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Sample records for bandpass butterworth filter

  1. Colloidal Bandpass and Bandgap Filters

    NASA Astrophysics Data System (ADS)

    Yellen, Benjamin; Tahir, Mukarram; Ouyang, Yuyu; Nori, Franco

    2013-03-01

    Thermally or deterministically-driven transport of objects through asymmetric potential energy landscapes (ratchet-based motion) is of considerable interest as models for biological transport and as methods for controlling the flow of information, material, and energy. Here, we provide a general framework for implementing a colloidal bandpass filter, in which particles of a specific size range can be selectively transported through a periodic lattice, whereas larger or smaller particles are dynamically trapped in closed-orbits. Our approach is based on quasi-static (adiabatic) transition in a tunable potential energy landscape composed of a multi-frequency magnetic field input signal with the static field of a spatially-periodic magnetization. By tuning the phase shifts between the input signal and the relative forcing coefficients, large-sized particles may experience no local energy barriers, medium-sized particles experience only one local energy barrier, and small-sized particles experience two local energy barriers. The odd symmetry present in this system can be used to nudge the medium-sized particles along an open pathway, whereas the large or small beads remain trapped in a closed-orbit, leading to a bandpass filter, and vice versa for a bandgap filter. NSF CMMI - 0800173, Youth 100 Scholars Fund

  2. Divergence-tolerant resonant bandpass filters.

    PubMed

    Ko, Yeong Hwan; Niraula, Manoj; Magnusson, Robert

    2016-07-15

    Bandpass filters based on subwavelength dielectric gratings are grounded in physical principles that are totally distinct from their thin-film counterparts. Ease in fabrication, design scalability, material sparsity, and on-chip integration compatibility makes them a promising alternative especially for long-wavelength applications. Here we demonstrate the interesting attribute of resonant bandpass filters of high angular stability for fully conical light incidence. Fashioning an experimental bandpass filter with a subwavelength silicon grating on a quartz substrate, we show that fully conical incidence provides an angular full width at half-maximum linewidth of ∼9.5° compared to a linewidth of ∼0.1° for classical incidence. Slow angular variation of the central wavelength with full conical incidence arises via a corresponding slow angular variation of the resonant second diffraction orders driving the pertinent leaky modes. Moreover, full conical incidence maintains a profile with a single passband as opposed to the formation of two passbands characteristic of resonant subwavelength gratings under classical incidence. Our experimental results demonstrate excellent stability in angle, spectral profile, linewidth, and efficiency. PMID:27420521

  3. Narrow bandpass cryogenic filter for microwave measurements.

    PubMed

    Ivanov, B I; Klimenko, D N; Sultanov, A N; Il'ichev, E; Meyer, H-G

    2013-05-01

    An ultra-wide stopband hairpin bandpass filter with integrated nonuniform transmission lines was designed and fabricated for highly sensitive measurements at cryogenic temperatures down to millikelvin and a frequency range of 10 Hz-10 GHz. The scattering matrices of the filter were characterized at T = 4.2 K. The filter provides a stopband from 10 Hz to 2.2 GHz and from 2.3 GHz to 10 GHz with more than 50 dB and 40 dB of amplitude suppression, respectively. The center frequency of the passband is f0 = 2.25 GHz with a bandwidth Δf = 80 MHz. The maximum insertion loss in the passband is 4 dB. The filter has a 50 Ω input and output impedance, SubMiniature version A connector termination, and significantly reduced form factor. The wide stopband frequency range and narrow passband in conjunction with small dimensions make the filter suitable to use it as a part of a high sensitive readout for superconducting quantum circuits, such as superconducting quantum bits and cryogenic parametric amplifiers. PMID:23742575

  4. Narrow bandpass cryogenic filter for microwave measurements

    NASA Astrophysics Data System (ADS)

    Ivanov, B. I.; Klimenko, D. N.; Sultanov, A. N.; Il'ichev, E.; Meyer, H.-G.

    2013-05-01

    An ultra-wide stopband hairpin bandpass filter with integrated nonuniform transmission lines was designed and fabricated for highly sensitive measurements at cryogenic temperatures down to millikelvin and a frequency range of 10 Hz-10 GHz. The scattering matrices of the filter were characterized at T = 4.2 K. The filter provides a stopband from 10 Hz to 2.2 GHz and from 2.3 GHz to 10 GHz with more than 50 dB and 40 dB of amplitude suppression, respectively. The center frequency of the passband is f0 = 2.25 GHz with a bandwidth Δf = 80 MHz. The maximum insertion loss in the passband is 4 dB. The filter has a 50 Ω input and output impedance, SubMiniature version A connector termination, and significantly reduced form factor. The wide stopband frequency range and narrow passband in conjunction with small dimensions make the filter suitable to use it as a part of a high sensitive readout for superconducting quantum circuits, such as superconducting quantum bits and cryogenic parametric amplifiers.

  5. Improving holographic reconstruction by automatic Butterworth filtering for microelectromechanical systems characterization.

    PubMed

    Matrecano, Marcella; Memmolo, Pasquale; Miccio, Lisa; Persano, Anna; Quaranta, Fabio; Siciliano, Pietro; Ferraro, Pietro

    2015-04-10

    Digital holographic microscopy is an important interferometric tool in optical metrology allowing the investigation of engineered surfaces with microscale lateral resolution and nanoscale axial precision. In particular, microelectromechanical systems (MEMS) surface analysis, conducted by holographic characterization, requires high accuracy for functional testing. The main issues related to MEMS inspection are the superficial roughness and the complex geometry resulting from the several fabrication steps. Here, an automatic procedure, particularly suited in the case of high-roughness surfaces, is presented to selectively filter the spectrum, providing very low-noise reconstructed images. The numerical procedure is based on Butterworth filtering, and the obtained results demonstrate a significant increase in the images' quality and in the accuracy of the measurements, making our technique highly applicable for quantitative phase imaging in MEMS analysis. Furthermore, our method is fully tunable to the spectrum under investigation and automatic. This makes it highly suitable for real-time applications. Several experimental tests show the suitability of the proposed approach. PMID:25967334

  6. Photonic microwave bandpass filter with improved dynamic range.

    PubMed

    Yan, Yu; Yao, Jianping

    2008-08-01

    A technique to improve the dynamic range of a photonic microwave bandpass filter is proposed and experimentally demonstrated. The filter is implemented based on phase modulation to intensity modulation conversion using fiber Bragg gratings (FBGs) serving as frequency discriminators, with the optical carriers located at the left or right slopes of the FBGs, to generate positive or negative tap coefficients. The dynamic range of the photonic microwave bandpass filter is increased by reducing the optical-carrier-induced shot noise and relative intensity noise at the photodetector, which is realized by placing the optical carriers at the lower slopes of the FBG reflection spectra. A photonic microwave bandpass filter with an improvement in dynamic range of about 10 dB is demonstrated. PMID:18670527

  7. Cryogenic metal mesh bandpass filters for submillimeter astronomy

    NASA Technical Reports Server (NTRS)

    Dragovan, M.

    1984-01-01

    The design and performance of a tunable double-half-wave bandpass filter centered at 286 microns (Delta lambda/lambda = 0.16) and operating at cryogenic temperatures (for astronomy applications) are presented. The operating principle is explained, and the fabrication of the device, which comprises two identical mutually coupled Fabry-Perot filters with electroformed Ni-mesh reflectors and is tuned by means of variable spacers, is described. A drawing of the design and graphs of computed and measured performance are provided. Significantly improved bandpass characteristics are obtained relative to the single Fabry-Perot filter.

  8. A compact triple-band bandpass filter based on metamaterials

    NASA Astrophysics Data System (ADS)

    Zhao, Ya-juan; Jiang, Bo; Li, Bao-yi; Wang, Dong-hong

    2016-07-01

    This paper presents a compact triple-band bandpass filter based on metamaterials. The miniaturization is realized by the principle of phase compensation of metamaterial. Compared with the conventional half-wavelength filter, the metamaterial filter has a small size of 10 mm×10 mm. The triple-band bandpass filter performance has been validated by the electromagnetic simulation software of high frequency structure simulator (HFSS). The results illustrate that the filter is designed with center frequencies of 2.4 GHz, 5.1 GHz and 8.8 GHz, bandwidths of about 7.9% (2.31—2.50 GHz), 7.8% (5.0—5.4 GHz) and 7.4% (8.50—9.15 GHz), respectively, and it shows good band pass characteristics.

  9. Thermoluminescence dosimeters with narrow bandpass filters

    SciTech Connect

    Walker, Scottie W.

    2004-07-20

    A dosimetry method exposes more than one thermoluminescence crystals to radiation without using conventional filters, and reads the energy stored in the crystals by converting the energy to light in a conventional manner, and then filters each crystal output in a different portion of the spectrum generated by the crystals.

  10. Spectral performance of WFIRST/AFTA bandpass filter prototypes

    NASA Astrophysics Data System (ADS)

    Quijada, Manuel A.; Huang, Winson; Miller, Kevin H.; Seide, Laurie; Content, David; Kruk, Jeffrey

    2015-09-01

    The current baseline for the Wide-Field Infrared Survey Telescope Astrophysics Focused Telescope Assets (WFIRST/AFTA) instrument includes a single wide-field channel instrument for both imaging and spectroscopy. The only routinely moving part during scientific observations for this wide-field channel is the element wheel (EW) assembly. This filter-wheel assembly will have 8 positions that will be populated with 6 bandpass filters, a blank position, and a grism assembly that will consist of a three-element assembly to disperse the central wavelength undeviated for galaxy redshift surveys. All elements in the EW assembly will be made out of fused silica substrates (110 mm diameter) that will have the appropriate bandpass coatings according to the filter designations (Z087, Y106, J129, H158, F184, W149 and Grism). This paper will present and discuss spectral performance (including spectral transmission and surface-figure wavefront errors ) for a subset of the bandpass filter complement that include filters such as Z087, W149, and Grism. These filter coatings have been procured from three different vendors to assess the most challenging aspects in terms of the in-band throughput (> 95 %), out of band rejection (< 10-4), spatial uniformity (< 1% transmission level) and the cut-on and cut-off slopes (≍ 3% for the filters and 0.3% for the grism coatings).

  11. Compact Micromachined Infrared Bandpass Filters for Planetary Spectroscopy

    NASA Technical Reports Server (NTRS)

    Merrell, Willie C., II; Aslam, Shahid; Brown, Ari D.; Chervenak, James A.; Huang, Wei-Chung; Quijada, Manuel; Wollack, Edward

    2011-01-01

    The future needs of space based observational planetary and astronomy missions include low mass and small volume radiometric instruments that can operate in high radiation and low temperature environments. Here we focus on a central spectroscopic component, the bandpass filter. We model the bandpass response of the filters to target the wavelength of the resonance peaks at 20, 40, and 60 micrometers and report good agreement between the modeled and measured response. We present a technique of using common micromachining processes for semiconductor fabrication to make compact, free standing resonant metal mesh filter arrays with silicon support frames. The process can accommodate multiple detector array architectures and the silicon frame provides lightweight mechanical support with low form factor. We also present a conceptual hybridization of the filters with a detector array.

  12. Switched Band-Pass Filters for Adaptive Transceivers

    NASA Technical Reports Server (NTRS)

    Wang, Ray

    2007-01-01

    Switched band-pass filters are key components of proposed adaptive, software- defined radio transceivers that would be parts of envisioned digital-data-communication networks that would enable real-time acquisition and monitoring of data from geographically distributed sensors. Examples of sensors to be connected to such networks include security cameras, radio-frequency identification units, and geolocation units based on the Global Positioning System. Through suitable software configuration and without changing hardware, these transceivers could be made to operate according to any of a number of complex wireless-communication standards that could be characterized by diverse modulation schemes, bandwidths, and data-handling protocols. The adaptive transceivers would include field-programmable gate arrays (FPGAs) and digital signal-processing hardware. In the receiving path of a transceiver, the incoming signal would be amplified by a low-noise amplifier (LNA). The output spectrum of the LNA would be processed by a band-pass filter operating in the frequency range between 900 MHz and 2.4 GHz. Then a down-converter would translate the signal to a lower frequency range to facilitate analog-to-digital conversion, which would be followed by baseband processing by one or more FPGAs. In the transmitting path, a digital stream would first be converted to an analog signal, which would then be up-converted to a selected frequency band before being applied to a transmitting power amplifier. The aforementioned band-pass filter in the receiving path would be a combination of resonant inductor-and-capacitor filters and switched band-pass filters. The overall combination would implement a switch function designed mathematically to exhibit desired frequency responses and to switch the signal in each frequency band to an analog-to-digital converter appropriate for that band to produce a digital intermediate-frequency signal for digital signal processing.

  13. Rational engineering of nanoporous anodic alumina optical bandpass filters

    NASA Astrophysics Data System (ADS)

    Santos, Abel; Pereira, Taj; Law, Cheryl Suwen; Losic, Dusan

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  14. Rational engineering of nanoporous anodic alumina optical bandpass filters.

    PubMed

    Santos, Abel; Pereira, Taj; Law, Cheryl Suwen; Losic, Dusan

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  15. Dual-band bandpass filter using composite metamaterial resonator

    NASA Astrophysics Data System (ADS)

    Jin, Yu-Ting; Si, Li-Ming; Zhang, Qing-Le; Wu, Yu-Ming; Lv, Xin

    2016-03-01

    A dual-band bandpass filter at X-band is proposed using composite metamaterial resonator consisting of an outer square closed-ring resonator (SCRR) and two inner electric inductance-capacitance (ELC) resonators. Numerical simulation and microwave measurement reveal that the filter exhibits two passbands centered at 8.76 GHz and 11.04 GHz, with 3 dB bandwidths of 130 MHz and 290 MHz, respectively. The complex dispersion relation of the filter is further derived based on the effective medium theory, where two balanced composite right-/left-handed bands are found, i.e. lines exhibiting two left-handed and two right-handed bands alternating. The proposed filter may find useful in dual-band or multi-band wireless communication systems.

  16. 3D Display Using Conjugated Multiband Bandpass Filters

    NASA Technical Reports Server (NTRS)

    Bae, Youngsam; White, Victor E.; Shcheglov, Kirill

    2012-01-01

    Stereoscopic display techniques are based on the principle of displaying two views, with a slightly different perspective, in such a way that the left eye views only by the left eye, and the right eye views only by the right eye. However, one of the major challenges in optical devices is crosstalk between the two channels. Crosstalk is due to the optical devices not completely blocking the wrong-side image, so the left eye sees a little bit of the right image and the right eye sees a little bit of the left image. This results in eyestrain and headaches. A pair of interference filters worn as an optical device can solve the problem. The device consists of a pair of multiband bandpass filters that are conjugated. The term "conjugated" describes the passband regions of one filter not overlapping with those of the other, but the regions are interdigitated. Along with the glasses, a 3D display produces colors composed of primary colors (basis for producing colors) having the spectral bands the same as the passbands of the filters. More specifically, the primary colors producing one viewpoint will be made up of the passbands of one filter, and those of the other viewpoint will be made up of the passbands of the conjugated filter. Thus, the primary colors of one filter would be seen by the eye that has the matching multiband filter. The inherent characteristic of the interference filter will allow little or no transmission of the wrong side of the stereoscopic images.

  17. Narrow bandpass tunable terahertz filter based on photonic crystal cavity.

    PubMed

    He, Jinglong; Liu, Pingan; He, Yalan; Hong, Zhi

    2012-02-20

    We have fabricated a very narrow bandpass tunable terahertz (THz) filter based on a one-dimensional photonic crystal cavity. Since the filter consists of silicon wafers and air spacers, it has a very high quality factor of about 1500. The full width at half maximum (FWHM) of the passband is only about 200 MHz, and the peak transmission is higher than -4 dB. Besides, the central frequency can be tuned rapidly over the entire bandgap with the length of cavity adjusted by a motorized linear stage. Further analytical calculations indicate that a high-Q tunable filter with both high peak transmission and wide tunable range is possible if thinner silicon layers are used. PMID:22358169

  18. Rational engineering of nanoporous anodic alumina optical bandpass filters

    NASA Astrophysics Data System (ADS)

    Santos, Abel; Pereira, Taj; Law, Cheryl Suwen; Losic, Dusan

    2016-08-01

    Herein, we present a rationally designed advanced nanofabrication approach aiming at producing a new type of optical bandpass filters based on nanoporous anodic alumina photonic crystals. The photonic stop band of nanoporous anodic alumina (NAA) is engineered in depth by means of a pseudo-stepwise pulse anodisation (PSPA) approach consisting of pseudo-stepwise asymmetric current density pulses. This nanofabrication method makes it possible to tune the transmission bands of NAA at specific wavelengths and bandwidths, which can be broadly modified across the UV-visible-NIR spectrum through the anodisation period (i.e. time between consecutive pulses). First, we establish the effect of the anodisation period as a means of tuning the position and width of the transmission bands of NAA across the UV-visible-NIR spectrum. To this end, a set of nanoporous anodic alumina bandpass filters (NAA-BPFs) are produced with different anodisation periods, ranging from 500 to 1200 s, and their optical properties (i.e. characteristic transmission bands and interferometric colours) are systematically assessed. Then, we demonstrate that the rational combination of stacked NAA-BPFs consisting of layers of NAA produced with different PSPA periods can be readily used to create a set of unique and highly selective optical bandpass filters with characteristic transmission bands, the position, width and number of which can be precisely engineered by this rational anodisation approach. Finally, as a proof-of-concept, we demonstrate that the superposition of stacked NAA-BPFs produced with slight modifications of the anodisation period enables the fabrication of NAA-BPFs with unprecedented broad transmission bands across the UV-visible-NIR spectrum. The results obtained from our study constitute the first comprehensive rationale towards advanced NAA-BPFs with fully controllable photonic properties. These photonic crystal structures could become a promising alternative to traditional optical

  19. Frequency Selective Surface Bandpass Filters Applied To Thermophotovoltaic Generators

    NASA Astrophysics Data System (ADS)

    Horne, W. E.; Morgan, Mark D.; Horne, W. Paul; Sundaram, Vasan S.

    2004-11-01

    EDTEK, Inc. is developing three TPV applications, a portable diesel fueled generator for military and remote users, a hybrid solar-gas fueled power system intended for light industry and commercial 24-hour use, and a radioisotope fueled generator for deep-space spacecraft. The application of FSS bandpass filters for spectral control in these three different TPV applications has been analyzed. It has been determined that the design of the filter cannot be evaluated solely on the parameters of the filter itself. The interactions between the filter and the emitter and the TPV cells must be taken into account. In addition to the technical analysis of the converter, the overall system losses must be included in the analysis and the design requirements such as fuel efficiency, weight, generator size, cost and other factors must be included in the analysis. The analysis shows that the FSS filters are useful for producing the three systems with good efficiencies; however, different designs are required for the filters for each application.

  20. Far-infrared band-pass grid filters

    NASA Astrophysics Data System (ADS)

    MacDonald, Michael E.; Grossman, Erich N.

    1996-12-01

    The spectral performance of bandpass grid filters centered at terahertz frequencies is presented. The filters are composed of a periodic array of cross-shaped apertures in an evaporated metal film on a thin dielectric substrate. A commercial Fourier-transform spectrometer is used to measure spectral transmittance. Results are presented for filters using gold films of different thickness. The peak transmittance is correlated with the DC surface resistance Rs of the film, which is probed using an in situ test structure on the fabricated filters. This is true even though the gold films all have a thickness several times the classical skin depth at the resonant frequency. Measurements of Rs and peak transmittance at 77 K show an equivalent correlation, indicating that some of the loss is due to the finite conductivity of the gold film. The dielectric substrate causes a downward shift in the center frequency of the filter proportional to the dielectric constant and thickness of the substrate. The center frequency shifts rapidly with increasing dielectric thickness and reaches an asymptotic value reduced from the freestanding case by the square root of the mean dielectric constant. Measurements are compared to a finite-difference time domain model, which accurately predicts the center frequency, but does not account for losses. The performance of these filters, along with their simple fabrication, makes them useful frequency- selective elements at far-IR wavelengths.

  1. Bandpass filter arrays patterned by photolithography for multispectral remote sensing

    NASA Astrophysics Data System (ADS)

    Bauer, T.; Thome, Heidi; Eisenhammer, Thomas

    2014-10-01

    Optical remote sensing of the earth from air and space typically utilizes several channels from visible (VIS), near infrared (NIR) up to the short wave infrared (SWIR) spectral region. Thin-film optical filters are applied to select these channels. Filter wheels and arrays of discrete stripe filters are standard configurations. To achieve compact and light weight camera designs multi-channel filter plates or assemblies can be mounted close to the electronic detectors. Optics Balzers has implemented a micro-structuring process based on a sequence of multiple coatings and photolithography on the same substrate. High-performance band pass filters are applied by plasma assisted evaporation (plasma IAD) with advance plasma source (APS) technology and optical broad-band monitoring (BBM). This technology has already proven for various multi spectral imager (MSI) configurations on fused silica, sapphire and other substrates for remote sensing application. The optical filter design and performance is limited by the maximum coating thickness micro-structurable by photolithographic lift-off processes and by thermal and radiation load on the photoresist mask during the process Recent progress in image resolution and sensor selectivity requires improvements of optical filter performance. Blocking in the UV and NIR and in between the spectral cannels, in-band transmission and filter edge steepness are subject of current development. Technological limits of the IAD coating accuracy can be overcome by more precise coating technologies like plasma assisted reactive magnetron sputtering (PARMS) and combination with optical broadband monitoring (BBM). We present an overview about concepts and technologies for band-pass filter arrays for multi-spectral imaging at Optics Balzers. Recent performance improvements of filter arrays made by micro-structuring will be presented.

  2. Optically tunable acoustic wave band-pass filter

    SciTech Connect

    Swinteck, N.; Lucas, P.; Deymier, P. A.

    2014-12-15

    The acoustic properties of a hybrid composite that exhibits both photonic and phononic behavior are investigated numerically with finite-element and finite-difference time-domain simulations. The structure is constituted of a periodic array of photonic resonant cavities embedded in a background superlattice. The resonant cavities contain a photo-elastic chalcogenide glass that undergoes atomic-scale structural reorganization when irradiated with light having energy close to its band-gap. Photo-excitation of the chalcogenide glass changes its elastic properties and, consequently, augments the acoustic transmission spectrum of the composite. By modulating the intensity of light irradiating the hybrid photonic/phononic structure, the position and spectral width of phonon passing-bands can be controlled. This demonstration offers the technological platform for optically-tunable acoustic wave band-pass filters.

  3. 1 THz Micromachined Waveguide Band-Pass Filter

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Hu, Jiang; Zhang, Yong; Zheng, Zhongwan; Liu, Yupeng; Xu, Ruimin; Xue, Quan

    2016-05-01

    This paper presents a waveguide band-pass filter operating at the 0.75 ˜ 1.1 THz frequency band. The metal conductivity, the surface impedance, and the skin depth are investigated in the terahertz (THz) frequency band for more accurate designs, especially at the 1 THz and higher frequencies. Because the influence of the fabrication tolerance on the component performance cannot be negligible while the frequency increases, it is a necessary to adopt the simple structure with less resonant cavities for obtaining the given performance. Therefore, the filter in this paper is designed based on the TE301/TE102 dual-mode rectangular waveguide resonant cavities, which has fewer cavities and better rejection of the stop-band. The proposed filter is fabricated using the deep reactive ion etching (DRIE) micromachining technique. Measured results are in good agreement with simulations, which verifies the accuracy of the analysis above, and the design process is valuable to realize high-performance passive components while the frequency is up to 1 THz or higher frequencies.

  4. Dynamic, infrared bandpass filters prepared from polymer-stabilized cholesteric liquid crystals.

    PubMed

    Worth, Bradley; Lee, Kyung Min; Tondiglia, Vincent P; Myers, Joshua; Mou, Shin; White, Timothy J

    2016-09-01

    We report on the formulation and electrical control of the position and bandwidth of reflective bandpass filters prepared from cholesteric liquid crystal (CLC) in the infrared (3-5 μm). These filters are prepared from alignment cells employing infrared transparent electrodes and substrates. The optical nature of the electrodes is shown to strongly influence the resulting transmission of the bandpass filters outside of the spectral reflection. PMID:27607292

  5. Flexibly tunable multichannel filter and bandpass filter based on long-period fiber gratings

    NASA Astrophysics Data System (ADS)

    Han, Young-Geun; Hyuck Kim, Sang; Lee, Sang Bae

    2004-05-01

    The voltage-controllable multichannel filter based on multiply cascaded long-period fiber gratings with a divided coil heater will be proposed and experimentally demonstrated. It has several advantages of the large tuning range in both C- and L-band, multichannel operation, multiwavelength electivity, and bandwidth controllability. The tunable bandpass filter based on long-period fiber gratings ith the broad bandwidth over 6.5 nm, large tuning range over 30 nm, and excellent side mode suppression more than 40 dB will be also discussed.

  6. 1D linear-phase band-pass multiplierless FIR Hilbert transformers and filters

    NASA Astrophysics Data System (ADS)

    Pavlović, Vlastimir D.; Dončov, Nebojša S.; Ćirić, Dejan G.

    2016-06-01

    An original analytical method, based on modified Christoffel-Darboux formula, is used in the paper in order to synthesise a linear-phase band-pass finite impulse response (FIR) filter function that can have an effect of Hilbert transformer. New structure of the band-pass FIR filter in recursive realisation, together with the corresponding difference equation, is presented providing the efficient filter solution without multipliers. Several examples of filter types for different parity of two real free integer parameters, including a particular solution of Hilbert transformer, are considered in terms of required number of adders and values of cut-off frequencies of the pass and stop bands. A comparison of the proposed band-pass filter characteristics with those of a classical filter solution is provided in the paper.

  7. Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared.

    PubMed

    Stolberg-Rohr, Thomine; Hawkins, Gary J

    2015-01-12

    The ability of narrow bandpass filters to discriminate wavelengths between closely-separated gas absorption lines is crucial in many areas of infrared spectroscopy. As improvements to the sensitivity of infrared detectors enables operation in uncontrolled high-temperature environments, this imposes demands on the explicit bandpass design to provide temperature-invariant behavior. The unique negative temperature coefficient (dn/dT<0) of Lead-based (Pb) salts, in combination with dielectric materials enable bandpass filters with exclusive immunity to shifts in wavelength with temperature. This paper presents the results of an investigation into the interdependence between multilayer bandpass design and optical materials together with a review on invariance at elevated temperatures. PMID:25835704

  8. High-performance RC bandpass filter is adapted to miniaturized construction

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Miniaturized bandpass filter with RC networks is suitable for use in integrated circuits. The circuit consists of three stages of amplification with additional resistive and capacitive components to obtain the desired characteristics. The advantages of the active RC filter network are the reduction in size and weight and elimination of magnetic materials.

