAC) microtremor surveys

    NASA Astrophysics Data System (ADS)

    Roberts, James; Asten, Michael

    2008-07-01

    Array-based methods for exploiting ambient seismic noise are receiving increasing attention in the literature, particularly for use in providing shear wave velocity profiles to assist with simulation of site-specific earthquake responses. Many of these microtremor methods-such as the spatial autocorrelation technique (SPAC)-operate under the fundamental assumption of plane wave propagation of surface waves. However, when there are significant microtremor sources in close proximity to an array, wave front curvature becomes significant, and the plane wave assumption becomes a tenuous one. This paper explains the use of a simplified geometry-based approach to examine the effect of source distance on SPAC spectra for hexagonal (six-station) and triangular (three-station) arrays. The results suggest that near source effects are generally minimal provided that most of the sources are located a distance equal to at least two array radii from the centre of the array, although this distance increases when attenuation is considered. Results of a field trial involving the deliberate use of near-sources in proximity to a hexagonal (six-station) array support the findings of the theoretical model. Near source effects generally result in the measured SPAC curve being offset to lower frequencies for wavenumbers less than the first secondary maximum of the SPAC curve (kr < 7.0; λ > 0.86R), resulting in underestimates of shear velocity values in the inverted layered earth model. For the field example, shear velocity was underestimated by up to approximately 17 per cent. Studies of near source effects in a number of theoretical source distributions for hexagonal arrays revealed that cyclic variation in the imaginary SPAC coefficients are indicative of near source effects, although field examples indicate this effect is less significant than the geometric modelling suggests. Modelling of linear microtremor source distributions (intended to represent traffic travelling along a road

  11. Readout concept employing a novel on-chip 16-bit ADC for smart IR focal plane arrays

    NASA Astrophysics Data System (ADS)

    Ringh, Ulf; Jansson, Christer; Liddiard, Kevin C.

    1996-06-01

    This paper discusses CMOS readout for an uncooled 2D IR array of resistance bolometers. Factors influencing the architectural choice and detailed noise considerations for the pixel select switch are covered. A parallel readout concept using one ADC per column is the suggested architecture for an uncooled CMOS IR array. In order to meet the requirement on speed and resolution a new ADC principle had to be developed. The ADC is however of general interest where resolution above 10 bits at medium speed and low cost are desired. High linearity is obtained utilizing the first- order delta-sigma converter technique, while resolution and speed is enhanced by a successive approximation of the delta-sigma integrator residual voltage. An experimental 16 X 16 infrared bolometer detector array has been designed where a row-by-row readout operation of the bolometer array is supported by a column-wise 16-bit A/D conversion. The 16- column preamplifiers and ADC structure has been implemented in a standard 0.8 micrometers CMOS process with 40 micrometers column pitch. Measured results of the experimental array is presented, including both electronics and detectors.

  12. Development, characterization and application of compact spectrometers based on MEMS with in-plane capacitive drives

    NASA Astrophysics Data System (ADS)

    Kenda, A.; Kraft, M.; Tortschanoff, A.; Scherf, Werner; Sandner, T.; Schenk, Harald; Luettjohann, Stephan; Simon, A.

    2014-05-01

    With a trend towards the use of spectroscopic systems in various fields of science and industry, there is an increasing demand for compact spectrometers. For UV/VIS to the shortwave near-infrared spectral range, compact hand-held polychromator type devices are widely used and have replaced larger conventional instruments in many applications. Still, for longer wavelengths this type of compact spectrometers is lacking suitable and affordable detector arrays. In perennial development Carinthian Tech Research AG together with the Fraunhofer Institute for Photonic Microsystems endeavor to close this gap by developing spectrometer systems based on photonic MEMS. Here, we review on two different spectrometer developments, a scanning grating spectrometer working in the NIR and a FT-spectrometer accessing the mid-IR range up to 14 μm. Both systems are using photonic MEMS devices actuated by in-plane comb drive structures. This principle allows for high mechanical amplitudes at low driving voltages but results in gratings respectively mirrors oscillating harmonically. Both systems feature special MEMS structures as well as aspects in terms of system integration which shall tease out the best possible overall performance on the basis of this technology. However, the advantages of MEMS as enabling technology for high scanning speed, miniaturization, energy efficiency, etc. are pointed out. Whereas the scanning grating spectrometer has already evolved to a product for the point of sale analysis of traditional Chinese medicine products, the purpose of the FT-spectrometer as presented is to demonstrate what is achievable in terms of performance. Current developments topics address MEMS packaging issues towards long term stability, further miniaturization and usability.

  13. Liquid crystal-based hydrophone arrays

    NASA Astrophysics Data System (ADS)

    Brodzeli, Zourab; Silvestri, Leonardo; Michie, Andrew; Chigrinov, Vladimir G.; Guo, Qi; Pozhidaev, Eugene P.; Kiselev, Alexei D.; Ladouceur, Francois

    2012-09-01

    We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications (e.g. military, counter terrorist, and customs authorities in protecting ports and harbors), offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.

  14. New Regimes of Implosions of Larger Sized Wire Arrays With and Without Modified Central Plane at 1.5-1.7 MA Zebra

    NASA Astrophysics Data System (ADS)

    Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Stafford, A.; Keim, S. F.; Petkov, E. E.; Lorance, M.; Chuvatin, A. S.; Coverdale, C. A.; Jones, B.

    2013-10-01

    The recent experiments at 1.5-1.7 MA on Zebra at UNR with larger sized planar wires arrays (compared to the wire loads at 1 MA current) have demonstrated higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions. Such multi-planar wire arrays had two outer wire planes from mid-Z material to create a global magnetic field (gmf) and mid-Z plasma flow between them. Also, they included a modified central plane with a few Al wires at the edges to influence gmf and to create Al plasma flow in the perpendicular direction. The stationary shock waves which existed over tens of ns on shadow images and the early x-ray emissions before the PCD peak on time-gated spectra were observed. The most recent experiments with similar loads but without the central wires demonstrated a very different regime of implosion with asymmetrical jets and no precursor formation. This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984 and in part by DE-FC52-06NA27616. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  15. Hydrogen sensing array based on weak fiber Bragg grating

    NASA Astrophysics Data System (ADS)

    Bai, Wei; Yang, Minghong; Hu, Chenyuan; Dai, Jixiang; Li, Zhi; Yu, Haihu

    2015-09-01

    Optical fiber hydrogen sensing system based on weak fiber Bragg grating (WFBG) array deposited with palladium (Pd) film is proposed and experimentally demonstrated. For multi-point measurement, three hydrogen WFBG sensors array are weld in a single optical fiber. A time-division multiplexing (TDM) interrogation system is employed to demodulate the sensing array. Sensing experiments to different hydrogen concentrations ranging from 0 to 3.6% are conducted, and the results show good agreement with standard FBG technology. Due to its strong multiplexing capability of weak FBG, the system is possible to integrate thousands of WFBG hydrogen sensors in a single optical fiber.

  16. A two-axis in-plane motion measurement system based on optical beam deflection

    NASA Astrophysics Data System (ADS)

    Sriramshankar, R.; Mrinalini, R. Sri Muthu; Jayanth, G. R.

    2013-10-01

    Measurement of in-plane motion with high resolution and large bandwidth enables model-identification and real-time control of motion-stages. This paper presents an optical beam deflection based system for measurement of in-plane motion of both macro- and micro-scale motion stages. A curved reflector is integrated with the motion stage to achieve sensitivity to in-plane translational motion along two axes. Under optimal settings, the measurement system is shown to theoretically achieve sub-angstrom measurement resolution over a bandwidth in excess of 1 kHz and negligible cross-sensitivity to linear motion. Subsequently, the proposed technique is experimentally demonstrated by measuring the in-plane motion of a piezo flexure stage and a scanning probe microcantilever. For the former case, reflective spherical balls of different radii are employed to measure the in-plane motion and the measured sensitivities are shown to agree with theoretical values, on average, to within 8.3%. For the latter case, a prototype polydimethylsiloxane micro-reflector is integrated with the microcantilever. The measured in-plane motion of the microcantilever probe is used to identify nonlinearities and the transient dynamics of the piezo-stage upon which the probe is mounted. These are subsequently compensated by means of feedback control.

  17. A two-axis in-plane motion measurement system based on optical beam deflection

    SciTech Connect

    Sriramshankar, R.; Mrinalini, R. Sri Muthu; Jayanth, G. R.

    2013-10-15

    Measurement of in-plane motion with high resolution and large bandwidth enables model-identification and real-time control of motion-stages. This paper presents an optical beam deflection based system for measurement of in-plane motion of both macro- and micro-scale motion stages. A curved reflector is integrated with the motion stage to achieve sensitivity to in-plane translational motion along two axes. Under optimal settings, the measurement system is shown to theoretically achieve sub-angstrom measurement resolution over a bandwidth in excess of 1 kHz and negligible cross-sensitivity to linear motion. Subsequently, the proposed technique is experimentally demonstrated by measuring the in-plane motion of a piezo flexure stage and a scanning probe microcantilever. For the former case, reflective spherical balls of different radii are employed to measure the in-plane motion and the measured sensitivities are shown to agree with theoretical values, on average, to within 8.3%. For the latter case, a prototype polydimethylsiloxane micro-reflector is integrated with the microcantilever. The measured in-plane motion of the microcantilever probe is used to identify nonlinearities and the transient dynamics of the piezo-stage upon which the probe is mounted. These are subsequently compensated by means of feedback control.

  18. Photon-counting detector arrays based on microchannel array plates. [for image enhancement

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1975-01-01

    The recent development of the channel electron multiplier (CEM) and its miniaturization into the microchannel array plate (MCP) offers the possibility of fully combining the advantages of the photographic and photoelectric detection systems. The MCP has an image-intensifying capability and the potential of being developed to yield signal outputs superior to those of conventional photomultipliers. In particular, the MCP has a photon-counting capability with a negligible dark-count rate. Furthermore, the MCP can operate stably and efficiently at extreme-ultraviolet and soft X-ray wavelengths in a windowless configuration or can be integrated with a photo-cathode in a sealed tube for use at ultraviolet and visible wavelengths. The operation of one- and two-dimensional photon-counting detector arrays based on the MCP at extreme-ultraviolet wavelengths is described, and the design of sealed arrays for use at ultraviolet and visible wavelengths is briefly discussed.

  19. Subarray coherence based postfilter for eigenspace based minimum variance beamformer in ultrasound plane-wave imaging.

    PubMed

    Zhao, Jinxin; Wang, Yuanyuan; Yu, Jinhua; Guo, Wei; Li, Tianjie; Zheng, Yong-Ping

    2016-02-01

    This paper introduces a new beamformer, which combines the eigenspace based minimum variance (ESBMV) beamformer with a subarray coherence based postfilter (SCBP), for improving the quality of ultrasound plane-wave imaging. The ESBMV beamformer has been validated in improving the imaging contrast, but the difficulty in dividing the signal subspace limits the usage of it in the low signal-to-noise ratio (SNR) scenarios. Coherence factor (CF) based methods could optimize the output of a distortionless beamformer to reduce sidelobes, but the influence by the subarray decorrelation technique on the postfilter design has not attracted enough concern before. Accordingly, an ESBMV-SCBP beamformer was proposed in this paper, which used the coherence of the subarray signal to compute an SCBP to optimize the ESBMV results. Simulated and experimental data were used to evaluate the performance of the proposed method. The results showed that the ESBMV-SCBP method achieved an improved imaging quality compared with the ESBMV beamformer. In the simulation study, the contrast ratio (CR) for an anechoic cyst was improved by 9.88 dB and the contrast-to-noise ratio (CNR) was improved by 0.97 over the ESBMV. In the experimental study, the CR improvements for two anechoic cysts were 7.32 dB and 9.45 dB, while the CNRs were improved by 1.27 and 0.66, respectively. The ESBMV-SCBP also showed advantages over the ESBMV-Wiener beamformer in preserving a less grainy speckle, which is closer to that of distortionless beamformers and benefits the imaging contrast. With a relatively small extra computational load, the proposed method has potential to enhance the quality of the ultrasound plane-wave imaging. PMID:26582600

  20. Optimum plane selection for transport-of-intensity-equation-based solvers.

    PubMed

    Martinez-Carranza, J; Falaggis, K; Kozacki, T

    2014-10-20

    Deterministic single beam phase retrieval techniques based on the transport of intensity equation (TIE) use the axial intensity derivative obtained from a series of intensities recorded along the propagation axis as an input to the TIE-based solver. The common belief is that, when reducing the error present in the axial intensity derivative, there will be minimal error in the retrieved phase. Thus, reported optimization schemes of measurement condition focuses on the minimization of error in the axial intensity derivative. As it is shown in this contribution, this assumption is not correct and leads to underestimating the value of plane separation, which increases the phase retrieval errors and sensitivity to noise of the TIE-based measurement system. Therefore, in this paper, a detailed analysis that shows the existence of an optimal separation that minimizes the error in the retrieved phase for a given TIE-based solver is carried out. The developed model is used to derive analytical expressions that provide an optimal plane separation for a given number of planes and level of noise for the case of equidistant plane separation. The obtained results are derived for the widely used Fourier-transform-based TIE solver, but it is shown that they can also be applied to multigrid-based techniques. PMID:25402794

  1. Performance of near-infrared InGaAs focal plane array with different series resistances to p-InP layer

    NASA Astrophysics Data System (ADS)

    Shao, Xiumei; Li, Xue; Li, Tao; Huang, Zhangcheng; Chen, Yu; Tang, Hengjing; Gong, Haimei

    2014-05-01

    A planar-type InGaAs linear detector was designed and fabricated based on n-i-n+ type InP/In0.53Ga0.47As/InP epitaxial materials. The major process of the detector contains planar diffusion, surface passivation, metal contact and annealing. The I-V curves and the relative spectral response were measured at room temperature. The relative spectral response is in the range of 0.9 μm to 1.68 μm. The R0A of the detector is about 2×106 Ω•cm2 and the dark current density is 5~10nA/cm2 at -10mV bias voltage. The linear detectors were wire-bonded with readout integrated circuits (ROIC) to form focal plane array (FPA). The input stage of the ROIC is based on capacitive-feedback transimpedance amplifier (CTIA) with a capacitor (Cint) to be 0.1pF. However, the FPA signals are oscillating especially when close to the saturation. The ohmic contact on p-InP region plays an important role in the performance of detectors and FPAs. In this case, the series resistance to p-InP layer of each pixel is up to 1×106Ω. The FPAs were simulated in case of InGaAs detectors with different series resistances. According to the simulation results, the bandwidth of CTIA is lowering along with Rs increasing, and the signals of the FPAs oscillate when the series resistances are beyond 4×104Ω. The reason for the unstable oscillation of FPA is due to the series resistance of the detector which is too high enough. Then, the annealing process of the detectors was improved and the series resistances were lower than 1×104Ω. The optimized InGaAs linear detectors were wire-bonded with the same ROIC. The oscillation of the signals disappears and the FPA shows good stability.

  2. Phased-array sources based on nonlinear metamaterial nanocavities

    SciTech Connect

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil Andrew; Shaner, Eric A.; Klem, John Frederick; Sinclair, Michael B.; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. As a result, proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  3. Phased-array sources based on nonlinear metamaterial nanocavities

    NASA Astrophysics Data System (ADS)

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil A.; Shaner, Eric A.; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  4. MEMS-based phased arrays for army applications

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul B.; Holt, James C.; Mullins, James H.; Hudson, Tracy; Rock, Janice

    2007-04-01

    The Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) initiated a research and development project several years ago to develop Micro Electro-Mechanical Systems (MEMS)-based phased arrays to provide rapid beam steering for sensors, optical and Radio Frequency (RF) missile seekers, and RF communication links. In particular, the joint AMRDEC/Army Research Laboratory (ARL) project, which leverages low-cost phased array components developed under the Defense Advanced Research Projects Agency (DARPA) Low Cost Cruise Missile Defense (LCCMD) project, is developing RF switches, phase shifters, and passive phased sub-arrays to provide a fast scanning capability for pointing, acquisition, tracking, and data communication; and rugged, optical MEMS-based phased arrays to be employed in small volume, low-cost Laser Detection and Ranging (LADAR) seekers. The current status of the project is disclosed in this paper. Critical technical challenges, which include design and fabrication of the RF switches and phase shifters, design and fabrication of micro lens arrays, control of beam steering, scanning angular resolution and array losses, are discussed. Our approach to overcoming the technical barriers and achieving required performance is also discussed. Finally, the validity of a MEMS technology approach against competing low cost technologies is presented.

  5. Agarose microwell based neuronal micro-circuit arrays on microelectrode arrays for high throughput drug testing.

    PubMed

    Kang, Gyumin; Lee, Ji-Hye; Lee, Chang-Soo; Nam, Yoonkey

    2009-11-21

    For cell-based biosensor applications, dissociated neurons have been cultured on planar microelectrode arrays (MEAs) to measure the network activity with substrate-embedded microelectrodes. There has been a need for a multi-well type platform to reduce the data collection time and increase the statistical power for data analysis. This study presents a novel method to convert a conventional MEA into a multi-well MEA with an array of micrometre-sized neuronal culture ('neuronal micro-circuit array'). An MEA was coated first with cell-adhesive layer (poly-D-lysine) which was subsequently patterned with a cell-repulsive layer (agarose hydrogel) to both pattern the cell adhesive region and isolate neuronal micro-circuits from each other. For a few weeks, primary hippocampal neurons were cultured on the agarose microwell MEA and the development of spontaneous electrical activities were characterized with extracellular action potentials. Using neurotransmission modulators, the simultaneous monitoring of drug responses from neuronal micro-circuit arrays was also demonstrated. The proposed approach will be powerful for neurobiological functional assay studies or neuron-based biosensor fields which require repeated trials to obtain a single data point due to biological variations. PMID:19865730

  6. Determination of cleavage planes and fracture characterization of Ni-based single crystal superalloys

    NASA Technical Reports Server (NTRS)

    Merrill, John M.; Wilcox, Roy C.

    1992-01-01

    The room temperature fracture behavior of the Ge Rene N-4, CMSX-2, and CMSX-4C single crystal Ni-based superalloys was studied. All crystals were grown along the (001) direction and tensile tested in both helium and hydrogen atmospheres. A stereoscopic technique developed for use with a scanning electron microscope was applied to determine cleavage planes. Planar gamma(') morphologies also were examined to help determine cleavage planes. Helium charged specimens failed on a number of planes including the (111), (110), and (320). In most cases planes of the (111)-type initiated at the notch region and became smaller and smaller as they moved in radially. Tensile strengths in helium averaged 1000 MPa higher than that of the hydrogen charged specimens. Specimens tested in hydrogen generally failed on (100)-type planes originating from the notch region. This (100) region comprised 60 to 80 percent of the total fracture surface on most samples and appeared as large flat planes perpendicular to the growth direction of the crystal. The interior regions contained (100)-type planes as well as (321), (320), (210), and (111)-types. Hydrogen charged specimens also showed a high percentage of large cracks oriented at 90 deg to one another, indicative of the (100)-type fracture. The Ge Rene N4 and the CMSX-4C samples contained 3-5 percent gamma/gamma(') eutectic, while the CMSX-2 samples had little or no gamma/gamma(') eutectic. The relationship between gamma/gamma(') eutectic and the fracture surface has not been fully determined, but it is thought that the gamma/gamma(') eutectic may serve as a possible trapping site for hydrogen.

  7. Vision communications based on LED array and imaging sensor

    NASA Astrophysics Data System (ADS)

    Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    In this paper, we propose a brand new communication concept, called as "vision communication" based on LED array and image sensor. This system consists of LED array as a transmitter and digital device which include image sensor such as CCD and CMOS as receiver. In order to transmit data, the proposed communication scheme simultaneously uses the digital image processing and optical wireless communication scheme. Therefore, the cognitive communication scheme is possible with the help of recognition techniques used in vision system. By increasing data rate, our scheme can use LED array consisting of several multi-spectral LEDs. Because arranged each LED can emit multi-spectral optical signal such as visible, infrared and ultraviolet light, the increase of data rate is possible similar to WDM and MIMO skills used in traditional optical and wireless communications. In addition, this multi-spectral capability also makes it possible to avoid the optical noises in communication environment. In our vision communication scheme, the data packet is composed of Sync. data and information data. Sync. data is used to detect the transmitter area and calibrate the distorted image snapshots obtained by image sensor. By making the optical rate of LED array be same with the frame rate (frames per second) of image sensor, we can decode the information data included in each image snapshot based on image processing and optical wireless communication techniques. Through experiment based on practical test bed system, we confirm the feasibility of the proposed vision communications based on LED array and image sensor.

  8. Arrays of hollow out-of-plane microneedles made by metal electrodeposition onto solvent cast conductive polymer structures

    NASA Astrophysics Data System (ADS)

    Mansoor, I.; Liu, Y.; Häfeli, U. O.; Stoeber, B.

    2013-08-01

    Transdermal drug delivery using microneedles is a technique to potentially replace hypodermic needles for injection of many vaccines and drugs. Fabrication of hollow metallic microneedles so far has been associated with time-consuming steps that restrict batch production of these devices. Here, we are presenting a novel method for making metallic microneedles with any desired height, spacing, and lumen size. In our process, we use solvent casting to coat a mold, which contains an array of pillars, with a conductive polymer composite layer. The conductive layer is then used as a seed layer in a metal electrodeposition process. To characterize the process, the conductivity of the polymer composite with respect to different filler concentrations was investigated. In addition, plasma etching of the polymer was characterized. The electroplating process was also studied further to control the thickness of the microneedle array plate. The strength of the microneedle devices was evaluated through a series of compression tests, while their performance for transdermal drug delivery was tested by injection of 2.28 µm fluorescent microspheres into animal skin. The fabricated metallic microneedles seem appropriate for subcutaneous delivery of drugs and microspheres.

  9. Focal plane array readout integrated circuit with per-pixel analog-to-digital and digital-to-analog conversion

    NASA Astrophysics Data System (ADS)

    Kleinfelder, Stuart; Hottes, Alison; Pease, R. Fabian W.

    2000-07-01

    A pixel array readout integrated circuit (ROIC) containing per-pixel analog-to-digital conversion (ADC) and digital-to- analog conversion (DAC) for infrared detectors is presented with design and test result details. Fabricated in a standard 0.35 micron, 3.3 volt CMOS technology. the prototype consists of a linear array of 64 pixels, containing over 100 transistors per 30 by 30 micron pixel. The 8-bit per-pixel ADC is a Nyquist-rate single-slope design consisting of a three stage comparator and an 8 bit memory. This fully pixel- parallel ADC architecture operates in full-frame 'snapshot' mode and can reach over 1,000 frames per second. Each pixel also contains cascoded current source, globally biased to subtract an identical, fixed amount of current from each pixel in order to remove a common background signal by 'charge skimming.' It operates over more than 3 decades of current cancellation (approximately 10 pA to > 10 nA). As well, each pixel contains a 4 to 6+ bit current-mode DAC, intended to trim-out pixel-to-pixel variations in background current. It consists of 16 unit-cells of switched cascoded current sources per pixel, organized as two separately biased weights and controlled by a 16-bit per-pixel memory. The DAC operates over more than 4 decades of current cancellation (< 10 pA to approximately equals 100 nA) per least significant bit (LSB).

  10. The dynamics of a body with an axisymmetric base sliding on a rough plane

    NASA Astrophysics Data System (ADS)

    Borisov, Alexey V.; Erdakova, Nadezhda N.; Ivanova, Tatiana B.; Mamaev, Ivan S.

    2014-11-01

    In this paper we investigate the dynamics of a body with a flat base sliding on a horizontal and inclined rough plane under the assumption of linear pressure distribution of the body on the plane as the simplest dynamically consistent friction model. For analysis we use the descriptive function method similar to the methods used in the problems of Hamiltonian dynamics with one degree of freedom and allowing a qualitative analysis of the system to be made without explicit integration of equations of motion. In addition, we give a systematic review of the well-known experimental and theoretical results in this area.

  11. Learning-based scan plane identification from fetal head ultrasound images

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Annangi, Pavan; Gupta, Mithun; Yu, Bing; Padfield, Dirk; Banerjee, Jyotirmoy; Krishnan, Kajoli

    2012-03-01

    Acquisition of a clinically acceptable scan plane is a pre-requisite for ultrasonic measurement of anatomical features from B-mode images. In obstetric ultrasound, measurement of gestational age predictors, such as biparietal diameter and head circumference, is performed at the level of the thalami and cavum septum pelucidi. In an accurate scan plane, the head can be modeled as an ellipse, the thalami looks like a butterfly, the cavum appears like an empty box and the falx is a straight line along the major axis of a symmetric ellipse inclined either parallel to or at small angles to the probe surface. Arriving at the correct probe placement on the mother's belly to obtain an accurate scan plane is a task of considerable challenge especially for a new user of ultrasound. In this work, we present a novel automated learning-based algorithm to identify an acceptable fetal head scan plane. We divide the problem into cranium detection and a template matching to capture the composite "butterfly" structure present inside the head, which mimics the visual cues used by an expert. The algorithm uses the stateof- the-art Active Appearance Models techniques from the image processing and computer vision literature and tie them to presence or absence of the inclusions within the head to automatically compute a score to represent the goodness of a scan plane. This automated technique can be potentially used to train and aid new users of ultrasound.

  12. Image-based pupil plane characterization via principal component analysis for EUVL tools

    NASA Astrophysics Data System (ADS)

    Levinson, Zac; Burbine, Andrew; Verduijn, Erik; Wood, Obert; Mangat, Pawitter; Goldberg, Kenneth A.; Benk, Markus P.; Wojdyla, Antoine; Smith, Bruce W.

    2016-03-01

    We present an approach to image-based pupil plane amplitude and phase characterization using models built with principal component analysis (PCA). PCA is a statistical technique to identify the directions of highest variation (principal components) in a high-dimensional dataset. A polynomial model is constructed between the principal components of through-focus intensity for the chosen binary mask targets and pupil amplitude or phase variation. This method separates model building and pupil characterization into two distinct steps, thus enabling rapid pupil characterization following data collection. The pupil plane variation of a zone-plate lens from the Semiconductor High-NA Actinic Reticle Review Project (SHARP) at Lawrence Berkeley National Laboratory will be examined using this method. Results will be compared to pupil plane characterization using a previously proposed methodology where inverse solutions are obtained through an iterative process involving least-squares regression.

  13. Deployable aerospace PV array based on amorphous silicon alloys

    NASA Technical Reports Server (NTRS)

    Hanak, Joseph J.; Walter, Lee; Dobias, David; Flaisher, Harvey

    1989-01-01

    The development of the first commercial, ultralight, flexible, deployable, PV array for aerospace applications is discussed. It is based on thin-film, amorphous silicon alloy, multijunction, solar cells deposited on a thin metal or polymer by a proprietary, roll-to-roll process. The array generates over 200 W at AM0 and is made of 20 giant cells, each 54 cm x 29 cm (1566 sq cm in area). Each cell is protected with bypass diodes. Fully encapsulated array blanket and the deployment mechanism weigh about 800 and 500 g, respectively. These data yield power per area ratio of over 60 W/sq m specific power of over 250 W/kg (4 kg/kW) for the blanket and 154 W/kg (6.5 kg/kW) for the power system. When stowed, the array is rolled up to a diameter of 7 cm and a length of 1.11 m. It is deployed quickly to its full area of 2.92 m x 1.11 m, for instant power. Potential applications include power for lightweight space vehicles, high altitude balloons, remotely piloted and tethered vehicles. These developments signal the dawning of a new age of lightweight, deployable, low-cost space arrays in the range from tens to tens of thousands of watts for near-term applications and the feasibility of multi-100 kW to MW arrays for future needs.

  14. Developing barbed microtip-based electrode arrays for biopotential measurement.

    PubMed

    Hsu, Li-Sheng; Tung, Shu-Wei; Kuo, Che-Hsi; Yang, Yao-Joe

    2014-01-01

    This study involved fabricating barbed microtip-based electrode arrays by using silicon wet etching. KOH anisotropic wet etching was employed to form a standard pyramidal microtip array and HF/HNO3 isotropic etching was used to fabricate barbs on these microtips. To improve the electrical conductance between the tip array on the front side of the wafer and the electrical contact on the back side, a through-silicon via was created during the wet etching process. The experimental results show that the forces required to detach the barbed microtip arrays from human skin, a polydimethylsiloxane (PDMS) polymer, and a polyvinylchloride (PVC) film were larger compared with those required to detach microtip arrays that lacked barbs. The impedances of the skin-electrode interface were measured and the performance levels of the proposed dry electrode were characterized. Electrode prototypes that employed the proposed tip arrays were implemented. Electroencephalogram (EEG) and electrocardiography (ECG) recordings using these electrode prototypes were also demonstrated. PMID:25014098

  15. Characterization of winds through the rotor plane using a phased array SODAR and recommendations for future work.

    SciTech Connect

    Deola, Regina Anne

    2010-02-01

    Portable remote sensing devices are increasingly needed to cost effectively characterize the meteorology at a potential wind energy site as the size of modern wind turbines increase. A short term project co-locating a Sound Detection and Ranging System (SODAR) with a 200 meter instrumented meteorological tower at the Texas Tech Wind Technology Field Site was performed to collect and summarize wind information through an atmospheric layer typical of utility scale rotor plane depths. Data collected identified large speed shears and directional shears that may lead to unbalanced loads on the rotors. This report identifies suggestions for incorporation of additional data in wind resource assessments and a few thoughts on the potential for using a SODAR or SODAR data to quantify or investigate other parameters that may be significant to the wind industry.

  16. Small Arrays for Seismic Intruder Detections: A Simulation Based Experiment

    NASA Astrophysics Data System (ADS)

    Pitarka, A.

    2014-12-01

    Seismic sensors such as geophones and fiber optic have been increasingly recognized as promising technologies for intelligence surveillance, including intruder detection and perimeter defense systems. Geophone arrays have the capability to provide cost effective intruder detection in protecting assets with large perimeters. A seismic intruder detection system uses one or multiple arrays of geophones design to record seismic signals from footsteps and ground vehicles. Using a series of real-time signal processing algorithms the system detects, classify and monitors the intruder's movement. We have carried out numerical experiments to demonstrate the capability of a seismic array to detect moving targets that generate seismic signals. The seismic source is modeled as a vertical force acting on the ground that generates continuous impulsive seismic signals with different predominant frequencies. Frequency-wave number analysis of the synthetic array data was used to demonstrate the array's capability at accurately determining intruder's movement direction. The performance of the array was also analyzed in detecting two or more objects moving at the same time. One of the drawbacks of using a single array system is its inefficiency at detecting seismic signals deflected by large underground objects. We will show simulation results of the effect of an underground concrete block at shielding the seismic signal coming from an intruder. Based on simulations we found that multiple small arrays can greatly improve the system's detection capability in the presence of underground structures. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

  17. Physics-based simulation of the modulation transfer function in HgCdTe infrared detector arrays.

    PubMed

    Pinkie, Benjamin; Schuster, Jonathan; Bellotti, Enrico

    2013-07-15

    We have developed a numerical technique for performing physics-based simulations of the modulation transfer function (MTF) of infrared detector focal plane arrays. The finite-difference time-domain and finite element methods are employed to determine the electromagnetic and electrical response, respectively. We show how the total MTF can be decomposed to analyze the effect of lateral diffusion of charge carriers and present several methods for mitigation of such effects. We employ our numerical technique to analyze the MTF of a HgCdTe two-color bias-selectable infrared detector array. PMID:23939107

  18. A microspectrometer based on subwavelength metal nanohole array

    NASA Astrophysics Data System (ADS)

    Cui, Jun; Xia, Liangping; Yang, Zheng; Yin, Lu; Zheng, Guoxing; Yin, Shaoyun; Du, Chunlei

    2014-11-01

    Catering to the active demand of the miniaturization of spectrometers, a simple microspectrometer with small size and light weight is presented in this paper. The presented microspectrometer is a typical filter-based spectrometer using the extraordinary optical transmission property of subwavelength metal hole array structure. Different subwavelength metal nanohole arrays are designed to work as different filter units obtained by changing the lattice parameters. By processing the filter spectra with a unique algorithm based on sparse representation, the proposed spectrometer is demonstrated to have the capability of high spectral resolution and accuracy. Benefit for the thin filmed feature, the microspectrometer is expected to find its application in integrated optical systems.

  19. Low Power Systolic Array Based Digital Filter for DSP Applications.

    PubMed

    Karthick, S; Valarmathy, S; Prabhu, E

    2015-01-01

    Main concepts in DSP include filtering, averaging, modulating, and correlating the signals in digital form to estimate characteristic parameter of a signal into a desirable form. This paper presents a brief concept of low power datapath impact for Digital Signal Processing (DSP) based biomedical application. Systolic array based digital filter used in signal processing of electrocardiogram analysis is presented with datapath architectural innovations in low power consumption perspective. Implementation was done with ASIC design methodology using TSMC 65 nm technological library node. The proposed systolic array filter has reduced leakage power up to 8.5% than the existing filter architectures. PMID:25922854

  20. On the potential of atmospheric Cherenkov telescope arrays for resolving TeV gamma-ray sources in the Galactic plane

    NASA Astrophysics Data System (ADS)

    Ambrogi, L.; De Oña Wilhelmi, E.; Aharonian, F.

    2016-07-01

    The potential of an array of imaging atmospheric Cherenkov telescopes to detect gamma-ray sources in complex regions has been investigated. The basic characteristics of the gamma-ray instrument have been parameterized using simple analytic representations. In addition to the ideal (Gaussian form) point spread function (PSF), the impact of more realistic non-Gaussian PSFs with tails has been considered. Simulations of isolated point-like and extended sources have been used as a benchmark to test and understand the response of the instrument. The capability of the instrument to resolve multiple sources has been analyzed and the corresponding instrument sensitivities calculated. The results are of particular interest for weak gamma-ray emitters located in crowded regions of the Galactic plane, where the chance of clustering of two or more gamma-ray sources within 1 deg is high.

  1. A 20MHz 15μm pitch 128×128 CTIA ROIC for InGaAs focal plane array

    NASA Astrophysics Data System (ADS)

    Huang, Zhangcheng; Chen, Yu; Huang, Songlei; Fang, Jiaxiong

    2014-11-01

    A 128×128 matrix readout integrated circuit (ROIC) for 15×15 μm2 InGaAs focal plane array (FPA) is reported in this paper. Capacitive-feedback Trans-Impedance Amplifier (CTIA) and correlated double sampling (CDS) are both involved in ROIC pixel which dissipates 90nW and has a full-well-capacity (FWC) of about 78,000 e-. Noises of ROIC pixel are analyzed and distribution method of capacitors in pixel is discussed in order to obtain low-noise performance. In column buffer circuit, a new pre-charging technique is developed to realize readout rate of 20 MHz with low power consumption. The ROIC is fabricated with 0.18-μm 3.3 V mixed signal CMOS process. Test results show that the ROIC has an equivalent input noise of about 181e- and can achieve a readout rate of 20 MHz.

  2. MEMS-based sensor arrays for military applications

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul B.