  9. Miniaturized sharp band-pass filter based on complementary electric-LC resonator

    NASA Astrophysics Data System (ADS)

    Torabi, Yalda; Dadashzadeh, Golamreza; Oraizi, Homayoon

    2016-04-01

    In this paper, a novel application of complementary electric-LC (CELC) resonator as a basic element to synthesize miniaturized sharp band-pass filters is introduced. The proposed metamaterial band-pass filter is a three-stage CELC-based device, where two shunt short-circuited stubs are employed in the input and output stages and a series gap is etched in the middle stage. By these means, a high-selectivity prototype band-pass filter with 2 % fractional bandwidth in S band is designed and fabricated. The out-of-band attenuation is better than 40 dB, and the upper and lower transition bands are also quite sharp due to the presence of two transmission zeros (nearly 60 and 30 dB fall in 0.2 GHz at lower and upper edges, respectively). Moreover, the filter is substantially miniaturized with a size of effective region of 1.3 cm × 1 cm at 2.9 GHz, which is quite smaller relative to conventional designs with the same performance. The fabrication and measurement of the proposed filter configuration attest to its expected desirable features. Therefore, the application of CELC resonator is proposed for super-compact sharp band-pass filters.

  10. Tunable optical bandpass filter with multiple flat-top bands in nanostructured resonators

    NASA Astrophysics Data System (ADS)

    Xie, Jun; Chen, Yuping; Lu, Wenjie; Chen, Xianfeng

    2011-03-01

    Based on second-order nonlinearity, we present a tunable optical bandpass filter at c-band by introducing a back quasiphase-matching technique with a nanostructured named multiple resonator waveguide. Two injecting forward lights and one backward propagating light interact with difference frequency generation. At that juncture, the transmission of the forward signal can be modulated via changing the forward control power. As a result, a tunable optical bandpass filter with multiple flat-top transmit bands of the forward signal can be formed in the waveguide.

  11. Alkali metal for ultraviolet band-pass filter

    NASA Technical Reports Server (NTRS)

    Mardesich, Nick (Inventor); Fraschetti, George A. (Inventor); Mccann, Timothy A. (Inventor); Mayall, Sherwood D. (Inventor); Dunn, Donald E. (Inventor); Trauger, John T. (Inventor)

    1993-01-01

    An alkali metal filter having a layer of metallic bismuth deposited onto the alkali metal is provided. The metallic bismuth acts to stabilize the surface of the alkali metal to prevent substantial surface migration from occurring on the alkali metal, which may degrade optical characteristics of the filter. To this end, a layer of metallic bismuth is deposited by vapor deposition over the alkali metal to a depth of approximately 5 to 10 A. A complete alkali metal filter is described along with a method for fabricating the alkali metal filter.

  12. Spectral and Wavefront Error Performance of WFIRST-AFTA Bandpass Filter Coating Prototypes

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Seide, Laurie; Pasquale, Bert A.; McMann, Joseph C.; Hagopian, John G.; Dominguez, Margaret Z.; Gong, Quian; Marx, Catherine T.

    2016-01-01

    The Cycle 5 design baseline for the Wide-Field Infrared Survey Telescope Astrophysics Focused Telescope Assets (WFIRST/AFTA) instrument includes a single wide-field channel (WFC) instrument for both imaging and slit-less spectroscopy. The only routinely moving part during scientific observations for this wide-field channel is the element wheel (EW) assembly. This filter-wheel assembly will have 8 positions that will be populated with 6 bandpass filters, a blank position, and a Grism that will consist of a three-element assembly to disperse the full field with an undeviated central wavelength for galaxy redshift surveys. All filter elements in the EW assembly will be made out of fused silica substrates (110 mm diameter) that will have the appropriate bandpass coatings according to the filter designations (Z087, Y106, J129, H158, F184, W149 and Grism). This paper presents and discusses the performance (including spectral transmission and reflected/transmitted wavefront error measurements) of a subset of bandpass filter coating prototypes that are based on the WFC instrument filter compliment. The bandpass coating prototypes that are tested in this effort correspond to the Z087, W149, and Grism filter elements. These filter coatings have been procured from three different vendors to assess the most challenging aspects in terms of the in-band throughput, out of band rejection (including the cut-on and cutoff slopes), and the impact the wavefront error distortions of these filter coatings will have on the imaging performance of the wide-field channel in the WFIRST/AFTA observatory.

  13. An optically tunable wideband optoelectronic oscillator based on a bandpass microwave photonic filter.

    PubMed

    Jiang, Fan; Wong, Jia Haur; Lam, Huy Quoc; Zhou, Junqiang; Aditya, Sheel; Lim, Peng Huei; Lee, Kenneth Eng Kian; Shum, Perry Ping; Zhang, Xinliang

    2013-07-15

    An optoelectronic oscillator (OEO) with wideband frequency tunability and stable output based on a bandpass microwave photonic filter (MPF) has been proposed and experimentally demonstrated. Realized by cascading a finite impulse response (FIR) filter and an infinite impulse response (IIR) filter together, the tunable bandpass MPF successfully replaces the narrowband electrical bandpass filter in a conventional single-loop OEO and serves as the oscillating frequency selector. The FIR filter is based on a tunable multi-wavelength laser and dispersion compensation fiber (DCF) while the IIR filter is simply based on an optical loop. Utilizing a long length of DCF as the dispersion medium for the FIR filter also provides a long delay line for the OEO feedback cavity and as a result, optical tuning over a wide frequency range can be achieved without sacrificing the quality of the generated signal. By tuning the wavelength spacing of the multi-wavelength laser, the oscillation frequency can be tuned from 6.88 GHz to 12.79 GHz with an average step-size of 0.128 GHz. The maximum frequency drift of the generated 10 GHz signal is observed to be 1.923 kHz over 1 hour and its phase noise reaches the -112 dBc/Hz limit of our measuring equipment at 10 kHz offset frequency. PMID:23938489

  14. Design and implementation of waveguide bandpass filter using complementary metaresonator

    NASA Astrophysics Data System (ADS)

    Haq, Tanveer ul; Khan, M. F.; Siddiqui, O. F.

    2016-01-01

    During past few years, designing of complementary metamaterials-based microwave devices have extensively increased. In this paper, passband filter for rectangular waveguide is designed using complementary symmetric split-ring resonator (CSSRR). By varying different geometrical parameters of CSSRR, the passband frequency and bandwidth can be varied. Effect of design parameter on quality factor of filter is also calculated. By appropriate choice of CSSRR geometrical parameters, a filter is proposed which gives passband of 2 GHz. The results are calculated numerically using HFSS 14.0.

  15. A novel band-pass filter based on a periodically drilled SIW structure

    NASA Astrophysics Data System (ADS)

    Coves, A.; Torregrosa-Penalva, G.; San-Blas, A. A.; Sánchez-Soriano, M. A.; Martellosio, A.; Bronchalo, E.; Bozzi, M.

    2016-04-01

    The design and fabrication of a band-pass step impedance filter based on high and low dielectric constant sections has been realized on substrate integrated waveguide (SIW) technology. The overall process includes the design of the ideal band-pass prototype filter, where the implementation of the impedance inverters has been carried out by means of waveguide sections of lower permittivity. This can be practically achieved by implementing arrays of air holes along the waveguide. Several SIW structures with and without arrays of air holes have been simulated and fabricated in order to experimentally evaluate their relative permittivity. Additionally, the equivalent filter in SIW technology has been designed and optimized. Finally, a prototype of the designed filter has been fabricated and measured, showing a good agreement between measurements and simulations, which demonstrates the validity of the proposed design approach.

  16. Compact Micromachined Bandpass Filters for Infrared Planetary Spectroscopy

    NASA Technical Reports Server (NTRS)

    Brown, Ari D.; Aslam, Shahid; Chervenak, James A.; Huang, Wei-Chung; Merrell, Willie; Quijada, Manuel

    2011-01-01

    The thermal instrument strawman payload of the Jupiter Europa Orbiter on the Europa Jupiter Science Mission will map out thermal anomalies, the structure, and atmospheric conditions of Europa and Jupiter within the 7-100 micron spectral range. One key requirement for the payload is that the mass cannot exceed 3.7 kg. Consequently, a new generation of light-weight miniaturized spectrometers needs to be developed. On the path toward developing these spectrometers is development of ancillary miniaturized spectroscopic components. In this paper, we present a strategy for making radiation hard and low mass FIR band pass metal mesh filters. Our strategy involves using MEMS-based fabrication techniques, which will permit the quasi-optical filter structures to be made with micron-scale precision. This will enable us to achieve tight control over both the pass band of the filter and the micromachined silicon support structure architecture, which will facilitate integration of the filters for a variety of applications.

  17. Effect of bandpass filtering on melodic contour identification by cochlear implant users.

    PubMed

    Galvin, John J; Fu, Qian-Jie

    2011-02-01

    Melodic contour identification was measured in cochlear implant (CI) and normal-hearing (NH) subjects for piano samples processed by four bandpass filters: low (310-620 Hz), middle (620-2480 Hz), high (2480-4960 Hz), and full (310-4960 Hz). NH performance was near-perfect for all filter ranges and much higher than CI performance. The best mean CI performance was with the middle frequency range; performance was much better for some CI subjects with the middle rather than the full filter. These results suggest that acoustic filtering may reduce potential mismatches between fundamental frequencies and harmonic components thereby improving CI users' melodic pitch perception. PMID:21361410

  18. Microwave bandpass filters based on thin-film acoustic resonators: theory and experiment

    NASA Astrophysics Data System (ADS)

    Dvoesherstov, M. Yu.; Cherednik, V. I.

    2015-11-01

    We theoretically and experimentally analyze microwave thin-film acoustoelectronic bandpass ladder filters built on AlN-based thin-film acoustoelectronic microwave resonators operating in the frequency range 4.6-5 GHz and describe the technology of their fabrication. We demonstrate that the parameters of filters are mainly determined by the characteristics of resonators that make up the filter and show that the characteristics of a three-section ladder filter can be significantly improved by optimizing the areas of the upper electrodes of the series and parallel resonators contained in it.

  19. Microstrip Hairpin Bandpass Filter Using Modified Minkowski Fractal-Shape for Suppression of Second Harmonic

    NASA Astrophysics Data System (ADS)

    Lalbakhsh, Ali; Lotfi Neyestanak, Abbas Ali; Naser-Moghaddasi, Mohammad

    In this paper, a novel microstrip hairpin-line bandpass filter which employs a modified Minkowski fractal shape is proposed. Although conventional hairpin-line filters are popular for RF front ends, they suffer from undesired spurious responses located at the second harmonic, which causes asymmetry in the upper skirt band. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shape. To validate this novel geometry, the proposed filters are fabricated and measured. Simulated results are in good agreement with measured results.

  20. Ultra-narrow bandpass filters for infrared applications with improved angle of incidence performance

    NASA Astrophysics Data System (ADS)

    Rahmlow, Thomas D.; Fredell, Markus; Chanda, Sheetal; Johnson, Robert

    2016-05-01

    Narrow band-pass optical interference filters are used for a variety of applications to improve signal quality in laser based systems. Applications include LIDAR, sensor processing and free space communications. A narrow band width optical filter allows for passage of the laser signal while rejecting ambient light. The more narrow the bandwidth, the better the signal to noise. However, the bandwidth of a design for a particular application is typically limited by a number of factors including spectral shift over the operational angles of incidence, thermal shift over the range of operating temperature and, in the case of laser communication, rejection of adjacent laser channels. The trade-off of these parameters can significantly impact system design and performance. This paper presents design and material approaches to maximize the performance of narrow bandpass filters in the infrared.

  1. Tunable coherence-free microwave photonic bandpass filter based on double cross gain modulation technique.

    PubMed

    Chan, Erwin H W

    2012-10-01

    A tunable, coherence-free, high-resolution microwave photonic bandpass filter, which is compatible to be inserted in a conventional fiber optic link, is presented. It is based on using two cross gain modulation based wavelength converters in a recursive loop. The double cross gain modulation technique solves the semiconductor optical amplifier facet reflection problem in the conventional recursive structure; hence the new microwave photonic signal processor has no coherent interference and no phase-induced intensity noise. It allows arbitrary narrow-linewidth telecommunication-type lasers to be used while enabling stable filter operation to be realized. The filter passband frequency can be tuned by using a wavelength tunable laser and a wavelength dependent time delay component. Experimental results demonstrate robust high-resolution bandpass filter operation with narrow-linewidth sources, no phase-induced intensity noise and a high signal-to-noise ratio performance. Tunable coherence-free operation of the high-resolution bandpass filter is also demonstrated. PMID:23188262

  2. Widely tunable single bandpass microwave photonic filter based on Brillouin-assisted optical carrier recovery.

    PubMed

    Wang, Wen Ting; Liu, Jian Guo; Sun, Wen Hui; Wang, Wei Yu; Wang, Sun Long; Zhu, Ning Hua

    2014-12-01

    A widely tunable single bandpass microwave photonic filter (MPF) based on Brillouin-assisted optical carrier recovery in a highly nonlinear fiber (HNLF) with only one optical filter is proposed and experimentally demonstrated. The fundamental principle lies in the fact that the suppressed optical carrier of the phase modulated optical signal could be recovered by the stimulated Brillouin scattering (SBS) amplification effect. When phase modulated optical signals go through an optical filter with a bandpass response, the optical carrier and the upper sidebands suffer from the suppression of the optical filter because they fall in the stopband of that. In our system, the optical carrier could be recovered by the SBS operation around 38 dB. The MPF is achieved by one-to-one mapping from the optical domain to the electrical domain only when one of phase modulated sidebands lies in the bandpass of the optical filter. It shows an excellent selectivity with a 3-dB bandwidth of 170 MHz over a tuning frequency range of 9.5-32.5 GHz. The out-of-band suppression of the MPF is more than 20 dB. Moreover, the MPF shows an excellent shape factor with 10-dB bandwidth of only 520 MHz. The frequency response of the MPF could be widely tuned by changing the frequency difference between the frequency of the optical carrier and the center frequency of the bandpass of the optical filter. A proof-of-concept experiment is carried out to verify the proposed approach. PMID:25606864

  3. Radiation Hard Bandpass Filters for Mid- to Far-IR Planetary Instruments

    NASA Technical Reports Server (NTRS)

    Brown, Ari D.; Aslam, Shahid; Chervenack, James A.; Huang, Wei-Chung; Merrell, Willie C.; Quijada, Manuel; Steptoe-Jackson, Rosalind; Wollack, Edward J.

    2012-01-01

    We present a novel method to fabricate compact metal mesh bandpass filters for use in mid- to far-infrared planetary instruments operating in the 20-600 micron wavelength spectral regime. Our target applications include thermal mapping instruments on ESA's JUICE as well as on a de-scoped JEO. These filters are novel because they are compact, customizable, free-standing copper mesh resonant bandpass filters with micromachined silicon support frames. The filters are well suited for thermal mapping mission to the outer planets and their moons because the filter material is radiation hard. Furthermore, the silicon support frame allows for effective hybridization with sensors made on silicon substrates. Using a Fourier Transform Spectrometer, we have demonstrated high transmittance within the passband as well as good out-of-band rejection [1]. In addition, we have developed a unique method of filter stacking in order to increase the bandwidth and sharpen the roll-off of the filters. This method allows one to reliably control the spacing between filters to within 2 microns. Furthermore, our method allows for reliable control over the relative position and orienta-tion between the shared faces of the filters.

  4. Compact Bandpass Filter Based on Parallel-coupled Lines and Quasi-lumped Structure

    NASA Astrophysics Data System (ADS)

    Ding, Chen; Li, Jiao; Wei, Feng; Shi, Xiao-Wei

    2016-01-01

    A compact microstrip bandpass filter (BPF) using quarter-wavelength resonators is proposed based on the parallel-coupled lines (PCLs) and quasi-lumped structure. A method based on the matrix and network transformation of cascaded-quadruplet (CQ) filters is investigated and successfully applied to the BPF design. The design formulas for the proposed BPF are analytically developed. Specifically, in order to verify the feasibility of the proposed method, three BPFs centering at 1.575 GHz with different FBWs are designed. Good agreement between the simulated and measured results is observed. Moreover, the designed filters can achieve a wide stopband.

  5. A band-pass plasmonic filter with dual-square ring resonator

    NASA Astrophysics Data System (ADS)

    Duan, Gaoyan; Lang, Peilin; Wang, Lulu; Yu, Li; Xiao, Jinghua

    2014-09-01

    In this paper, we show the simulation of a plasmonic band-pass filter which consists of two surface plasmon polaritons (SPPs) waveguides and a resonator in metal-insulator-metal (MIM) structure. The resonator is formed by two square rings and a patch between them. The patch is a tiny rectangle cavity in order to transfer the SPPs from one ring to the other. The finite element method (FEM) method is employed in simulation. The results show that the dual-ring resonator performs better than a single ring does. The 3 dB bandwidth near the peak wavelength λ = 1054 nm is merely 31.7 nm. The resonant wavelength can be shifted by changing the side length of the square ring. This narrow band-pass filter is easy to fabricate and has potential applications in future integrated optical circuits.

  6. Design and manufacture of a bandpass filter with high transmittance and steep edge on both sides

    NASA Astrophysics Data System (ADS)

    Wang, Ruisheng; Lü, Shaobo; Yin, Xiaojun; Zhao, Shuaifeng; Sun, Yan

    2016-01-01

    By using Nb2O5 and SiO2 as the coating material, a 152 layers (12 cavities) bandpass film stack with steep edge on both sides was designed. Multiple thickness control methods, including direct optical monitoring control and time control were used in coating strategy. To confirm the feasibility of this coating strategy, a process simulation was performed using Simulator software, and the simulation result indicated that relative thickness errors for all layers were less than ±0.1%. A bandpass filter with this film stack on one side was manufactured by using a plasma assisted reactive magnetic sputtering coating machine. The measuring result shows that the peak transmittance of the filter (without AR on backside) is up to 95.4%, and the steepness of both blocking slope are less than λ/100.

  7. Project Report: Reducing Color Rivalry in Imagery for Conjugated Multiple Bandpass Filter Based Stereo Endoscopy

    NASA Technical Reports Server (NTRS)

    Ream, Allen

    2011-01-01

    A pair of conjugated multiple bandpass filters (CMBF) can be used to create spatially separated pupils in a traditional lens and imaging sensor system allowing for the passive capture of stereo video. This method is especially useful for surgical endoscopy where smaller cameras are needed to provide ample room for manipulating tools while also granting improved visualizations of scene depth. The significant issue in this process is that, due to the complimentary nature of the filters, the colors seen through each filter do not match each other, and also differ from colors as seen under a white illumination source. A color correction model was implemented that included optimized filter selection, such that the degree of necessary post-processing correction was minimized, and a chromatic adaptation transformation that attempted to fix the imaged colors tristimulus indices based on the principle of color constancy. Due to fabrication constraints, only dual bandpass filters were feasible. The theoretical average color error after correction between these filters was still above the fusion limit meaning that rivalry conditions are possible during viewing. This error can be minimized further by designing the filters for a subset of colors corresponding to specific working environments.

  8. Method for experimental determination of the contribution of individual sources to total noise. [using bandpass filter for signal analysis

    NASA Technical Reports Server (NTRS)

    Rubichev, N. A.

    1973-01-01

    Multiple noise sources generating signals in a mechanical device are analyzed by considering the medium transmitting the sound as linear, and by using a band filter with bandpass for synchronous detection and signal transformation.

  9. Note: An ultranarrow bandpass filter system for single-photon experiments in quantum optics

    NASA Astrophysics Data System (ADS)

    Höckel, David; Martin, Eugen; Benson, Oliver

    2010-02-01

    We describe a combined ultranarrow bandpass filtering setup for single-photon experiments in quantum optics. The filter is particularly suitable for single-photon electromagnetically induced transparency (EIT) experiments, but can also be used in several similar applications. A multipass planar Fabry-Pérot etalon together with polarization filters and spatial filtering allows 114 dB pump beam suppression, while the signal beam is attenuated by just 4 dB, although both wavelengths are only separated by 0.025 nm (9.2 GHz). The multipass etalon alone accounts for 46 dB suppression while it has a peak transmission of 65%. We demonstrate EIT experiments in Cs vapor at room temperature with probe power in the femtowatt regime using this filter.

  10. System design for a million channel digital spectrum analyzer /MCSA/. [of bandpass filtering in SETI receivers

    NASA Technical Reports Server (NTRS)

    Peterson, A.; Narasimha, M.; Narayan, S.

    1980-01-01

    The system design of a wideband (8 MHz) million-channel digital spectrum analyzer for use with a SETI receiver is presented. The analyzer makes use of a digital bandpass filter bank for transforming the wideband input signal into a specified number (120) of uniform narrowband output channels by the use of a Fourier transform digital processor combined with a prototype digital weighting network (finite impulse response filter). The output is then processed separately by 120 microprocessor-based discrete Fourier transform computers, each producing 8190 output channels of approximately 8 Hz bandwidth by the use of an 8190-point prime factor algorithm.

  11. An algorithm used for quality criterion automatic measurement of band-pass filters and its device implementation

    NASA Astrophysics Data System (ADS)

    Liu, Qianshun; Liu, Yan; Yu, Feihong

    2013-08-01

    As a kind of film device, band-pass filter is widely used in pattern recognition, infrared detection, optical fiber communication, etc. In this paper, an algorithm for automatic measurement of band-pass filter quality criterion is proposed based on the proven theory calculation of derivate spectral transmittance of filter formula. Firstly, wavelet transform to reduce spectrum data noises is used. Secondly, combining with the Gaussian curve fitting and least squares method, the algorithm fits spectrum curve and searches the peak. Finally, some parameters for judging band-pass filter quality are figure out. Based on the algorithm, a pipeline for band-pass filters automatic measurement system has been designed that can scan the filter array automatically and display spectral transmittance of each filter. At the same time, the system compares the measuring result with the user defined standards to determine if the filter is qualified or not. The qualified product will be market with green color, and the unqualified product will be marked with red color. With the experiments verification, the automatic measurement system basically realized comprehensive, accurate and rapid measurement of band-pass filter quality and achieved the expected results.

  12. Metamaterial composite bandpass filter with an ultra-broadband rejection bandwidth of up to 240 terahertz

    NASA Astrophysics Data System (ADS)

    Strikwerda, Andrew C.; Zalkovskij, Maksim; Lund Lorenzen, Dennis; Krabbe, Alexander; Lavrinenko, Andrei V.; Uhd Jepsen, Peter

    2014-05-01

    We present a metamaterial, consisting of a cross structure and a metal mesh filter, that forms a composite with greater functional bandwidth than any terahertz (THz) metamaterial to date. Metamaterials traditionally have a narrow usable bandwidth that is much smaller than common THz sources, such as photoconductive antennas and difference frequency generation. The composite structure shown here expands the usable bandwidth to exceed that of current THz sources. To highlight the applicability of this combination, we demonstrate a series of bandpass filters with only a single pass band, with a central frequency (f0) that is scalable from 0.86-8.51 THz, that highly extinguishes other frequencies up to >240 THz. The performance of these filters is demonstrated in experiment, using both air biased coherent detection and a Fourier transform infrared spectrometer (FTIR), as well as in simulation. We present equations—and discuss their scaling laws—which detail the f0 and full width at half max (Δf) of the pass band, as well as the required geometric dimensions for their fabrication using standard UV photolithography and easily achievable fabrication linewidths. With these equations, the geometric parameters and Δf for a desired frequency can be quickly calculated. Using these bandpass filters as a proof of principle, we believe that this metamaterial composite provides the key for ultra-broadband metamaterial design.

  13. Optical bandpass filters for detector arrays' modulation transfer function estimation by means of laser speckle

    NASA Astrophysics Data System (ADS)

    Astar, William

    1996-06-01

    Two apertures, a square slit (SS) and a diamond slit (DS), both zero'th-order magnitude transparencies with bandpass filters in their optical transfer functions (OTFs), are designed and optimized for the purpose of modulation transfer function (MTF) evaluation of detector arrays by means of laser speckle. The SS and DS apertures are compared to an existing design, the extended frequency aperture, and show, respectively, improvements of 464% and 58% in filter magnitude; improvements of -13.4% (a compromise) and 17% in bandwidth; and improvements of 627% and 423% in throughput, implying a greatly reduced laser power requirement. As a result, they should significantly enhance detector arrays' MTF evaluations and at a greatly reduced cost. The DS aperture possesses identical OTFs in both the horizontal and vertical directions, enabling MTF evaluation using the bandpass filters in those directions from the same speckle data frame--previously not possible. The DS aperture can be further modified to yield filter magnitude and bandwidth improvements of 111% and 40%, respectively; although becoming easier to fabricate, this modification would be a lower throughput improvement of 310% over the existing design.

  14. W-band waveguide bandpass filter with E-plane cut.

    PubMed

    Furtula, Vedran; Salewski, Mirko

    2014-07-01

    In this paper, we present a design and measurements of a five-section bandpass filter with a passband from 96 to 106 GHz. The insertion loss is less than 1.4 dB in the passband, and the rejection is better than 40 dB in the range from 115 to 142 GHz. We use transmission line coupling theory based on Tchebyscheff's synthesis in order to provide an initial guess for the geometrical parameters of the filter such as cavity lengths and coupling widths. The filter is manufactured from brass in two halves in the E-plane cut topology. The S-parameters of the filter are measured and compared with the simulations. The measured passband insertion loss is approximately 0.4 dB worse than in the simulation, and the measured passband width is approximately 3.4% narrower. The measured filter attenuation roll-off corresponds well to the simulation. We also compare our S-parameter measurements of the E-plane filter with corresponding measurements of a very similar H-plane filter. The transmission and reflection characteristics of the E-plane filter are better than those of the H-plane filter. PMID:25085158

  15. Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot

    PubMed Central

    Mezaal, Yaqeen S.; Eyyuboglu, Halil T.

    2016-01-01

    A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered. PMID:27054755

  16. Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot.

    PubMed

    Mezaal, Yaqeen S; Eyyuboglu, Halil T

    2016-01-01

    A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered. PMID:27054755

  17. Solar-blind ultraviolet band-pass filter based on metal—dielectric multilayer structures

    NASA Astrophysics Data System (ADS)

    Wang, Tian-Jiao; Xu, Wei-Zong; Lu, Hai; Ren, Fang-Fang; Chen, Dun-Jun; Zhang, Rong; Zheng, You-Dou

    2014-07-01

    Solar-blind ultraviolet (UV) band-pass filter has significant value in many scientific, commercial, and military applications, in which the detection of weak UV signal against a strong background of solar radiation is required. In this work, a solar-blind filter is designed based on the concept of “transparent metal”. The filter consisting of Al/SiO2 multilayers could exhibit a high transmission in the solar-blind wavelength region and a wide stopband extending from near-ultraviolet to infrared wavelength range. The central wavelength, bandwidth, Q factor, and rejection ratio of the passband are numerically studied as a function of individual layer thickness and multilayer period.

  18. Investigation of Spectral Characteristics for Microstructured Quasi-Optical Bandpass Subteraherz Filters

    NASA Astrophysics Data System (ADS)

    Kuznetsov, S. A.; Gelfand, A. V.

    2016-03-01

    The electrodynamic features of quasi-optical bandpass filters based on multilayer microstructured frequency selective surfaces intended for effective spectral selection of subteraherz electromagnetic radiation are considered. As an optimal solution, the multiplex filters are highlighted wherein tripole-slot self-bearing copper microstructures free from dielectric substrates are employed. The results of the experimental development for such filters are presented by the example of structures with resonant transmission at the frequencies of 0.6 and 1 THz, and the details of testing their spectral performance in the range of 0.1-1.5 THz using a BWO spectroscopy technique are described. Good agreement between the experimental data and the results of theoretical predictions is demonstrated.

  19. Polarization insensitive wide-angle triple-band metamaterial bandpass filter

    NASA Astrophysics Data System (ADS)

    Fu, Wenyue; Han, Yuchen; Li, Jiandong; Wang, Haoshen; Li, Haipeng; Han, Kui; Shen, Xiaopeng; Cui, Tiejun

    2016-07-01

    In this letter, we report the design, fabrication and measurement of a polarization insensitive wide-angle triple-band metamaterial bandpass filter (BPF) in the microwave frequency. The proposed BPF consists of two identical metal resonant units which have three concentric square slots separated by a dielectric layer. Experimental results show that the BPF has three distinctive transmission bands centered at frequencies 6.22 GHz, 9.46 GHz and 12.14 GHz with transmission rates of  ‑0.40 dB, ‑0.71 dB and  ‑1.40 dB, respectively, agreeing well with simulation results. By introducing the substrate integrated waveguide, the filter is valid to a wide range of incident angles for both transverse electric and transverse magnetic polarizations. The triple-band metamaterial BPF can be used as multiband filters and radomes owing to its multiband transmissions, polarizations insensitive and wide-angle responses.

  20. Photosensitive post tuning of chalcogenide Te 20As 30Se 50 narrow bandpass filters

    NASA Astrophysics Data System (ADS)

    Shen, Weidong; Cathelinaud, Michel; Lequime, Michel; Nazabal, Virginie; Liu, Xu

    2008-07-01

    We present an experimental study on the photosensitive properties of narrow bandpass filters based on a chalcogenide Te 20As 30Se 50 (TAS) spacer. The transmittance curve of single TAS layer was shifted towards long wavelength direction after 2 h exposure by Xenon arc lamp. The refractive index and extinction coefficient were both increased together with a red shift of optical gap. A maximum 1.7% photo-induced effect was observed. Narrow band filters constituted by TAS and cryolite were manufactured by electron beam deposition. The transmittance spectrum of the filter during the exposure by a wide band source was in situ measured and the resonant wavelength was observed to turn longer gradually till saturation. A spatially localized central wavelength change up to 5.7 nm was finally obtained. The stability of the photo-induced effect was studied and some comments were given at the end of this paper.

  1. Dual-band bandpass tunable microwave photonic filter based on stimulated Brillouin scattering

    NASA Astrophysics Data System (ADS)

    Li, Jia-qi; Xiao, Yong-chuan; Dong, Wei; Zhang, Xin-dong

    2016-07-01

    A dual-band bandpass microwave photonic filter (MPF) based on stimulated Brillouin scattering (SBS) is theoretically analyzed and experimentally demonstrated. Two separated tunable laser sources (TLSs) are employed to generate two passbands by implementing phase modulation to amplitude modulation conversion by using SBS induced sideband amplification. The center frequencies of both passbands can be independently tuned ranging from 1 GHz to 19 GHz. High resolution with 3 dB bandwidth less than 30 MHz and large out-of-band rejection about 40 dB under 25 mW optical pump power are achieved.

  2. Design of cross-coupled planar microstrip band-pass filters using a novel adjustment method

    NASA Astrophysics Data System (ADS)

    Alkafaji, Muhammed S. S.

    2015-02-01

    In this paper the design of a cross-coupled planar microwave band-pass filter using open-loop square microstrip resonators, with two symmetrically placed attenuation poles, is presented. The design starts from the following specifications: central frequency 3GHz, 150MHz bandwidth, 1dB ripple in the pass-band corresponding to return loss of 6.8dB.The adjustment method using additional ports placed on each resonator of the filter is used, allowing the interconnection of the filter structure with external lumped elements. Connecting a reactive element (capacitor) from such an additional port to ground allows a fine tuning of the resonator. Connecting a reactive element between two such additional ports allows a fine change in the coupling coefficient between these resonators. After adding four extra ports and connecting the external elements (capacitors), it is possible to use fast circuit simulation software to optimize the filter's response. Then all these capacitors have to be gradually eliminated, by compensating their effects through fine changes back in the layouts. If some specific issues are properly handled, this procedure improves considerably the quality of the final design of the filter. After a thorough optimization of the layout, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing this way the efficiency of the applied optimization method.

  3. Design and Specification of Optical Bandpass Filters for Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.; Tsevetanov, Zlatan; Woodruff, Bob; Mooney, Thomas A.

    1998-01-01

    Advanced optical bandpass filters for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) have been developed on a filter-by-filter basis through detailed studies which take into account the instrument's science goals, available optical filter fabrication technology, and developments in ACS's charge-coupled-device (CCD) detector technology. These filters include a subset of filters for the Sloan Digital Sky Survey (SDSS) which are optimized for astronomical photometry using today's charge-coupled-devices (CCD's). In order for ACS to be truly advanced, these filters must push the state-of-the-art in performance in a number of key areas at the same time. Important requirements for these filters include outstanding transmitted wavefront, high transmittance, uniform transmittance across each filter, spectrally structure-free bandpasses, exceptionally high out of band rejection, a high degree of parfocality, and immunity to environmental degradation. These constitute a very stringent set of requirements indeed, especially for filters which are up to 90 mm in diameter. The highly successful paradigm in which final specifications for flight filters were derived through interaction amongst the ACS Science Team, the instrument designer, the lead optical engineer, and the filter designer and vendor is described. Examples of iterative design trade studies carried out in the context of science needs and budgetary and schedule constraints are presented. An overview of the final design specifications for the ACS bandpass and ramp filters is also presented.

  4. Compact Dual-Band Bandpass Filter Using Stubs Loaded Ring Resonator

    NASA Astrophysics Data System (ADS)

    Xu, Jin

    2016-01-01

    This paper presents a novel second-order dual-band bandpass filter (BPF) by using proposed stubs loaded ring resonator. The resonant behavior of proposed stubs loaded ring resonator is analyzed by even-/odd-mode method, which shows its multiple-mode resonant characteristic. Parameters sweep is done so as to give the design guidelines. As an example, a second-order dual-band BPF operating at 1.8/5.2 GHz for GSM and WLAN applications is designed, fabricated and measured. The fabricated filter has a very compact size of 0.05λg×0.15λg. Measured results also show that the proposed dual-band BPF has a better than 20 dB rejection upper stopband from 5.47 GHz to 12.56 GHz. Good agreement is shown between the simulated and measured results.

  5. Tunable all-optical single-bandpass photonic microwave filter based on spectrally sliced broad optical source and phase modulation.

    PubMed

    Chen, Ming; Pan, Wei; Zou, Xihua; Luo, Bin; Yan, Lianshan; Liu, Xinkai

    2013-01-10

    A tunable all-optical single-bandpass photonic microwave filter (PMF) based on spectrally sliced broadband optical source and phase modulation is proposed and experimentally demonstrated. A broadband optical source and a Mach-Zehnder interferometer (MZI) are used to generate continuous optical spectral samples, which are employed to form a finite impulse response filter with a single-bandpass response with the help of a single-mode fiber. A phase modulator is then adopted to eliminate the baseband components in the filtering response. The center frequency of the PMF can be tuned by changing the free spectral range of the MZI. An experiment is performed, and the results demonstrate that the proposed PMF has a single-bandpass without baseband components and a tuning range of 5-15 GHz. PMID:23314649

  6. Continued Development of an Ultra-Narrow Bandpass Filter for Solar Research

    NASA Technical Reports Server (NTRS)

    Rust, David M.

    1993-01-01

    The objective of work under this task was to develop ultranarrow optical bandpass filters and related technology necessary for construction of a compact solar telescope capable of operating unattended in space. The scientific problems to which such a telescope could be applied include solar seismology, solar activity monitoring, solar irradiance variations, solar magnetic field evolution, and the location of targets for narrow-field specialized telescopes. We have demonstrated a Y-cut lithium-niobate Fabry-Perot etalon. This filter will be used on the Flare Genesis Experiment. We also obtained solar images with a Z-cut etalon. The technical report on etalon filters is attached to this final report. We believe that work under this grant will lead to the commercial availability of a universal optical filter with approximately 0.1 A bandwidth. Progress was made toward making a suitable 1-2 A tunable blocker filter, but it now appears that the best approach is to make a double-cavity etalon that will not require such a narrow blocker. Broader band blockers are commercially available.

  7. Wide Bandpass and Narrow Bandstop Microstrip Filters based on Hilbert fractal geometry: design and simulation results.

    PubMed

    Mezaal, Yaqeen S; Eyyuboglu, Halil T; Ali, Jawad K

    2014-01-01

    This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, -28 dB return loss and -0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, -0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems. PMID:25536436

  8. Wide Bandpass and Narrow Bandstop Microstrip Filters Based on Hilbert Fractal Geometry: Design and Simulation Results

    PubMed Central

    Mezaal, Yaqeen S.; Eyyuboglu, Halil T.; Ali, Jawad K.

    2014-01-01

    This paper presents new Wide Bandpass Filter (WBPF) and Narrow Bandstop Filter (NBSF) incorporating two microstrip resonators, each resonator is based on 2nd iteration of Hilbert fractal geometry. The type of filter as pass or reject band has been adjusted by coupling gap parameter (d) between Hilbert resonators using a substrate with a dielectric constant of 10.8 and a thickness of 1.27 mm. Numerical simulation results as well as a parametric study of d parameter on filter type and frequency responses are presented and studied. WBPF has designed at resonant frequencies of 2 and 2.2 GHz with a bandwidth of 0.52 GHz, −28 dB return loss and −0.125 dB insertion loss while NBSF has designed for electrical specifications of 2.37 GHz center frequency, 20 MHz rejection bandwidth, −0.1873 dB return loss and 13.746 dB insertion loss. The proposed technique offers a new alternative to construct low-cost high-performance filter devices, suitable for a wide range of wireless communication systems. PMID:25536436

  9. Symmetrical band-pass loudspeaker systems

    NASA Astrophysics Data System (ADS)

    Matusiak, Grzegorz Piotr

    2001-12-01

    Loudspeaker systems are analyzed in a doctoral dissertation. The dissertation concerns loudspeaker systems, which are known as subwoofers or band-pass loudspeaker systems. Their advantages include: high- quality sound reproduction in the low-frequency range, small dimensions, small nonlinear distortions and the fact that they can be placed anywhere in a room or car. Band-pass loudspeaker systems are used widely in the so- called Home Theatre as well as to provide sound in cinema, theatre, concert, discotheque, opera, operetta, philharmonic and amphitheater halls, at open-air concerts, and so on. Various designs are mass-produced by a large number of manufacturers. The study covers an analysis of band-pass loudspeaker systems to which the frequency transformation, i.e. the reactance transformation, has been applied. Since this is a symmetrical transformation, amplitude frequency responses of the studied band-pass systems are also symmetrical (logarithmic scale of a frequency). As a result, the high-pass loudspeaker system design method, known as the Thiele-Small, Benson analysis, can be employed. The investigations include the formulation of band-pass system equations (fourth, sixth and eighth-order polynomials) and the subsequent derivation of relations for the calculation of system parameters. The obtained results enable the calculation of optimum designs for prescribed alignments, e.g. (Chebyshev) equal-ripple, (Butterworth) maximally flat, or quasi-maximally flat (QB). The analysis covers fourth, sixth and eighth-order symmetrical systems. Eighth-order systems have been divided into three kinds according to three ways of physical realization. The doctoral dissertation includes band-pass loudspeaker systems, which can be designed with active or passive filters or without the filter. Designed systems consist of a loudspeaker whose front of a diaphragm is loaded with a Helmholtz resonator, i.e. an enclosure with a vent, which radiates sound outwards. The back is

  10. Thermally stable narrow-bandpass filter prepared by reactive ion-assisted sputtering.

    PubMed

    Tsai, R Y; Chang, C S; Chu, C W; Chen, T; Dai, F; Lin, D; Yan, S; Chang, A

    2001-04-01

    Thermal stabilities of three-cavity narrow-bandpass (NB) filters with high-index half-wave spacers and 78-102 layers of Ta(2)O(5) and SiO(2) prepared by reactive ion-assisted bipolar direct-current (dc) magnetron sputtering of tantalum and silicon targets, respectively, were investigated. Pure argon and pure oxygen were used as the sputtering gas and the reactant, respectively. The oxygen gas was introduced and ionized through the ion gun and toward the unheated BK7 glass substrate. The refractive indices of single-layer Ta(2)O(5) and SiO(2) films were 2.1 and 1.45, respectively, at 1550 nm, which were comparable with those of films prepared by other ion-assisted coating techniques. The moisture-resistant properties of the films were excellent as evidenced from the water-immersion test, implying that the packing density of the films was close to that of their bulk materials. The temperature-dependant wavelength shifts of the NB filters were <3 x 10(-3) nm/ degrees C at temperatures of <75 degrees C, indicating that the temperature-induced wavelength shift of the filter was <0.15 nm when the temperatures were raised from room temperature to 75 degrees C, which was compliant with Bellcore GR-1209-CORE generic requirements of NB filters used for optical-fiber communication systems. PMID:18357152

  11. Learning Multiple Band-Pass Filters for Sleep Stage Estimation: Towards Care Support for Aged Persons

    NASA Astrophysics Data System (ADS)

    Takadama, Keiki; Hirose, Kazuyuki; Matsushima, Hiroyasu; Hattori, Kiyohiko; Nakajima, Nobuo

    This paper proposes the sleep stage estimation method that can provide an accurate estimation for each person without connecting any devices to human's body. In particular, our method learns the appropriate multiple band-pass filters to extract the specific wave pattern of heartbeat, which is required to estimate the sleep stage. For an accurate estimation, this paper employs Learning Classifier System (LCS) as the data-mining techniques and extends it to estimate the sleep stage. Extensive experiments on five subjects in mixed health confirm the following implications: (1) the proposed method can provide more accurate sleep stage estimation than the conventional method, and (2) the sleep stage estimation calculated by the proposed method is robust regardless of the physical condition of the subject.

  12. Photonic-assisted microwave phase shifter using a DMZM and an optical bandpass filter.

    PubMed

    Li, Wei; Sun, Wen Hui; Wang, Wen Ting; Wang, Li Xian; Liu, Jian Guo; Zhu, Ning Hua

    2014-03-10

    We propose and demonstrate a photonic-assisted wideband 360° microwave phase shifter based on a conventional dual-drive Mach-Zehnder modulator (DMZM) and an optical bandpass filter (OBPF). The two arms of the DMZM are driven by the fundamental microwave signal to be phase shifted and its frequency doubled component, respectively. The OBPF followed after the DMZM is used to remove the optical carrier and the sidebands at either side of the optical carrier. As a result, only two sidebands corresponding to the fundamental microwave signal and its frequency doubled component, respectively, are left. Moreover, the phase shift between the two sidebands can be continuously tunable by adjusting the bias voltage of the DMZM. This phase shift is mapped to the fundamental microwave signal which is recovered by beating the two sidebands in a photodetector (PD). The proposed approach is theoretically analyzed and experimentally verified. PMID:24663892

  13. Tunable bandpass microwave photonic filter with ultrahigh stopband attenuation and skirt selectivity.

    PubMed

    Jiang, Fan; Yu, Yuan; Tang, Haitao; Xu, Lu; Zhang, Xinliang

    2016-08-01

    we propose and demonstrate a bandpass microwave photonic filter (MPF) with ultrahigh stopband attenuation and skirt selectivity based on a simple signal cancellation technique. By injecting two phase modulated signals located on opposite sides of two resonant gain peaks of a Fabry-Pérot semiconductor optical amplifier (FP-SOA), two microwave frequency responses can be generated by the two input signals, respectively. The two frequency responses will add together within the passband but cancel each other out within the stopband, thus generating a MPF with simultaneous ultrahigh stopband attenuation and skirt selectivity. In the experiment the obtained MPF exhibits single passband in the range from 0 to 18 GHz and is tunable from 4 to 16 GHz by adjusting the laser wavelengths. During the tuning process the maximum stopband attenuation is 76.3 dB and the minimum 30-dB to 3-dB bandwidth shape factor is 3.5. PMID:27505828

  14. Electronically reconfigurable bandpass microwave photonic filter using a windowed optical frequency comb

    NASA Astrophysics Data System (ADS)

    Deng, Hong; Fu, Songnian; Tang, Ming; Liu, Deming

    2015-03-01

    A center frequency-tunable multi-tap bandpass microwave photonic filter (MPF) is proposed and experimentally demonstrated, with reconfigurable capability by electronic control. A Mach-Zehnder modulator-based optical frequency comb (OFC) is used as an optical source, and its output is optically shaped before introducing a time delay by 70 km single-mode fiber (SMF) transmission. After an optical-to-electronic conversion, the frequency response in terms of central frequency and passband bandwidth can be electronically reconfigurable by varying either the input microwave frequency of the OFC or the waveshaper configuration without modification of the optical configuration. The experimental results show that more than a 35 dB out-of-band rejection ratio and at least a 3 GHz continuously tuning range of passband center frequency without any DC response can be successfully achieved.

  15. The Ring of Fire - an internal illimination system for detector sensitivity and filter bandpass characterization

    SciTech Connect

    Scarpine, Victor E.; Kent, Stephen M.; Deustua, Susana E.; Sholl, Michael J.; Mufson, Stuart L.; Ott, Melanie N.; Wiesner, Matthew P.; Baptitst, Brian J.; /Indiana U.

    2010-07-01

    We describe a prototype of an illumination system, the Ring of Fire (ROF), which is used as part of an internal calibration system for large focal plane detector arrays in TMA (Three Mirror Anastigmat) telescope designs. Such designs have been proposed for the SNAP (SuperNova Acceleration Probe) version of a Joint Dark Energy Mission (JDEM). The ROF system illuminates the focal plane with a light beam the closely matches that of the telescope and is used for creating high spatial frequency flat fields and monitoring filter bandpasses for experiments that demand a highly accurate characterization of the detectors. We present measurements of a mockup of this prototype ROF design including studies in variations in illumination across a large focal plane.

  16. Spin-wave band-pass filters based on yttrium iron garnet films for tunable microwave photonic oscillators

    NASA Astrophysics Data System (ADS)

    Ustinov, A. B.; Drozdovskii, A. V.; Nikitin, A. A.; Kalinikos, B. A.

    2015-12-01

    The paper reports on development of tunable band-pass microwave filters for microwave photonic generators. The filters were fabricated with the use of epitaxial yttrium iron garnet films. Principle of operation of the filters was based on excitation, propagation, and reception of spin waves. In order to obtain narrow pass band, the filtering properties of excitation and reception antennas were exploited. The filters demonstrated insertion losses of 2-3 dB, bandwidth of 25-35 MHz, and tuning range of up to 1.5 GHz in the range 3-7 GHz.

  17. Bandwidth stretching in interdigital bandpass RF filter on silicon substrate using bulk micromachining

    NASA Astrophysics Data System (ADS)

    Bhadauria, Avanish; Jangid, Harsh Vardhan; Singh, Kulwant

    2016-03-01

    We first time proposed a new technique to strech the fractional bandwidth (FBW) of an interdigital bandpass RF filter (IDBPF) on a silicon substrate using MEMS based micromachining and studied its RF performance through a circuit model under micromachining. When a silicon substrate is selectively etched vertically beneath the coupled line resonators in IDBPF, a mixed air-silicon region is created inside the substrate. This mixed region manipulates the effective dielectric constant and electromagnetic coupling among resonators, which finally leads to a signifant change in FWB of filter. To study transmission properties under micromachining, a five pole IDBPF is designed on a 500 µm thick high resistivity silicon substrate centered at 5.00 GHz with FBW of 56.8% and simulated by FEM based electromagnetic software HFSS. It has been seen by simulation results that at 50% micromached height from the ground plane, the IDBPF has achieved a maximum FBW of 79.8%, which is difficult to realize in conventional IDBPF on same substrate due to requirement of very tight coupling. Finally, we have developed an equivalent circuit model and studied the variation of its electrical parameters under micromachining and RF performance of filter in terms of circuit components.

  18. Microwave Band-Pass Filter with Aerosol-Deposited Al2O3-Polytetrafluoroethylene Composite Thick Films.

    PubMed

    Lee, Ji-Won; Koh, Jung-Hyuk

    2015-03-01

    Fabrication of microwave band-pass filter with coplanar waveguide with ground structure was realized by employing Al2O3-polytetrafluoroethylene (Al2O3-PTFE) composite thick films for integrated substrates produced by aerosol deposition (AD). In order to predict the performance of the band-pass filter, 3-D electromagnetic simulations were performed by high-frequency structure analysis. The thick Al2O3-PTFE composite films prepared by the AD process had submicron-sized Al2O3 crystallites due to the shock-absorbing effect of PTFE during the film growth. The thick films were characterized by X-ray diffraction and scanning electron microscopy. The Cu transmission lines with the thickness of 300 nm were deposited by electron-beam evaporation to form the band-pass filter. The fabricated band-pass filter showed similar characteristics to the simulation results. The insertion loss and resonance frequency were 9.5 dB and 2.3 GHz, respectively. PMID:26413656

  19. Performance Enhancement of Tunable Bandpass Filters Using Selective Etched Ferroelectric Thin Films

    NASA Technical Reports Server (NTRS)

    Miranda, Felix A.; Mueller, Carl H.; VanKeuls, Fred W.; Subramanyam, Guru; Vignesparamoorthy, Sivaruban

    2003-01-01

    The inclusion of voltage-tunable barium strontium titanate (BSTO) thin films into planar band pass filters offers tremendous potential to increase their versatility. The ability to tune the passband so as to correct for minor deviations in manufacturing tolerances, or to completely reconfigure the operating frequencies of a microwave communication system, are highly sought-after goals. However, use of ferroelectric films in these devices results in higher dielectric losses, which in turn increase the insertion loss and decrease the quality factors of the filters. This study explores the use of patterned ferroelectric layers to minimize dielectric losses without degrading tunability. Patterning the ferroelectric layers enables us to constrict the width of the ferroelectric layers between the coupled microstrip lines, and minimize losses due to ferroelectric layers. Coupled one-pole microstrip bandpass filters with fundamental resonances at approx. 7.2 GHz and well defined harmonic resonances at approx. 14.4 and approx. 21.6 GHz, were designed, simulated and tested. For one of the filters, experimental results verified that its center frequency was tunable by 528 MHz at a center frequency of 21.957 GHz, with insertion losses varying from 4.3 to 2.5 dB, at 0 and 3.5 V/micron, respectively. These data demonstrate that the tuning-to-loss figure of merit of tunable microstrip filters can be greatly improved using patterned ferroelectric thin films as the tuning element, and tuning can be controlled by engineering the ferroelectric constriction in the coupled sections.

  20. All-optical microwave bandpass filter with negative coefficients based on a phase modulator and linearly chirped fiber Bragg gratings.

    PubMed

    Zeng, Fei; Wang, Jun; Yao, Jianping

    2005-09-01

    A novel all-optical microwave bandpass filter with negative coefficients is presented. Positive and negative coefficients are obtained through conversion from phase modulation to intensity modulation by passing the phase-modulated optical carriers through chirped fiber Bragg gratings having group-delay responses with positive and negative slopes. A two-tap transversal microwave filter with one negative coefficient is experimentally implemented. PMID:16190418

  1. Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

    2016-07-01

    A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application.

  2. Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal.

    PubMed

    Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin

    2016-07-01

    A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application. PMID:27475583

  3. Application of Cu2O-doped phosphate glasses for bandpass filter

    NASA Astrophysics Data System (ADS)

    Elhaes, H.; Attallah, M.; Elbashar, Y.; El-Okr, M.; Ibrahim, M.

    2014-09-01

    Phosphate glasses doped with copper ions having general composition 42P2O5-39ZnO-(18-x) Na2O-1CaO-xCu2O [x=2, 4, 6, 8, 10 mol%] were prepared using a conventional melt-quench technique. Physical and chemical properties of the glasses were investigated using X-ray diffraction technique and UV-visible optical absorption. The density was measured by Archimedes' method, and molar volume (VM) was calculated. It is found that density and molar volume show opposite trend by increasing Cu2O content. Absorbance and transmittance at the normal incidence are measured by a spectrophotometer in the spectral range of 190-1100 nm. Analyses of the obtained results were considered in the frame of current theories. Absorption data were used for absorption coefficient, the optical band gap (Eopt), the cutoff in UV and IR bands to the bandpass filter, which confirmed the optical properties of this type of filter. Eopt values for different glass samples are found to decrease with increasing Cu2O content.

  4. A K-band Frequency Agile Microstrip Bandpass Filter using a Thin Film HTS/Ferroelectric/dielectric Multilayer Configuration

    NASA Technical Reports Server (NTRS)

    Subramanyam, Guru; VanKeuls, Fred; Miranda, Felix A.

    1998-01-01

    We report on YBa2Cu3O(7-delta) (YBCO) thin film/SrTiO3 (STO) thin film K-band tunable bandpass filters on LaAlO3 (LAO) dielectric substrates. The 2 pole filter has a center frequency of 19 GHz and a 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO(epsilon(sub rSTO). A large tunability ((Delta)f/f(sub 0) = (f(sub Vmax) - f(sub 0)/f(sub 0), where f(sub 0) is the center frequency of the filter at no bias and f(sub Vmax) is the center frequency of the filter at the maximum applied bias) of greater than 10% was obtained in YBCO/STO/LAO microstrip bandpass filters operating below 77 K. A center frequency shift of 2.3 GHz (i.e., a tunability factor of approximately 15%) was obtained at a 400 V bipolar dc bias, and 30 K, with minimal degradation in the insertion loss of the filter. This paper addresses design, fabrication and testing of tunable filters based on STO ferroelectric thin films. The performance of the YBCO/STO/LAO filters is compared to that of gold/STO/LAO counterparts.

  5. A Novel K-Band Tunable Microstrip Bandpass Filter Using a Thin Film HTS/Ferroelectric/ Dielectric Configuration

    NASA Technical Reports Server (NTRS)

    Subramanyam, G.; VanKeuls, F.; Miranda, F. A.

    1998-01-01

    We report on YBCO/strontium titanate (STO) thin film K-band tunable bandpass filters on lanthanum aluminate substrates. The 2 pole filters were designed for a center frequency of 19 GHz and 4% bandwidth. Tunability is achieved through the non-linear dc electric field dependence of the relative dielectric constant of STO (epsilon-rSTO). Center frequency shifts greater than 2 GHz were obtained at a 400V bipolar dc bias at temperatures below 77K, with minimum degradation in the insertion loss of the filters.