    2002-07-01

    Scientists and engineers at the Army Aviation Missile Command's (AMCOM) Research, Development and Engineering Center (RDEC) are cooperatively working with the Defense Advanced Research Projects Agency (DARPA), other Army agencies, and industry to provide technical solutions for the Army's transformation efforts into the 21st Century force. Advanced technologies are being exposed to achieve the performance and cost goals dictated by the emerging missions of the Transformed Army. It is well established that MEMS technology offers the potential solution to cost, size, and weight issues for the soldier, missile, gun, ground vehicles, and aircraft applications. MEMS sensor arrays are currently being investigated to meet system performance requirements and provide more robust mission capability. A Science and Technology Objective, Research and Development Project is underway at AMCOM/RDEC to develop controlled MEMS sensor arrays to provide for full military dynamic performance ranges using miniature sensor system. MEMS-based angular rate sensors are enhanced with vibration feedback form MEMS accelerometers for output signal stabilization in high-vibration environments. Multi-range MEMS-based accelerometers, cooperatively developed by Government and industry, are being multiplexed to provide dynamic range expansion. An array of integrated accelerometers is expected to increase the dynamic range by an order of magnitude. Future projections suggest that MEMS sensor array technology will be applicable to a broad range of military applications, which include environmental sensor suites for structural health monitoring and forward reconnaissance and surveillance; and optical and radio frequency phased arrays for fast beam steering.

  3. Model Based Reconstruction of UT Array Data

    NASA Astrophysics Data System (ADS)

    Calmon, P.; Iakovleva, E.; Fidahoussen, A.; Ribay, G.; Chatillon, S.

    2008-02-01

    Beyond the detection of defects, their characterization (identification, positioning, sizing) is one goal of great importance often assigned to the analysis of NDT data. The first step of such analysis in the case of ultrasonic testing amounts to image in the part the detected echoes. This operation is in general achieved by considering time of flights and by applying simplified algorithms which are often valid only on canonical situations. In this communication we present an overview of different imaging techniques studied at CEA LIST and based on the exploitation of direct models which enable to address complex configurations and are available in the CIVA software plat-form. We discuss in particular ray-model based algorithms, algorithms derived from classical synthetic focusing and processing of the full inter-element matrix (MUSIC algorithm).

  4. In-plane structural and electronic anisotropy of iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Blomberg, Erick

    Many iron-based superconductors undergo a tetragonal to orthorhombic change of their crystallographic lattice symmetry, as well as paramagnetic to anti-ferromagnetic ordering upon cooling through a characteristic temperature TN. The anisotropic structure of the orthorhombic crystal symmetry would naturally lead one to expect to find in-plane electronic anisotropy. Upon cooling through Ts, and going into the orthorhombic symmetry, crystals divide into many small twin domains. Although crystallographically identical, the twin domains express four different rotations of the orthorhombic lattice within the ab-plane making direct measurements along an individual orthorhombic axis impossible. This complication lead to the developement of uniaxial stress and strain detwinning, which makes one of the four domain rotations far more energetically favorable than the other three, to the extent that more than 90% of the entire crystal volume may be represented by the dominant domain. Once in this detwinned state, measurements may be made along the individual orthorhombic axes, allowing one to probe in-plane anisotropy. Following the developement of the detwinning technique, measurements of the in-plane resistivity anisotropy between the orthorhombic a o and bo axes were made. The results, however, turned out to be the opposite of what is predicted from simple models of electrical resistivity. Many different competing theories were developed to understand this unusual behavior. The goal of my doctoral research is to understand the validitiy of these different theories and discover the primary driving force behind this unexpected result. My experiments on the effects of doping on the in-plane resistivity anisotropy yielded an interesting result that not only is there an assymetry between electron and hole doping, but also that the sign of the anisotropy changes sign with sufficient hole doping. This result, along with the tempreature dependence of the in-plane resistivity

  5. A substrate integrated folded waveguide (SIFW) H-plane band-pass filter with double H-plane septa based on LTCC.

    PubMed

    Wang, Zhengwei; Bu, Shirong; Luo, Zhengxiang

    2012-03-01

    In this paper, a novel substrate integrated folded waveguide (SIFW) H-plane band-pass filter based on low-temperature co-fired ceramic technology (LTCC) is proposed which employs double H-plane septa of a short-ended evanescent waveguide as an impedance inverter. The filter has advantages of convenient integration, compact, low cost, mass-producibility, and ease of fabrication, and it also has frequency responses similar to those of traditional E-plane double-iris waveguide band-pass filters. To validate the new proposed topology, a three-pole narrowband band-pass filter is designed and fabricated using half-wavelength resonators. A comparison between measured results and simulated results shows good agreement. PMID:22481793

  6. Midsagittal plane extraction from brain images based on 3D SIFT

    NASA Astrophysics Data System (ADS)

    Wu, Huisi; Wang, Defeng; Shi, Lin; Wen, Zhenkun; Ming, Zhong

    2014-03-01

    Midsagittal plane (MSP) extraction from 3D brain images is considered as a promising technique for human brain symmetry analysis. In this paper, we present a fast and robust MSP extraction method based on 3D scale-invariant feature transform (SIFT). Unlike the existing brain MSP extraction methods, which mainly rely on the gray similarity, 3D edge registration or parameterized surface matching to determine the fissure plane, our proposed method is based on distinctive 3D SIFT features, in which the fissure plane is determined by parallel 3D SIFT matching and iterative least-median of squares plane regression. By considering the relative scales, orientations and flipped descriptors between two 3D SIFT features, we propose a novel metric to measure the symmetry magnitude for 3D SIFT features. By clustering and indexing the extracted SIFT features using a k-dimensional tree (KD-tree) implemented on graphics processing units, we can match multiple pairs of 3D SIFT features in parallel and solve the optimal MSP on-the-fly. The proposed method is evaluated by synthetic and in vivo datasets, of normal and pathological cases, and validated by comparisons with the state-of-the-art methods. Experimental results demonstrated that our method has achieved a real-time performance with better accuracy yielding an average yaw angle error below 0.91° and an average roll angle error no more than 0.89°.

  7. Design of 800×2 low-noise readout circuit for near-infrared InGaAs focal plane array

    NASA Astrophysics Data System (ADS)

    Huang, Zhangcheng; Huang, Songlei; Fang, Jiaxiong

    2012-12-01

    InGaAs near-infrared (NIR) focal plane arrays (FPA) have important applications in space remote sensing. A design of 800×2 low-noise readout integrated circuit (T800 ROIC) with a pitch of 25 μm is presented for a dual-band monolithic InGaAs FPA. Mathematical analysis and transient noise simulations have been presented for predicting and lowering the noise in T800 ROIC. Thermal noise from input-stage amplifier which plays a dominant role in ROIC is reduced by increasing load capacitor under tradeoff and a low input offset voltage in the range of +/-5 mV is obtained by optimizing transistors in the input-stage amplifier. T800 ROIC has been fabricated with 0.5-μm 5V mixed signal CMOS process and interfaced with InGaAs detector arrays. Test results show that ROIC noise is around 90 μV and input offset voltage shows a good correspondence with simulation results. 800×2 InGaAs FPA has a peak detectivity (D*) of about 1.1×1012 cmHz1/2/ W, with dynamic range of above 80dB.

  8. Challenges, constraints, and results of lens design for 17 micron-bolometer focal plane arrays in 8-12 micron waveband

    NASA Astrophysics Data System (ADS)

    Schuster, Norbert; Franks, John

    2011-06-01

    In the 8-12 micron waveband Focal Plane Arrays (FPA) are available with a 17 micron pixel pitch in different arrays sizes (e.g. 512 x 480 pixels and 320 x 240 pixels) and with excellent electrical properties. Many applications become possible using this new type of IR-detector which will become the future standard in uncooled technology. Lenses with an f-number faster than f/1.5 minimize the diffraction impact on the spatial resolution and guarantee a high thermal resolution for uncooled cameras. Both effects will be quantified. The distinction between Traditional f-number (TF) and Radiometric f-number (RF) is discussed. Lenses with different focal lengths are required for applications in a variety of markets. They are classified by their Horizontal field of view (HFOV). Respecting the requirements for high volume markets, several two lens solutions will be discussed. A commonly accepted parameter of spatial resolution is the Modulation Transfer Function (MTF)-value at the Nyquist frequency of the detector (here 30cy/mm). This parameter of resolution will be presented versus field of view. Wide Angle and Super Wide Angle lenses are susceptible to low relative illumination in the corner of the detector. Measures to reduce this drop to an acceptable value are presented.

  9. Small Area Array-Based LED Luminaire Design

    SciTech Connect

    Thomas Yuan

    2008-01-09

    This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency LED luminaire designs based on small area array-based gallium nitride diodes. Novel GaN-based LED array designs are described, specifically addressing the thermal, optical, electrical and mechanical requirements for the incorporation of such arrays into viable solid-state LED luminaires. This work resulted in the demonstration of an integrated luminaire prototype of 1000 lumens cool white light output with reflector shaped beams and efficacy of 89.4 lm/W at CCT of 6000oK and CRI of 73; and performance of 903 lumens warm white light output with reflector shaped beams and efficacy of 63.0 lm/W at CCT of 2800oK and CRI of 82. In addition, up to 1275 lumens cool white light output at 114.2 lm/W and 1156 lumens warm white light output at 76.5 lm/W were achieved if the reflector was not used. The success to integrate small area array-based LED designs and address thermal, optical, electrical and mechanical requirements was clearly achieved in these luminaire prototypes with outstanding performance and high efficiency.

  10. Antenna coupled Kinetic Inductance arrays for space and ground based imaging arrays

    NASA Astrophysics Data System (ADS)

    Yates, S. J. C.; Baselmans, J. J. A.; Baryshev, A. M.; Neto, A.; Gerini, G.; Barends, R.; Lankwarden, Y. J. Y.

    2009-12-01

    Very large arrays of Microwave Kinetic Inductance Detectors (MKIDs) have the potential to revolutionize ground and space based astronomy. They can offer in excess of 10000 pixels with large dynamic range and very high sensitivity in combination with very efficient frequency division multiplexing at GHz frequencies. In this paper we present the development for a ~100 pixel MKID demonstration array based upon an single pixel consisting of an integrated MKID-antenna detector, with the antenna placed in the second focus of an elliptical Si lens. The design presented can be scaled to any frequency between 80 GHz and >5 THz because there is no need for superconducting structures that become lossy at frequencies above the gap frequency of the materials used. We present measurements of the optical coupling efficiency, sensitivity and discuss array development. We have obtained a dark sensitivity of 7×10-19W/Hz1/2 using 100 nm thick A1 devices and an optical coupling efficiency of 35% referring to the power of a single polarization optical signal in front of the Si lens of the detector.

  11. A New Multiaxial High-Cycle Fatigue Criterion Based on the Critical Plane for Ductile and Brittle Materials

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Shang, De-Guang; Wang, Xiao-Wei

    2015-02-01

    An improved high-cycle multiaxial fatigue criterion based on the critical plane was proposed in this paper. The critical plane was defined as the plane of maximum shear stress (MSS) in the proposed multiaxial fatigue criterion, which is different from the traditional critical plane based on the MSS amplitude. The proposed criterion was extended as a fatigue life prediction model that can be applicable for ductile and brittle materials. The fatigue life prediction model based on the proposed high-cycle multiaxial fatigue criterion was validated with experimental results obtained from the test of 7075-T651 aluminum alloy and some references.

  12. Compressive Sensing Based Design of Sparse Tripole Arrays

    PubMed Central

    Hawes, Matthew; Liu, Wei; Mihaylova, Lyudmila

    2015-01-01

    This paper considers the problem of designing sparse linear tripole arrays. In such arrays at each antenna location there are three orthogonal dipoles, allowing full measurement of both the horizontal and vertical components of the received waveform. We formulate this problem from the viewpoint of Compressive Sensing (CS). However, unlike for isotropic array elements (single antenna), we now have three complex valued weight coefficients associated with each potential location (due to the three dipoles), which have to be simultaneously minimised. If this is not done, we may only set the weight coefficients of individual dipoles to be zero valued, rather than complete tripoles, meaning some dipoles may remain at each location. Therefore, the contributions of this paper are to formulate the design of sparse tripole arrays as an optimisation problem, and then we obtain a solution based on the minimisation of a modified l1 norm or a series of iteratively solved reweighted minimisations, which ensure a truly sparse solution. Design examples are provided to verify the effectiveness of the proposed methods and show that a good approximation of a reference pattern can be achieved using fewer tripoles than a Uniform Linear Array (ULA) of equivalent length. PMID:26690436

  13. Compressive Sensing Based Design of Sparse Tripole Arrays.

    PubMed

    Hawes, Matthew; Liu, Wei; Mihaylova, Lyudmila

    2015-01-01

    This paper considers the problem of designing sparse linear tripole arrays. In such arrays at each antenna location there are three orthogonal dipoles, allowing full measurement of both the horizontal and vertical components of the received waveform. We formulate this problem from the viewpoint of Compressive Sensing (CS). However, unlike for isotropic array elements (single antenna), we now have three complex valued weight coefficients associated with each potential location (due to the three dipoles), which have to be simultaneously minimised. If this is not done, we may only set the weight coefficients of individual dipoles to be zero valued, rather than complete tripoles, meaning some dipoles may remain at each location. Therefore, the contributions of this paper are to formulate the design of sparse tripole arrays as an optimisation problem, and then we obtain a solution based on the minimisation of a modified l1 norm or a series of iteratively solved reweighted minimisations, which ensure a truly sparse solution. Design examples are provided to verify the effectiveness of the proposed methods and show that a good approximation of a reference pattern can be achieved using fewer tripoles than a Uniform Linear Array (ULA) of equivalent length. PMID:26690436

  14. Gas sensor array based on metal-decorated carbon nanotubes.

    PubMed

    Star, Alexander; Joshi, Vikram; Skarupo, Sergei; Thomas, David; Gabriel, Jean-Christophe P

    2006-10-26

    Here we demonstrate design, fabrication, and testing of electronic sensor array based on single-walled carbon nanotubes (SWNTs). Multiple sensor elements consisting of isolated networks of SWNTs were integrated into Si chips by chemical vapor deposition (CVD) and photolithography processes. For chemical selectivity, SWNTs were decorated with metal nanoparticles. The differences in catalytic activity of 18 catalytic metals for detection of H(2), CH(4), CO, and H(2)S gases were observed. Furthermore, a sensor array was fabricated by site-selective electroplating of Pd, Pt, Rh, and Au metals on isolated SWNT networks located on a single chip. The resulting electronic sensor array, which was comprised of several functional SWNT network sensors, was exposed to a randomized series of toxic/combustible gases. Electronic responses of all sensor elements were recorded and the sensor array data was analyzed using pattern-recognition analysis tools. Applications of these small-size, low-power, electronic sensor arrays are in the detection and identification of toxic/combustible gases for personal safety and air pollution monitoring. PMID:17048920

  15. Localization using ground- and air-based acoustic arrays

    NASA Astrophysics Data System (ADS)

    Goldman, Geoffrey H.; Reiff, Chris

    2011-06-01

    Techniques were developed to localize acoustic quasiperiodic signals using microphone arrays located on the ground and on an aerostat. The direction of arrival (DOA) was computed at each array and then the position of the source was estimated using algorithms based upon triangulation. Differential time delays between the microphones in a tetrahedral array were estimated in the frequency domain, and then DOA estimates were calculated using a weighted least squares approach. The location of the target was calculated by minimizing the weighted squared error of a cost function for different combinations of DOA estimates. The algorithms were tested offline using data collected by the U.S. Army Research Laboratory on an aircraft. The ground-truth position of the target was recorded using a GPS system as it maneuvered and compared to the results obtained from the localization algorithms. The algorithms performed well when estimating the x and y positions, but had difficulty obtaining consistently good z positions, or equivalently, height estimates.

  16. Controllable adhesive superhydrophobic surfaces based on PDMS microwell arrays.

    PubMed

    Yong, Jiale; Chen, Feng; Yang, Qing; Zhang, Dongshi; Bian, Hao; Du, Guangqing; Si, Jinhai; Meng, Xiangwei; Hou, Xun

    2013-03-12

    This paper presents a one-step method to fabricate superhydrophobic surfaces with extremely controllable adhesion based on PDMS microwell arrays. The microwell array structures are rapidly produced on PDMS films by a point-by-point femtosecond laser scanning process. The as-prepared superhydrophobic surfaces show water controllable adhesion that ranges from ultrahigh to ultralow by adjusting the extent of overlap of the adjacent microwells, on which the sliding angle can be controlled from 180° (a water droplet can not slide down even when the as-prepared surface is turned upside down) to 3°. A "micro-airbag effect" is introduced to explain the adhesion transition phenomenon of the microwell array structures. This work provides a facile and promising strategy to fabricate superhydrophobic surfaces with controllable adhesion. PMID:23391207

  17. Neural network based analysis for chemical sensor arrays

    SciTech Connect

    Hashem, S.; Keller, P.E.; Kouzes, R.T.; Kangas, L.J.

    1995-04-01

    Compact, portable systems capable of quickly identifying contaminants in the field are of great importance when monitoring the environment. In this paper, we examine the effectiveness of using artificial neural networks for real-time data analysis of a sensor array. Analyzing the sensor data in parallel may allow for rapid identification of contaminants in the field without requiring highly selective individual sensors. We use a prototype sensor array which consists of nine tin-oxide Taguchi-type sensors, a temperature sensor, and a humidity sensor. We illustrate that by using neural network based analysis of the sensor data, the selectivity of the sensor array may be significantly improved, especially when some (or all) the sensors are not highly selective.

  18. Electronic tongue based on an array of metallic potentiometric sensors.

    PubMed

    Lvova, Larisa; Martinelli, Eugenio; Mazzone, Emiliano; Pede, Andrea; Paolesse, Roberto; Di Natale, Corrado; D'Amico, Arnaldo

    2006-11-15

    An electronic tongue system based on the array of six metallic potentiometric sensors (metallic wires) was developed and utilized for discrimination of foodstuffs: several types of vinegar and fruit juices. Copper, tin, iron, aluminum, brass and stainless steel wires were included in the array and supplemented by pH glass electrode. The response of potentiometric metallic sensors towards various organic acids has been studied and possible sensitivity mechanisms were discussed. Overall potential changes of metallic sensors were exanimate as complex mixed signals influenced by several components presenting in analyte employing chemometric approach. The multisensor array of such a type can be useful for several applications since of simplicity in handling, low cost of sensors and easy measure procedure. PMID:18970847

  19. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications.