  6. Integrated InP-InGaAsP tunable coupled ring optical bandpass filters with zero insertion loss.

    PubMed

    Guzzon, Robert S; Norberg, Erik J; Parker, John S; Johansson, Leif A; Coldren, Larry A

    2011-04-11

    Second and third-order monolithically integrated coupled ring bandpass filters are demonstrated in the InP-InGaAsP material system with active semiconductor optical amplifiers (SOAs) and current injection phase modulators (PMs). Such integration achieves a high level of tunability and precise generation of optical filters in the RF domain at telecom wavelengths while simultaneously compensating for device insertion loss. Passband bandwidth tunability of 3.9 GHz to 7.1 GHz and stopband extinction up to 40 dB are shown for third-order filters. Center frequency tunability over a full free spectral range (FSR) is demonstrated, allowing for the placement of a filter anywhere in the telecom C-band. A Z-transform representation of coupled resonator filters is derived and compared with experimental results. A theoretical description of filter tunability is presented. PMID:21503092

  7. Tin-polyimide and indium-polyimide thin-film composites as soft X-ray bandpass filters

    NASA Technical Reports Server (NTRS)

    Powell, Stephen F.; Allen, Maxwell J.; Willis, Thomas D.

    1993-01-01

    A tin-polyimide and an indium-polyimide soft X-ray bandpass filter were fabricated with thicknesses of 1400 and 1750 A for the metal and polyimide components, respectively. The transmission of each filter was measured at the Stanford Synchrotron Radiation Laboratory. The transmission of the tin-polyimide filter was found to be about 40 percent for radiation with wavelengths between 60 and 80 A. The transmission of the indium-polyimide filter was greater than 40 percent between 70 and 90 A. The indium was about 5 percent more transmissive than the tin and attained a maximum transmission of about 48 percent at 76 A. Such filters have potential applications to soft X-ray telescopes that operate in this region. They might also be of interest to investigators who work with X-ray microscopes that image live biological specimens in the 23-44-A water window.

  8. Development of simple band-spectral pyranometer and quantum meter using photovoltaic cells and bandpass filters

    NASA Astrophysics Data System (ADS)

    Bilguun, Amarsaikhan; Nakaso, Tetsushi; Harigai, Toru; Suda, Yoshiyuki; Takikawa, Hirofumi; Tanoue, Hideto

    2016-02-01

    In recent years, greenhouse automatic-control, based on the measurement of solar irradiance, has been attracting attention. This control is an effective method for improving crop production. In the agricultural field, it is necessary to measure Photon Flux Density (PFD), which is an important parameter in the promotion of plant growth. In particular, the PFD of Photosynthetically Active Radiation (PAR, 400-700 nm) and Plant Biologically Active Radiation (PBAR, 300-800 nm) have been discussed in agricultural plant science. The commercial quantum meter (QM, PAR meter) can only measure Photosynthetically Photon Flux Density (PPFD) which is the integrated PFD quantity on the PAR wavelength. In this research, a band-spectral pyranometer or quantum meter using PVs with optical bandpass filters for dividing the PBAR wavelength into 100 nm bands (five independent channels) was developed. Before field testing, calibration of the instruments was carried out using a solar simulator. Next, a field test was conducted in three differing weather conditions such as clear, partly cloudy and cloudy skies. As a result, it was found that the response rate of the developed pyranometer was faster by four seconds compared with the response rate of the commercial pyranometer. Moreover, the outputs of each channel in the developed pyranometer were very similar to the integrated outputs of the commercial spectroradiometer. It was confirmed that the solar irradiance could be measured in each band separately using the developed band-spectral pyranometer. It was indicated that the developed band-spectral pyranometer could also be used as a PV band-spectral quantum meter which is obtained by converting the band irradiance into band PFD.

  9. Ultra-compact UHF Band-pass Filter Designed by Archimedes Spiral Capacitor and Shorted-loaded Stubs

    NASA Astrophysics Data System (ADS)

    Peng, Lin; Jiang, Xing

    2015-01-01

    UHF microstrip band-pass filters (BPFs) that much smaller than the referred BPFs are proposed in this communication. For the designing purpose of compactness, archimedes spiral capacitor and ground-loaded stubs are utilized to enhance capacitances and inductance of a filter. Two compact BPFs denoted as BPF 1 and BPF 2 are designed by applying these techniques. The size of BPF 1 and BPF 2 are 0.062 λg × 0.056 λg and 0.047 λg × 0.043 λg, respectively, where λg are guided wavelengths of the centre frequencies of the corresponding filters. The proposed filters were constructed and measured, and the measured results are in good agreement with the simulated ones.

  10. Novel Compact Ultra-Wideband Bandpass Filter by Application of Short-Circuited Stubs and Stepped-Impedance-Resonator

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Ping; Ma, Zhewang; Anada, Tetsuo

    To realize the compact ultra-wideband (UWB) bandpass filters, a novel filter prototype with two short-circuited stubs loaded at both sides of a stepped-impedance resonator (SIR) via the parallel coupled lines is proposed based on a distributed filter synthesis theory. The equivalent circuit of this filter is established, while the corresponding 7-pole Chebyshev-type transfer function is derived for filter synthesis. Then, a distributed-circuit-based technique was presented to synthesize the elements' values of this filter. As an example, a FCC UWB filter with the fractional bandwidth (FWB) @ -10dB up to 110% was designed using the proposed prototype and then re-modeled by commercial microwave circuit simulator to verify the correctness and accuracy of the synthesis theory. Furthermore, in terms of EM simulator, the filter was further-optimized and experimentally-realized by using microstrip line. Good agreements between the measurement results and theoretical ones validate the effectiveness of our technique. In addition, compared with the conventional SIR-type UWB filter without short-circuited stubs, the new one significantly improves the selectivity and out-of-band characteristics (especially in lower one -45dB@1-2GHz) to satisfy the FCC's spectrum mask. The designed filter also exhibits very compact size, quite low insertion loss, steep skirts, flat group delay and the easily-fabricatable structure (the coupling gap dimension in this filter is 0.15mm) as well. Moreover, it should be noted that, in terms of the presented design technique, the proposed filter prototype can be also used to easily realize the UWB filters with other FBW even greater than 110%.

  11. A bandpass filter for the enhancement of an X-ray reconstruction of the tissue in the spinal canal

    NASA Technical Reports Server (NTRS)

    Reed, I. S.; Glenn, W. V.; Kwoh, Y. S.; Truong, T. K.

    1980-01-01

    In this communication, a new bandpass reconstruction filter is developed to partially remove the low spatial frequencies of the bone and the soft tissue in an X-ray reconstruction of a lumbar spine. This partial removal of the low frequencies suppresses the bony vertebral body and the soft tissue components within the projections of actual clinical data. It also has the effect of enhancing the sharp edges of the fatty tissue surrounding the spinal cord region. The intent of this effort is to directly visualize the spinal cord without the need for water-soluble contrast (e.g., metrizamide) to be installed through lumbar punctures.

  12. 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

  13. HTS Dual-band Bandpass Filter Using Stub-loaded Hair-pin Resonators with Independently Controllable Bandwidths

    NASA Astrophysics Data System (ADS)

    Sekiya, N.; Sugiyama, S.

    We have developed a high-temperature superconducting (HTS) dual-band bandpass filter (BPF) using stub-loaded hair-pin resonators with independently controllable bandwidths. The proposed dual-band BPF is composed of five stub-loaded hair-pin resonators with H-shaped waveguides placed at the center in the spaces between them. The resonator enables independent control of the first and second band resonant frequencies. The main advantage of the proposed filter was to enable independent control of the bandwidths of the first and second band. The coupling coefficient of the second one was controlled by the distance between the resonators, which did not affect the coupling coefficient of the first one. On the other hand, the coupling coefficient of the first one was controlled by the H-shaped waveguide, which did not affect the coupling coefficient of the secondone. An electromagnetic simulator was used to design and analyze the filter. The filter was designed at 3.5 GHz with a 70-MHz (2%) bandwidth for the first band and at 5.0 GHz with a 250-MHz (5%) bandwidth for the second band. The filter was fabricated using YBa2Cu3Oy thin film on a CeO2-bufferd Al2O3 substrate. The measured results agree well with the simulated ones.

  14. Study of SNS and SIS NbN Josephson junctions coupled to a microwave band-pass filter

    NASA Astrophysics Data System (ADS)

    Baggetta, E.; Setzu, R.; Villégier, J. C.

    2006-06-01

    We have fabricated both NbN/TaxN/NbN SN*S-type, NbN/MgO/NbN SIS-type Josephson junctions and microwave band-pass filters on different substrates (Si, Sapphire, MgO). NbN films have been deposited on both sides of (100) oriented, 250 µm thick, MgO substrates with a high crystalline texture quality. The aim was to investigate the performances and the maximum achievable operating frequency in an NbN based RSFQ modulator front-end of an ADC in the 4 K-10 K temperature range. We observed that TaxN thin films can be tuned from an insulating phase to a superconducting phase (Tc ~4K) by varying the nitrogen content during sputter deposition while the barrier height of MgO can also be controlled by deposition conditions and by tri-layer postdeposition annealing. Junction properties (Jc~10-25 kA/cm2), Mac Cumber parameter and RnIc product measured up to 1 mV are shown to be controlled by the reactive sputtering conditions. We have designed three pole band-pass filters and resonators in a micro-strip configuration and studied the junction coupling with the filters. We will show that a sigma-delta NbN technology is a suitable solution for analogue-to-digital conversion in the future generations of telecommunication satellites to achieve high sampling frequency and large bandwidth at high carrier frequency signal.

  15. The enlargement of high reflectance range in ultra-narrow bandpass filter with disordered one-dimensional photonic crystal

    SciTech Connect

    Chen, Guibin; Yu, Haichun

    2014-01-21

    The conventional ultra-narrow bandpass filter structure has only a very limited width of high-reflectance range. This study, by introducing disorder into one-dimensional (1D) photonic crystal, attempts to enlarge the width of high-reflectance range while keeping the ultra-narrow bandpass. Enlargement by 46.8% was obtained after theoretical design. Since this structure contains some degree of disorder already, it has a strong tolerance of the variation of layer thicknesses. Unlike studies using conventional periodic structures, theoretical statistical results in this study demonstrate that high quality remains even after allowing for ±5% variation of layer thicknesses. This indicates that only a very low thickness control precision is required in the future and the production difficulty is immensely lowered. To put the construction to test, a structure has been developed and demonstrated by a magnetron reactive sputtering coating system, which agrees with the theoretical result very well. By introducing disorder into the periodic 1D photonic crystal structure, the high-reflectance range is significantly extended by 37%, with an ultra-narrow pass band of 0.8 nm and intensity of 82%.

  16. A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

    2015-11-01

    We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies.

  17. A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters

    PubMed Central

    Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

    2015-01-01

    We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies. PMID:26552584

  18. Miniature bandpass microwave filter with interference suppression by more than 100 dB in a wide rejection band

    NASA Astrophysics Data System (ADS)

    Belyaev, B. A.; Serzhantov, A. M.; Tyurnev, V. V.; Leksikov, A. A.; Bal'va, Ya. F.

    2013-08-01

    A new planar resonator design in which a single conductor is replaced by three parallel stripe conductors located one above the other on a suspended two-layer substrate is proposed. It is shown that the resonator longitudinal sizes can be significantly reduced and, at the same time, the resonator intrinsic Q factor and frequencies of higher oscillation modes can be increased. A fourth-order bandpass filter with a central frequency of the transmission band (relative width 5%) of 1 GHz has been developed and fabricated. This filter has a -100-dB rejection band up to frequencies exceeding 10 GHz. The filter is enclosed in a metallic case with an internal size of 38 × 12 × 7.5 mm. It is shown that a similar filter fabricated in accordance with low-temperature cofired ceramic (LTCC) technology has a -40-dB rejection band up to 30 GHz, with sizes reduced to 5.0 × 4.25 × 1.24 mm.

  19. A Hybrid Circuit for Spoof Surface Plasmons and Spatial Waveguide Modes to Reach Controllable Band-Pass Filters.

    PubMed

    Zhang, Qian; Zhang, Hao Chi; Wu, Han; Cui, Tie Jun

    2015-01-01

    We propose a hybrid circuit for spoof surface plasmon polaritons (SPPs) and spatial waveguide modes to develop new microwave devices. The hybrid circuit includes a spoof SPP waveguide made of two anti-symmetric corrugated metallic strips and a traditional substrate integrated waveguide (SIW). From dispersion relations, we show that the electromagnetic waves only can propagate through the hybrid circuit when the operating frequency is less than the cut-off frequency of the SPP waveguide and greater than the cut-off frequency of SIW, generating efficient band-pass filters. We demonstrate that the pass band is controllable in a large range by designing the geometrical parameters of SPP waveguide and SIW. Full-wave simulations are provided to show the large adjustability of filters, including ultra wideband and narrowband filters. We fabricate a sample of the new hybrid device in the microwave frequencies, and measurement results have excellent agreements to numerical simulations, demonstrating excellent filtering characteristics such as low loss, high efficiency, and good square ratio. The proposed hybrid circuit gives important potential to accelerate the development of plasmonic integrated functional devices and circuits in both microwave and terahertz frequencies. PMID:26552584

  20. Tailoring the time delay of optical pulse/sequence employing cascaded SOA and band-pass filter

    NASA Astrophysics Data System (ADS)

    Wang, Fu; Wang, Zhi; Wu, Chongqing; Mao, Yaya; Shang, Chao; Gao, Kaiqiang; Li, Qiang

    2016-06-01

    A tunable time delay for a 100-ps pulse is achieved via a SOA cascaded band-pass filter, which can be tailored by tuning the filter or changing the SOA injection current. For a single pulse, when the pulse propagates through the cascaded system, a delay of 99.6 ps and an advance of 42.6 ps can be achieved by altering the SOA injection current at two different wavelengths located in the red band and blue band of the filter, respectively. The corresponding tunable delay range is 165 ps, and the maximum delay-bandwidth product (DBP) is 1.65. For an optical sequence, to our knowledge, it is the first time that the time delay is tailored over 145.6 ps corresponding to a DBP of 1.46 by tuning the wavelength from 1556.075 to 1556.955 nm, and 45.2 ps (95.6 ps) advance (delay) by tuning the injection current from 100 to 500 mA at 1556.155 nm (1556.955 nm). The dependence of the time delay on the injection current and filtering configuration has been discussed based on plenty of experiments data. Based on SOA's fast switching, this device can be used for signal synchronization and bit-by-bit signal processing in a communication system.

  1. Tunable photonic filters: a digital signal processing design approach.

    PubMed

    Binh, Le Nguyen

    2009-05-20

    Digital signal processing techniques are used for synthesizing tunable optical filters with variable bandwidth and centered reference frequency including the tunability of the low-pass, high-pass, bandpass, and bandstop optical filters. Potential applications of such filters are discussed, and the design techniques and properties of recursive digital filters are outlined. The basic filter structures, namely, the first-order all-pole optical filter (FOAPOF) and the first-order all-zero optical filter (FOAZOF), are described, and finally the design process of tunable optical filters and the designs of the second-order Butterworth low-pass, high-pass, bandpass, and bandstop tunable optical filters are presented. Indeed, we identify that the all-zero and all-pole networks are equivalent with well known principles of optics of interference and resonance, respectively. It is thus very straightforward to implement tunable optical filters, which is a unique feature. PMID:19458728

  2. A Multispectral Image Creating Method for a New Airborne Four-Camera System with Different Bandpass Filters

    PubMed Central

    Li, Hanlun; Zhang, Aiwu; Hu, Shaoxing

    2015-01-01

    This paper describes an airborne high resolution four-camera multispectral system which mainly consists of four identical monochrome cameras equipped with four interchangeable bandpass filters. For this multispectral system, an automatic multispectral data composing method was proposed. The homography registration model was chosen, and the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) were used to generate matching points. For the difficult registration problem between visible band images and near-infrared band images in cases lacking manmade objects, we presented an effective method based on the structural characteristics of the system. Experiments show that our method can acquire high quality multispectral images and the band-to-band alignment error of the composed multiple spectral images is less than 2.5 pixels. PMID:26205264

  3. Multilayer micromachined bandpass filter for L/S band satellite communication systems

    NASA Astrophysics Data System (ADS)

    Qureshi, A. Q. A.; Pelliccia, L.; Colpo, S.; Iannacci, J.; Farinelli, P.; Margesin, B.

    2013-05-01

    This paper presents the design and fabrication of a 2nd order L/S band filter used as a test vehicle for the development of a fabrication technology for cavity microwave filters based on micromachining in order to preliminary explore all the technological constraints on a simpler structure. The multilayered 2nd order pseudo-elliptic L/S band filter is based on λ/4 TEM mode resonators which are patterned on a dielectric layer. For convenience 500 μm thick Si wafers have been used even if this limits the simulated Q factor of the 2nd order L/S band filter to about 200. The test structures presented here amount to the more sophisticated 4th order filters in an extended technological concept (i.e. 1500 μm thick Si wafer and two additional modules) but still based on similar resonating elements aiming to replace the existing bulky metallic waveguide filters installed in many satellite transceivers. A five mask fabrication process is employed for the realization of the elements of said filter which is based on three modules. Module A and B are fabricated on the same wafer while module C which served as ground is fabricated on a separate wafer. A 2 μm high sealing ring is etched on the back of module A and B by DRIE (Deep Reactive Ion Etching) while cavities and TSVs (Through Silicon Vias) are etched by TMAH (TetraMethylAmmonium Hydroxide). The surface mounting compatibility of the filter is obtained by adopting vertical via holes to connect the external feeding lines (e.g. microstrip or coplanar) with the filter resonators. Such a transition separates the input/output from the filter input/output coupling mechanism. The final wafers are diced and specimens are vertically stacked and bonded through thermocompression bonding. The overall filter dimensions are 48x20x1.5 mm3.

  4. Spoof surface plasmon-based bandpass filter with extremely wide upper stopband

    NASA Astrophysics Data System (ADS)

    Xiaoyong, Liu; Lei, Zhu; Yijun, Feng

    2016-03-01

    We investigate the guiding modes of spoof surface plasmon polaritons (SPPs) on a symmetric ultra-thin plasmonic structure. From the analysis, we deduce the operating frequency region of the single-mode propagation. Based on this property, a spoof SPPs lowpass filter is then constituted in the microwave frequency. By introducing a transmission zero at the lower frequency band using a pair of stepped-impedance stubs, a wide passband filter is further realized. The proposed filter is fed by a transducer composed of a microstrip line with a flaring ground. The simulated results show that the presented filter has an extremely wide upper stopband in addition to excellent passband filtering characteristics such as low loss, wide band, and high square ratio. A prototype passband filter is also fabricated to validate the predicted performances. The proposed spoof-SPPs filter is believed to be very promising for other surface waveguide components in microwave and terahertz bands. Project supported by the Key Grant Project of Ministry of Education of China (Grant No. 313029), the FDCT Research Grant from Macao Science and Technology Development Fund, China (Grant No. 051/2014/A1), and the Multi-Year Research Grant from University of Macau, Macau SAR, China (Grant No. MYRG2014-00079-FST).

  5. Active tuning of a microstrip hairpin-line microwave bandpass filter on a polycrystalline yttrium iron garnet substrate using small magnetic fields

    NASA Astrophysics Data System (ADS)

    Gillette, S. M.; Geiler, A. L.; Chen, Z.; Chen, Y.; Arruda, T.; Xie, C.; Wang, L.; Zhu, X.; Liu, M.; Mukerjee, S.; Vittoria, C.; Harris, V. G.

    2011-04-01

    Active magnetic tuning of a microstrip hairpin-line coupled resonator bandpass filter fabricated on a polycrystalline yttrium iron garnet substrate has been demonstrated. The filter exhibits a five-pole Chebyshev response with passband center frequency tunability from 8.3 to 9 GHz under low applied H fields of 50-200 Oe. The instantaneous bandwidth was measured to be approximately 1 GHz. During tuning, passband center frequency insertion loss varies between 1 and 1.4 dB. Good agreement between simulated and measured device performance was demonstrated. Advantages of the proposed filter design include planar geometry, compact size, low insertion loss, and low field tunability. The proposed design approach lends itself to the implementation of a wide range of filter responses, including low pass, high pass, bandpass, and band stop, as well as passband characteristics, including center frequency, fractional bandwidth, passband ripple, out-of-band rejection, etc.

  6. "The Design of a Compact, Wide Spurious-Suppression Bandwidth Bandpass Filter Using Stepped Impedance Resonators"

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop; Wollack, Edward J.; Doiron, Terence; Papapolymerou, John; Laskar, Joy

    2005-01-01

    We propose an analytical design for a microstrip broadband spurious-suppression filter. The proposed design uses every section of the transmission lines as both a coupling and a spurious suppression element, which creates a very compact, planar filter. While a traditional filter length is greater than the multiple of the quarter wavelength at the center passband frequency (lambda(sub g)/4), the proposed filter length is less than (order n(Ssup th) + l)center dot lambda(sub g)/8. The filter s spurious response and physical dimension are controlled by the step impedance ratio (R) between two transmission line sections as a lambda(sub g)/4 resonator. The experimental result shows that, with R of 0.2, the out-of-band attenuation is greater than 40 dB; and the first spurious mode is shifted to more than 5 times the fundamental frequency. Moreover, it is the most compact planar filter design to date. The results also indicate a low in-band insertion loss.

  7. Design of high-order HTS dual-band bandpass filters with receiver subsystem for future mobile communication systems

    NASA Astrophysics Data System (ADS)

    Sekiya, N.

    2016-08-01

    We have developed two high-order high-temperature superconducting (HTS) dual-band bandpass filters (BPFs) with a receiver subsystem for future mobile communication systems. They feature stub-loaded hair-pin resonators with two types of microstrip lines between them. One has a six-pole design, and the other has an eight-pole design. Both were designed to operate at 2.15 GHz with a 43-MHz (2%) bandwidth for the lower passband and at 3.50 GHz with a 70-MHz (2%) bandwidth for the upper one. They were fabricated using YBa2Cu3Oy thin film on a CeO2-bufferd r-Al2O3 substrate. The measured results for both filters agree well with the simulated ones. The HTS dual-band BPF receiver subsystem uses a pulse tube cryocooler and a wideband low noise amplifier (LNA). We measured the frequency response of the six-pole dual-band BPF with and without a wideband LNA with a gain of 10 dB. The measured return losses were close.

  8. A Dual-Mode Bandpass Filter with Multiple Controllable Transmission-Zeros Using T-Shaped Stub-Loaded Resonators

    PubMed Central

    Yao, Zh.; Wang, C.; Kim, N. Y.

    2014-01-01

    A dual-mode broadband bandpass filter (BPF) with multiple controllable transmission-zeros using T-shaped stub-loaded resonators (TSSLRs) is presented. Due to the symmetrical plane, the odd-even-mode theory can be adopted to characterize the BPF. The proposed filter consists of a dual-mode TSSLR and two modified feed-lines, which introduce two capacitive and inductive source-load (S-L) couplings. Five controllable transmission zeros (TZs) can be achieved for the high selectivity and the wide stopband because of the tunable amount of coupling capacitance and inductance. The center frequency of the proposed BPF is 5.8 GHz, with a 3 dB fraction bandwidth of 8.9%. The measured insertion and return losses are 1.75 and 28.18 dB, respectively. A compact size and second harmonic frequency suppression can be obtained by the proposed BPF with S-L couplings. PMID:24688406

  9. Optimization of excitation-emission band-pass filter for visualization of viable bacteria distribution on the surface of pork meat.

    PubMed

    Nishino, Ken; Nakamura, Kazuaki; Tsuta, Mizuki; Yoshimura, Masatoshi; Sugiyama, Junichi; Nakauchi, Shigeki

    2013-05-20

    A novel method of optically reducing the dimensionality of an excitation-emission matrix (EEM) by optimizing the excitation and emission band-pass filters was proposed and applied to the visualization of viable bacteria on pork. Filters were designed theoretically using an EEM data set for evaluating colony-forming units on pork samples assuming signal-to-noise ratios of 100, 316, or 1000. These filters were evaluated using newly measured EEM images. The filters designed for S/N = 100 performed the best and allowed the visualization of viable bacteria distributions. The proposed method is expected to be a breakthrough in the application of EEM imaging. PMID:23736477

  10. Dual-band bandpass terahertz wave filter based on microstrip resonant structure

    NASA Astrophysics Data System (ADS)

    Liu, Yu-hang; Li, Jiu-sheng

    2011-11-01

    The terahertz (THz) band, which refers to the spectral region between 0.1 and 10THz, covers the fingerprints of many chemical and biological materials. Within the past few years, there are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, chemical and biological sensing, terahertz wave communications, and medical diagnostics. For potential applications, the functional devices, such as beam polarizers, switchs and filters, are crucial components for a terahertz system. Terahertz wave filter based on two kinds of microstrip resonant structures, has been characterized by terahertz time-domain spectroscopy in the region from 0.1 to 3THz. The experimental results for the frequency dependence of the transmittance of the terahertz wave filter show that the terahertz wave transmittance peak is of 79.5% at 0.5THz and 82.5% at 0.81THz.

  11. Dual-band bandpass terahertz wave filter based on microstrip resonant structure

    NASA Astrophysics Data System (ADS)

    Liu, Yu-hang; Li, Jiu-sheng

    2012-03-01

    The terahertz (THz) band, which refers to the spectral region between 0.1 and 10THz, covers the fingerprints of many chemical and biological materials. Within the past few years, there are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, chemical and biological sensing, terahertz wave communications, and medical diagnostics. For potential applications, the functional devices, such as beam polarizers, switchs and filters, are crucial components for a terahertz system. Terahertz wave filter based on two kinds of microstrip resonant structures, has been characterized by terahertz time-domain spectroscopy in the region from 0.1 to 3THz. The experimental results for the frequency dependence of the transmittance of the terahertz wave filter show that the terahertz wave transmittance peak is of 79.5% at 0.5THz and 82.5% at 0.81THz.

  12. Silicon on-chip bandpass filters for the multiplexing of high sensitivity photonic crystal microcavity biosensors

    SciTech Connect

    Yan, Hai Zou, Yi; Yang, Chun-Ju; Chakravarty, Swapnajit; Wang, Zheng; Tang, Naimei; Chen, Ray T.; Fan, Donglei

    2015-03-23

    A method for the dense integration of high sensitivity photonic crystal (PC) waveguide based biosensors is proposed and experimentally demonstrated on a silicon platform. By connecting an additional PC waveguide filter to a PC microcavity sensor in series, a transmission passband is created, containing the resonances of the PC microcavity for sensing purpose. With proper engineering of the passband, multiple high sensitivity PC microcavity sensors can be integrated into microarrays and be interrogated simultaneously between a single input and a single output port. The concept was demonstrated with a 2-channel L55 PC biosensor array containing PC waveguide filters. The experiment showed that the sensors on both channels can be monitored simultaneously from a single output spectrum. Less than 3 dB extra loss for the additional PC waveguide filter is observed.

  13. Micro-electro-mechanical bandpass filters for signal processing by standard CMOS process

    NASA Astrophysics Data System (ADS)

    Huang, Tsungwei; Chang, Peizen; Lee, ChiYuan; Xiao, Fuyuan

    2000-06-01

    This investigation fabricates a laminated-suspension microelectromechanical filter by a fully compatible CMOS process. Experimentally, due to the top metal layer begin used as the etch-resistant mask during the subsequent dry etching. Therefore, this study performs maskless etching with plasma and obtains excellent result including high selectivity and full release of the structure. Additionally, the MEMS filter can be driven by applying low-voltage of around 5 volts and a measured center frequency of around 13.1kHz and a quality factor of around 1871 were obtained for a single-comb resonator operate din air. The filter proposed herein has a monolithic integration capability with the relative electric circuits.

  14. Substrate integrated waveguide (SIW) inductive window band-pass filter based on post-wall irises

    NASA Astrophysics Data System (ADS)

    Nouri, K.; Haddadi, K.; Benzaïm, O.; Lasri, T.; Feham, M.

    2011-03-01

    In this article, we demonstrate a new inductive-window 5.245-GHz-band-pass filter based on post-wall irises by standard PcB process on Epoxy FR4 substrate. A new and easy to build microstrip-to-waveguide transition that consists of three tapers is also designed to connect the filter to standard measurement system. Both simulated results and measurements have shown insertion-loss lower than 5 dB within 14% bandwidth around 5.245 GHz and input return loss better than 25 dB over the frequency range.

  15. Systematic studies of the effect of a bandpass filter on a Josephson-junction noise thermometer

    SciTech Connect

    Soulen, R.J. Jr. ); Fogle, W.E.; Colwell, J.H. )

    1991-03-01

    This paper present the results of an extensive study of the effect of a filter upon the performance of a resistive SQUID noise thermometer used to define an absolute temperature scale below 1 K. Agreement between the model for this effect and the experimental results indicated that the temperature scale defined by the noise thermometer is accurate to 0.1%.

  16. A multiband THz bandpass filter based on multiple-resonance excitation of a composite metamaterial

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Fan, Wen-Hui

    2015-05-01

    We present a systematic numerical study on a metal-dielectric-metal (MDM) sandwich structure for multiple resonance transmission in terahertz (THz) region. The designed structure consists of periodic square close ring array on both side of a flexible dielectric substrate, exhibits a multiband transmission, with low average insertion loss, steep skirts and high out-of-band rejection. In addition, due to its rotationally symmetric structure, this filter is polarization-insensitive for normal incidence of the electromagnetic waves, keeping highly transmission at a wide range of incident angles for transverse electric waves and transverse magnetic waves. The metamaterial structure can be utilized as a desirable multiband filter with many practical applications, especially for THz communication, spectroscopic detection and phase imaging.

  17. U and Pu Gamma-Ray Measurements of Spent Fuel Using a Gamma-Ray Mirror Band-Pass Filter

    SciTech Connect

    Ziock, Klaus-Peter; Alameda, J.B.; Brejnholt, N.F.; Decker, T.A.; Descalle, M.A.; Fernandez-Perea, M.; Hill, R.M.; Kisner, R.A.; Melin, A.M.; Patton, B.W.; Ruz, J.; Soufli, R.; Pivovaroff, M.J.

    2014-01-01

    Abstract. We report on the use of grazing incidence gamma-ray mirrors to serve as a narrow band-pass filter for advanced non-destructive analysis (NDA) of spent nuclear fuel. The purpose of the mirrors is to limit the radiation reaching a HPGe detector to narrow spectral bands around characteristic emission lines from fissile isotopes in the fuel. This overcomes the normal rate issues when performing gamma-ray NDA measurements. In a proof-of-concept experiment, a set of simple flat gamma-ray mirrors were used to directly observe the atomic florescence lines from U and Pu from spent fuel pins with the detector located in a shirt-sleeve environment. The mirrors, consisting of highly polished silicon substrates deposited with WC/SiC multilayer coatings, successfully deflected the lines of interest while the intense primary radiation beam from the fuel was blocked by a lead beam stop. The gamma-ray multilayer coatings that make the mirrors work at the gamma-ray energies used here (~ 100 keV) have been experimentally tested at energies as high as 645 keV, indicating that direct observation of nuclear emission lines from 239Pu should be possible with an appropriately designed optic and shielding configuration.

  18. The role of excitation-pattern cues in the detection of frequency shifts in bandpass-filtered complex tones.

    PubMed

    Marmel, Frederic; Plack, Christopher J; Hopkins, Kathryn; Carlyon, Robert P; Gockel, Hedwig E; Moore, Brian C J

    2015-05-01

    One task intended to measure sensitivity to temporal fine structure (TFS) involves the discrimination of a harmonic complex tone from a tone in which all harmonics are shifted upwards by the same amount in hertz. Both tones are passed through a fixed bandpass filter centered on the high harmonics to reduce the availability of excitation-pattern cues and a background noise is used to mask combination tones. The role of frequency selectivity in this "TFS1" task was investigated by varying level. Experiment 1 showed that listeners performed more poorly at a high level than at a low level. Experiment 2 included intermediate levels and showed that performance deteriorated for levels above about 57 dB sound pressure level. Experiment 3 estimated the magnitude of excitation-pattern cues from the variation in forward masking of a pure tone as a function of frequency shift in the complex tones. There was negligible variation, except for the lowest level used. The results indicate that the changes in excitation level at threshold for the TFS1 task would be too small to be usable. The results are consistent with the TFS1 task being performed using TFS cues, and with frequency selectivity having an indirect effect on performance via its influence on TFS cues. PMID:25994700

  19. Reduction of timing jitter and intensity noise in normal-dispersion passively mode-locked fiber lasers by narrow band-pass filtering.

    PubMed

    Qin, Peng; Song, Youjian; Kim, Hyoji; Shin, Junho; Kwon, Dohyeon; Hu, Minglie; Wang, Chingyue; Kim, Jungwon

    2014-11-17

    Fiber lasers mode-locked with normal cavity dispersion have recently attracted great attention due to large output pulse energy and femtosecond pulse duration. Here we accurately characterized the timing jitter of normal-dispersion fiber lasers using a balanced cross-correlation method. The timing jitter characterization experiments show that the timing jitter of normal-dispersion mode-locked fiber lasers can be significantly reduced by using narrow band-pass filtering (e.g., 7-nm bandwidth filtering in this work). We further identify that the timing jitter of the fiber laser is confined in a limited range, which is almost independent of cavity dispersion map due to the amplifier-similariton formation by insertion of the narrow bandpass filter. The lowest observed timing jitter reaches 0.57 fs (rms) integrated from 10 kHz to 10 MHz Fourier frequency. The rms relative intensity noise (RIN) is also reduced from 0.37% to 0.02% (integrated from 1 kHz to 5 MHz Fourier frequency) by the insertion of narrow band-pass filter. PMID:25402069

  20. An antenna-coupled bolometer with an integrated microstrip bandpass filter

    NASA Astrophysics Data System (ADS)

    Myers, Michael J.; Holzapfel, William; Lee, Adrian T.; O'Brient, Roger; Richards, P. L.; Tran, Huan T.; Ade, Peter; Engargiola, Greg; Smith, Andy; Spieler, Helmuth

    2005-03-01

    We describe the fabrication and testing of antenna-coupled superconducting transition-edge bolometers for use at millimeter wavelengths. The design uses a double-slot dipole antenna connected to superconducting niobium microstrip. Band defining filters are implemented in the microstrip, which is then terminated with a load resistor. The power dissipated in the load resistor is measured by a superconducting transition-edge sensor (TES). The load resistor and TES are thermally well connected and are supported by a silicon nitride substrate. The substrate is suspended by four narrow silicon nitride legs for thermal isolation. The bolometers have been optically characterized and the spectral response is presented. This detector is a prototype element for use in an array designed for studies of the cosmic microwave background polarization.

  1. A 1microW 85nV/ radicalHz pseudo open-loop preamplifier with programmable band-pass filter for neural interface system.

    PubMed

    Chang, Sun-Il; Yoon, Euisik

    2009-01-01

    We report an energy efficient pseudo open-loop amplifier with programmable band-pass filter developed for neural interface systems. The proposed amplifier consumes 400nA at 2.5V power supply. The measured thermal noise level is 85nV/ radicalHz and input-referred noise is 1.69microV(rms) from 0.3Hz to 1 kHz. The amplifier has a noise efficiency factor of 2.43, the lowest in the differential topologies reported up to date to our knowledge. By programming the switched-capacitor frequency and bias current, we could control the bandwidth of the preamplifier from 138 mHz to 2.2 kHz to meet various application requirements. The entire preamplifier including band-pass filters has been realized in a small area of 0.043mm(2) using a 0.25microm CMOS technology. PMID:19964762

  2. Insertion loss and noise-temperature contribution of high-temperature superconducting bandpass filters centered at 2.3 and 8.45 GHz

    NASA Technical Reports Server (NTRS)

    Prater, J. L.; Bautista, J. J.

    1993-01-01

    Two superconducting Tl-Ca-Cu-Ba-O bandpass filters were fabricated for JPL by Superconductor Technologies Incorporated, Santa Barbara, California. The filters were designed to operate at 2.3 GHz (S-band) with a 0.5-dB bandwidth of 60 MHz and at 8.45 GHz (X-band) with a 0.5-dB bandwidth of 150 MHz. The structure selected for both filters incorporates half-wavelength thin-film resonators in a stripline configuration. The S-band filter uses an edge-coupled interdigital design and the X-band filter uses an end-coupled design. The insertion loss and the noise-temperature contribution were measured at 12 K for both filters.

  3. Emergence of band-pass filtering through adaptive spiking in the owl's cochlear nucleus

    PubMed Central

    MacLeod, Katrina M.; Lubejko, Susan T.; Steinberg, Louisa J.; Köppl, Christine; Peña, Jose L.

    2014-01-01

    In the visual, auditory, and electrosensory modalities, stimuli are defined by first- and second-order attributes. The fast time-pressure signal of a sound, a first-order attribute, is important, for instance, in sound localization and pitch perception, while its slow amplitude-modulated envelope, a second-order attribute, can be used for sound recognition. Ascending the auditory pathway from ear to midbrain, neurons increasingly show a preference for the envelope and are most sensitive to particular envelope modulation frequencies, a tuning considered important for encoding sound identity. The level at which this tuning property emerges along the pathway varies across species, and the mechanism of how this occurs is a matter of debate. In this paper, we target the transition between auditory nerve fibers and the cochlear nucleus angularis (NA). While the owl's auditory nerve fibers simultaneously encode the fast and slow attributes of a sound, one synapse further, NA neurons encode the envelope more efficiently than the auditory nerve. Using in vivo and in vitro electrophysiology and computational analysis, we show that a single-cell mechanism inducing spike threshold adaptation can explain the difference in neural filtering between the two areas. We show that spike threshold adaptation can explain the increased selectivity to modulation frequency, as input level increases in NA. These results demonstrate that a spike generation nonlinearity can modulate the tuning to second-order stimulus features, without invoking network or synaptic mechanisms. PMID:24790170

  4. Emergence of band-pass filtering through adaptive spiking in the owl's cochlear nucleus.

    PubMed

    Fontaine, Bertrand; MacLeod, Katrina M; Lubejko, Susan T; Steinberg, Louisa J; Köppl, Christine; Peña, Jose L

    2014-07-15

    In the visual, auditory, and electrosensory modalities, stimuli are defined by first- and second-order attributes. The fast time-pressure signal of a sound, a first-order attribute, is important, for instance, in sound localization and pitch perception, while its slow amplitude-modulated envelope, a second-order attribute, can be used for sound recognition. Ascending the auditory pathway from ear to midbrain, neurons increasingly show a preference for the envelope and are most sensitive to particular envelope modulation frequencies, a tuning considered important for encoding sound identity. The level at which this tuning property emerges along the pathway varies across species, and the mechanism of how this occurs is a matter of debate. In this paper, we target the transition between auditory nerve fibers and the cochlear nucleus angularis (NA). While the owl's auditory nerve fibers simultaneously encode the fast and slow attributes of a sound, one synapse further, NA neurons encode the envelope more efficiently than the auditory nerve. Using in vivo and in vitro electrophysiology and computational analysis, we show that a single-cell mechanism inducing spike threshold adaptation can explain the difference in neural filtering between the two areas. We show that spike threshold adaptation can explain the increased selectivity to modulation frequency, as input level increases in NA. These results demonstrate that a spike generation nonlinearity can modulate the tuning to second-order stimulus features, without invoking network or synaptic mechanisms. PMID:24790170

  5. A Triple-band Bandpass Filter using Tri-section Step-impedance and Capacitively Loaded Step-impedance Resonators for GSM, WiMAX, and WLAN systems

    NASA Astrophysics Data System (ADS)

    Chomtong, P.; Akkaraekthalin, P.

    2014-05-01

    This paper presents a triple-band bandpass filter for applications of GSM, WiMAX, and WLAN systems. The proposed filter comprises of the tri-section step-impedance and capacitively loaded step-impedance resonators, which are combined using the cross coupling technique. Additionally, tapered lines are used to connect at both ports of the filter in order to enhance matching for the tri-band resonant frequencies. The filter can operate at the resonant frequencies of 1.8 GHz, 3.7 GHz, and 5.5 GHz. At resonant frequencies, the measured values of S11 are -17.2 dB, -33.6 dB, and -17.9 dB, while the measured values of S21 are -2.23 dB, -2.98 dB, and -3.31 dB, respectively. Moreover, the presented filter has compact size compared with the conventional open-loop cross coupling triple band bandpass filters

  6. Design and fabrication of UV band-pass filters based on SiO2/Si3N4 dielectric distributed bragg reflectors

    NASA Astrophysics Data System (ADS)

    Dai, Jiangping; Gao, Wang; Liu, Bin; Cao, Xianlei; Tao, Tao; Xie, Zili; Zhao, Hong; Chen, Dunjun; Ping, Han; Zhang, Rong

    2016-02-01

    We have designed one kind of optical filters based on double stacks of 13.5-pairs SiO2/Si3N4 dielectric distributed Bragg reflector (DDBR) structures, to realize the passband with different central wavelengths in ultraviolet (UV) range. These SiO2/Si3N4 multi-layers have been successfully fabricated on (0001) sapphire substrates by plasma-enhanced chemical vapor deposition (PECVD). The reflectance spectra measured by the UV-visible spectrometer manifest that a series of band-pass filters with fixed passband width of ∼30 nm and central passband varied from 310 nm to 370 nm have been obtained successfully. Besides, the other series of filters with passband width varied from 30 nm to 45 nm can be achieved. With good control of PECVD deposition parameters, all samples exhibit smooth surface with root mean square roughness less than 4.5 nm. Moreover, cross-section scanning electron microscope (SEM) images show these DDBR structures have good periodicity in accordance with the design, indicating that these band-pass filter structures are suitable for wavelength-window-selection UV photodetectors.

  7. A compact, higher order, high temperature superconductor microstrip bandpass filter on a two-inch lanthanum aluminate substrate for personal communication service applications

    NASA Astrophysics Data System (ADS)

    Pal, Srikanta; Stevens, Chris; Edwards, David

    2005-10-01

    A practical design methodology for a compact parallel-coupled microstrip bandpass filter structure with steep attenuation is introduced using a computer-aided full wave electromagnetic simulation based on the method of moments. The structure consists of an array of fully aligned half-wavelength spiral meander line resonators. Aimed at application in the front-end receiver of digital cellular communication service, a 12-pole high temperature superconductor filter with 2.27% fractional bandwidth at 883.0 MHz was designed. The filter is fabricated using thallium-barium-calcium-copper oxide (TBCCO) thin films on a two-inch lanthanum aluminate (LaAlO3) wafer. The S-parameter measurements show a good agreement with the simulated results. At 70 K, the 12-pole filter shows less than 0.4 dB insertion loss, 0.3 dB passband ripple, better than 12 dB return loss. The out of band rejection at 3 MHz below the passband edges is more than 60.0 dB. In order to estimate the power handling capability of the filter, the third-order intermodulation distortion was measured. A sensitivity analysis for the observed frequency shift in the filter is reported. Also from this analysis an approach for using the same design in 0.5% FBW applications is discussed.

  8. Combination of highly nonlinear fiber, an optical bandpass filter, and a Fabry-Perot filter to improve the signal-to-noise ratio of a supercontinuum continuous-wave optical source

    NASA Astrophysics Data System (ADS)

    Nan, Yinbo; Huo, Li; Lou, Caiyun

    2005-05-01

    We present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented. Numerical simulations show that the improvement in modulation depth is relative to the HNLF's length, the 3-dB bandwidth of the optical bandpass filter, and the reflection ratio of the FP filter and that the average improvement in modulation depth is 13.7 dB under specified conditions.

  9. Combination of highly nonlinear fiber, an optical bandpass filter, and a Fabry-Perot filter to improve the signal-to-noise ratio of a supercontinuum continuous-wave optical source.

    PubMed

    Nan, Yinbo; Huo, Li; Lou, Caiyun

    2005-05-20

    We present a theoretical study of a supercontinuum (SC) continuous-wave (cw) optical source generation in highly nonlinear fiber and its noise properties through numerical simulations based on the nonlinear Schrödinger equation. Fluctuations of pump pulses generate substructures between the longitudinal modes that result in the generation of white noise and then in degradation of coherence and in a decrease of the modulation depths and the signal-to-noise ratio (SNR). A scheme for improvement of the SNR of a multiwavelength cw optical source based on a SC by use of the combination of a highly nonlinear fiber (HNLF), an optical bandpass filter, and a Fabry-Perot (FP) filter is presented. Numerical simulations show that the improvement in modulation depth is relative to the HNLF's length, the 3-dB bandwidth of the optical bandpass filter, and the reflection ratio of the FP filter and that the average improvement in modulation depth is 13.7 dB under specified conditions. PMID:15929296

  10. GPR signal enhancement using band-pass and K-L filtering: a case study for the evaluation of grout in a shielded tunnel

    NASA Astrophysics Data System (ADS)

    Xie, Xiongyao; Zeng, Chenchao; Wang, Zhigao

    2013-06-01

    The rapidness, non-destructiveness and high precision of ground penetrating radar (GPR) technology has enabled it to be widely and increasingly used in tunnel detection. However, data acquisition was usually restricted by physical and many other limitations. In order to improve the signal-to-noise ratio, band-pass and Karhunen-Loève (K-L) filtering are recommended. An evaluation of Yingbin No. 3 Road Tunnel is presented to illustrate the effectiveness of GPR in the inspection of the thickness of the grouting layer behind the segment and the function of the two methods mentioned above. The advantages and limitations of these two processing methods are discussed in this paper and suggestions are provided.

  11. Fibre coupled micro-light emitting diode array light source with integrated band-pass filter for fluorescence detection in miniaturised analytical systems.

    PubMed

    Vaculovičová, Markéta; Akther, Mahbub; Maaskant, Pleun; Brabazon, Dermot; Macka, Mirek

    2015-04-29

    In this work, a new type of miniaturized fibre-coupled solid-state light source is demonstrated as an excitation source for fluorescence detection in capillary electrophoresis. It is based on a parabolically shaped micro-light emitting diode (μ-LED) array with a custom band-pass optical interference filter (IF) deposited at the back of the LED substrate. The GaN μ-LED array consisted of 270 individual μ-LED elements with a peak emission at 470 nm, each about 14 μm in diameter and operated as a single unit. Light was extracted through the transparent substrate material, and coupled to an optical fibre (OF, 400 μm in diameter, numerical aperture NA=0.37), to form an integrated μ-LED-IF-OF light source component. This packaged μ-LED-IF-OF light source emitted approximately 225 μW of optical power at a bias current of 20 mA. The bandpass IF filter was designed to reduce undesirable LED light emissions in the wavelength range above 490 nm. Devices with and without IF were compared in terms of the optical power output, spectral characteristics as well as LOD values. While the IF consisted of only 7.5 pairs (15 layers) of SiO2/HfO2 layers, it resulted in an improvement of the baseline noise as well as the detection limit measured using fluorescein as test analyte, both by approximately one order of magnitude, with a LOD of 1×10(-8) mol L(-1) obtained under optimised conditions. The μ-LED-IF-OF light source was then demonstrated for use in capillary electrophoresis with fluorimetric detection. The limits of detection obtained by this device were compared to those obtained with a commercial fibre coupled LED device. PMID:25847165

  12. Exploring mechanisms of spontaneous functional connectivity in MEG: how delayed network interactions lead to structured amplitude envelopes of band-pass filtered oscillations.

    PubMed

    Cabral, Joana; Luckhoo, Henry; Woolrich, Mark; Joensson, Morten; Mohseni, Hamid; Baker, Adam; Kringelbach, Morten L; Deco, Gustavo

    2014-04-15

    Spontaneous (or resting-state) brain activity has attracted a growing body of neuroimaging research over the last decades. Whole-brain network models have proved helpful to investigate the source of slow (<0.1 Hz) correlated hemodynamic fluctuations revealed in fMRI during rest. However, the mechanisms mediating resting-state long-distance correlations and the relationship with the faster neural activity remain unclear. Novel insights coming from MEG studies have shown that the amplitude envelopes of alpha- and beta-frequency oscillations (~8-30 Hz) display similar correlation patterns as the fMRI signals. In this work, we combine experimental and theoretical work to investigate the mechanisms of spontaneous MEG functional connectivity. Using a simple model of coupled oscillators adapted to incorporate realistic whole-brain connectivity and conduction delays, we explore how slow and structured amplitude envelopes of band-pass filtered signals - fairly reproducing MEG data collected from 10 healthy subjects at rest - are generated spontaneously in the space-time structure of the brain network. Our simulation results show that the large-scale neuroanatomical connectivity provides an optimal network structure to support a regime with metastable synchronization. In this regime, different subsystems may temporarily synchronize at reduced collective frequencies (falling in the 8-30 Hz range due to the delays) while the global system never fully synchronizes. This mechanism modulates the frequency of the oscillators on a slow time-scale (<0.1 Hz) leading to structured amplitude fluctuations of band-pass filtered signals. Taken overall, our results reveal that the structured amplitude envelope fluctuations observed in resting-state MEG data may originate from spontaneous synchronization mechanisms naturally occurring in the space-time structure of the brain. PMID:24321555

  13. Ultra-Compact Broadband High-Spurious Suppression Bandpass Filter Using Double Split-end Stepped Impedance Resonators

    NASA Technical Reports Server (NTRS)

    U-Yen, Kongpop; Wollack, Ed; Papapolymerou, John; Laskar, Joy

    2005-01-01

    We propose an ultra compact single-layer spurious suppression band pass filter design which has the following benefit: 1) Effective coupling area can be increased with no fabrication limitation and no effect on the spurious response; 2) Two fundamental poles are introduced to suppress spurs; 3) Filter can be designed with up to 30% bandwidth; 4) The Filter length is reduced by at least 100% when compared to the conventional filter; 5) Spurious modes are suppressed up to at the seven times the fundamental frequency; and 6) It uses only one layer of metallization which minimize the fabrication cost.

  14. A new facility for manufacturing and testing very large narrow bandpass filters and other high performance optical coatings

    NASA Astrophysics Data System (ADS)

    Mooney, Thomas; Pawlewicz, Walter; Merrill, Michael; Leclerc, David; Hurd, Kerry

    2014-07-01

    Optical coatings are key elements of any optical system. They can reduce surface reflection loss, isolate spectral bands, re-direct the light path and split light beams by wavelength. For decades, astronomers have made use of these special characteristics embodied in Anti-Reflection (AR) coatings, Band Pass (BP) filters, mirrors and Dichroic Beamsplitters (DBS). In the last several years, a need has arisen for much larger high performance filters and coatings. This is being driven by the ever increasing size of new and planned telescopes with their correspondingly larger focal planes. Typical Broadband filters require modest wavelength uniformity and can be produced in legacy (existing) coating chambers, even in fairly large formats. However, some new instruments require narrow BP (NBP) filters of 60 cm or greater diameter in order to perform efficiently. Some planned systems will even require filters in the 75 cm diameter range. The implications for coating such large, very expensive optics are that the equipment must not only accommodate a large optic, but the process must achieve excellent uniformity over broad areas. It must also exhibit excellent performance, reproducibility and reliability in depositions consisting of well over one hundred layers and many hours duration. And finally, the spectral performance must be verifiable, not through an indirect method, but directly of the science optic itself. To address these challenges, Materion designed, built, tested and put into production a purposebuilt laboratory. This paper will describe in detail the elements of the lab creation and initial achievements.

  15. Compact ultra wide band microstrip bandpass filter based on multiple-mode resonator and modified complementary split ring resonator.

    PubMed

    Marcotegui, J Antonio; Illescas, Jesús Miguel; Estevez, Aritz; Falcone, Francisco

    2013-01-01

    A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring Resonator (MCSRR)-a concept proposed here for the first time-are adjusted to obtain the desired response with broadband, sharp rejection, low insertion loss, and low return loss. Full wave simulation results as well as measurement results from fabricated prototypes are presented, showing good agreement. The proposed technique offers a new alternative to implement low-cost high-performance filter devices, applicable to a wide range of communication systems. PMID:24319366

  16. Compact Ultra Wide Band Microstrip Bandpass Filter Based on Multiple-Mode Resonator and Modified Complementary Split Ring Resonator

    PubMed Central

    Marcotegui, J. Antonio; Illescas, Jesús Miguel; Estevez, Aritz

    2013-01-01

    A new class of broadband microstrip filters for Ultra Wide Band (UWB) applications is proposed. In the design, different stages of parallel-coupled microstrip line and other stages with a Modified Complementary Split Ring Resonator (MCSRR)—a concept proposed here for the first time—are adjusted to obtain the desired response with broadband, sharp rejection, low insertion loss, and low return loss. Full wave simulation results as well as measurement results from fabricated prototypes are presented, showing good agreement. The proposed technique offers a new alternative to implement low-cost high-performance filter devices, applicable to a wide range of communication systems. PMID:24319366

  17. Linear absorption coefficient of beryllium in the 50-300-A wavelength range. [bandpass filter materials for ultraviolet astronomy instrumentation

    NASA Technical Reports Server (NTRS)

    Barstow, M. A.; Lewis, M.; Petre, R.

    1983-01-01

    Transmittances of thin-film filters fabricated for an extreme-UV astronomy sounding-rocket experiment yield values for the linear absorption coefficient of beryllium in the 50-300-A wavelength range, in which previous measurements are sparse. The inferred values are consistent with the lowest data previously published and may have important consequences for extreme-UV astronomers.