    PubMed

    Zacchia, Nicholas A; Valentine, Megan T

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy. PMID:26026529

  20. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    SciTech Connect

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  1. Improving the detection of explosive hazards with LIDAR-based ground plane estimation

    NASA Astrophysics Data System (ADS)

    Buck, A.; Keller, J. M.; Popescu, M.

    2016-05-01

    Three-dimensional point clouds generated by LIDAR offer the potential to build a more complete understanding of the environment in front of a moving vehicle. In particular, LIDAR data facilitates the development of a non-parametric ground plane model that can filter target predictions from other sensors into above-ground and below-ground sets. This allows for improved detection performance when, for example, a system designed to locate above-ground targets considers only the set of above-ground predictions. In this paper, we apply LIDAR-based ground plane filtering to a forward looking ground penetrating radar (FLGPR) sensor system and a side looking synthetic aperture acoustic (SAA) sensor system designed to detect explosive hazards along the side of a road. Additionally, we consider the value of the visual magnitude of the LIDAR return as a feature for identifying anomalies. The predictions from these sensors are evaluated independently with and without ground plane filtering and then fused to produce a combined prediction confidence. Sensor fusion is accomplished by interpolating the confidence scores of each sensor along the ground plane model to create a combined confidence vector at specified points in the environment. The methods are tested along an unpaved desert road at an arid U.S. Army test site.

  2. Multiresolution Techniques for Interactive Texture-Based Rendering of Arbitrarily Oriented Cutting Planes

    SciTech Connect

    LaMar, E; Duchaineau, M A; Hamann, B; Joy, K I

    2001-10-03

    We present a multiresolution technique for interactive texture based rendering of arbitrarily oriented cutting planes for very large data sets. This method uses an adaptive scheme that renders the data along a cutting plane at different resolutions: higher resolution near the point-of-interest and lower resolution away from the point-of-interest. The algorithm is based on the segmentation of texture space into an octree, where the leaves of the tree define the original data and the internal nodes define lower-resolution versions. Rendering is done adaptively by selecting high-resolution cells close to a center of attention and low-resolution cells away from it. We limit the artifacts introduced by this method by blending between different levels of resolution to produce a smooth image. This technique can be used to produce viewpoint-dependent renderings.

  3. An automated image-based tool for pupil plane characterization of EUVL tools

    NASA Astrophysics Data System (ADS)

    Levinson, Zac; Smith, Jack S.; Fenger, Germain; Smith, Bruce W.

    2016-03-01

    Pupil plane characterization will play a critical role in image process optimization for EUV lithography (EUVL), as it has for several lithography generations. In EUVL systems there is additional importance placed on understanding the ways that thermally-induced system drift affect pupil variation during operation. In-situ full pupil characterization is therefore essential for these tools. To this end we have developed Quick Inverse Pupil (QUIP)—a software suite developed for rapid characterization of pupil plane behavior based on images formed by that system. The software consists of three main components: 1) an image viewer, 2) the model builder, and 3) the wavefront analyzer. The image viewer analyzes CDSEM micrographs or actinic mask micrographs to measure either CDs or through-focus intensity volumes. The software is capable of rotation correction and image registration with subpixel accuracy. The second component pre-builds a model for a particular imaging system to enable rapid pupil characterization. Finally, the third component analyzes the results from the image viewer and uses the optional pre-built model for inverse solutions of pupil plane behavior. Both pupil amplitude and phase variation can be extracted using this software. Inverse solutions are obtained through a model based algorithm which is built on top of commercial rigorous full-vector simulation software.

  4. Quantitative Characterization of Super-Resolution Infrared Imaging Based on Time-Varying Focal Plane Coding

    NASA Astrophysics Data System (ADS)

    Wang, X.; Yuan, Y.; Zhang, J.; Chen, Y.; Cheng, Y.

    2014-10-01

    High resolution infrared image has been the goal of an infrared imaging system. In this paper, a super-resolution infrared imaging method using time-varying coded mask is proposed based on focal plane coding and compressed sensing theory. The basic idea of this method is to set a coded mask on the focal plane of the optical system, and the same scene could be sampled many times repeatedly by using time-varying control coding strategy, the super-resolution image is further reconstructed by sparse optimization algorithm. The results of simulation are quantitatively evaluated by introducing the Peak Signal-to-Noise Ratio (PSNR) and Modulation Transfer Function (MTF), which illustrate that the effect of compressed measurement coefficient r and coded mask resolution m on the reconstructed image quality. Research results show that the proposed method will promote infrared imaging quality effectively, which will be helpful for the practical design of new type of high resolution ! infrared imaging systems.

  5. Mixed Linear/Square-Root Encoded Single Slope Ramp Provides a Fast, Low Noise Analog to Digital Converter with Very High Linearity for Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Wrigley, Christopher James (Inventor); Hancock, Bruce R. (Inventor); Newton, Kenneth W. (Inventor); Cunningham, Thomas J. (Inventor)

    2014-01-01

    An analog-to-digital converter (ADC) converts pixel voltages from a CMOS image into a digital output. A voltage ramp generator generates a voltage ramp that has a linear first portion and a non-linear second portion. A digital output generator generates a digital output based on the voltage ramp, the pixel voltages, and comparator output from an array of comparators that compare the voltage ramp to the pixel voltages. A return lookup table linearizes the digital output values.

  6. Nine-analyte detection using an array-based biosensor

    NASA Technical Reports Server (NTRS)

    Taitt, Chris Rowe; Anderson, George P.; Lingerfelt, Brian M.; Feldstein, s. Mark. J.; Ligler, Frances S.

    2002-01-01

    A fluorescence-based multianalyte immunosensor has been developed for simultaneous analysis of multiple samples. While the standard 6 x 6 format of the array sensor has been used to analyze six samples for six different analytes, this same format has the potential to allow a single sample to be tested for 36 different agents. The method described herein demonstrates proof of principle that the number of analytes detectable using a single array can be increased simply by using complementary mixtures of capture and tracer antibodies. Mixtures were optimized to allow detection of closely related analytes without significant cross-reactivity. Following this facile modification of patterning and assay procedures, the following nine targets could be detected in a single 3 x 3 array: Staphylococcal enterotoxin B, ricin, cholera toxin, Bacillus anthracis Sterne, Bacillus globigii, Francisella tularensis LVS, Yersiniapestis F1 antigen, MS2 coliphage, and Salmonella typhimurium. This work maximizes the efficiency and utility of the described array technology, increasing only reagent usage and cost; production and fabrication costs are not affected.

  7. Phased-array sources based on nonlinear metamaterial nanocavities

    DOE PAGESBeta

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil Andrew; Shaner, Eric A.; Klem, John Frederick; Sinclair, Michael B.; et al

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization.more » As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. As a result, proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.« less

  8. Phased-array sources based on nonlinear metamaterial nanocavities

    PubMed Central

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil A.; Shaner, Eric A.; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-01-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum. PMID:26126879

  9. Phased-array sources based on nonlinear metamaterial nanocavities.

    PubMed

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P; Liu, Sheng; Luk, Ting S; Kadlec, Emil A; Shaner, Eric A; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-01-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum. PMID:26126879

  10. Engineering of optical polarization based on electronic band structures of A-plane ZnO layers under biaxial strains

    SciTech Connect

    Matsui, Hiroaki Tabata, Hitoshi; Hasuike, Noriyuki; Harima, Hiroshi

    2014-09-21

    In-plane anisotropic strains in A-plane layers on the electronic band structure of ZnO were investigated from the viewpoint of optical polarization anisotropy. Investigations utilizing k·p perturbation theory revealed that energy transitions and associated oscillation strengths were dependent on in-plane strains. The theoretical correlation between optical polarizations and in-plane strains was experimentally demonstrated using A-plane ZnO layers with different in-plane strains. Finally, optical polarization anisotropy and its implications for in-plane optical properties are discussed in relation to the energy shift between two orthogonal directions. Higher polarization rotations were obtained in an A-plane ZnO layer with in-plane biaxially compressive strains as compared to strain-free ZnO. This study provides detailed information concerning the role played by in-plane strains in optically polarized applications based on nonpolar ZnO in the ultra-violet region.

  11. Physics-based signal processing algorithms for micromachined cantilever arrays

    DOEpatents

    Candy, James V; Clague, David S; Lee, Christopher L; Rudd, Robert E; Burnham, Alan K; Tringe, Joseph W

    2013-11-19

    A method of using physics-based signal processing algorithms for micromachined cantilever arrays. The methods utilize deflection of a micromachined cantilever that represents the chemical, biological, or physical element being detected. One embodiment of the method comprises the steps of modeling the deflection of the micromachined cantilever producing a deflection model, sensing the deflection of the micromachined cantilever and producing a signal representing the deflection, and comparing the signal representing the deflection with the deflection model.

  12. Fracture Angle Analysis of Rock Burst Faulting Planes Based on True-Triaxial Experiment

    NASA Astrophysics Data System (ADS)

    Gong, Weili; Peng, Yanyan; Wang, Hu; He, Manchao; Ribeiro e Sousa, L.; Wang, Jiong

    2015-05-01

    The aim of this paper is to estimate fracture angles in deep-seated rock bursts encountered in intact hard rock tunnels. The fracture angles of fault planes in rock burst failure are analytically formulated by employing stress analysis based on Mohr's circle construction. Mohr's circle construction suits well for representing the rock burst stress states including the static loading and dynamic unloading processes existing at or near the excavation surface. Four fracture angles can be precisely predicted using the proposed mathematical models, including two minimum angles for two conjugate planes where the shear stress is equal to the maximum static shear stress τ max while the normal stress approaches to zero, and two maximum angles for two conjugate planes where the normal stress is reduced from σ 1 to σ 1/2 while shear stress increases markedly from ±( σ 1- σ 3)/2 to the maximum dynamic shear τ dmax = ± σ 1/2. For validation of the analytical solutions to fracture angles, rock burst experiments on Laizhou granite were conducted using a modified true-triaxial apparatus. The predicted fracture angles are compared very well with the results obtained from the laboratory rock burst tests and are in good agreement with the in situ observations. The proposed solutions to the fracture angle are a function of the static stresses only which can be known a priori from a field survey.

  13. An out-of-plane linear motion measurement system based on optical beam deflection

    NASA Astrophysics Data System (ADS)

    Piyush, P.; Jayanth, G. R.

    2016-02-01

    Measurement of out-of-plane linear motion with high precision and bandwidth is indispensable for development of precision motion stages and for dynamic characterization of mechanical structures. This paper presents an optical beam deflection (OBD) based system for measurement of out-of-plane linear motion for fully reflective samples. The system also achieves nearly zero cross-sensitivity to angular motion, and a large working distance. The sensitivities to linear and angular motion are analytically obtained and employed to optimize the system design. The optimal shot-noise limited resolution is shown to be less than one angstrom over a bandwidth in excess of 1 kHz. Subsequently, the system is experimentally realized and the sensitivities to out-of-plane motions are calibrated using a novel strategy. The linear sensitivity is found to be in agreement with theory. The angular sensitivity is shown to be over 7.5-times smaller than that of conventional OBD. Finally, the measurement system is employed to measure the transient response of a piezo-positioner, and, with the aid of an open-loop controller, reduce the settling time by about 90%. It is also employed to operate the positioner in closed-loop and demonstrate significant minimization of hysteresis and positioning error.

  14. Detonation discrimination techniques using a Fourier transform infrared spectrometer system and a near-infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Dills, Anthony N.; Gross, Kevin; Perram, Glen P.

    2003-09-01

    To investigate the possibility of battlespace characterization, including the ability to classify munitions type and size, experimental data has been collected remotely from ground-based sensors, processed, and analyzed for several conventional munitions. The spectral, temporal and spatial infrared signatures from bomb detonations were simultaneously recorded using a Bomem MR157 Fourier Transform Infrared Spectrometer and an Indigo Systems Alpha Near-Infrared camera. Three different high explosive materials at three different quantities each were examined in one series of field studies. The FTIR spectra were recorded at 4 cm-1 spectral resolution and 123-ms temporal resolution using both HgCdTd (500-6000 cm-1) and InSb (1800-6000 cm-1) detectors. Novel key features have been identified that will aid in discriminating various types and sizes of flashes. These features include spectral dependent projections of one event's temporal data onto another event's temporal data, time dependence of the fireball size, ratios of specific integrated bands, and spectral dependence of temporal fit constants. Using Fisher discrimination and principal component techniques these features are projected onto a line that maximizes the differences in the classes of flashes and then identify the Bayesian decision boundaries for classification.

  15. Technology of uncooled fast polycrystalline PbSe focal plane arrays in systems for muzzle flash detection

    NASA Astrophysics Data System (ADS)

    Kastek, Mariusz; PiÄ tkowski, Tadeusz; Polakowski, Henryk; Barela, Jaroslaw; Firmanty, Krzysztof; Trzaskawka, Piotr; Vergara, German; Linares, Rodrigo; Gutierrez, Raul; Fernandez, Carlos; Montojo Supervielle, Maria Teresa

    2014-05-01

    The paper presents some aspects of muzzle flash detection using low resolution polycrystalline PbSe 32×32 and 80×80 detectors FPA operating at room temperature (uncooled performance). These sensors, which detect in MWIR (3 - 5 microns region) and are manufactured using proprietary technology from New Infrared Technologies (VPD PbSe - Vapor Phase Deposition of polycrystalline PbSe), can be applied to muzzle flash detection. The system based in the uncooled 80×80 FPA monolithically integrated with the CMOS readout circuitry has allowed image recording with frame rates over 2000 Hz (true snapshot acquisition), whereas the lower density, uncooled 32×32 FPA is suitable for being used in low cost infrared imagers sensitive in the MWIR band with frame rates above 1000 Hz. The FPA detector, read-out electronics and processing electronics (allows the implementation of some algorithms for muzzle flash detection) of both systems are presented. The systems have been tested at field test ground. Results of detection range measurement with two types of optical systems (wide and narrow field of view) have been shown. The theoretical analysis of possibility detection of muzzle flash and initial results of testing of some algorithms for muzzle flash detection have been presented too.

  16. An Array of Ice-Based Observatories for Arctic Studies

    NASA Astrophysics Data System (ADS)

    Plueddemann, A.; Proshutinsky, A.; Toole, J.; Ashjian, C.; Krishfield, R.; Carmack, E.; Dethloff, K.; Fahrbach, E.; Gascard, J.; Perovich, D.; Pryamikov, S.

    2004-12-01

    The Arctic Ocean's role in global climate - while now widely appreciated - remains poorly understood. Lack of information about key processes within the oceanic, cryospheric, biologic, atmospheric and geologic disciplines will continue to impede physical understanding, model validation, and climate prediction until a practical observing system is designed and implemented. Requirements, challenges and recommendations for Ice-Based Observatories (IBO?s) for the Arctic Ocean were formulated by workshop participants of an international workshop entitled "Arctic Observing Based on Ice-Tethered Platforms" held at the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts, USA, June 28-30, 2004. The principal conclusion from the workshop was that practical, cost-effective and proven IBO designs presently exist, can be readily extended to provide interdisciplinary observations, and should be implemented expeditiously as part of a coordinated Arctic observing system. Ice-based instrument systems are a proven means of acquiring unattended high quality air, ice, and ocean data from the central Arctic during all seasons. Arctic Change is ongoing and measurements need to begin now. An array of approximately 25-30 IBO units maintained throughout the Arctic Ocean is envisioned to observe the annual and interannual variations of the polar atmosphere-ice-ocean environment. An international body will be required to coordinate the various national programs (eliminate overlap, insure no data holes) and insure compatibility of data and their widespread distribution. A long-term, internationally coordinated logistics plan should be implemented as an essential complement to scientific and technical plans for an IBO array. The 25 years of IABP drift trajectories, existing data climatologies and available numerical simulations should be exploited to derive insight to optimal array design, deployment strategies, sampling intervals, and expected performance of an IBO array. IBO

  17. A digital output readout circuit with substrate temperature and bias heating compensation for uncooled micro-bolometer infrared focal plane arrays

    NASA Astrophysics Data System (ADS)

    Que, Longcheng; Wei, Linhai; Lv, Jian; Jiang, Yadong

    2015-07-01

    Uncooled micro-bolometer FPAs (focal plane arrays) are influenced by substrate temperature and bias heating effect seriously. When the substrate temperature of the FPA changes greatly, the output and the responsivity of the FPA will vary a lot, thus the images' quality is poor without the substrate temperature and bias heating effect compensation. In this paper, a new substrate temperature compensation method is proposed, which is completed during analog-to-digital converting with a 12-bit ADC (analog-to-digital converter), and the bias heating effect is canceled by trimming blind bolometers with on-chip DAC (digital-to-analog converter). The simulation result presents the achievable substrate temperature compensation range is about 80 K. The proposed structure has been adopted in a readout circuit and successfully fabricated with 0.5 μm CMOS process. For normal temperature scene (300 K), the digital output only changes 16% when the substrate temperature changes from 253 K to 333 K. And the equivalent analog output only changes 546.2 mV with a 3.4 V output swing. As a result, the scene DR (dynamic range) does not change rapidly along with the variation of the substrate temperature and the images' quality is improved greatly.

  18. Analysis of the Maillard reaction in human hair using Fourier transform infrared spectroscopic imaging and a focal-plane array detector.