  18. Silicon band-rejection and band-pass filter based on asymmetric Bragg sidewall gratings in a multimode waveguide.

    PubMed

    Qiu, Huiye; Jiang, Jianfei; Yu, Ping; Dai, Tingge; Yang, Jianyi; Yu, Hui; Jiang, Xiaoqing

    2016-06-01

    A silicon photonic wire filter based on an asymmetric sidewall Bragg grating in a multimode silicon-on-insulator strip waveguide is demonstrated. The operating principle is based on the contra-directional coupling between the transverse electric fundamental (TE0) and first-order (TE1) modes, which is enabled by the asymmetric spatially periodic refractive-index perturbations. An asymmetric Y-junction is cascaded at the input port of the filter so as to drop the Bragg reflection. Compared with conventional Bragg grating-based filters, this device eliminates the back reflection at the input port and the 6 dB inherent insertion loss at the drop port; moreover, a narrow 3 dB bandwidth can be obtained with a large critical dimension as a result of the weak coupling strength between the TE0 and TE1 modes inside the multimode waveguide. Experimental results show that a bandwidth of ∼2.8  nm is achieved by a large corrugation width of 150 nm. The insertion loss at the drop port is -2.1  dB, and the extinction ratio is -33  dB at the through port. PMID:27244386

  19. Correlation of microwave nonlinearity and magnetic pinning in high-temperature superconductor thin film band-pass filters

    NASA Astrophysics Data System (ADS)

    Zhao, Hua; Wang, Xiang; Wu, Judy Z.

    2008-08-01

    Third-order intermodulation has been studied in two-pole X-band microstrip filters made of three high-temperature superconductors (HTS), including HgBa2CaCu2O6+δ (Hg-1212), Tl2Ba2CaCu2Oy (Tl-2212) and YBa2Cu3O7-δ (YBCO) at >=77 K. In addition, the dc critical current density Jc was investigated in these three types of HTS films in the same temperature range. Interestingly, the dc Jc and the rf critical current density JIP3 derived from the third-order intercept (IP3) have a similar dependence on the reduced temperature, suggesting that the magnetic vortex depinning in HTS materials dominates the microwave nonlinearity at elevated temperatures. This observation agrees with the recent theoretical discussion on the origin of the microwave nonlinearity. Disagreement between Jc and JIP3, however, has been observed in the trilayer YBCO/CeO2/YBCO filters. Although magnetic flux pinning and hence Jc were improved by the insertion of a 20 nm thin CeO2 layer, the reduced JIP3 is attributed to the high power loss from the extra interfaces between YBCO and CeO2.

  20. Flat-top bandpass microwave photonic filter with tunable bandwidth and center frequency based on a Fabry-Pérot semiconductor optical amplifier.

    PubMed

    Jiang, Fan; Yu, Yuan; Cao, Tong; Tang, Haitao; Dong, Jianji; Zhang, Xinliang

    2016-07-15

    We propose a flat-top bandpass microwave photonic filter (MPF) with flexible tunability of the bandwidth and center frequency based on optical nonlinearities in a Fabry-Pérot semiconductor optical amplifier (FP-SOA). Phase-inverted modulation induced by cross-gain modulation (XGM) and optical spectral broadening induced by self-phase modulation (SPM) are exploited to achieve flat-top and bandwidth tuning, respectively. Wideband and continuous tuning of the center frequency is achieved by altering the bias current of the FP-SOA. Experimental results demonstrate a flat-top single-passband MPF with its center frequency tunable from 6.0 to 18.3 GHz by adjusting the bias current from 54.05 to 107.85 mA. The 3-dB bandwidth of the passband when centered at 10.0 GHz is shown to be variable from 680 to 1.43 GHz, by increasing the injected optical power from -1 to +5  dBm. During the bandwidth tuning, the amplitude ripple within the passband is maintained at less than ±0.5  dB. Excellent main to secondary sidelobe ratio exceeding 45 dB is achieved when the MPF is centered at 18.3 GHz. PMID:27420520

  1. Intensive Plasmonic Flash Light Sintering of Copper Nanoinks Using a Band-Pass Light Filter for Highly Electrically Conductive Electrodes in Printed Electronics.

    PubMed

    Hwang, Yeon-Taek; Chung, Wan-Ho; Jang, Yong-Rae; Kim, Hak-Sung

    2016-04-01

    In this work, an intensive plasmonic flash light sintering technique was developed by using a band-pass light filter matching the plasmonic wavelength of the copper nanoparticles. The sintering characteristics, such as resistivity and microstructure, of the copper nanoink films were studied as a function of the range of the wavelength employed in the flash white light sintering. The flash white light irradiation conditions (e.g., wavelength range, irradiation energy, pulse number, on-time, and off-time) were optimized to obtain a high conductivity of the copper nanoink films without causing damage to the polyimide substrate. The wavelength range corresponding to the plasmonic wavelength of the copper nanoparticles could efficiently sinter the copper nanoink and enhance its conductivity. Ultimately, the sintered copper nanoink films under optimal light sintering conditions showed the lowest resistivity (6.97 μΩ·cm), which was only 4.1 times higher than that of bulk copper films (1.68 μΩ·cm). PMID:26975337

  2. Effect of RF Filtering on the Performance of Uncoded PCM/PM Telemetry Channels

    NASA Technical Reports Server (NTRS)

    Koerner, M. A.

    1984-01-01

    A method for calculating the increase in received telemetry signal power required to compensate for the use of a radio frequency interference (RFI) filter in front of the DSN receiving system low-noise amplifier is described. The telemetry system for which the degradation is calculated is an uncoded PCM/PM system in which the NRZ data directly modulates the carrier at a modulation level which leaves a discrete carrier. A phase-locked loop in the RF receiver tracks the discrete carrier and coherently demodulates the PCM data. The RFI filter may be a series of Butterworth, Tchebychev, or Bessel low-pass, high-pass, band-pass, or band-reject filters, each with arbitrary bandwidth, number of poles, and, for band-pass or band-reject filters, resonant frequency. The only restriction is that the RFI filter must have only simple poles. Numerical results are presented for the RFI filters the DSN plans to place in front of the S-band FET, S-band maser, and X-band maser low noise amplifiers. The main conclusion is that the filters will produce negligible degradation at data rates below 4 Mbps.

  3. Study of a mode-locked erbium-doped frequency-shifted-feedback fiber laser incorporating a broad bandpass filter: Experimental results

    NASA Astrophysics Data System (ADS)

    Vazquez-Zuniga, Luis Alonso; Jeong, Yoonchan

    2013-10-01

    We present rigorous experimental studies on the spectral and temporal behaviors of an erbium-doped frequency-shifted-feedback fiber laser (FSFL), with respect to various parameters of the laser cavity, including the direction of the frequency-shift mechanism, the quantity of frequency-shift, and the output coupling ratio (OCR) of the cavity. We show that if the filter bandwidth is much broader than the laser linewidth, the laser spectrum tends to split and form a secondary spectral band (SSB) on the shorter or longer wavelength side of the primary spectrum, depending on whether the direction of the frequency-shift mechanism is upward or downward, respectively. We found that the SSB forms a parasitic pulse with much lower peak power traveling on the leading or trailing edge of the primary pulse, which leads to a significant asymmetry in the whole pulse formation in the time domain.

  4. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  5. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  6. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  7. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  8. 46 CFR 35.30-10 - Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Cargo tank hatches, ullage holes, and Butterworth plates-TB/ALL. 35.30-10 Section 35.30-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS OPERATIONS General Safety Rules § 35.30-10 Cargo tank hatches, ullage holes, and Butterworth...

  9. Filter Design and Performance Evaluation for Fingerprint Image Segmentation

    PubMed Central

    Thai, Duy Hoang; Huckemann, Stephan; Gottschlich, Carsten

    2016-01-01

    Fingerprint recognition plays an important role in many commercial applications and is used by millions of people every day, e.g. for unlocking mobile phones. Fingerprint image segmentation is typically the first processing step of most fingerprint algorithms and it divides an image into foreground, the region of interest, and background. Two types of error can occur during this step which both have a negative impact on the recognition performance: ‘true’ foreground can be labeled as background and features like minutiae can be lost, or conversely ‘true’ background can be misclassified as foreground and spurious features can be introduced. The contribution of this paper is threefold: firstly, we propose a novel factorized directional bandpass (FDB) segmentation method for texture extraction based on the directional Hilbert transform of a Butterworth bandpass (DHBB) filter interwoven with soft-thresholding. Secondly, we provide a manually marked ground truth segmentation for 10560 images as an evaluation benchmark. Thirdly, we conduct a systematic performance comparison between the FDB method and four of the most often cited fingerprint segmentation algorithms showing that the FDB segmentation method clearly outperforms these four widely used methods. The benchmark and the implementation of the FDB method are made publicly available. PMID:27171150

  10. Filter Design and Performance Evaluation for Fingerprint Image Segmentation.

    PubMed

    Thai, Duy Hoang; Huckemann, Stephan; Gottschlich, Carsten

    2016-01-01

    Fingerprint recognition plays an important role in many commercial applications and is used by millions of people every day, e.g. for unlocking mobile phones. Fingerprint image segmentation is typically the first processing step of most fingerprint algorithms and it divides an image into foreground, the region of interest, and background. Two types of error can occur during this step which both have a negative impact on the recognition performance: 'true' foreground can be labeled as background and features like minutiae can be lost, or conversely 'true' background can be misclassified as foreground and spurious features can be introduced. The contribution of this paper is threefold: firstly, we propose a novel factorized directional bandpass (FDB) segmentation method for texture extraction based on the directional Hilbert transform of a Butterworth bandpass (DHBB) filter interwoven with soft-thresholding. Secondly, we provide a manually marked ground truth segmentation for 10560 images as an evaluation benchmark. Thirdly, we conduct a systematic performance comparison between the FDB method and four of the most often cited fingerprint segmentation algorithms showing that the FDB segmentation method clearly outperforms these four widely used methods. The benchmark and the implementation of the FDB method are made publicly available. PMID:27171150

  11. Design and experimental characterization of a bandpass sampling receiver

    NASA Astrophysics Data System (ADS)

    Singh, Avantika; Kumar, Devika S.; Venkateswaran, Gomathy; Manjukrishna, S.; Singh, Amrendra Kumar; Kurup, Dhanesh G.

    2016-03-01

    In this paper, we present a robust and efficient approach for deigning reconfigurable Radio receivers based on Bandpass sampling. The direct sampled RF frontend is followed by signal processing blocks implemented on an FPGA and consists of a PLL based on second order Costas technique and a Kaiser windowing based lowpass filtering. The proposed method can be used for implementing a cost effective multi-channel receiver for data, audio, video etc. over various channels.

  12. Bandpass x-ray diode and x-ray multiplier detector

    DOEpatents

    Wang, C.L.

    1982-09-27

    An absorption-edge of an x-ray absorption filter and a quantum jump of a photocathode determine the bandpass characteristics of an x-ray diode detector. An anode, which collects the photoelectrons emitted by the photocathode, has enhanced amplification provided by photoelectron-multiplying means which include dynodes or a microchannel-plate electron-multiplier. Suppression of undesired high frequency response for a bandpass x-ray diode is provided by subtracting a signal representative of energies above the passband from a signal representative of the overall response of the bandpass diode.

  13. Soliton transmission control by super-Gaussian filters

    NASA Astrophysics Data System (ADS)

    Peral, E.; Capmany, J.; Marti, J.

    1996-12-01

    Bandwidth-limited filtering has been proven to overcome certain limitations in soliton transmission systems. We propose super-Gaussian filters instead of Butterworth filter response obtained with conventionally used Fabry-Perot etalons as a method to improve soliton stability and reduce dispersion degradation and theoretically demonstrate their practical implementation in the form of holographic fiber gratings.

  14. Band-pass processing in a GPCR signaling pathway selects for NFAT transcription factor activation.

    PubMed

    Sumit, M; Neubig, R R; Takayama, S; Linderman, J J

    2015-11-01

    Many biological processes are rhythmic and proper timing is increasingly appreciated as being critical for development and maintenance of physiological functions. To understand how temporal modulation of an input signal influences downstream responses, we employ microfluidic pulsatile stimulation of a G-protein coupled receptor, the muscarinic M3 receptor, in single cells with simultaneous real-time imaging of both intracellular calcium and NFAT nuclear localization. Interestingly, we find that reduced stimulation with pulses of ligand can give more efficient transcription factor activation, if stimuli are timed appropriately. Our experiments and computational analyses show that M3 receptor-induced calcium oscillations form a low pass filter while calcium-induced NFAT translocation forms a high pass filter. The combination acts as a band-pass filter optimized for intermediate frequencies of stimulation. We demonstrate that receptor desensitization and NFAT translocation rates determine critical features of the band-pass filter and that the band-pass may be shifted for different receptors or NFAT dynamics. As an example, we show that the two NFAT isoforms (NFAT4 and NFAT1) have shifted band-pass windows for the same receptor. While we focus specifically on the M3 muscarinic receptor and NFAT translocation, band-pass processing is expected to be a general theme that applies to multiple signaling pathways. PMID:26374065

  15. Low-Noise Band-Pass Amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L.

    1982-01-01

    Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.

  16. Properties of multilayer filters

    NASA Technical Reports Server (NTRS)

    Baumeister, P. W.

    1973-01-01

    New methods were investigated of using optical interference coatings to produce bandpass filters for the spectral region 110 nm to 200 nm. The types of filter are: triple cavity metal dielectric filters; all dielectric reflection filters; and all dielectric Fabry Perot type filters. The latter two types use thorium fluoride and either cryolite films or magnesium fluoride films in the stacks. The optical properties of the thorium fluoride were also measured.

  17. Nonuniformly-spaced photonic microwave delayline filter.

    PubMed

    Dai, Yitang; Yao, Jianping

    2008-03-31

    A new technique to implement a photonic microwave delay-line filter based on nonuniform tap spacing with arbitrary bandpass response is proposed and experimentally demonstrated. Being different from a regular photonic microwave delay-line filter where the taps are uniformly spaced, the proposed filter in this paper has nonuniformly-spaced taps. The key feature of this technique is that a photonics microwave delay-line filter with arbitrary bandpass response can be realized with only positive taps via nonuniform tap spacing. The use of the proposed technique to implement a flat-top bandpass filter is experimentally demonstrated. PMID:18542568

  18. Microwave photonic bandstop filter with wide tunability and adjustable bandwidth.

    PubMed

    Li, Wei; Yang, Chengwu; Wang, Ling; Yuan, Zhilin; Liu, Jianguo; Li, Ming; Zhu, Ninghua

    2015-12-28

    A microwave photonic bandstop filter is proposed and experimentally demonstrated in this work. The filter exhibits promising performance combination of reconfigurability, frequency tunability, and bandwidth adjustment. The phase modulation on two orthogonal polarization states produces a bandpass and a lowpass MPF, respectively. The key concept of destructive interference between the bandpass and lowpass MPF enables the reconfiguration of MPF from bandpass to bandstop. By adjusting the wavelength of two orthogonally polarized optical carriers and the bandwidth of an optical bandpass filter, the bandstop filter is tunable in terms of center frequency and bandwidth. PMID:26832021

  19. Photonic crystal fiber π-phase-shifted long-period gratings with wide bandpass and temperature insensitivity

    NASA Astrophysics Data System (ADS)

    Zheng, Shijie; Zhu, Yinian

    2015-11-01

    In order to solve for the mode intensity distributions in a photonic crystal fiber (PCF) cross section and the propagation constant for the design of fiber bandpass filters, we numerically analyze the modal distributions of the fundamental core mode and different cladding modes. Based on the simulation results, we also experimentally demonstrate a simple fabrication of bandpass filters inscribed on the PCF by inserting a π-phase shift in a 12-period long-period grating (LPG). Two rejection bands with greater than 18 dB isolation and an ultra-wide band of 85.3 nm are achieved. The phase-shifted PCF-LPGs are fabricated using a CO2 laser with point-by-point focused pulses. The proposed fiber bandpass filter is compact and is not influenced by temperature effects.

  20. DFB fiber laser hydrophone with band-pass response.

    PubMed

    Zhang, Faxiang; Zhang, Wentao; Li, Fang; Liu, Yuliang

    2011-11-15

    A distributed-feedback fiber laser hydrophone with band-pass response is presented. The design of the hydrophone aims to equalize static pressure and eliminate signal aliasing of high-frequency acoustic components. Theoretical analysis is presented based on electro-acoustic theory. The experimental results agree well with the theory. The measured underwater responses show that the hydrophone has a pressure sensitivity of -170 dB re:pm/μPa over a bandwidth between 100 Hz and 500 Hz. A sensitivity reduction exceeding -35 dB is observed at 2500 Hz. The tested static pressure sensitivity of the hydrophone is -226 dB. The proposed fiber laser hydrophone of this kind is expected to have important application in deep water fiber-optic sonar systems with anti-aliasing, and the understanding gained through this work can be extended to a guide of hydrophone design for required filtering bandwidth. PMID:22089550

  1. FORTRAN IV Digital Filter Design Programs. Digital Systems Education Project.

    ERIC Educational Resources Information Center

    Reuss, E.; And Others

    The goals of the Digital Systems Education Project (DISE) include the development and distribution of educational/instructional materials in the digital systems area. Toward that end, this document contains three reports: (1) A FORTRAN IV Design Program for Low-Pass Butterworth and Chebychev Digital Filters; (2) A FORTRAN IV Design Program for…

  2. Tunable Filter Made From Three Coupled WGM Resonators

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Iltchenko, Vladimir; Maleki, Lute; Matsko, Andrey

    2006-01-01

    A tunable third-order band-pass optical filter has been constructed as an assembly of three coupled, tunable, whispering-gallery-mode resonators similar to the one described in Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter (NPO-30896), NASA Tech Briefs, Vol. 28, No. 4 (April 2004), page 5a. This filter offers a combination of four characteristics that are desirable for potential applications in photonics: (1) wide real-time tunability accompanied by a high-order filter function, (2) narrowness of the passband, (3) relatively low loss between input and output coupling optical fibers, and (4) a sparse spectrum. In contrast, prior tunable band-pass optical filters have exhibited, at most, two of these four characteristics. As described in several prior NASA Tech Briefs articles, a whispering-gallery-mode (WGM) resonator is a spheroidal, disklike, or toroidal body made of a highly transparent material. It is so named because it is designed to exploit whispering-gallery electromagnetic modes, which are waveguide modes that propagate circumferentially and are concentrated in a narrow toroidal region centered on the equatorial plane and located near the outermost edge. Figure 1 depicts the optical layout of the present filter comprising an assembly of three coupled, tunable WGM resonators. Each WGM resonator is made from a disk of Z-cut LiNbO3 of 3.3-mm diameter and 50-m thickness. The perimeter of the disk is polished and rounded to a radius of curvature of 40 microns. The free spectral range of each WGM resonator is about 13.3 GHz. Gold coats on the flat faces of the disk serve as electrodes for exploiting the electro-optical effect in LiNbO3 for tuning. There is no metal coat on the rounded perimeter region, where the whispering-gallery modes propagate. Light is coupled from an input optical fiber into the whispering-gallery-modes of the first WGM resonator by means of a diamond prism. Another diamond prism is used to couple light from the whispering

  3. Sensitivity of bandpass filters using recirculating delay-line structures

    NASA Astrophysics Data System (ADS)

    Heyde, Eric C.

    1996-12-01

    Recirculating delay lines have value notably as sensors and optical signal processors. Most useful applications depend on a high-finesse response from a network. A proof that, with given response parameters, more complex systems can produce behavior that is more stable to the effects of nonidealities than a single recirculating loop is presented.

  4. Tunable microwave photonic notch filter based on sliced broadband optical source.

    PubMed

    Yu, Yang; Li, Shangyuan; Zheng, Xiaoping; Zhang, Hanyi; Zhou, Bingkun

    2015-09-21

    A microwave photonic filter is demonstrated with both tunable center frequency and bandwidth. This filter is switchable from all-pass, bandpass to notch filter, and the notch filter is a result of the subtraction of a bandpass filter from an all-pass filter based on a balanced photodetector. The all-pass filter is achieved based on a single wavelength radio over fiber link, and the bandpass one is acquired by using the spectrum-sliced broadband optical source. Theoretical analysis and experimental results show that both the center frequency and the bandwidth of the notch filter can be widely tuned. PMID:26406636

  5. Comparison of deformation at ends of the results obtained by some commonly used filters

    NASA Astrophysics Data System (ADS)

    Liao, Dechun; Liao, Xinhao

    By using some commonly used filters, such as MULTI-STAGE, ELLIPSE, CHEBYSHEV, and BUTTERWORTH, seasonal, interannual, and decadal components are separated from a synthetic LOD series which was composed of 11 periodic terms extracted from a real LOD series during 1962 - 1998. And then comparisons of the filtered results with the original components have been made to investigate the deformations induced by the different filters at the two ends of the data series. Some results are shown. It is clear by the comparison that the MULTI-STAGE filter has least deformation rate at the two ends of series either it is used for high or low pass filtering, the BUTTERWORTH (for high pass filtering) and CHEBYSHEV (for low pass filtering) have less deformation among the others. For the band pass filtering, however, the CHEBYSHEV filter has least deformation. After adding some extended data obtained by fitting the original data series as a linear statistical model, comparison of the filtered results show that the BUTTERWORTH and ELLIPSE filters have least deformations for band pass filtering. The ends deformation induced by filtering will be smaller for any filters after adding of some statistically extended data to the original series.

  6. A class of orthogonal nonrecursive binomial filters.

    NASA Technical Reports Server (NTRS)

    Haddad, R. A.

    1971-01-01

    The time- and frequency-domain properties of the orthogonal binomial sequences are presented. It is shown that these sequences, or digital filters based on them, can be generated using adders and delay elements only. The frequency-domain behavior of these nonrecursive binomial filters suggests a number of applications as low-pass Gaussian filters or as inexpensive bandpass filters.

  7. Optimum filters for narrow-band frequency modulation.

    NASA Technical Reports Server (NTRS)

    Shelton, R. D.

    1972-01-01

    The results of a computer search for the optimum type of bandpass filter for low-index angle-modulated signals are reported. The bandpass filters are discussed in terms of their low-pass prototypes. Only filter functions with constant numerators are considered. The pole locations for the optimum filters of several cases are shown in a table. The results are fairly independent of modulation index and bandwidth.

  8. Reliability of Three-Dimensional Linear Kinematics and Kinetics of Swimming Derived from Digitized Video at 25 and 50 Hz with 10 and 5 Frame Extensions to the 4(th) Order Butterworth Smoothing Window.

    PubMed

    Sanders, Ross H; Gonjo, Tomohiro; McCabe, Carla B

    2015-06-01

    The purpose of this study was to explore the reliability of estimating three-dimensional (3D) linear kinematics and kinetics of a swimmer derived from digitized video and to assess the effect of framing rate and smoothing window size. A stroke cycle of two high-level front crawl swimmers and one high level backstroke swimmer was recorded by four underwater and two above water video cameras. One of the front crawl swimmers was recorded and digitized at 50 Hz with a window for smoothing by 4(th) order Butterworth digital filter extending 10 frames beyond the start and finish of the stroke cycle, while the other front crawl and backstroke swimmer were recorded and digitized at 25 Hz with the window extending five frames beyond the start and finish of the stroke cycle. Each camera view of the stroke cycle was digitized five times yielding five independent 3D data sets from which whole body centre of mass (CM) component velocities and accelerations were derived together with wrist and ankle linear velocities. Coefficients of reliability ranging from r = 0.942 to r = 0.999 indicated that both methods are sufficiently reliable to identify real differences in net force production during the pulls of the right and left hands. Reliability of digitizing was better for front crawl when digitizing at 50Hz with 10 frames extension than at 25 Hz with 5 frames extension (p < 0.01) and better for backstroke than front crawl (p < 0.01). However, despite the extension and reflection of data, errors were larger in the first 15% of the stroke cycle than the period between 15 and 85% of the stroke cycle for CM velocity and acceleration and for foot speed (p < 0.01). Key pointsAn inverse dynamics based on 3D position data digitized from multiple camera views above and below the water surface is sufficiently reliable to yield insights regarding force production in swimming additional to those of other approaches.The ability to link the force profiles to swimming actions and technique is

  9. Temperature Tunable Air-Gap Etalon Filter

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Stephen, Mark A.; Lunt, David L.

    1998-01-01

    We report on experimental measurements of a temperature tuned air-gap etalon filter. The filter exhibits temperature dependent wavelength tuning of 54 pm/C. It has a nominal center wavelength of 532 nm. The etalon filter has a 27 pm optical bandpass and 600 pm free spectral range (finesse approximately 22). The experimental results are in close agreement with etalon theory.

  10. Mechanism for bandpass frequency characteristic in distortion product otoacoustic emission generation.

    PubMed

    Fahey, P F; Stagner, B B; Martin, G K

    2006-02-01

    It is commonly observed that the levels of the 2f1-f2 and the other mf1-nf2 (m = n + 1 = integer) distortion product otoacoustic emissions (DPOAEs) initially increase in level for fixed f2 as fl -->f2, starting at f1 bandpass shape. It has been hypothesized that this effect is due to (1) a second filter, (2) suppression of distortion generation by the primary tones, (3) reemission of distortion products from the distortion product place (on the basilar membrane), (4) the presence of an even order nonlinearity, and (5) cancellation of the DPOAE due to the vector addition of multiple sources of distortion product. In this study distortion products were produced with f1 sweep conditions where there would be minimal vector cancellation of multiple DPOAE sources. It was observed that under this condition, there is no or minimal bandpass shape of the DPOAE generation curve. Therefore, the data support the hypothesis that the bandpass shape obtained with traditional f1 sweeps is due to vector cancellation from multiple sources. PMID:16521760

  11. Optimizing the performance of bandpass photon detectors for inverse photoemission: Transmission of alkaline earth fluoride window crystals

    SciTech Connect

    Thiede, Christian Schmidt, Anke B.; Donath, Markus

    2015-08-15

    Bandpass photon detectors are widely used in inverse photoemission in the isochromat mode at energies in the vacuum-ultraviolet spectral range. The energy bandpass of gas-filled counters is usually formed by the ionization threshold of the counting gas as high-pass filter and the transmission cutoff of an alkaline earth fluoride window as low-pass filter. The transmission characteristics of the window have, therefore, a crucial impact on the detector performance. We present transmission measurements in the vacuum-ultraviolet spectral range for alkaline earth fluoride window crystals in the vicinity of the transmission cutoff as a function of crystal purity, surface finish, surface contamination, temperature, and thickness. Our findings reveal that the transmission characteristics of the window crystal and, thus, the detector performance depend critically on these window parameters.

  12. Research on spectroscopic imaging. Volume 1: Technical discussion. [birefringent filters

    NASA Technical Reports Server (NTRS)

    Title, A.; Rosenberg, W.

    1979-01-01

    The principals of operation and the capabilities of birefringent filters systems are examined. Topics covered include: Lyot, Solc, and partial polarizer filters; transmission profile management; tuning birefringent filters; field of view; bandpass control; engineering considerations; and recommendations. Improvements for field of view effects, and the development of birefringent filters for spaceflight are discussed in appendices.

  13. Reconfigurable microwave photonic filter based on polarization modulation

    NASA Astrophysics Data System (ADS)

    Xu, Enming; Pan, Shilong; Li, Peili

    2016-03-01

    A reconfigurable microwave photonic filter based on a polarization modulator (PolM) is proposed and experimentally demonstrated. The PolM together with a polarization controller (PC) and a polarization beam splitter (PBS) implements two complementary intensity modulations in two separated branches. Then, optical components are inserted in the two branches to realize a bandpass filter and an allpass filter, respectively. When the two branches are combined by a second PBS, a filter with a frequency response that equals the subtraction of the frequency responses of the allpass filter and bandpass filter is achieved. By adjusting the PCs placed before the second PBS, a notch filter with a tunable notch depth or a bandpass filter can be achieved.

  14. Active imaging system with Faraday filter

    DOEpatents

    Snyder, J.J.

    1993-04-13

    An active imaging system has a low to medium powered laser transmitter and receiver wherein the receiver includes a Faraday filter with an ultranarrow optical bandpass and a bare (nonintensified) CCD camera. The laser is locked in the vicinity of the passband of the Faraday filter. The system has high sensitivity to the laser illumination while eliminating solar background.

  15. Active imaging system with Faraday filter

    DOEpatents

    Snyder, James J.

    1993-01-01

    An active imaging system has a low to medium powered laser transmitter and receiver wherein the receiver includes a Faraday filter with an ultranarrow optical bandpass and a bare (nonintensified) CCD camera. The laser is locked in the vicinity of the passband of the Faraday filter. The system has high sensitivity to the laser illumination while eliminating solar background.

  16. Design and application of finite impulse response digital filters.

    PubMed

    Miller, T R; Sampathkumaran, K S

    1982-01-01

    The finite impulse response (FIR) digital filter is a spatial domain filter with a frequency domain representation. The theory of the FIR filter is presented and techniques are described for designing FIR filters with known frequency response characteristics. Rational design principles are emphasized based on characterization of the imaging system using the modulation transfer function and physical properties of the imaged objects. Bandpass, Wiener, and low-pass filters were designed and applied to 201Tl myocardial images. The bandpass filter eliminates low-frequency image components that represent background activity and high-frequency components due to noise. The Wiener, or minimum mean square error filter 'sharpens' the image while also reducing noise. The Wiener filter illustrates the power of the FIR technique to design filters with any desired frequency response. The low-pass filter, while of relative limited use, is presented to compare it with a popular elementary 'smoothing' filter. PMID:7060600

  17. Band-Pass Amplifier Without Discrete Reactance Elements

    NASA Technical Reports Server (NTRS)

    Kleinberg, L.

    1984-01-01

    Inherent or "natural" device capacitance exploited. Band-Pass Circuit has input impedance of equivalent circuit at frequencies much greater than operational-amplifier rolloff frequency. Apparent inductance and capacitance arise from combined effects of feedback and reactive component of amplifier gain in frequency range.

  18. Eulerian Time-Domain Filtering for Spatial LES

    NASA Technical Reports Server (NTRS)

    Pruett, C. David

    1997-01-01

    Eulerian time-domain filtering seems to be appropriate for LES (large eddy simulation) of flows whose large coherent structures convect approximately at a common characteristic velocity; e.g., mixing layers, jets, and wakes. For these flows, we develop an approach to LES based on an explicit second-order digital Butterworth filter, which is applied in,the time domain in an Eulerian context. The approach is validated through a priori and a posteriori analyses of the simulated flow of a heated, subsonic, axisymmetric jet.

  19. [Restoration filtering based on projection power spectrum for single-photon emission computed tomography].

    PubMed

    Kubo, N

    1995-04-01

    To improve the quality of single-photon emission computed tomographic (SPECT) images, a restoration filter has been developed. This filter was designed according to practical "least squares filter" theory. It is necessary to know the object power spectrum and the noise power spectrum. The power spectrum is estimated from the power spectrum of a projection, when the high-frequency power spectrum of a projection is adequately approximated as a polynomial exponential expression. A study of the restoration with the filter based on a projection power spectrum was conducted, and compared with that of the "Butterworth" filtering method (cut-off frequency of 0.15 cycles/pixel), and "Wiener" filtering (signal-to-noise power spectrum ratio was a constant). Normalized mean-squared errors (NMSE) of the phantom, two line sources located in a 99mTc filled cylinder, were used. NMSE of the "Butterworth" filter, "Wiener" filter, and filtering based on a power spectrum were 0.77, 0.83, and 0.76 respectively. Clinically, brain SPECT images utilizing this new restoration filter improved the contrast. Thus, this filter may be useful in diagnosis of SPECT images. PMID:7776546

  20. Second-order optical filter based on a mirrored gradient index lens.

    PubMed

    Liang, W; Savchenkov, A A; Matsko, A B; Ilchenko, V S; Seidel, D; Maleki, L

    2010-07-15

    We demonstrate a second-order bandpass filter using a single gradient index lens (GRIN) coated with mirrors. The filter becomes possible because of the residual and externally introduced small birefringence of the GRIN lens material. We show that the filter function can be trimmed by mechanical strain of the lens. Applications of the filter in microwave photonics are discussed. PMID:20634829

  1. Restoration of combined conjugate images in SPECT; Comparison of a new Weiner filter and the image-dependent Metz filter

    SciTech Connect

    Penny, B.C.; King, M.A.; Glick, S.J. . Dept. of Nuclear Medicine)

    1990-04-01

    This study applies two image-dependent restoration filters to projection image sets obtained with single photon emission computed tomography (SPECT). Wiener and Metz restoration of combined conjugate views are compared to: each other, Wiener restoration of individual projection images, and to one-dimensional (1D) Butterworth smoothing. The combined view restoration filters adapt to the average thickness of the object by estimating a modulation transfer function (MTF) for that thickness. Simulated Tc-99m liver-spleen studies with randomly placed cold spot tumors, a projector which accounts for the spatially variant blurring in SPECT, and a Poisson noise generator are used to compute simulated projection image sets.

  2. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification

    NASA Astrophysics Data System (ADS)

    Jena, D. P.; Panigrahi, S. N.

    2016-03-01

    Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.

  3. Magnetoencephalographic responses correspond to individual annoyance of bandpass noise

    NASA Astrophysics Data System (ADS)

    Soeta, Y.; Nakagawa, S.; Tonoike, M.; Ando, Y.

    2004-10-01

    The relation between human brain responses to an individual's annoyance of bandpass noise was investigated using magnetoencephalography (MEG) measurements and analysis by autocorrelation function (ACF) and cross-correlation function (CCF). Pure tone and bandpass noises with a centre frequency of 1000 Hz were used as source signals. The sound pressure level was constant at 74 dBA and the duration of the stimulus was 2.0 s. The scale values of annoyance for each subject were obtained by paired-comparison tests. In MEG measurements, the combination of a reference stimulus (pure tone) and test stimuli (bandpass noise) was alternately presented 30 times at a constant 2 s interstimulus interval. The results show that the effective duration of the ACF, τe, of MEG in the 8-13 Hz range, which represent repetitive features within the signal itself, became shorter during the presentation of an annoying stimulus. Also, the maximum value of the CCF, |φ(τ)|max, became smaller. The shorter τe and smaller |φ(τ)|max indicate that a wider area of the brain is unstable for longer with annoying auditory stimuli.

  4. Image quality, space-qualified UV interference filters

    NASA Technical Reports Server (NTRS)

    Mooney, Thomas A.

    1992-01-01

    The progress during the contract period is described. The project involved fabrication of image quality, space-qualified bandpass filters in the 200-350 nm spectral region. Ion-assisted deposition (IAD) was applied to produce stable, reasonably durable filter coatings on space compatible UV substrates. Thin film materials and UV transmitting substrates were tested for resistance to simulated space effects.

  5. Image pre-filtering for measurement error reduction in digital image correlation

    NASA Astrophysics Data System (ADS)

    Zhou, Yihao; Sun, Chen; Song, Yuntao; Chen, Jubing

    2015-02-01

    In digital image correlation, the sub-pixel intensity interpolation causes a systematic error in the measured displacements. The error increases toward high-frequency component of the speckle pattern. In practice, a captured image is usually corrupted by additive white noise. The noise introduces additional energy in the high frequencies and therefore raises the systematic error. Meanwhile, the noise also elevates the random error which increases with the noise power. In order to reduce the systematic error and the random error of the measurements, we apply a pre-filtering to the images prior to the correlation so that the high-frequency contents are suppressed. Two spatial-domain filters (binomial and Gaussian) and two frequency-domain filters (Butterworth and Wiener) are tested on speckle images undergoing both simulated and real-world translations. By evaluating the errors of the various combinations of speckle patterns, interpolators, noise levels, and filter configurations, we come to the following conclusions. All the four filters are able to reduce the systematic error. Meanwhile, the random error can also be reduced if the signal power is mainly distributed around DC. For high-frequency speckle patterns, the low-pass filters (binomial, Gaussian and Butterworth) slightly increase the random error and Butterworth filter produces the lowest random error among them. By using Wiener filter with over-estimated noise power, the random error can be reduced but the resultant systematic error is higher than that of low-pass filters. In general, Butterworth filter is recommended for error reduction due to its flexibility of passband selection and maximal preservation of the allowed frequencies. Binomial filter enables efficient implementation and thus becomes a good option if computational cost is a critical issue. While used together with pre-filtering, B-spline interpolator produces lower systematic error than bicubic interpolator and similar level of the random

  6. Metal mesh resonant filters for terahertz frequencies.

    PubMed

    Melo, Arline M; Kornberg, Mariano A; Kaufmann, Pierre; Piazzetta, Maria H; Bortolucci, Emílio C; Zakia, Maria B; Bauer, Otto H; Poglitsch, Albrecht; da Silva, Alexandre M P Alves

    2008-11-10

    The interest in terahertz photometric and imaging measurements has motivated the development of bandpass resonant filters to be coupled to multiple-pixel devices such as bolometer arrays. Resonant grids are relatively simple to fabricate, exhibiting high transmission at the central frequency, a narrow bandpass, and good rejection of the side frequencies of the spectrum. We have fabricated filters centered at different frequencies between 0.4 and 10 THz, using photolithography and electroforming techniques. Transmission measurements have shown center frequencies and bandwidths close to the design predictions. The performance of the filters was found not to be critically dependent on small physical deformations in the mesh, becoming more noticeable at higher frequencies (i.e., for smaller physical sizes). Wider bandwidths, needed to attain higher sensitivities in the continuum, were obtained by changing the design parameters for filters at 2 and 3 THz. PMID:19002231

  7. Bandpass sampling in heterodyne receivers for coherent optical access networks.

    PubMed

    Bakopoulos, Paraskevas; Dris, Stefanos; Schrenk, Bernhard; Lazarou, Ioannis; Avramopoulos, Hercules

    2012-12-31

    A novel digital receiver architecture for coherent heterodyne-detected optical signals is presented. It demonstrates the application of bandpass sampling in an optical communications context, to overcome the high sampling rate requirement of conventional receivers (more than twice the signal bandwidth). The concept is targeted for WDM coherent optical access networks, where applying heterodyne detection constitutes a promising approach to reducing optical hardware complexity. The validity of the concept is experimentally assessed in a 76 km WDM-PON scenario, where the developed DSP achieves a 50% ADC rate reduction with penalty-free operation. PMID:23388768

  8. Advanced astronomical interference filters from SCHOTT technology

    NASA Astrophysics Data System (ADS)

    Hull, Anthony B.; Reichel, Steffen; Brauneck, Ulf; Bourquin, Sebastien; Marin-Franch, Antoni

    2016-01-01

    Developing precision interference filters for astronomical radiometry often requires simultaneous solutions to very difficult requirements. SCHOTT's 80-year legacy methods with interference filters and 9,200-m2 facility dedicated to filters and optical fabrication bring multiple disciplines together to simultaneously solve requirements that include: narrow-band high-transmission, steep-edge bandpasses, extremely high out-of-band rejection across Si response, sizes accommodating large fields-of-view, precision mechanical filter assemblies and both spectral uniformity and excellent transmitted wavefront across the field. We discuss solutions as satisfied for Spain's state-of-the-art new fast LOCAL UNIVERSE 3° wide-field survey telescope.

  9. Spectral analysis and filtering techniques in digital spatial data processing

    USGS Publications Warehouse

    Pan, Jeng-Jong

    1989-01-01

    A filter toolbox has been developed at the EROS Data Center, US Geological Survey, for retrieving or removing specified frequency information from two-dimensional digital spatial data. This filter toolbox provides capabilities to compute the power spectrum of a given data and to design various filters in the frequency domain. Three types of filters are available in the toolbox: point filter, line filter, and area filter. Both the point and line filters employ Gaussian-type notch filters, and the area filter includes the capabilities to perform high-pass, band-pass, low-pass, and wedge filtering techniques. These filters are applied for analyzing satellite multispectral scanner data, airborne visible and infrared imaging spectrometer (AVIRIS) data, gravity data, and the digital elevation models (DEM) data. -from Author

  10. Synthesis of Band Filters and Equalizers Using Microwav FIR Techniques

    SciTech Connect

    Deibele, C.; /Fermilab

    2000-01-01

    It is desired to design a passive bandpass filter with both a linear phase and flat magnitude response within the band and also has steep skirts. Using the properties of both coupled lines and elementary FIR (Finite Impulse Response) signal processing techniques can produce a filter of adequate phase response and magnitude control. The design procedure will first be described and then a sample filter will then be synthesized and results shown.

  11. Detecting and Characterizing Exoplanets with the WFIRST Coronagraph: Colors of Planets in Standard and Designer Bandpasses-SETI

    NASA Astrophysics Data System (ADS)

    Turnbull, Margaret

    The WFIRST mission is now envisioned to include a coronagraph for the purpose of direct detection of nearby exoplanets, including planets known to exist via radial velocity detection and new discoveries. Assuming that starlight rejection sufficient for planet detection (~1e-9) can be achieved, what can be learned about these planets given a realistic spectral resolution and signal-to-noise ratio? We propose to investigate the potential for WFIRST to efficiently discriminate planets from background sources, and to characterize planets in terms of important diagnostic atmospheric features, using broad- and intermediate band color data. We will map out this capability as a function of signal-to-noise ratio, bandpass location, and bandpass width. Our investigation will place emphasis on gas giants, ice giants, and mini-Neptunes (compatible with current AFTA-C baseline performance specifications), as well as a variety of super-Earths (an AFTA-C "stretch" goal). We will explore a variety of compositions, cloud types, phase angles, and (in the case of super-Earths with semi-transparent atmospheres) surface types. Noiseless spectra generated for these model planets will be passed through (a) standard bandpasses for comparison to prior work and (b) filter transmission curves corresponding to bandpasses of 5-20% over the full range of WFIRST's expected bandpass (400 - 1,000 nm). From this, filter combinations will be used to generate planet colors and find filter sets that most efficiently discriminate between planets and background sources, and between planets of different type. We will then repeat this exercise for S/N levels of 1-1,000 in order to (1) explore the true efficacy of broadband measurements in exoplanet studies, and (2) provide an estimate of total required integration time for a compelling WFIRST exoplanet program. To accomplish this, we will use model spectra for mini-Neptunes, and ice and gas giants of varying composition (Hu et al. 2013), and observed

  12. Filters in 2D and 3D Cardiac SPECT Image Processing

    PubMed Central

    Ploussi, Agapi; Synefia, Stella

    2014-01-01

    Nuclear cardiac imaging is a noninvasive, sensitive method providing information on cardiac structure and physiology. Single photon emission tomography (SPECT) evaluates myocardial perfusion, viability, and function and is widely used in clinical routine. The quality of the tomographic image is a key for accurate diagnosis. Image filtering, a mathematical processing, compensates for loss of detail in an image while reducing image noise, and it can improve the image resolution and limit the degradation of the image. SPECT images are then reconstructed, either by filter back projection (FBP) analytical technique or iteratively, by algebraic methods. The aim of this study is to review filters in cardiac 2D, 3D, and 4D SPECT applications and how these affect the image quality mirroring the diagnostic accuracy of SPECT images. Several filters, including the Hanning, Butterworth, and Parzen filters, were evaluated in combination with the two reconstruction methods as well as with a specified MatLab program. Results showed that for both 3D and 4D cardiac SPECT the Butterworth filter, for different critical frequencies and orders, produced the best results. Between the two reconstruction methods, the iterative one might be more appropriate for cardiac SPECT, since it improves lesion detectability due to the significant improvement of image contrast. PMID:24804144

  13. Piecewise spectrally band-pass for compressive coded aperture spectral imaging

    NASA Astrophysics Data System (ADS)

    Qian, Lu-Lu; Lü, Qun-Bo; Huang, Min; Xiang, Li-Bin

    2015-08-01

    Coded aperture snapshot spectral imaging (CASSI) has been discussed in recent years. It has the remarkable advantages of high optical throughput, snapshot imaging, etc. The entire spatial-spectral data-cube can be reconstructed with just a single two-dimensional (2D) compressive sensing measurement. On the other hand, for less spectrally sparse scenes, the insufficiency of sparse sampling and aliasing in spatial-spectral images reduce the accuracy of reconstructed three-dimensional (3D) spectral cube. To solve this problem, this paper extends the improved CASSI. A band-pass filter array is mounted on the coded mask, and then the first image plane is divided into some continuous spectral sub-band areas. The entire 3D spectral cube could be captured by the relative movement between the object and the instrument. The principle analysis and imaging simulation are presented. Compared with peak signal-to-noise ratio (PSNR) and the information entropy of the reconstructed images at different numbers of spectral sub-band areas, the reconstructed 3D spectral cube reveals an observable improvement in the reconstruction fidelity, with an increase in the number of the sub-bands and a simultaneous decrease in the number of spectral channels of each sub-band. Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 61225024) and the National High Technology Research and Development Program of China (Grant No. 2011AA7012022).

  14. Isotropically sensitive optical filter employing atomic resonance transitions

    DOEpatents

    Marling, John B.

    1981-01-01

    An ultra-high Q isotropically sensitive optical filter or optical detector employing atomic resonance transitions. More specifically, atomic resonance transitions utilized in conjunction with two optical bandpass filters provide an optical detector having a wide field of view (.about.2.pi. steradians) and very narrow acceptance bandwidth approaching 0.01 A. A light signal to be detected is transmitted through an outer bandpass filter into a resonantly absorbing atomic vapor, the excited atomic vapor then providing a fluorescence signal at a different wavelength which is transmitted through an inner bandpass filter. The outer and inner bandpass filters have no common transmission band, thereby resulting in complete blockage of all optical signals that are not resonantly shifted in wavelength by the intervening atomic vapor. Two embodiments are disclosed, one in which the light signal raises atoms contained in the atomic vapor from the ground state to an excited state from which fluorescence occurs, and the other in which a pump laser is used to raise the atoms in the ground state to a first excited state from which the light signal then is resonantly absorbed, thereby raising the atoms to a second excited state from which fluorescence occurs. A specific application is described in which an optical detector according to the present invention can be used as an underwater detector for light from an optical transmitter which could be located in an orbiting satellite.

  15. Compact continuously tunable microwave photonic filters based on cascaded silicon microring resonators

    NASA Astrophysics Data System (ADS)

    Liu, Li; He, Mengying; Dong, Jianji

    2016-03-01

    We propose and experimentally demonstrate a photonic approach to achieving tunable bandpass microwave photonic filters (MPFs) based on cascaded microring resonators (CMRRs). The optical spectrum of the silicon CMRRs could offer two bandpass response to separately filter the optical carrier and one of the sidebands generated by the phase modulation. Thus we could achieve a bandpass MPF. Moreover, as the central frequencies and bandwidths of the two bandpass response can be tuned by adjusting the laser wavelength and voltages applied on one MRR, the central operating frequency or 3-dB bandwidth of the MPF can be continuously tuned in wide ranges respectively. A proof-of-concept experiment illustrates a central frequency tuning range from 19 GHz to 40 GHz, and a wide bandwidth tuning range from 5.5 GHz to 17.5 GHz.

  16. A Quadrupole Band-Pass Filter for a White Proton Source

    NASA Astrophysics Data System (ADS)

    Morrow, Jonathon; Peterson, Jerry

    2009-10-01

    The LANSCE facility at Los Alamos National Laboratory uses a beam of 800 MeV protons as a source of continuous (white) beams of neutrons, used for a wide range of basic and applied science. The same source also provides a white source of protons, which would be very useful for research, if some degree of energy resolution were available. We are designing a quadrupole magnet system that will provide such energy resolution by focusing only the desired momentum onto a sample, with protons of more or less momentum more widely diffused. Results will be given for designs based on simple thin lens optics to understand the criteria and general trends. A full design will require use of magnetic beam transport codes and a specific magnet system.

  17. A Study on Compact Wide Bandpass Filter Using Inter-Digital Resonator

    NASA Astrophysics Data System (ADS)

    Yamamoto, Jumpei; Yasuzumi, Takenori; Uwano, Tomoki; Hashimoto, Osamu

    A new type of the wide-band BPF made up of an inter-digital resonator and parallel-coupled lines was proposed. The bandwidth of the inter-digital resonator becomes wider by increasing the number of fingers. The design of the parallel-coupled line was performed by optimazing the structural parameters so that the bandwidth is the same as that of the inter-digital resonator. The measured results of the combination of above elements for the BPF agreed well with the simulated ones such that the insertion loss is less than 0.67dB and that the sharp skirt characteristics are realized by attenuation poles near the edges of the passband.

  18. Bandpass-resampling effects for the retrieval of surface emissivity.

    PubMed

    Richter, Rudolf; Coll, Cesar

    2002-06-20

    The retrieval of surface emissivity in the 8-14-microm region from remotely sensed thermal imagery requires channel-averaged values of atmospheric transmittance, path radiance, and downwelling sky flux. Band-pass resampling introduces inherent retrieval errors that depend on atmospheric conditions, spectral region, bandwidth, flight altitude, and surface temperature. This simulation study is performed for clear sky conditions and moderate atmospheric water vapor contents. It shows that relative emissivity retrieval errors can reach as much as 3% for broadband sensors (1-2-microm bandwidth) and 0.8% for narrowband instruments (0.15 microm), even for constant surface emissivity. For spectrally varying surface emissivities the relative retrieval error increases for the broadband instrument by approximately 2% in channels with strong emissivity changes of 0.05-0.1. The corresponding retrieval errors for narrowband sensors increase by approximately 3-4%. The channels in the atmospheric window regions with lower transmittance, i.e., 8-8.5 and 12.5-14 microm, are most sensitive to retrieval errors. PMID:12078676

  19. Terahertz filter with tailored passband using multiple phase shifted fiber Bragg gratings.

    PubMed

    Zhou, Shu Fan; Reekie, Laurence; Chan, Hau Ping; Luk, Kwai Man; Chow, Yuk Tak

    2013-02-01

    Transmission filters for the terahertz domain having a shaped bandpass have been modeled and demonstrated. The filter designs were based on the desired filter type and bandwidth, and implemented by cascading quarter wave phase shifted fiber Bragg gratings written in Topas polymer subwavelength fiber. As an example, a 5-pole Chebyshev filter with <3 GHz bandwidth was designed and fabricated. Experimental and simulated results are in good agreement. PMID:23381404

  20. Flexible RF filter using a nonuniform SCISSOR.

    PubMed

    Zhuang, Leimeng

    2016-03-15

    This work presents a flexible radiofrequency (RF) filter using an integrated microwave photonic circuit that comprises a nonuniform side-coupled integrated spaced sequence of resonators (N-SCISSOR). The filter passband can be reconfigured by varying the N-SCISSOR parameters. When employing a dual-parallel Mach-Zechnder modulator, the filter is also able to perform frequency down-conversion. In the experiment, various filter response shapes are shown, ranging from a flat-top band-pass filter to a total opposite high-rejection (>40  dB) notch filter, with a frequency coverage of greater than two octaves. The frequency down-conversion function is also demonstrated. PMID:26977648

  1. Adaptive Spatial Filtering with Principal Component Analysis for Biomedical Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Nagaoka, Ryo; Yamazaki, Rena; Saijo, Yoshifumi

    Photoacoustic (PA) signal is very sensitive to noise generated by peripheral equipment such as power supply, stepping motor or semiconductor laser. Band-pass filter is not effective because the frequency bandwidth of the PA signal also covers the noise frequency. The objective of the present study is to reduce the noise by using an adaptive spatial filter with principal component analysis (PCA).

  2. Adaptive Mallow's optimization for weighted median filters

    NASA Astrophysics Data System (ADS)

    Rachuri, Raghu; Rao, Sathyanarayana S.

    2002-05-01

    This work extends the idea of spectral optimization for the design of Weighted Median filters and employ adaptive filtering that updates the coefficients of the FIR filter from which the weights of the median filters are derived. Mallows' theory of non-linear smoothers [1] has proven to be of great theoretical significance providing simple design guidelines for non-linear smoothers. It allows us to find a set of positive weights for a WM filter whose sample selection probabilities (SSP's) are as close as possible to a SSP set predetermined by Mallow's. Sample selection probabilities have been used as a basis for designing stack smoothers as they give a measure of the filter's detail preserving ability and give non-negative filter weights. We will extend this idea to design weighted median filters admitting negative weights. The new method first finds the linear FIR filter coefficients adaptively, which are then used to determine the weights of the median filter. WM filters can be designed to have band-pass, high-pass as well as low-pass frequency characteristics. Unlike the linear filters, however, the weighted median filters are robust in the presence of impulsive noise, as shown by the simulation results.

  3. Performance measures in the selection of reconstruction filters for SPECT imaging

    SciTech Connect

    Appledorn, C.R.; Oppenheim, B.E.; Wellman, H.N.

    1985-05-01

    Filter selection in SPECT image reconstruction poses an implicit tradeoff between image smoothness, image contrast and noise texture. It is known that the Ramachandran or ramp filter provides the greatest contrast (and resolution) in a reconstructed image at the expense of poor noise handling. In order to improve detection of either hot or cold lesions, practical experience dictates that some image smoothing must be provided. Thus, the question of the ''optimal'' filter selection has been the subject of this investigation. Using an extension of the approach as originally developed by Beck and Metz, the authors derived a figure-of-merit (FOM) that quantifies the performance of the reconstruction algorithm being tested. The FOM can be separated into two components: smoothness factor (SF) which is a measure of noise reduction and contrast factor (CF) which is a measure of the spatial resolution of the filter being tested. Each component is measured separately. The optimum filter should maintain the contrast of the Ramachandran filter (CF = 0.313) but improve the noise handling (SF = 8.86). A variety of commercially available filters were tested: rectangular, Hann, and Butterworth. Also examined were the order of the filter and the interpolation method (nearest-neighbor, linear, and Fourier methods with padding of zeros). The authors found that high order Butterworth filters performed best in maintaining contrast but reducing noise. Using a cutoff frequency of 0.200 (Nyquist = 0.500) and an order of 30, the filter provided a CF = 0.313 and a SF = 30.31. Linear interpolation was marginally better.