    PubMed

    Jung, In-Keun; Park, Sang-Chul; Bin, Sung-Ah; Roh, Young Sup; Lee, John Hwan; Kim, Boo-Min

    2016-03-01

    The Maillard reaction has been well researched and used in the food industry and the fields of environmental science and organic chemistry. Here, we induced the Maillard reaction inside human hair and analyzed its effects by using Fourier transform infrared spectroscopy with a focal-plane array (FTIR-FPA) detector. We used arginine (A), glycine (G), and D-xylose (X) to generate the Maillard reaction by dissolving them in purified water and heating it to 150 °C. This label-free process generated a complex compound (named AGX after its ingredients) with a monomer structure, which was determined by using nuclear magnetic resonance (NMR) and FTIR-FPA. This compound was stable in hair and substantially increased its tensile strength. To our knowledge, we are the first to report the formation of this monomer in human hair, and our study provides insights into a new method that could be used to improve the condition of damaged or aging hair. PMID:26905862

  19. Study of LWIR and VLWIR Focal Plane Array Developments: Comparison Between p-on- n and Different n-on- p Technologies on LPE HgCdTe

    NASA Astrophysics Data System (ADS)

    Gravrand, O.; Mollard, L.; Largeron, C.; Baier, N.; Deborniol, E.; Chorier, Ph.

    2009-08-01

    The very long infrared wavelength (>14 μm) is a very challenging range for the design of mercury cadmium telluride (HgCdTe) large focal plane arrays (FPAs). The need (mainly expressed by the space industry) for very long wave FPAs appears very difficult to fulfil. High homogeneity, low defect rate, high quantum efficiency, low dark current, and low excess noise are required. Indeed, for such wavelength, the corresponding HgCdTe gap becomes smaller than 100 meV and each step from the metallurgy to the technology becomes critical. This paper aims at presenting a status of long and very long wave FPAs developments at DEFIR (LETI-LIR/Sofradir joint venture). This study will focus on results obtained in our laboratory for three different ion implanted technologies: n-on- p mercury vacancies doped technology, n-on- p extrinsic doped technology, and p-on- n arsenic on indium technology. Special focus is given to 15 μm cutoff n/ p FPA fabricated in our laboratory demonstrating high uniformity, diffusion and shot noise limited photodiodes at 50 K.

  20. Development of a 2.0W at 60K single-stage coaxial pulse tube cryocooler for long-wave infrared focal plane array applications

    NASA Astrophysics Data System (ADS)

    Dang, H. Z.; Wang, L. B.; Wu, Y. N.; Yang, K. X.; Li, S. S.; Shen, W. B.

    2010-04-01

    A 2.0W@60K single-stage coaxial pulse tube cryocooler has been developed to provide reliable low-vibration cooling for the space-borne long wave infrared focal plane array. The coaxial configuration result in a compact system and the inertance tube together with a gas reservoir serves as the only phase-shifting to realize a highly reliable system. The inertance tube consists of two parts with different inner diameter and length to obtain the desirable phase relationship. Both cold tip and warm flange integrated with fine slit heat exchanges fabricated with electro discharge machining technology to enhance heat exchange performance. A split Oxford-type linear compressor with dual-opposed piston configuration is connected to the cold finger with a 30 cm flexible metallic tube. The overall weight without control electronics is below 8 kg. The preliminary experiments show that a no-load temperature of 46 K and a cooling power of 2 W at 60 K with 104 W of input power at 300K reject temperature have been achieved.

  1. Composite x-ray image assembly for large-field digital mammography with one- and two-dimensional positioning of a focal plane array

    NASA Technical Reports Server (NTRS)

    Halama, G.; McAdoo, J.; Liu, H.

    1998-01-01

    To demonstrate the feasibility of a novel large-field digital mammography technique, a 1024 x 1024 pixel Loral charge-coupled device (CCD) focal plane array (FPA) was positioned in a mammographic field with one- and two-dimensional scan sequences to obtain 950 x 1800 pixel and 3600 x 3600 pixel composite images, respectively. These experiments verify that precise positioning of FPAs produced seamless composites and that the CCD mosaic concept has potential for high-resolution, large-field imaging. The proposed CCD mosaic concept resembles a checkerboard pattern with spacing left between the CCDs for the driver and readout electronics. To obtain a complete x-ray image, the mosaic must be repositioned four times, with an x-ray exposure at each position. To reduce the patient dose, a lead shield with appropriately patterned holes is placed between the x-ray source and the patient. The high-precision motorized translation stages and the fiber-coupled-scintillating-screen-CCD sensor assembly were placed in the position usually occupied by the film cassette. Because of the high mechanical precision, seamless composites were constructed from the subimages. This paper discusses the positioning, image alignment procedure, and composite image results. The paper only addresses the formation of a seamless composite image from subimages and will not consider the effects of the lead shield, multiple CCDs, or the speed of motion.

  2. Printed paper-based arrays as substrates for biofilm formation

    PubMed Central

    2014-01-01

    The suitability of paper-based arrays for biofilm formation studies by Staphylococcus aureus is demonstrated. Laboratory-coated papers with different physicochemical properties were used as substrates. The array platform was fabricated by patterning the coated papers with vinyl-substituted polydimethylsiloxane (PDMS) -based ink. The affinity of bacteria onto the flexographically printed hydrophobic and smooth PDMS film was very low whereas bacterial adhesion and biofilm formation occurred preferentially on the unprinted areas, i.e. in the reaction arrays. The concentration of the attached bacteria was quantified by determining the viable colony forming unit (CFU/cm2) numbers. The distribution and the extent of surface coverage of the biofilms were determined by atomic force microscopy. In static conditions, the highest bacterial concentration and most highly organized biofilms were observed on substrates with high polarity. On a rough paper surface with low polarity, the biofilm formation was most hindered. Biofilms were effectively removed from a polar substrate upon exposure to (+)-dehydroabietic acid, an anti-biofilm compound. PMID:25006538

  3. Digital camcorder image stabilizer based on gray-coded bit-plane block matching

    NASA Astrophysics Data System (ADS)

    Yeh, YeouMin; Chiang, Huang-Cheng; Wang, Sheng-Jyh

    2001-10-01

    We propose an efficient algorithm to eliminate the nonpleasing effect caused by involuntary hand movement of camera holders. In our approach, 1-bit gray-coded bit- plane block matching, instead of 8-bit gray-level block matching, is used to greatly simplify the computation of motion estimation. This computation saving makes possible a finer division of image frame and thus facilitates the employment of a much more robust procedure for motion decision. To deal with various interfering factors in motion estimation, the temporal information of each local motion vector is also used to efficiently distinguish random-like movement from temporally correlated movement. To compensate for camera rotation, an affine model is used in the motion compensation unit without adding too much computation load. Having considered both programming flexibility and hardware efficiency, the motion decision unit and the motion compensation unit are coded in a microprocessor that interconnects with the stabilization hardware, which consists of the motion estimation unit and the digital zooming unit. A slightly simplified version of the proposed stabilizer is implemented on a field programmable gate array (FPGA) board.

  4. Simulation of an array-based neural net model

    NASA Technical Reports Server (NTRS)

    Barnden, John A.

    1987-01-01

    Research in cognitive science suggests that much of cognition involves the rapid manipulation of complex data structures. However, it is very unclear how this could be realized in neural networks or connectionist systems. A core question is: how could the interconnectivity of items in an abstract-level data structure be neurally encoded? The answer appeals mainly to positional relationships between activity patterns within neural arrays, rather than directly to neural connections in the traditional way. The new method was initially devised to account for abstract symbolic data structures, but it also supports cognitively useful spatial analogue, image-like representations. As the neural model is based on massive, uniform, parallel computations over 2D arrays, the massively parallel processor is a convenient tool for simulation work, although there are complications in using the machine to the fullest advantage. An MPP Pascal simulation program for a small pilot version of the model is running.

  5. Array-based functional screening of heparin glycans.

    PubMed

    Puvirajesinghe, Tania M; Ahmed, Yassir A; Powell, Andrew K; Fernig, David G; Guimond, Scott E; Turnbull, Jeremy E

    2012-05-25

    Array methodologies have become powerful tools for interrogation of glycan-protein interactions but have critically lacked the ability to generate cell response data. Here, we report the development of a slide-based array method exemplified by measurement of activation of fibroblast growth factor signaling by heparin saccharides. Heparan sulfate-deficient Swiss 3T3 cells were overlaid onto an aminosilane-coated slide surface onto which heparin saccharides had been spotted and immobilized. The cells were transiently stimulated with FGF2 and immunofluorescence measured to assess downstream ERK1/2 phosphorylation. Activation of this signaling pathway response was restricted to cells exposed to heparin saccharides competent to activate FGF2 signaling. Differential activation of the overlaid cells by different-sized heparin saccharides was demonstrated by quantitative measurement of fluorescence intensity. This "glycobioarray" platform has significant potential as a generic tool for functional glycomics screening. PMID:22633407

  6. Heterodyne detection with mismatch correction based on array detector

    NASA Astrophysics Data System (ADS)

    Dong, Hongzhou; Li, Guoqiang; Yang, Ruofu; Yang, Chunping; Ao, Mingwu

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  7. Heterodyne detection with mismatch correction base on array detector

    NASA Astrophysics Data System (ADS)

    Hongzhou, Dong; Guoqiang, Li; Ruofu, Yang; Chunping, Yang; Mingwu, Ao

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  8. Polycyanurate nanorod arrays for optical-waveguide-based biosensing.

    PubMed

    Gitsas, Antonis; Yameen, Basit; Lazzara, Thomas Dominic; Steinhart, Martin; Duran, Hatice; Knoll, Wolfgang

    2010-06-01

    We demonstrate high-sensitivity biosensing by optical waveguide spectroscopy (OWS) at visible wavelengths using aligned polycyanurate thermoset nanorods (PCNs) arranged in extended arrays as waveguides. The PCNs formed by thermal polymerization of a cyanate ester monomer in self-ordered nanoporous alumina templates were 60 nm in diameter and 650 nm in length. Subtle refractive index changes of the medium surrounding the nanorods could be detected by monitoring the angular shifts of waveguiding modes. The sensing figure of merit thus achieved amounted to 196 reciprocal refractive index units and is, therefore, higher than that of other sensors based on angular modulation, while the configuration used here is eligible for further surface functionalization. Kinetics of the binding of taurine to the surface cyanate groups of the PCNs was monitored by OWS. Thus, modified PCNs bearing sulfonic acid groups at their surfaces were obtained. PCN arrays may represent a versatile platform for the design of biosensors. PMID:20527931

  9. Plane-based sampling for ray casting algorithm in sequential medical images.

    PubMed

    Lin, Lili; Chen, Shengyong; Shao, Yan; Gu, Zichun

    2013-01-01

    This paper proposes a plane-based sampling method to improve the traditional Ray Casting Algorithm (RCA) for the fast reconstruction of a three-dimensional biomedical model from sequential images. In the novel method, the optical properties of all sampling points depend on the intersection points when a ray travels through an equidistant parallel plan cluster of the volume dataset. The results show that the method improves the rendering speed at over three times compared with the conventional algorithm and the image quality is well guaranteed. PMID:23424608

  10. Assessment of planarity of the golf swing based on the functional swing plane of the clubhead and motion planes of the body points.

    PubMed

    Kwon, Young-Hoo; Como, Christopher S; Singhal, Kunal; Lee, Sangwoo; Han, Ki Hoon

    2012-06-01

    The purposes of this study were (1) to determine the functional swing plane (FSP) of the clubhead and the motion planes (MPs) of the shoulder/arm points and (2) to assess planarity of the golf swing based on the FSP and the MPs. The swing motions of 14 male skilled golfers (mean handicap = -0.5 +/- 2.0) using three different clubs (driver, 5-iron, and pitching wedge) were captured by an optical motion capture system (250Hz). The FSP and MPs along with their slope/relative inclination and direction/direction of inclination were obtained using a new trajectory-plane fitting method. The slope and direction of the FSP revealed a significant club effect (p < 0.001). The relative inclination and direction of inclination of the MP showed significant point (p < 0.001) and club (p < 0.001) effects and interaction (p < 0.001). Maximum deviations of the points from the FSP revealed a significant point effect (p < 0.001) and point-club interaction (p < 0.001). It was concluded that skilled golfers exhibited well-defined and consistent FSP and MPs, and the shoulder/arm points moved on vastly different MPs and exhibited large deviations from the FSP. Skilled golfers in general exhibited semi-planar downswings with two distinct phases: a transition phase and a planar execution phase. PMID:22900396

  11. Iterative diagonalization in augmented plane wave based methods in electronic structure calculations

    SciTech Connect

    Blaha, P.; Laskowski, R.; Schwarz, K.

    2010-01-20

    Due to the increased computer power and advanced algorithms, quantum mechanical calculations based on Density Functional Theory are more and more widely used to solve real materials science problems. In this context large nonlinear generalized eigenvalue problems must be solved repeatedly to calculate the electronic ground state of a solid or molecule. Due to the nonlinear nature of this problem, an iterative solution of the eigenvalue problem can be more efficient provided it does not disturb the convergence of the self-consistent-field problem. The blocked Davidson method is one of the widely used and efficient schemes for that purpose, but its performance depends critically on the preconditioning, i.e. the procedure to improve the search space for an accurate solution. For more diagonally dominated problems, which appear typically for plane wave based pseudopotential calculations, the inverse of the diagonal of (H - ES) is used. However, for the more efficient 'augmented plane wave + local-orbitals' basis set this preconditioning is not sufficient due to large off-diagonal terms caused by the local orbitals. We propose a new preconditioner based on the inverse of (H - {lambda}S) and demonstrate its efficiency for real applications using both, a sequential and a parallel implementation of this algorithm into our WIEN2k code.

  12. A Cosmic Dust Sensor Based on an Array of Grid Electrodes

    NASA Astrophysics Data System (ADS)

    Li, Y. W.; Bugiel, S.; Strack, H.; Srama, R.

    2014-04-01

    We described a low mass and high sensitivity cosmic dust trajectory sensor using a array of grid segments[1]. the sensor determines the particle velocity vector and the particle mass. An impact target is used for the detection of the impact plasma of high speed particles like interplanetary dust grains or high speed ejecta. Slower particles are measured by three planes of grid electrodes using charge induction. In contrast to conventional Dust Trajectory Sensor based on wire electrodes, grid electrodes a robust and sensitive design with a trajectory resolution of a few degree. Coulomb simulation and laboratory tests were performed in order to verify the instrument design. The signal shapes are used to derive the particle plane intersection points and to derive the exact particle trajectory. The accuracy of the instrument for the incident angle depends on the particle charge, the position of the intersection point and the signal-to-noise of the charge sensitive amplifier (CSA). There are some advantages of this grid-electrodes based design with respect to conventional trajectory sensor using individual wire electrodes: the grid segment electrodes show higher amplitudes (close to 100%induced charge) and the overall number of measurement channels can be reduced. This allows a compact instrument with low power and mass requirements.

  13. High sensitivity carbon nanotube based electrochemiluminescence sensor array

    PubMed Central

    Venkatanarayanan, Anita; Crowley, Karl; Lestini, Elena; Keyes, Tia E.; Rusling, James F.; Forster, Robert J.

    2012-01-01

    Ink jet printed carbon nanotube forest arrays capable of detecting picomolar concentrations of immunoglobulin G (IgG) using electrochemiluminescence (ECL) are described. Patterned arrays of vertically aligned single walled carbon nanotube (SWCNT) forests were printed on indium tin oxide (ITO) electrodes. Capture anti-IgG antibodies were then coupled through peptide bond formation to acidic functional groups on the vertical nanotubes. IgG immunoassays were performed using silica nano particles (Si NP) functionalized with the ECL luminophore [Ru(bpy)2 PICH2]2+], and IgG labelled G1.5 acid terminated PAMAM dendrimers. PAMAM is poly(amido amine), bpy is 2,2′-bipyridyl and PICH2 is (2-(4-carboxyphenyl)imidazo[4,5-f][1,10]phenanthroline). The carboxyl terminal of [Ru(bpy)2 PICH2]2+ (fluorescence lifetime ≈682 ± 5 ns) dye was covalently coupled to amine groups on the 800 nm diameter silica spheres in order to produce significant ECL enhancement in the presence of sodium oxalate as co-reactant in PBS at pH 7.2). Significantly, this SWCNT-based sensor array shows a wide linear dynamic range for IgG coated spheres (106 to 1012 spheres) corresponding to IgG concentrations between 20 pM and 300 nM. A detection limit of 1.1 ± 0.1 pM IgG is obtained under optimal conditions. PMID:22137061

  14. Cell pairing using microwell array electrodes based on dielectrophoresis.

    PubMed

    Yoshimura, Yuki; Tomita, Masahiro; Mizutani, Fumio; Yasukawa, Tomoyuki

    2014-07-15

    We report a simple device with an array of 10,000 (100 × 100) microwells for producing vertical pairs of cells in individual microwells with a rapid manipulation based on positive dielectrophoresis (p-DEP). The areas encircled with micropoles which fabricated from an electrical insulating photosensitive polymer were used as microwells. The width (14 μm) and depth (25 μm) of the individual microwells restricted the size to two vertically aligned cells. The DEP device for the manipulation of cells consisted of a microfluidic channel with an upper indium tin oxide (ITO) electrode and a lower microwell array electrode fabricated on an ITO substrate. Mouse myeloma cells stained in green were trapped within 1 s in the microwells by p-DEP by applying an alternating current voltage between the upper ITO and the lower microwell array electrode. The cells were retained inside the wells even after switching off the voltage and washing with a fluidic flow. Other myeloma cells stained in blue were then trapped in the microwells occupied by the cells stained in green to form the vertical cell pairing in the microwells. Cells stained in different colors were paired within only 1 min and a pairing efficiency of over 50% was achieved. PMID:24947270

  15. High-resolution seismic array imaging based on numerical seismic wave simulations

    NASA Astrophysics Data System (ADS)

    Liu, Q.; Tong, P.; Chen, C.

    2012-12-01

    Adjoint tomography, i.e., seismic tomography based on full numerical simulations and adjoint methods, is a powerful tool for high-resolution imaging in heterogeneous media. It resolves large velocity contrasts through the use of 3D initial models and exploits more quantitative information from observed seismograms. However, for regions with limited local seismicity, seismic imaging relies more on teleseismic records. In particular coda and converted waves of main teleseismic arrivals used in scattering imaging are vital in resolving subsurface interfaces and velocity anomalies beneath seismic arrays. It remains numerically challenging to accurately and efficiently simulate the full propagation of seismic waves at the frequencies relevant to scattering imaging. In this work, to simulate the propagation of teleseismic planes waves into localized heterogeneous structures, we apply a hybrid method that interacts a spectral-element solver within the domain with a semi-analytical solution for 1D background medium at the absorbing boundaries. This technique will be implemented in both SPECFEM2D and SPECFEM3D packages and make it possible to invert both regional and teleseismic recordings in the framework of adjoint tomography. Synthetic tests will be performed to show the feasibility of high-resolution seismic array imaging of coda and converted waves based on adjoint techniques.

  16. Long wave focal plane array detector: development and performance assessment of an 8X8 Sterling cooled photovoltaic MCT detector module

    NASA Astrophysics Data System (ADS)

    Rochette, Luc; Smithson, Tracy; Gurgenian, Raymond; St. Pierre, Guy

    2007-09-01

    In June 2005, a newly develop long wave Focal Pane Array (FPA), based on photo-voltaic technology was delivered to the Defense Research & Development of Canada (DRDC). This development was part of technological Demonstration program that was founded by the DRDC. This paper will describe the FPA configuration along with its performance assessment configured in the Air PIRATE FTIR spectrometer. Air PIRATE is an airborne version of the hyper spectral spectrometer used by the Canadian Defense for target identification, as well as chemical agent identification.

  17. Geoacoustic Inversion Based on a Vector Hydrophone Array

    NASA Astrophysics Data System (ADS)

    Peng, Han-Shu; Li, Feng-Hua

    2007-07-01

    We propose a geoacoustic inversion scheme employing a vector hydrophone array based on the fact that vector hydrophone can provide more acoustic field information than traditional pressure hydrophones. Firstly, the transmission loss of particle velocities is discussed. Secondly, the sediment sound speed is acquired by a matched-field processing (MFP) procedure, which is the optimization in combination of the pressure field and vertical particle velocity field. Finally, the bottom attenuation is estimated from the transmission loss difference between the vertical particle velocity and the pressure. The inversion method based on the vector hydrophone array mainly has two advantages: One is that the MFP method based on vector field can decrease the uncertain estimation of the sediment sound speed. The other is that the objective function based on the transmission loss difference has good sensitivity to the sediment attenuation and the inverted sediment attenuation is independent of source level. The validity of the inverted parameters is examined by comparison of the numerical results with the experimental data.

  18. Nonpolar m-plane gallium Nitride-based Laser Diodes in the Blue Spectrum

    NASA Astrophysics Data System (ADS)

    Kelchner, Kathryn M.

    Gallium nitride (GaN), together with its alloys with aluminum and indium, have revolutionized the solid-state optoelectronics market for their ability to emit a large portion of the visible electromagnetic spectrum from deep ultraviolet and into the infrared. GaN-based semiconductor laser diodes (LDs) with emission wavelengths in the violet, blue and green are already seeing widespread implementation in applications ranging from energy storage, lighting and displays. However, commercial GaN-based LDs use the basal c-plane orientation of the wurtzite crystal, which can suffer from large internal electric fields due to discontinuities in spontaneous and piezoelectric polarizations, limiting device performance. The nonpolar orientation of GaN benefits from the lack of polarization-induced electric field as well as enhanced gain. This dissertation discusses some of the benefits and limitations of m-plane oriented nonpolar GaN for LD applications in the true blue spectrum (450 nm). Topics include an overview of material growth by metal-organic chemical vapor deposition (MOCVD), waveguide design and processing techniques for improving device performance for multiple lateral mode and single lateral mode ridge waveguides.

  19. Application of Hybrid Fillers for Improving the Through-Plane Heat Transport in Graphite Nanoplatelet-Based Thermal Interface Layers

    NASA Astrophysics Data System (ADS)

    Tian, Xiaojuan; Itkis, Mikhail E.; Haddon, Robert C.

    2015-08-01

    The in-plane alignment of graphite nanoplatelets (GNPs) in thin thermal interface material (TIM) layers suppresses the though-plane heat transport thus limiting the performance of GNPs in the geometry normally required for thermal management applications. Here we report a disruption of the GNP in-plane alignment by addition of spherical microparticles. The degree of GNP alignment was monitored by measurement of the anisotropy of electrical conductivity which is extremely sensitive to the orientation of high aspect ratio filler particles. Scanning Electron Microscopy images of TIM layer cross-sections confirmed the suppression of the in-plane alignment. The hybrid filler formulations reported herein resulted in a synergistic enhancement of the through-plane thermal conductivity of GNP/Al2O3 and GNP/Al filled TIM layers confirming that the control of GNP alignment is an important parameter in the development of highly efficient GNP and graphene-based TIMs.

  20. Application of Hybrid Fillers for Improving the Through-Plane Heat Transport in Graphite Nanoplatelet-Based Thermal Interface Layers

    PubMed Central

    Tian, Xiaojuan; Itkis, Mikhail E.; Haddon, Robert C.

    2015-01-01

    The in-plane alignment of graphite nanoplatelets (GNPs) in thin thermal interface material (TIM) layers suppresses the though-plane heat transport thus limiting the performance of GNPs in the geometry normally required for thermal management applications. Here we report a disruption of the GNP in-plane alignment by addition of spherical microparticles. The degree of GNP alignment was monitored by measurement of the anisotropy of electrical conductivity which is extremely sensitive to the orientation of high aspect ratio filler particles. Scanning Electron Microscopy images of TIM layer cross-sections confirmed the suppression of the in-plane alignment. The hybrid filler formulations reported herein resulted in a synergistic enhancement of the through-plane thermal conductivity of GNP/Al2O3 and GNP/Al filled TIM layers confirming that the control of GNP alignment is an important parameter in the development of highly efficient GNP and graphene-based TIMs. PMID:26279183

  1. Transparent and flexible force sensor array based on optical waveguide.

    PubMed

    Kim, Youngsung; Park, Suntak; Park, Seung Koo; Yun, Sungryul; Kyung, Ki-Uk; Sun, Kyung

    2012-06-18

    This paper suggests a force sensor array measuring contact force based on intensity change of light transmitted throughout optical waveguide. For transparency and flexibility of the sensor, two soft prepolymers with different refractive index have been developed. The optical waveguide consists of two cladding layers and a core layer. The top cladding layer is designed to allow light scattering at the specific area in response to finger contact. The force sensor shows a distinct tendency that output intensity decreases with input force and measurement range is from 0 to -13.2 dB. PMID:22714510

  2. a Multi-View Image Matching Method for Feature Points Based on the Moving Z-Plane Constraint

    NASA Astrophysics Data System (ADS)

    Wang, J.; Song, W.; Bu, F.

    2012-07-01

    Focusing on the serious occlusion problem in city images, this paper makes full use of the advantage of multi-view image matching, and proposes a reliable multi-view image matching method based on the moving Z-Plane constraint. It supposes a fictitious plane in the object space, and the plane is divided to regular grid cell (small plane element) by a certain interval (≥ image resolution). By moving the plane to different elevation positions, this algorithm makes feature point projection ray in overall images intersect with the plane, and constrains the candidate points by grid cells in the plane. Feature points which come from different images projection ray in the same grid cell on the plane may be regarded as the matching candidates. It selects the images which matching candidate points by gray similarity constraint to avoid the effect from occlusion image. According to the number of projection ray in the grid cell, this algorithm adopts hierarchy matching strategy of "the best candidate will be matched in the first instant", and uses initial matching results as constraint condition in the latter matching process. Finally, the validity of the algorithm proposed in this paper is verified by the experiments using four UltraCamX (UCX) digital aerial images and the algorithm is shown to have reliable matching results.

  3. A study of the feasibility and performance of an active/passive imager using silicon focal plane arrays and incoherent continuous wave laser diodes

    NASA Astrophysics Data System (ADS)

    Vollmerhausen, Richard H.

    This dissertation describes an active/passive imager (API) that provides reliable, nighttime, target acquisition in a man-portable package with effective visual range of about 4 kilometers. The reflective imagery is easier to interpret than currently used thermal imagery. Also, in the active mode, the API provides performance equivalent to the big-aperture, thermal systems used on weapons platforms like tanks and attack helicopters. This dissertation describes the research needed to demonstrate both the feasibility and utility of the API. Part of the research describes implementation of a silicon focal plane array (SFPA) capable of both active and passive imaging. The passive imaging mode exceeds the nighttime performance of currently fielded, man-portable sensors. Further, when scene illumination is insufficient for passive imaging, the low dark current of SFPA makes it possible to use continuous wave laser diodes (CWLD) to add an active imaging mode. CWLD have advantages of size, efficiency, and improved eye safety when compared to high peak-power diodes. Because of the improved eye safety, the API provides user-demanded features like video output and extended range gates in the active as well as passive imaging modes. Like any other night vision device, the API depends on natural illumination of the scene for passive operation. Although it has been known for decades that "starlight" illumination is actually from diffuse airglow emissions, the research described in this dissertation provides the first estimates of the global and temporal variation of ground illumination due to airglow. A third related element of the current research establishes the impact of atmospheric aerosols on API performance. We know from day experience that atmospheric scattering of sunlight into the imager line-of-sight can blind the imager and drastically degrade performance. Atmospheric scattering of sunlight is extensively covered in the literature. However, previous literature did not

  4. Interface and facet control during Czochralski growth of (111) InSb crystals for cost reduction and yield improvement of IR focal plane array substrates

    NASA Astrophysics Data System (ADS)

    Gray, Nathan W.; Perez-Rubio, Victor; Bolke, Joseph G.; Alexander, W. B.

    2014-10-01

    Focal plane arrays (FPAs) made on InSb wafers are the key cost-driving component in IR imaging systems. The electronic and crystallographic properties of the wafer directly determine the imaging device performance. The "facet effect" describes the non-uniform electronic properties of crystals resulting from anisotropic dopant segregation during bulk growth. When the segregation coefficient of dopant impurities changes notably across the melt/solid interface of a growing crystal the result is non-uniform electronic properties across wafers made from these crystals. The effect is more pronounced in InSb crystals grown on the (111) axis compared with other orientations and crystal systems. FPA devices made on these wafers suffer costly yield hits due to inconsistent device response and performance. Historically, InSb crystal growers have grown approximately 9-19 degree off-axis from the (111) to avoid the facet effect and produced wafers with improved uniformity of electronic properties. It has been shown by researchers in the 1960s that control of the facet effect can produce uniform small diameter crystals. In this paper, we share results employing a process that controls the facet effect when growing large diameter crystals from which 4, 5, and 6" wafers can be manufactured. The process change resulted in an increase in wafers yielded per crystal by several times, all with high crystal quality and uniform electronic properties. Since the crystals are grown on the (111) axis, manufacturing (111) oriented wafers is straightforward with standard semiconductor equipment and processes common to the high-volume silicon wafer industry. These benefits result in significant manufacturing cost savings and increased value to our customers.

  5. Room geometry inference based on spherical microphone array eigenbeam processing.

    PubMed

    Mabande, Edwin; Kowalczyk, Konrad; Sun, Haohai; Kellermann, Walter

    2013-10-01

    The knowledge of parameters characterizing an acoustic environment, such as the geometric information about a room, can be used to enhance the performance of several audio applications. In this paper, a novel method for three-dimensional room geometry inference based on robust and high-resolution beamforming techniques for spherical microphone arrays is presented. Unlike other approaches that are based on the measurement and processing of multiple room impulse responses, here, microphone array signal processing techniques for uncontrolled broadband acoustic signals are applied. First, the directions of arrival (DOAs) and time differences of arrival (TDOAs) of the direct signal and room reflections are estimated using high-resolution robust broadband beamforming techniques and cross-correlation analysis. In this context, the main challenges include the low reflected-signal to background-noise power ratio, the low energy of reflected signals relative to the direct signal, and their strong correlation with the direct signal and among each other. Second, the DOA and TDOA information is combined to infer the room geometry using geometric relations. The high accuracy of the proposed room geometry inference technique is confirmed by experimental evaluations based on both simulated and measured data for moderately reverberant rooms. PMID:24116416

  6. Digital camcorder image stabilizer based on gray-coded bit-plane block matching

    NASA Astrophysics Data System (ADS)

    Yeh, YeouMin; Wang, Sheng-Jyh; Chiang, Hwang-Cheng

    2000-06-01

    In this paper, we proposed an efficient algorithm to do image stabilization for digital camcorder. This approach is based on gray-coded bit-plane block matching to eliminate the unpleasing effect caused by involuntary movement of camera holders. To improve moving object detection and stabilization performance, a frame is divided into several blocks to do localized motion estimation. Based on our architecture, the temporal correlation is used at the motion unit to efficiently detect moving objects and panning conditions. To compensate for camera rotation, an energy minimization is also applied to calculate the coefficients of affine transform without many complicated computations. Having considered both programming flexibility and hardware efficiency, the motion decision and motion compensation units are coded in a microprocessor that interconnects with the stabilization hardware. The proposed stabilizer is now implemented on FPGA 10K 100.

  7. Implications of adopting plane angle as a base quantity in the SI

    NASA Astrophysics Data System (ADS)

    Quincey, Paul; Brown, Richard J. C.

    2016-06-01

    The treatment of angles within the SI is anomalous compared with other quantities, and there is a case for removing this anomaly by declaring plane angle to be an additional base quantity within the system. It is shown that this could bring several benefits in terms of treating angle on an equal basis with other metrics, removing potentially harmful ambiguities, and bringing SI units more in line with concepts in basic physics, but at the expense of significant upheaval to familiar equations within mathematics and physics. This paper sets out the most important of these changes so that an alternative unit system containing angle as a base quantity can be seen in the round, irrespective of whether it is ever widely adopted. The alternative formulas and units can be treated as the underlying, more general equations of mathematical physics, independent of the units used for angle, which are conventionally simplified by implicitly assuming that the unit used for angle is the radian.

  8. Resolution enhancement using pulse width modulation in digital micromirror device-based point-array scanning pattern exposure

    NASA Astrophysics Data System (ADS)

    Kuo, Hung-Fei; Huang, Yi-Jun

    2016-04-01

    Digital-mask lithography systems, with a digital micromirror device (DMD) as their central piece, have been widely used for defining patterns on printed circuit board (PCB). This study designed optical module parameters for point-array projection lithography based on field tracing technique to improve the quality of the aerial image on the exposure plane. In the realized optical module for the point-array projection lithography, a DMD was used as the dynamic digital-mask, and a 405-nm-wavelength laser was used to illuminate the DMD. The laser was then focused through the micro-lens array in the optical module to form a point array and was projected onto a dynamic scanning stage. By calculating the beam-overlapping rate, stage velocity, spot diameter, and DMD frame rate and programming them into the stage- and DMD-synchronized controller, the point array formed line patterns on the photoresist. Furthermore, using pulse width modulation (PWM) technique to operate the activation periods of the DMD mirrors effectively controlled the exposure and achieved a feature linewidth of less than 10 μm.

  9. Automatic decomposition of a complex hologram based on the virtual diffraction plane framework

    NASA Astrophysics Data System (ADS)

    Jiao, A. S. M.; Tsang, P. W. M.; Poon, T.-C.; Liu, J.-P.; Lee, C.-C.; Lam, Y. K.

    2014-07-01

    Holography is a technique for capturing the hologram of a three-dimensional scene. In many applications, it is often pertinent to retain specific items of interest in the hologram, rather than retaining the full information, which may cause distraction in the analytical process that follows. For a real optical image that is captured with a camera or scanner, this process can be realized by applying image segmentation algorithms to decompose an image into its constituent entities. However, because it is different from an optical image, classic image segmentation methods cannot be applied directly to a hologram, as each pixel in the hologram carries holistic, rather than local, information of the object scene. In this paper, we propose a method to perform automatic decomposition of a complex hologram based on a recently proposed technique called the virtual diffraction plane (VDP) framework. Briefly, a complex hologram is back-propagated to a hypothetical plane known as the VDP. Next, the image on the VDP is automatically decomposed, through the use of the segmentation on the magnitude of the VDP image, into multiple sub-VDP images, each representing the diffracted waves of an isolated entity in the scene. Finally, each sub-VDP image is reverted back to a hologram. As such, a complex hologram can be decomposed into a plurality of subholograms, each representing a discrete object in the scene. We have demonstrated the successful performance of our proposed method by decomposing a complex hologram that is captured through the optical scanning holography (OSH) technique.

  10. Graphene-based in-plane micro-supercapacitors with high power and energy densities

    PubMed Central

    Wu, Zhong–Shuai; Parvez, Khaled; Feng, Xinliang; Müllen, Klaus

    2013-01-01

    Micro-supercapacitors are important on-chip micro-power sources for miniaturized electronic devices. Although the performance of micro-supercapacitors has been significantly advanced by fabricating nanostructured materials, developing thin-film manufacture technologies and device architectures, their power or energy densities remain far from those of electrolytic capacitors or lithium thin-film batteries. Here we demonstrate graphene-based in-plane interdigital micro-supercapacitors on arbitrary substrates. The resulting micro-supercapacitors deliver an area capacitance of 80.7 μF cm−2 and a stack capacitance of 17.9 F cm−3. Further, they show a power density of 495 W cm−3 that is higher than electrolytic capacitors, and an energy density of 2.5 mWh cm−3 that is comparable to lithium thin-film batteries, in association with superior cycling stability. Such microdevices allow for operations at ultrahigh rate up to 1,000 V s−1, three orders of magnitude higher than that of conventional supercapacitors. Micro-supercapacitors with an in-plane geometry have great promise for numerous miniaturized or flexible electronic applications. PMID:24042088

  11. Near-field coupling model between PCB and grounded transmission line based on plane wave spectrum

    NASA Astrophysics Data System (ADS)

    Leseigneur, Christelle; Baudry, David; Ravelo, Blaise; Louis, Anne

    2013-10-01

    This article presents an explicit model of electromagnetic (EM) coupling between electronic circuits and metallic wire placed above the ground plane. The model is based on the interaction between the EM near-field (NF) that has been treated with plane wave spectrum (PWS) and the Taylor model. The routine process illustrating the methodology is addressed is this article. The practicability of the model developed was upheld with different analytical and real demonstrators. First, the NF coupling between a straight transmission line (TL) and 1 GHz Wilkinson power divider (PWD) designed and implemented in planar technology was provided. Subsequently, simulations with a powerful commercial tool and measurements from 0.2 GHz to 2 GHz revealed a good agreement between the coupling voltages from the proposed model. As a second proof of concept, a printed circuit board incorporating a 40 MHz RF oscillator was placed 5 mm above the grounded TL. Once again, coupling voltages matched measurements were observed with magnitude relative difference lower than 5 dB. The hereby model presents huge benefits not only in terms of flexibility in the design process but it can also be run with very less computation time compared to the existing standard simulators. The model can be potentially a good candidate for investigating complex systems EMC engineering.

  12. Reduction in the amount of crosstalk with reduced number of focal spot rows in a grating array based zonal wavefront sensor

    NASA Astrophysics Data System (ADS)

    Pathak, Biswajit; Boruah, Bosanta R.

    2015-06-01

    The Shack Hartmann wavefront sensor (SHWS), named after Johannes Franz Hartmann and Roland Shack, is one of the most well-known and popularly used optical wavefront sensor that finds numerous applications in various optical technologies. SHWS samples the incident wavefront by means of a lenslet array to produce an array of regular 2D array of focal spots on the detector plane of a digital camera, in the case of an unaberrated plane wavefront. If the incident wavefront is aberrated or deviates from a plane wavefront, the respective focal spots get shifted from its reference positions corresponding to the regular grid. If the incident wavefront aberration increases or has a very large curvature, the focal spot of one lenslet may enter the detector sub-aperture of the nearby lenslet. Thus, the SHWS has a limited dynamic range that is restricted to aberrations which do not allow the sub-images to be displaced out from their own detector sub-array. It makes the SHWS sensitive to cross-talk when higher order aberrations are present thereby unavoidably a ecting the wavefront estimation process. The array of tiny lenses of the SHWS can be replaced by an array of gratings followed by a focusing lens, generating an array of focal spots which is similar to that as in the case of a SHWS. In this paper, the spatial frequency of such a grating array based zonal wavefront sensor is configured to produce lesser number of rows of focal spots. The reduction in the number of focal spot rows reduces the amount of cross talk in the vertical direction. In this paper we present preliminary experimental results to demonstrate the above stated reduction in crosstalk.

  13. Interdigitated design of a thermoelectric microgenerator based on silicon nanowire arrays

    NASA Astrophysics Data System (ADS)

    Donmez, I.; Salleras, M.; Calaza, C.; Santos, J. D.; Gadea, G.; Morata, A.; Dávila, D.; Tarancón, A.; Fonseca, L.

    2015-05-01

    Silicon nanowires thermoelectric properties are much better than those of silicon bulk. Taking advantage of silicon microfabrication techniques and compatibilizing the device fabrication with the CVD-VLS silicon nanowire growth, we present a thermoelectric microgenerator based on silicon nanowire arrays with interdigitated structures which enhance the power density compared to previous designs presented by the authors. The proposed design features a thermally isolated silicon platform on the silicon device layer of an SOI silicon wafer. This silicon platform has vertical walls exposing <111< planes where gold nanoparticles are deposited by galvanic displacement. These gold nanoparticles act as seeds for the silicon nanowires. The growth takes place in a CVD with silane precursor, and uses the Vapor-Solid-Liquid synthesis. Once the silicon nanowires are grown, they connect the silicon platform with the silicon bulk. The proposed thermoelectric generator is unileg, which means that only one type of semiconductor is used, and the second connection is made through a metal. In addition, to improve the thermal isolation of the silicon platform, multiple trenches of silicon nanowire arrays are used, up to a maximum of nine. After packaging the device with nanowires, we are able to measure the Seebeck voltage and the power obtained with different operation modes: harvesting mode, where the bottom device is heated up, and the silicon platform is cooled down by natural or forced convection, and test mode, where a heater integrated on the silicon platform is used to produce a thermal gradient.

  14. An Effective Amperometric Biosensor Based on Gold Nanoelectrode Arrays

    NASA Astrophysics Data System (ADS)

    Liu, Yanyan; Zhu, Yingchun; Zeng, Yi; Xu, Fangfang

    2009-03-01

    A sensitive amperometric biosensor based on gold nanoelectrode array (NEA) was investigated. The gold nanoelectrode array was fabricated by template-assisted electrodeposition on general electrodes, which shows an ordered well-defined 3D structure of nanowires. The sensitivity of the gold NEA to hydrogen peroxide is 37 times higher than that of the conventional electrode. The linear range of the platinum NEA toward H2O2 is from 1 × 10-6 to 1 × 10-2 M, covering four orders of magnitudes with detection limit of 1 × 10-7 M and a single noise ratio (S/N) of four. The enzyme electrode exhibits an excellent response performance to glucose with linear range from 1 × 10-5 to 1 × 10-2 M and a fast response time within 8 s. The Michaelis-Menten constant km and the maximum current density i max of the enzyme electrode were 4.97 mM and 84.60 μA cm-2, respectively. This special nanoelectrode may find potential application in other biosensors based on amperometric signals.

  15. High sensitivity carbon nanotube based electrochemiluminescence sensor array.

    PubMed

    Venkatanarayanan, Anita; Crowley, Karl; Lestini, Elena; Keyes, Tia E; Rusling, James F; Forster, Robert J

    2012-01-15

    Ink jet printed carbon nanotube forest arrays capable of detecting picomolar concentrations of immunoglobulin G (IgG) using electrochemiluminescence (ECL) are described. Patterned arrays of vertically aligned single walled carbon nanotube (SWCNT) forests were printed on indium tin oxide (ITO) electrodes. Capture anti-IgG antibodies were then coupled through peptide bond formation to acidic functional groups on the vertical nanotubes. IgG immunoassays were performed using silica nano particles (Si NP) functionalized with the ECL luminophore [Ru(bpy)(2)PICH(2)](2+)], and IgG labelled G1.5 acid terminated PAMAM dendrimers. PAMAM is poly(amido amine), bpy is 2,2'-bipyridyl and PICH(2) is (2-(4-carboxyphenyl)imidazo[4,5-f][1,10]phenanthroline). The carboxyl terminal of [Ru(bpy)(2)PICH(2)](2+) (fluorescence lifetime ≈ 682±5 ns) dye was covalently coupled to amine groups on the 800 nm diameter silica spheres in order to produce significant ECL enhancement in the presence of sodium oxalate as co-reactant in PBS at pH 7.2). Significantly, this SWCNT-based sensor array shows a wide linear dynamic range for IgG coated spheres (10(6) to 10(12) spheres) corresponding to IgG concentrations between 20 pM and 300 nM. A detection limit of 1.1±0.1 pM IgG is obtained under optimal conditions. PMID:22137061

  16. Evolutionary Based Techniques for Fault Tolerant Field Programmable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Larchev, Gregory V.; Lohn, Jason D.

    2006-01-01

    The use of SRAM-based Field Programmable Gate Arrays (FPGAs) is becoming more and more prevalent in space applications. Commercial-grade FPGAs are potentially susceptible to permanently debilitating Single-Event Latchups (SELs). Repair methods based on Evolutionary Algorithms may be applied to FPGA circuits to enable successful fault recovery. This paper presents the experimental results of applying such methods to repair four commonly used circuits (quadrature decoder, 3-by-3-bit multiplier, 3-by-3-bit adder, 440-7 decoder) into which a number of simulated faults have been introduced. The results suggest that evolutionary repair techniques can improve the process of fault recovery when used instead of or as a supplement to Triple Modular Redundancy (TMR), which is currently the predominant method for mitigating FPGA faults.

  17. Glide-plane symmetry and superconducting gap structure of iron-based superconductors.

    PubMed

    Wang, Y; Berlijn, T; Hirschfeld, P J; Scalapino, D J; Maier, T A

    2015-03-13

    We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories have proposed that so-called η-pairing states with nonzero total momentum can be realized and possess exotic properties such as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that η pairing is inevitable when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z; however, by explicit calculation, we conclude that the gap function that appears in observable quantities is identical to that found in earlier, 1 Fe per unit cell pseudocrystal momentum calculations. PMID:25815960

  18. LOBSTER: A tool to extract chemical bonding from plane-wave based DFT.

    PubMed

    Maintz, Stefan; Deringer, Volker L; Tchougréeff, Andrei L; Dronskowski, Richard

    2016-04-30

    The computer program LOBSTER (Local Orbital Basis Suite Towards Electronic-Structure Reconstruction) enables chemical-bonding analysis based on periodic plane-wave (PAW) density-functional theory (DFT) output and is applicable to a wide range of first-principles simulations in solid-state and materials chemistry. LOBSTER incorporates analytic projection routines described previously in this very journal [J. Comput. Chem. 2013, 34, 2557] and offers improved functionality. It calculates, among others, atom-projected densities of states (pDOS), projected crystal orbital Hamilton population (pCOHP) curves, and the recently introduced bond-weighted distribution function (BWDF). The software is offered free-of-charge for non-commercial research. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. PMID:26914535

  19. Glide-plane symmetry and superconducting gap structure of iron-based superconductors

    SciTech Connect

    Wang, Yan; Berlijn, Tom; Hirschfeld, Peter J.; Scalapino, Douglas J.; Maier, Thomas A.

    2015-03-10

    We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories propose that so-called η-pairing states with nonzero total momentum can be realized and possess such exotic properties as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z, η pairing is inevitable; however, we conclude from explicit calculation that the gap function appearing in observable quantities is identical to that found in earlier pseudocrystal momentum calculations with 1 Fe per unit cell.

  20. Glide-plane symmetry and superconducting gap structure of iron-based superconductors

    DOE PAGESBeta

    Wang, Yan; Berlijn, Tom; Hirschfeld, Peter J.; Scalapino, Douglas J.; Maier, Thomas A.

    2015-03-10

    We consider the effect of glide-plane symmetry of the Fe-pnictogen/chalcogen layer in Fe-based superconductors on pairing in spin fluctuation models. Recent theories propose that so-called η-pairing states with nonzero total momentum can be realized and possess such exotic properties as odd parity spin singlet symmetry and time-reversal symmetry breaking. Here we show that when there is orbital weight at the Fermi level from orbitals with even and odd mirror reflection symmetry in z, η pairing is inevitable; however, we conclude from explicit calculation that the gap function appearing in observable quantities is identical to that found in earlier pseudocrystal momentummore » calculations with 1 Fe per unit cell.« less

  1. FISST based method for multi-target tracking in the image plane of optical sensors.

    PubMed

    Xu, Yang; Xu, Hui; An, Wei; Xu, Dan

    2012-01-01

    A finite set statistics (FISST)-based method is proposed for multi-target tracking in the image plane of optical sensors. The method involves using signal amplitude information in probability hypothesis density (PHD) filter which is derived from FISST to improve multi-target tracking performance. The amplitude of signals generated by the optical sensor is modeled first, from which the amplitude likelihood ratio between target and clutter is derived. An alternative approach is adopted for the situations where the signal noise ratio (SNR) of target is unknown. Then the PHD recursion equations incorporated with signal information are derived and the Gaussian mixture (GM) implementation of this filter is given. Simulation results demonstrate that the proposed method achieves significantly better performance than the generic PHD filter. Moreover, our method has much lower computational complexity in the scenario with high SNR and dense clutter. PMID:22736984

  2. FISST Based Method for Multi-Target Tracking in the Image Plane of Optical Sensors

    PubMed Central

    Xu, Yang; Xu, Hui; An, Wei; Xu, Dan

    2012-01-01

    A finite set statistics (FISST)-based method is proposed for multi-target tracking in the image plane of optical sensors. The method involves using signal amplitude information in probability hypothesis density (PHD) filter which is derived from FISST to improve multi-target tracking performance. The amplitude of signals generated by the optical sensor is modeled first, from which the amplitude likelihood ratio between target and clutter is derived. An alternative approach is adopted for the situations where the signal noise ratio (SNR) of target is unknown. Then the PHD recursion equations incorporated with signal information are derived and the Gaussian mixture (GM) implementation of this filter is given. Simulation results demonstrate that the proposed method achieves significantly better performance than the generic PHD filter. Moreover, our method has much lower computational complexity in the scenario with high SNR and dense clutter. PMID:22736984

  3. The studies of Schottky-diode based co-plane detector for surface plasmon resonance sensing

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Sheng; Wen, Tsun-Yu; Wang, Da-Shin; Lin, Chii-Wann

    2010-08-01

    The Surface Plasmon Resonance (SPR) is a label-free, highly sensitive and real time sensing technique and has been extensively applied to biosensing and assay for decades. In a conventional SPR biosensor, a prism is used to create the total reflection in which the evanescent wave can excite the surface plasmon mode at the metal-dielectric interface at certain angle, at which condition the reflectivity of incident TM-polarized vanished as measured by a far-field photodetector. This is the optical detection of surface plasmon resonance. In this research, zinc oxide (ZnO) was used as the dielectric thin-film material above the gold surface on the glass substrate to form a co-plane Schottky diode; this structure is designed to be an alternative way to detect SPR. The strength of plasmonic field is possible to be monitored by measuring the photocurrent under the reverse bias. According to our experimental results, the measured photocurrents with TM-polarized illumination (representing the SPR case), TE-polarized illumination (non-SPR case) and no illumination conditions under DC -1.5V bias are -76.158mA (2.5μA), -76.085mA (3.6μA) and -76.089mA (3.4μA), respectively. Based on the results, we have demonstrated this Schottky diode based co-plane device has the potential to be used as the SPR detector and provides a possible solution for the need of a low-cost, miniaturized, electronically integrated, and portable SPR biosensor in the near future.

  4. Antenna of adjustable bandwidth based on a pentagonal array

    NASA Astrophysics Data System (ADS)

    Tecpoyotl-Torres, M.; Vera-Dimas, J. G.; Cabello Ruiz, R.; García-García, O.; Escobedo-Alatorre, J.; Sanchez-Mondragon, J.; Torres-Cisneros, M.; Varona, J.; Vargas-Bernal, R.

    2011-09-01

    Antenna characteristics are chosen according to the features determined by the systems where they will be used. While some systems require a very narrow bandwidth, others may operate with a much wider bandwidth. Some techniques used for increasing the bandwidth of a given antenna have considered mechanical adjustment of the air layer thickness, with the consequent change on the effective permittivity and performance. Some other systems consider a suitable choice of feeding techniques and impedance matching network. However, approaches for reducing the bandwidth have not received the same level of attention. Narrow bandwidth antennas are of particular interest in security and surveillance systems. In this work we present a technique, based on the design of a pentagonal antenna array, which allows for adjusting the bandwidth in either direction. The array is formed by an inner patch designed at the desired operating frequency of the system and a gap coupled external ring centered at a different frequency (lower or very near the operating frequency), which determines the potential bandwidth increment or decrement. The feed point is located on the inner patch. As a proof-of-concept, this work offers a tuning range that goes from -40% of the center frequency up to +50% of the center operating frequency of the patch antenna. The single patch antenna of this work was designed and simulated at an operating frequency of 4.9 GHz on RT/Duroid 5880.

  5. Performance comparison of Fresnel-based concentrator arrays

    NASA Astrophysics Data System (ADS)

    Mohedano, Rubén; Cvetkovic, Aleksandra; Benítez, Pablo; Zamora, Pablo; Miñano, Juan C.; Chaves, Julio; Hernandez, Maikel; Buljan, Marina; Vilaplana, Juan

    2010-08-01

    At module level (one single solar cell), the Fresnel-Köhler (FK) concentrator comprises a perfect irradiance uniformity along with quite high concentration-acceptance angle product. At the same time, it maintains the efficiency/simplicity of other Fresnel-based concentrators. In this work we will show the FK concentrator has loose manufacturing tolerances as well. All these facts, along with the pill-box shape of its transmission curve, permit an enhanced performance of this device, compared to its competitors, at array level, because the system is more insensitive to manufacturing errors, and current mismatch is less likely to occur. Or the same performance can be achieved at a lower cost, exhausting the tolerance budget by using inexpensive fabrication techniques. Depending on the concentrator, the actual power delivered by an array might drop significantly with respect to the sum of the power delivered by single modules. Under certain circumstances, the FK can reach a 1-10% electrical efficiency increase with regards to other concentrators sharing the same technology.

  6. Electrochemical DNA biosensor based on the BDD nanograss array electrode

    PubMed Central

    2013-01-01

    Background The development of DNA biosensor has attracted considerable attention due to their potential applications, including gene analysis, clinical diagnostics, forensic study and more medical applications. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry in this study. Results Electrochemical DNA biosensor was developed based on the BDD film electrode (fBDD) and BDD nanograss array electrode (nBDD). In comparison with fBDD and AuNPs/CA/fBDD electrode, the lower semicircle diameter of electrochemical impedance spectroscopy obtained on nBDD and AuNPs/CA/nBDD electrode indicated that the presence of nanograss array improved the reactive site, reduced the interfacial resistance, and made the electron transfer easier. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry. Conclusions The experimental results demonstrated that the prepared AuNPs/CA/nBDD electrode was suitable for DNA hybridization with favorable performance of faster response, higher sensitivity, lower detection limit and satisfactory selectivity, reproducibility and stability. PMID:23575250

  7. Fabrication of MEMS-Based Microshutter Arrays for Optical Transmission Selection

    NASA Technical Reports Server (NTRS)

    Lynch, Bernard A.; Franz, David E.; Hu, R. G.; Jhabvala, M. D.; Kotecki, C. A.; Li, M. J.; Oh, H.; Zheng, Y.

    2004-01-01

    A MEMS-based programmable aperture mask is under development at the NASA Goddard Space Flight Center. Termed the Microshutter (u-shutter) Array, the device will be used to control the transmission of light, with both high efficiency and contrast, to a multi-object spectrometer on the James Webb Space Telescope. Fabrication of the p-shutter array employs several novel designs and processing techniques. The current generation of micro-shutters consists of 128x64 pixel arrays with unit cell dimensions of 100x200 microns. Shutters are patterned in silicon nitride and sit on a 100 micron silicon frame that is DRIE etched below each shutter. The front and back sides of the device are shown. A magnetic cobalt-iron alloy patterned on top of the shutter allows it to be actuated 90 degrees out-of-plane, into the frame, by an external magnetic field. An electrode on the shutter and a vertical electrode on the sidewall of the frame, approximately 90pm deep, allow them to be electrostatically latched in their rotated position. The vertical electrode is deposited and patterned on the backside of the frame in a single step using a directionally controlled evaporation. Individual addressing of shutters for electrostatic latching is accomplished via a crosspoint addressing scheme, with no on-chip active components. A portion of an array with shutters in the open, latched, and closed positions is shown. Light loss at shutter edges is minimized by an overhanging aluminum light-shield that is anchored to the frame. A photoresist sacrificial layer is used to raise the light-shield up and over the 2 micron gap that surrounds each pixel. After completion, arrays are subjected to life cycle, environmental and optical testing. Fabricated devices have survived 10(exp 6) actuation cycles at both room and cryogenic temperatures and a 14g rms launch-simulation test. Optical testing has shown contrast measurements between open and closed shutters up to 10000:1.

  8. High-resolution seismic array imaging based on an SEM-FK hybrid method

    NASA Astrophysics Data System (ADS)

    Tong, Ping; Chen, Chin-wu; Komatitsch, Dimitri; Basini, Piero; Liu, Qinya

    2014-04-01

    We demonstrate the feasibility of high-resolution seismic array imaging based on teleseismic recordings using full numerical wave simulations. We develop a hybrid method that interfaces a frequency-wavenumber (FK) calculation, which provides analytical solutions to 1-D layered background models with a spectral-element (SEM) numerical solver to calculate synthetic responses of local media to plane-wave incidence.This hybrid method accurately deals with local heterogeneities and discontinuity undulations, and represents an efficient tool for the forward modelling of teleseismic coda (including converted and scattered) waves. We benchmark the accuracy of the SEM-FK hybrid method against FK solutions for 1-D media. We then compute sensitivity kernels for teleseismic coda waves by interacting the forward teleseismic waves with an adjoint wavefield, produced by injecting coda waves as adjoint sources, based on adjoint techniques. These sensitivity kernels provide the basis for mapping variations in subsurface discontinuities, density and velocity structures through non-linear conjugate-gradient methods. We illustrate various synthetic imaging experiments, including discontinuity characterization, volumetric structural inversion for the crust or subduction zones. These tests show that using pre-conditioners based upon the scaled product of sensitivity kernels for different phases, combining finite-frequency traveltime and waveform inversion, and/or adopting hierarchical inversions from long- to short-period waveforms could reduce the non-linearity of the seismic inverse problem and speed up its convergence. The encouraging results of these synthetic examples suggest that inversion of teleseismic coda phases based on the SEM-FK hybrid method and adjoint techniques is a promising tool for structural imaging beneath dense seismic arrays.

  9. High precision radiometry using an indium arsenide/indium gallium arsenide quantum dot-in-a-well infrared focal plane array

    NASA Astrophysics Data System (ADS)

    Andrews, Jonathan R.

    Sensitivity, noise and performance criteria were evaluated for different varieties of InAs/InGaAs quantum dots-in-a-well (DWELL) and quantum dots-in-a-double-well (double DWELL) focal plane arrays (FPAs). These characteristics were measured and compared to those measured from a commercial quantum well infrared photodetector (QWIP) in the same experimental setup to allow a side-by-side comparison of these devices with many system variables held constant. The QWIP device was expected to perform the best, due to its higher number of active regions and enhancement grating, but the performance of the other devices was unknown. The DWELL and double DWELL samples were grown by molecular beam epitaxy (MBE) and fabricated into 320 x 256 pixel FPAs with indium bumps via standard lithography at the University of New Mexico. All samples, including the 320 x 256 pixel QWIPs were hybridized to Indigo Systems Corporation ISC9705 read out integrated circuits and device performance was measured with the SE-IR Corporation CamIRa test system at part cooling of 60°K, 70°K and 80°K. The QWIP performed best at lower device cooling, but could not operate at 80°K. The DWELL device demonstrated favorable operation at 60°K, but performance at 70°K was poor and the device did not perform at 80°K. Both double DWELL devices under test performed well across all device temperatures. The mean NEDT for the DWELL was 143°mK and the two double DWELL devices were 105.7°mK and 160.6°mK at 60°K part temperature. The double DWELL devices showed the lower noise and higher responsivity at higher device temperatures. This document also reviewed methods of non-uniformity correction and suggested methods to improve performance and results by carefully choosing the method of correction and the values.

  10. Electro-Optical Characteristics of P+n In0.53Ga0.47As Hetero-Junction Photodiodes in Large Format Dense Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    DeWames, R.; Littleton, R.; Witte, K.; Wichman, A.; Bellotti, E.; Pellegrino, J.

    2015-08-01

    This paper is concerned with focal plane array (FPA) data and use of analytical and three-dimensional numerical simulation methods to determine the physical effects and processes limiting performance. For shallow homojunction P+n designs the temperature dependence of dark current for T < 300 K depends on the intrinsic carrier concentration of the In0.53Ga0.47As material, implying that the dominant dark currents are generation and recombination (G-R) currents originating in the depletion regions of the double layer planar heterostructure (DLPH) photodiode. In the analytical model differences from bulk G-R behavior are modeled with a G-R like perimeter-dependent shunt current conjectured to originate at the InP/InGaAs interface. In this description the fitting property is the effective conductivity, σ eff( T), in mho cm-1. Variation in the data suggests σ eff (300 K) values of 1.2 × 10-11-4.6 × 10-11 mho cm-1). Substrate removal extends the quantum efficiency (QE) spectral band into the visible region. However, dead-layer effects limit the QE to 10% at a wavelength of 0.5 μm. For starlight-no moon illumination conditions, the signal-to-noise ratio is estimated to be 50 at an operating temperature of 300 K. A major result of the 3D numerical simulation of the device is the prediction of a perimeter G-R current not associated with the properties of the metallurgical interface. Another is the prediction that for a junction positioned in the larger band gap InP cap layer the QE is bias-dependent and that a relatively large reverse bias ≥0.9 V is needed for the QE to saturate to the shallow homojunction value. At this higher bias the dark current is larger than the shallow homojunction value. The 3D numerical model and the analytical model agree in predicting and explaining the measured radiatively limited diffusion current originating at the n-side of the junction. The calculations of the area-dependent G-R current for the condition studied are also in agreement

  11. The data array, a tool to interface the user to a large data base

    NASA Technical Reports Server (NTRS)

    Foster, G. H.

    1974-01-01

    Aspects of the processing of spacecraft data is considered. Use of the data array in a large address space as an intermediate form in data processing for a large scientific data base is advocated. Techniques for efficient indexing in data arrays are reviewed and the data array method for mapping an arbitrary structure onto linear address space is shown. A compromise between the two forms is given. The impact of the data array on the user interface are considered along with implementation.

  12. Magnetic resonance imaging-based anatomical study of the multifidus-longissimus cleavage planes in the lumbar spine

    PubMed Central

    Li, Haijun; Yang, Lei; Chen, Jinhua; Xie, Hao; Tian, Weizhong; Cao, Xiaojian

    2016-01-01

    Purpose: The Wiltse approach allows spinal surgeries to be performed with minimal soft tissue trauma. The purpose of this study was to investigate the anatomy of the natural cleavage plane between multifidus and longissimus at different levels based on MRI images. Methods: MRI cross-sectional scans from L1 to S1 were collected from 205 out patients (103 males, 102 females). Based on the images, some parameters were defined and measured to describe the locations, curvature and directions of Wiltse approach. Besides, differences of these parameters between genders and segments were compared. Results: Among the total of 2460 one-sided images, cleavage planes between multifidus and longissimus were not able to be identified in 105 images. The locations, directions and curvature of the cleavage plane differed significantly among different segments but followed some regular pattern from L1-S1. The simultaneous rotation of the plane around its deepest points to the midline from S1 to L1 and the plane seemed to be the most curved at L3 and relatively straight for L5 and S1. Conclusions: With a better understanding of the natural cleavage plane between multifidus and longissimus, performers can correctly plan the distance of skin incisions from the midline and the direction of muscle dissection at each vertebral level, thus reducing trauma in the operation. PMID:27069544

  13. LAMBDA — Large Area Medipix3-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, D.; Lange, S.; Smoljanin, S.; Hirsemann, H.; Graafsma, H.

    2012-11-01

    Medipix3 is a photon-counting readout chip for X-ray detection. It has a small pixel size (55 μm) and a high frame rate with zero dead time, which makes it attractive for experiments at synchrotrons. Using Medipix3, DESY are developing the LAMBDA (Large Area Medipix3-Based Detector Array) system. A single LAMBDA module carries either a single large silicon sensor of 1536 by 512 pixels, or two smaller high-Z sensors. The sensor is bonded to 12 Medipix3 chips, and mounted on a ceramic carrier board. The readout system for the module then provides a fast FPGA, a large RAM and four 10 Gigabit Ethernet links to allow operation at high frame rates. Multiple modules may then be tiled together a larger area. Currently, the first large silicon modules have been constructed and tested at low speed, and the firmware for fast readout is being developed.

  14. Undersampling Correction for Array Detector-Based Satellite Spectrometers

    NASA Technical Reports Server (NTRS)

    Chance, Kelly; Kurosu, Thomas P.; Sioris, Christopher E.

    2004-01-01

    Array detector-based instruments are now fundamental to measurements of ozone and other atmospheric trace gases from space in the ultraviolet, visible, and infrared. The present generation of such instruments suffers, to a greater or lesser degree, from undersampling of the spectra, leading to difficulties in the analysis of atmospheric radiances. We provide extended analysis of the undersampling suffered by modem satellite spectrometers, which include Global Ozone Monitoring Experiment (GOME), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Ozone Monitoring Instrument (OMI), and Ozone Mapping and Profiler Suite (OMPS). The analysis includes basic undersampling, the effects of binning into separate detector pixels, and the application of high-resolution Fraunhofer spectral data to correct for undersampling in many useful cases.

  15. ArraySearch: A Web-Based Genomic Search Engine.

    PubMed

    Wilson, Tyler J; Ge, Steven X

    2012-01-01

    Recent advances in microarray technologies have resulted in a flood of genomics data. This large body of accumulated data could be used as a knowledge base to help researchers interpret new experimental data. ArraySearch finds statistical correlations between newly observed gene expression profiles and the huge source of well-characterized expression signatures deposited in the public domain. A search query of a list of genes will return experiments on which the genes are significantly up- or downregulated collectively. Searches can also be conducted using gene expression signatures from new experiments. This resource will empower biological researchers with a statistical method to explore expression data from their own research by comparing it with expression signatures from a large public archive. PMID:22474412

  16. ABINIT: Plane-Wave-Based Density-Functional Theory on High Performance Computers

    NASA Astrophysics Data System (ADS)

    Torrent, Marc

    2014-03-01

    For several years, a continuous effort has been produced to adapt electronic structure codes based on Density-Functional Theory to the future computing architectures. Among these codes, ABINIT is based on a plane-wave description of the wave functions which allows to treat systems of any kind. Porting such a code on petascale architectures pose difficulties related to the many-body nature of the DFT equations. To improve the performances of ABINIT - especially for what concerns standard LDA/GGA ground-state and response-function calculations - several strategies have been followed: A full multi-level parallelisation MPI scheme has been implemented, exploiting all possible levels and distributing both computation and memory. It allows to increase the number of distributed processes and could not be achieved without a strong restructuring of the code. The core algorithm used to solve the eigen problem (``Locally Optimal Blocked Congugate Gradient''), a Blocked-Davidson-like algorithm, is based on a distribution of processes combining plane-waves and bands. In addition to the distributed memory parallelization, a full hybrid scheme has been implemented, using standard shared-memory directives (openMP/openACC) or porting some comsuming code sections to Graphics Processing Units (GPU). As no simple performance model exists, the complexity of use has been increased; the code efficiency strongly depends on the distribution of processes among the numerous levels. ABINIT is able to predict the performances of several process distributions and automatically choose the most favourable one. On the other hand, a big effort has been carried out to analyse the performances of the code on petascale architectures, showing which sections of codes have to be improved; they all are related to Matrix Algebra (diagonalisation, orthogonalisation). The different strategies employed to improve the code scalability will be described. They are based on an exploration of new diagonalization

  17. Cell division plane orientation based on tensile stress in Arabidopsis thaliana.

    PubMed

    Louveaux, Marion; Julien, Jean-Daniel; Mirabet, Vincent; Boudaoud, Arezki; Hamant, Olivier

    2016-07-26

    Cell geometry has long been proposed to play a key role in the orientation of symmetric cell division planes. In particular, the recently proposed Besson-Dumais rule generalizes Errera's rule and predicts that cells divide along one of the local minima of plane area. However, this rule has been tested only on tissues with rather local spherical shape and homogeneous growth. Here, we tested the application of the Besson-Dumais rule to the divisions occurring in the Arabidopsis shoot apex, which contains domains with anisotropic curvature and differential growth. We found that the Besson-Dumais rule works well in the central part of the apex, but fails to account for cell division planes in the saddle-shaped boundary region. Because curvature anisotropy and differential growth prescribe directional tensile stress in that region, we tested the putative contribution of anisotropic stress fields to cell division plane orientation at the shoot apex. To do so, we compared two division rules: geometrical (new plane along the shortest path) and mechanical (new plane along maximal tension). The mechanical division rule reproduced the enrichment of long planes observed in the boundary region. Experimental perturbation of mechanical stress pattern further supported a contribution of anisotropic tensile stress in division plane orientation. Importantly, simulations of tissues growing in an isotropic stress field, and dividing along maximal tension, provided division plane distributions comparable to those obtained with the geometrical rule. We thus propose that division plane orientation by tensile stress offers a general rule for symmetric cell division in plants. PMID:27436908

  18. Cell division plane orientation based on tensile stress in Arabidopsis thaliana

    PubMed Central

    Louveaux, Marion; Julien, Jean-Daniel; Mirabet, Vincent; Boudaoud, Arezki; Hamant, Olivier

    2016-01-01

    Cell geometry has long been proposed to play a key role in the orientation of symmetric cell division planes. In particular, the recently proposed Besson–Dumais rule generalizes Errera’s rule and predicts that cells divide along one of the local minima of plane area. However, this rule has been tested only on tissues with rather local spherical shape and homogeneous growth. Here, we tested the application of the Besson–Dumais rule to the divisions occurring in the Arabidopsis shoot apex, which contains domains with anisotropic curvature and differential growth. We found that the Besson–Dumais rule works well in the central part of the apex, but fails to account for cell division planes in the saddle-shaped boundary region. Because curvature anisotropy and differential growth prescribe directional tensile stress in that region, we tested the putative contribution of anisotropic stress fields to cell division plane orientation at the shoot apex. To do so, we compared two division rules: geometrical (new plane along the shortest path) and mechanical (new plane along maximal tension). The mechanical division rule reproduced the enrichment of long planes observed in the boundary region. Experimental perturbation of mechanical stress pattern further supported a contribution of anisotropic tensile stress in division plane orientation. Importantly, simulations of tissues growing in an isotropic stress field, and dividing along maximal tension, provided division plane distributions comparable to those obtained with the geometrical rule. We thus propose that division plane orientation by tensile stress offers a general rule for symmetric cell division in plants. PMID:27436908

  19. T-L Plane Abstraction-Based Energy-Efficient Real-Time Scheduling for Multi-Core Wireless Sensors.

    PubMed

    Kim, Youngmin; Lee, Ki-Seong; Pham, Ngoc-Son; Lee, Sun-Ro; Lee, Chan-Gun

    2016-01-01

    Energy efficiency is considered as a critical requirement for wireless sensor networks. As more wireless sensor nodes are equipped with multi-cores, there are emerging needs for energy-efficient real-time scheduling algorithms. The T-L plane-based scheme is known to be an optimal global scheduling technique for periodic real-time tasks on multi-cores. Unfortunately, there has been a scarcity of studies on extending T-L plane-based scheduling algorithms to exploit energy-saving techniques. In this paper, we propose a new T-L plane-based algorithm enabling energy-efficient real-time scheduling on multi-core sensor nodes with dynamic power management (DPM). Our approach addresses the overhead of processor mode transitions and reduces fragmentations of the idle time, which are inherent in T-L plane-based algorithms. Our experimental results show the effectiveness of the proposed algorithm compared to other energy-aware scheduling methods on T-L plane abstraction. PMID:27399722

  20. T-L Plane Abstraction-Based Energy-Efficient Real-Time Scheduling for Multi-Core Wireless Sensors

    PubMed Central

    Kim, Youngmin; Lee, Ki-Seong; Pham, Ngoc-Son; Lee, Sun-Ro; Lee, Chan-Gun

    2016-01-01

    Energy efficiency is considered as a critical requirement for wireless sensor networks. As more wireless sensor nodes are equipped with multi-cores, there are emerging needs for energy-efficient real-time scheduling algorithms. The T-L plane-based scheme is known to be an optimal global scheduling technique for periodic real-time tasks on multi-cores. Unfortunately, there has been a scarcity of studies on extending T-L plane-based scheduling algorithms to exploit energy-saving techniques. In this paper, we propose a new T-L plane-based algorithm enabling energy-efficient real-time scheduling on multi-core sensor nodes with dynamic power management (DPM). Our approach addresses the overhead of processor mode transitions and reduces fragmentations of the idle time, which are inherent in T-L plane-based algorithms. Our experimental results show the effectiveness of the proposed algorithm compared to other energy-aware scheduling methods on T-L plane abstraction. PMID:27399722