  4. Auditory stream segregation using amplitude modulated bandpass noise.

    PubMed

    Nie, Yingjiu; Nelson, Peggy B

    2015-01-01

    The purpose of this study was to investigate the roles of spectral overlap and amplitude modulation (AM) rate for stream segregation for noise signals, as well as to test the build-up effect based on these two cues. Segregation ability was evaluated using an objective paradigm with listeners' attention focused on stream segregation. Stimulus sequences consisted of two interleaved sets of bandpass noise bursts (A and B bursts). The A and B bursts differed in spectrum, AM-rate, or both. The amount of the difference between the two sets of noise bursts was varied. Long and short sequences were studied to investigate the build-up effect for segregation based on spectral and AM-rate differences. Results showed the following: (1). Stream segregation ability increased with greater spectral separation. (2). Larger AM-rate separations were associated with stronger segregation abilities. (3). Spectral separation was found to elicit the build-up effect for the range of spectral differences assessed in the current study. (4). AM-rate separation interacted with spectral separation suggesting an additive effect of spectral separation and AM-rate separation on segregation build-up. The findings suggest that, when normal-hearing listeners direct their attention towards segregation, they are able to segregate auditory streams based on reduced spectral contrast cues that vary by the amount of spectral overlap. Further, regardless of the spectral separation they are able to use AM-rate difference as a secondary/weaker cue. Based on the spectral differences, listeners can segregate auditory streams better as the listening duration is prolonged-i.e., sparse spectral cues elicit build-up segregation; however, AM-rate differences only appear to elicit build-up when in combination with spectral difference cues. PMID:26300831

  5. Thermal control design of the Lightning Mapper Sensor narrow-band spectral filter

    NASA Technical Reports Server (NTRS)

    Flannery, Martin R.; Potter, John; Raab, Jeff R.; Manlief, Scott K.

    1992-01-01

    The performance of the Lightning Mapper Sensor is dependent on the temperature shifts of its narrowband spectral filter. To perform over a 10 degree FOV with an 0.8 nm bandwidth, the filter must be 15 cm in diameter and mounted externally to the telescope optics. The filter thermal control required a filter design optimized for minimum bandpass shift with temperature, a thermal analysis of substrate materials for maximum temperature uniformity, and a thermal radiation analysis to determine the parameter sensitivity of the radiation shield for the filter, the filter thermal recovery time after occultation, and heater power to maintain filter performance in the earth-staring geosynchronous environment.

  6. Test Of A Microwave Amplifier With Superconductive Filter

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

    1995-01-01

    Report describes design and low-temperature tests of low-noise GaAs microwave amplifier combined with microstrip band-pass filter. Two versions of microstrip filter used in alternate tests; in one version, microstrips formed as films of high-transition-temperature superconductor Y/Ba/Cu/O on lanthanum aluminate substrate with gold film as ground plane. Other version identical except microstrips as well as ground plane made of gold, normally conductive.

  7. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T.-C.; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators.

  8. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations.

    PubMed

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T-C; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators. PMID:27131699

  9. A novel filter bank for biotelemetry.

    PubMed

    Karagözoglu, B

    2001-03-01

    In a multichannel biotelemetry system, signals taken from a patient are distributed along the available frequency range (bandwidth) of the system through frequency-division-multiplexing, and combined into a single composite signal. Biological signals that are limited to low frequencies (below 10 Hz) modulate the frequencies of respective sub-carriers. Other biological signals are carried in amplitude-modulated forms. It is recognized that recovering original signals from a composite signal at the receiver side is a technical challenge when a telemetry system with narrow bandwidth capacity is used, since such a system leaves little frequency spacing between information channels. A filter bank is therefore utilized for recovering biological signals that are transmitted. The filter bank contains filter units comprising switched-capacitor filter integrated circuits. The filters have two distinct and opposing outputs (band-stop (notch) and band-pass). Since most biological signals are at low frequencies, and modulated signals occupy a narrow band around the carrier, notch filters can be used to efficiently stop signals in the narrow frequency range. Once the interim channels are removed, other channels become well separated from each other, and band-pass filters can select them. In the proposed system, efficient filtering of closely packed channels is achieved, with low interference, from neighboring channels. The filter bank is applied to a system that carries four biological signals and a battery status indicator signal. Experimental results reinforce theoretical predictions that the filter bank successfully de-multiplexes closely packed information channels with low crosstalk between them. It is concluded that the proposed filter bank allows utilization of cost-effective multichannel biotelemetry systems that are designed around commercial audio devices, and that it can be readily adapted to a broad range of physiological recording requirements. PMID:11458572

  10. Filter Circuit Design by Parallel Genetic Programming

    NASA Astrophysics Data System (ADS)

    Yano, Yuichi; Kato, Toshiji; Inoue, Kaoru; Miki, Mitsunori

    Genetic Programming (GP) is an extension of Genetic Algorithm(GA) to handle more structural problems. In this paper, an approach to filter circuit design by GP is proposed. By designing a gene which includes not only the parameters of consisting elements, but also the structural information of the circuit, it becomes possible to apply the proposed approach to various types of filter circuits. GP depends much on trial and error due to its probabilitic nature. To decrease this uncertainty and ensure the progress of the evolution, Parallel GP with multiple populations with the island model is also proposed. An MPI-based cluster system is used for realization of this parallel computing where each island correspondsd to each node. A lowpass and an asymmetric bandpass filters are designed. One hundred times of trials for multiple populations with and without migrations are tested in the design of lowpass filter to confirm the validity of the proposed method. In the asymmetric bandpass filter design, the results are compared with those of the circuit designed by hand to confirm the effectiveness of the proposed method. The proposed approach is applicable to various types of filter circuits. It can contribute to an automated design procedure, where it would require a expirenced designer if done by hand. It is also possible to obtain a new circuit design which would not be possible if done by hand.

  11. Applications of the magneto-optical filter to stellar pulsation measurements

    NASA Technical Reports Server (NTRS)

    Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.

    1984-01-01

    A proposed method of employing the Cacciani magneto-optical filter (MOF) for stellar seismology studies is described. The method relies on the fact that the separation of the filter bandpasses in the MOF can be changed by varying the level of input power to the filter cells. With the use of a simple servosystem the bandpass of a MOF can be tuned to compensate for the changes in the radial velocity of a star introduced by the orbital motion of the Earth. Such a tuned filter can then be used to record intensity fluctuations through the MOF bandpass over an extended period of time for each given star. Also, the use of a two cell version of the MOF makes it possible to alternately chop between the bandpass located in the stellar line wing and a second bandpass located in the stellar continuum. Rapid interchange between the two channels makes it possible for atmospheric-introduced noise to be removed from the time series.

  12. Applications of the magneto-optical filter to stellar pulsation measurements

    NASA Technical Reports Server (NTRS)

    Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk, Steven

    1986-01-01

    A proposed method of employing the Cacciani magneto-optical filter (MOF) for stellar seismology studies is described. The method relies on the fact that the separation of the filter bandpasses in the MOF can be changed by varying the level of input power to the filter cells. With the use of a simple servosystem the bandpass of a MOF can be tuned to compensate for the changes in the radial velocity of a star introduced by the orbital motion of the earth. Such a tuned filter can then be used to record intensity fluctuations through the MOF bandpass over an extended period of time for each given star. Also, the use of a two cell version of the MOF makes it possible to alternately chop between the bandpass located in the stellar line wing and a second bandpass located in the stellar continuum. Rapid interchange between the two channels makes it possible for atmospheric-introduced noise to be removed from the time series.

  13. Wideband tunable optoelectronic oscillator based on a phase modulator and a tunable optical filter.

    PubMed

    Xie, Xiaopeng; Zhang, Cheng; Sun, Tao; Guo, Peng; Zhu, Xiaoqi; Zhu, Lixin; Hu, Weiwei; Chen, Zhangyuan

    2013-03-01

    A widely tunable optoelectronic oscillator (OEO) based on a broadband phase modulator and a tunable optical bandpass filter is proposed and experimentally demonstrated. A tunable range from 4.74 to 38.38 GHz is realized by directly tuning the bandwidth of the optical bandpass filter. To the best of our knowledge, this is the widest fundamental frequency tunable range ever achieved by an OEO. The phase noise performance of the generated signal is also investigated. The single-sideband phase noise is below -120 dBc/Hz at an offset of 10 KHz within the whole tunable range. PMID:23455255

  14. Filter-free wavelength converter using Sagnac loop and delayed interferometer

    NASA Astrophysics Data System (ADS)

    Tsuji, K.; Yamaguchi, T.; Onodera, N.; Saruwatari, M.

    2006-01-01

    A filter-free fiber-XPM-based wavelength converter is proposed and experimentally demonstrated without conventional bandpass optical filters used to filter out the converted signal. The converter is constructed with a propagation-diversity Sagnac loop to separate a converted signal from a pump signal and a delayed interferometer to covert the XPM signal into intensity modulation. We show that 10-Gbit/s input signals are successfully converted to signals with allotted wavelengths by our proposed scheme.

  15. Far-infrared filters utilizing small particle scattering and antireflection coatings

    NASA Technical Reports Server (NTRS)

    Armstrong, K. R.; Low, F. J.

    1974-01-01

    High-transmission, low-pass scatter filters for blocking at wavelengths from 3.5 to 50 microns and single-layer antireflection coatings for optical materials used in the 25- to 300-micron region of the spectrum are described. The application of both techniques to liquid-He-cooled filters permits the construction of efficient low-pass and medium-width bandpass filters for use throughout the far infrared.

  16. Comparison of the Richardson-Lucy method and a classical approach for spectrometer bandpass correction

    NASA Astrophysics Data System (ADS)

    Eichstädt, S.; Schmähling, F.; Wübbeler, G.; Anhalt, K.; Bünger, L.; Krüger, U.; Elster, C.

    2013-04-01

    Bandpass correction in spectrometer measurements using monochromators is often necessary in order to obtain accurate measurement results. The classical approach of spectrometer bandpass correction is based on local polynomial approximations and the use of finite differences. Here we compare this approach with an extension of the Richardson-Lucy method, which is well known in image processing, but has not been applied to spectrum bandpass correction yet. Using an extensive simulation study and a practical example, we demonstrate the potential of the Richardson-Lucy method. In contrast to the classical approach, it is robust with respect to wavelength step size and measurement noise. In almost all cases the Richardson-Lucy method turns out to be superior to the classical approach both in terms of spectrum estimate and its associated uncertainties.

  17. Achieving all-dielectric metamaterial band-pass frequency selective surface via high-permittivity ceramics

    NASA Astrophysics Data System (ADS)

    Li, Liyang; Wang, Jiafu; Ma, Hua; Wang, Jun; Feng, Mingde; Du, Hongliang; Yan, Mingbao; Zhang, Jieqiu; Qu, Shaobo; Xu, Zhuo

    2016-03-01

    In this paper, we propose the design of all-dielectric metamaterial band-pass frequency selective surfaces (FSSs) using high-permittivity ceramics based on effective medium theory and dielectric resonator theory. The band-pass response can be determined by the permittivity of the dielectric material, the periodicity, and geometrical shape of the dielectric unit cell. As an example, a band-pass FSS composed of H shaped ceramic resonators is demonstrated. Both the simulation and experiment results show that the FSS can achieve a pass band in X-band. Since such FSSs are made of low-loss high-permittivity ceramics, they are of important application values, especially in high-temperature, high-power environments. The design method can be readily extended to the design of FSSs in other frequencies.

  18. Stack filters

    NASA Astrophysics Data System (ADS)

    Wendt, P. D.; Coyle, E. J.; Gallagher, N. C., Jr.

    1986-08-01

    A large class of easily implemented nonlinear filters called stack filters are discussed which includes the rank order operators in addition to the compositions of morphological operators. Techniques similar to those used to determine the root signal behavior of median filters are employed to study the convergence properties of the filters, and necessary conditions for a stack filter to preserve monotone regions or edges in signals, and the output distribution of the filters, are obtained. Among the stack filters of window width three are found asymmetric median filters in which one removes only positive going edges, the other removes only negative going edges, while the median filter removes impulses of both signs.

  19. Metal-mesh optical filter technology for mid-IR, far-IR, and submillimeter

    NASA Astrophysics Data System (ADS)

    McGovern, William R.; Swinehart, Philip R.; Hogue, Eric L.; Daughton, David R.; DeLombard, Jay V.

    2012-06-01

    The innovative, high transmission band-pass filter technology presented here for the mid infrared (IR), terahertz (THz) and submillimeter ranges can tolerate cryogenic temperatures (down to 4K and below), are radiation-hard, vacuum-compatible and vibration-tolerant making them launch-capable and durable for potential space applications. In addition, Lake Shore band-pass filters (BPF) are light weight, as they employ no heavy substrates, nor have any vibronic bands due to polymer support layers. The filters are less than 2 mm thick (mostly the mounting frame) which allows insertion into tight spaces and standard filter wheels. The thin, light weight, vacuum compatible design can be incorporated into almost any detector setup. Filters are available for quick delivery in 29 standard center wavelengths (CWL) with 4 standard diameter sizes, up to 40mm inner diameter (ID).

  20. Low-power Gm-C filter employing current-reuse differential difference amplifiers

    DOE PAGESBeta

    Mincey, John S.; Briseno-Vidrios, Carlos; Silva-Martinez, Jose; Rodenbeck, Christopher T.

    2016-08-10

    This study deals with the design of low-power, high performance, continuous-time filters. The proposed OTA architecture employs current-reuse differential difference amplifiers in order to produce more power efficient Gm-C filter solutions. To demonstrate this, a 6th order low-pass Butterworth filter was designed in 0.18 m CMOS achieving a 65-MHz -3-dB frequency, an in-band input-referred third-order intercept point of 12.0 dBm, and an input referred noise density of 40 nV/Hz1=2, while only consuming 8.07 mW from a 1.8 V supply and occupying a total chip area of 0.21 mm2 with a power consumption of only 1.19 mW per pole.

  1. Single cavity filters on end-faces of optical fibers

    NASA Astrophysics Data System (ADS)

    Meister, Stefan; Schweda, Dawid; Dziedzina, Marcus; Al-Saadi, Aws; Franke, Bülent A.; Scharfenorth, Chris; Grimm, Bernd; Dufft, Daniela; Schrader, Sigurd K.; Eichler, Hans J.

    2010-02-01

    We have developed thin film Fabry-Perot filters directly coated on optical fibers to archive a high level of integration with a reduction of optical elements. Such band-pass filters can be used in fiber optical sensor systems, and for fiber communication, e.g. CWDM applications. The filters cavities consist of a single spacer and two dielectric mirrors. The dielectric mirrors are deposited by PVD directly on end-faces of single-mode optical fibers. Dielectric as well as polymeric materials were applied as the spacer layer. Polymeric spacer layers were deposited by dip coating. The influence of the mirror reflectivity on the transmission band of the Fabry-Perot filters was investigated. Furthermore, the optical performance of filters with first order (λ/2) as well as higher order spacers was analyzed. The experimental results are compared with numerical analysis of Fabry-Perot cavities on the end-face of cylindrical waveguides. The spectral characteristic of the filters are calculated using a software solving Maxwelĺs equations by a FDTD method. The layer design of the filters and the deposition process were optimized for maximum transmission and narrow bandwidth of the transmission peak. Passive band-pass filters on fiber end-faces were designed, fabricated and characterized for transmission wavelengths of 945 nm, 1300 nm, as well as 1550 nm. Bandwidths as narrow as 1 nm could be achieved for 945 nm.

  2. Multi-frequency weak signal detection based on wavelet transform and parameter compensation band-pass multi-stable stochastic resonance

    NASA Astrophysics Data System (ADS)

    Han, Dongying; li, Pei; An, Shujun; Shi, Peiming

    2016-03-01

    In actual fault diagnosis, useful information is often submerged in heavy noise, and the feature information is difficult to extract. A novel weak signal detection method aimed at the problem of detecting multi-frequency signals buried under heavy background noise is proposed based on wavelet transform and parameter compensation band-pass multi-stable stochastic resonance (SR). First, the noisy signal is processed by parameter compensation, with the noise and system parameters expanded 10 times to counteract the effect of the damping term. The processed signal is decomposed into multiple signals of different scale frequencies by wavelet transform. Following this, we adjust the size of the scaled signals' amplitudes and reconstruct the signals; the weak signal frequency components are then enhanced by multi-stable stochastic resonance. The enhanced components of the signal are processed through a band-pass filter, leaving the enhanced sections of the signal. The processed signal is analyzed by FFT to achieve detection of the multi-frequency weak signals. The simulation and experimental results show that the proposed method can enhance the signal amplitude, can effectively detect multi-frequency weak signals buried under heavy noise and is valuable and usable for bearing fault signal analysis.

  3. Isotropically sensitive optical filter employing atomic resonance transitions

    DOEpatents

    Marling, J.B.

    An ultra-high Q isotropically sensitive optical filter or optical detector is disclosed employing atomic resonance transitions. More specifically, atomic resonance transitions utilized in conjunction with two optical bandpass filters provide an optical detector having a wide field of view (approx. 2 ..pi.. steradians) and very narrow acceptance bandwidth approaching 0.01A. A light signal to be detected is transmitted through an outer bandpass filter into a resonantly absorbing atomic vapor, the excited atomic vapor than providing a fluorescence signal at a different wavelength which is transmitted through an inner bandpass filters have no common transmission band, therby resulting in complete blockage of all optical signals that are not resonantly shifted in wavelength by the intervening atomic vapor. Two embodiments are disclosed, one in which the light signal raises atoms contained in the atomic vapor from the ground state to an excited state from which fluorescence occurs, and the other in which a pump laser is used to raise the atoms in the ground state to a first excited state from which the light signal then is resonantly absorbed, thereby raising the atoms to a second excited state from which fluorescence occurs. A specific application is described in which an optical detector according to the present invention can be located in an orbiting satellite.

  4. Simultaneous correction of bandpass and stray-light effects in array spectroradiometer data

    NASA Astrophysics Data System (ADS)

    Nevas, Saulius; Wübbeler, Gerd; Sperling, Armin; Elster, Clemens; Teuber, Annette

    2012-04-01

    A method for the simultaneous correction of bandpass and stray-light effects in array spectroradiometer data is presented. The method is based on the inversion of the instrument matrix of a device determined with the help of tuneable lasers. By applying the Tikhonov regularization technique, a straightforward correction of the measurement results is possible.

  5. Polarization and angle insensitive dual-band bandpass frequency selective surface using all-dielectric metamaterials

    NASA Astrophysics Data System (ADS)

    Yu, Fei; Wang, Jun; Wang, Jiafu; Ma, Hua; Du, Hongliang; Xu, Zhuo; Qu, Shaobo

    2016-04-01

    In this paper, we demonstrate a dual-band bandpass all-dielectric frequency selective surface (FSS), the building elements of which are high-permittivity ceramic particles rather than metallic patterns. With proper structural design and parameter adjustment, the resonant frequency can be tuned at will. Dual-band bandpass response can be realized due to the coupling between electric and magnetic resonances. As an example, a dual-band bandpass FSS is designed in Ku band, which is composed of two-dimensional periodic arrays of complementary quatrefoil structures (CQS) cut from dielectric plates. Moreover, cylindrical dielectric resonators are introduced and placed in the center of each CQS to broaden the bandwidth and to sharpen the cut-off frequency. Theoretical analysis shows that the bandpass response arises from impedance matching caused by electric and magnetic resonances. In addition, effective electromagnetic parameters and dynamic field distributions are presented to explain the mechanism of impedance matching. The proposed FSS has the merits of polarization independence, stable transmission, and sharp roll-off frequency. The method can also be used to design all-dielectric FSSs with continuum structures at other frequencies.

  6. Bandpass Sampling--An Opportunity to Stress the Importance of In-Depth Understanding

    ERIC Educational Resources Information Center

    Stern, Harold P. E.

    2010-01-01

    Many bandpass signals can be sampled at rates lower than the Nyquist rate, allowing significant practical advantages. Illustrating this phenomenon after discussing (and proving) Shannon's sampling theorem provides a valuable opportunity for an instructor to reinforce the principle that innovation is possible when students strive to have a complete…

  7. Band-pass design optimization of piezoelectric cantilever bimorph energy harvester

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Williams, Keith A.

    2011-03-01

    Piezoelectric energy harvesting has become a feasible method for powering micro portable electronics and wireless sensor networks by converting ambient vibration energy into electrical energy. As a thumb of rule, it is critical to tune the resonant frequency of the generator to the frequency of the environmental vibrations in order to induce the maximum structural deformation and then the maximum converted electrical energy through piezoelectric effect. However, it is well-known that the ambient vibrations are not usually fixed in only one single frequency and could span over a limited frequency band. In this paper, a band-pass design optimization of piezoelectric cantilever bimorph (PCB) energy harvester is presented based on the system transfer function of the PCB generator presented in a previous literature. For such an energy harvester, a group of PCB with dimensions appropriately selected can be integrated into a band-pass energy harvester working over a limited frequency band if the dimensions of piezoelectric bimorphs and proof masses are appropriately chosen. Further, the finite element analysis (FEA) of such a band-pass energy harvester is performed in ANSYS to validate the theoretical proposal. The result shows that the band-pass design optimization leads to a piezoelectric generator working over a certain frequency band while keeping outputting the relatively stable open-circuit voltage.

  8. Application of high-pass filtering techniques on gravity and magnetic data of the eastern Qattara Depression area, Western Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Zahra, Hesham Shaker; Oweis, Hesham T.

    2016-06-01

    In this work, a reconnaissance study is presented to delineate the subsurface tectonics and lithological inferences of the eastern area of Qattara Depression using the Bouguer gravity and aeromagnetic data. To achieve this goal, several transformation techniques and filtering processes are accomplished on these maps. At first, the total intensity aeromagnetic map is processed through the application of reduction to the magnetic north pole technique. The fast Fourier transform is carried out on the gravity and RTP magnetic data for establishing and defining the residual (shallow) sources. The frequency high-pass filtering is used to enhance the anomaly wavelengths associated with the shallow sources. The used processing techniques are the polynomial surface fitting enhancement, Laplacian, Strike Filtering, Enhancement Utilization, Suppression Utilization, Butterworth Filtering Utilization, Butterworth high-pass filter, Euler's deconvolution and forward modeling. The equivalent depths of the isolated short wavelength anomalies are 0.759 and 0.340 km below the flight surface, and the depths of the intermediate wavelength anomalies are 1.28 and 2.00 km for the gravity and magnetic data, respectively. Finally, the quantitative interpretations of the Bouguer gravity and RTP magnetic maps of the study area, reflect the occurrence of the various types of structures and their components. The main tectonic deformations of the study area have NNW-SSE, NNE-SSW, NE-SW, NW-SE and E-W trends.

  9. Input-Feedforward Two-Path Band-Pass Delta-Sigma Modulator Based on Horizontal or Vertical Opamp Sharing Technique

    NASA Astrophysics Data System (ADS)

    Waki, Naoya; Sato, Hiroki; Hyogo, Akira; Sekine, Keitaro

    In this paper, horizontal (where an opamp is shared in two adjacent stages) and vertical (where an opamp is shared across two paths) opamp sharing techniques for a two-path band-pass (BP) ΔΣ modulator are described, and input-feedforward two-path fourth-order BP ΔΣ modulators that have only two opamps are proposed. The proposed modulators are based on the horizontal or vertical opamp sharing technique. They can be realized with both a summation circuit using a switched capacitor (SC) network and a second-order high-pass filter (HPF) with a horizontal shared opamp or a double-sampling first-order HPF with a vertical shared opamp, which are based on an SC first-order HPF with an opamp. These techniques can reduce the number of opamps with no additional component and the chip area as well as realize lower power consumption.

  10. Surface plasmonic enhanced polarimetric longwave infrared photodetection with band pass spectral filtering

    NASA Astrophysics Data System (ADS)

    Vasinajindakaw, Puminun; Vaillancourt, Jarrod; Gu, Guiru; Lu, Xuejun

    2012-06-01

    In this paper, we report a surface plasmonic enhanced polarimetric longwave infrared (LWIR) photodetector. Polarization-selective detection of LWIR incidence with different polarizations is achieved at different plasmonic resonant modes. Band-pass spectral filtering is also provided at the plasmonic resonant modes by the plasmonic enhancement. The extinction ratio (ER) of the polarimetric detection and its limiting factor is discussed.

  11. Terahertz wave filter based on cinquefoil photonic crystal

    NASA Astrophysics Data System (ADS)

    Sun, Chao; Li, Jiu-sheng

    2012-03-01

    There are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, terahertz wave communications, and plasma diagnostics. For potential applications, the functional devices, such as beam polarizers, modulators and filters, are crucuial components for a terahertz system. As a dispensable device for ultrafast information processing and interconnection of terahertz wave communication, terahertz wave filter has attracted considerable attention. In this paper, we design the terahertz wave filter structure based on three kinds of photonic crystals structures. The finite-difference time-domain (FDTD) has been employed to analysis the performances of these terahertz wave filters. The simulation results show that these designed filters exhibit excellent transmission performance such as high transmission at the central frequency, adjustable bandpass, and good rejection of the sideband frequencies. Three kinds of compact and integrated terahertz wave filters are obtained.

  12. Terahertz wave filter based on cinquefoil photonic crystal

    NASA Astrophysics Data System (ADS)

    Sun, Chao; Li, Jiu-sheng

    2011-11-01

    There are increasing demands for experiments in terahertz frequencies, in different areas such as biotechnology, nanotechnology, space science, security, terahertz wave communications, and plasma diagnostics. For potential applications, the functional devices, such as beam polarizers, modulators and filters, are crucuial components for a terahertz system. As a dispensable device for ultrafast information processing and interconnection of terahertz wave communication, terahertz wave filter has attracted considerable attention. In this paper, we design the terahertz wave filter structure based on three kinds of photonic crystals structures. The finite-difference time-domain (FDTD) has been employed to analysis the performances of these terahertz wave filters. The simulation results show that these designed filters exhibit excellent transmission performance such as high transmission at the central frequency, adjustable bandpass, and good rejection of the sideband frequencies. Three kinds of compact and integrated terahertz wave filters are obtained.

  13. Spectral and Wavefront Error Performance of WFIRST/AFTA Prototype Filters

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel; Seide, Laurie; Marx, Cathy; Pasquale, Bert; McMann, Joseph; Hagopian, John; Dominguez, Margaret; Gong, Qian; Morey, Peter

    2016-01-01

    The Cycle 5 design baseline for the Wide-Field Infrared Survey Telescope Astrophysics Focused Telescope Assets (WFIRSTAFTA) instrument includes a single wide-field channel (WFC) instrument for both imaging and slit-less spectroscopy. The only routinely moving part during scientific observations for this wide-field channel is the element wheel (EW) assembly. This filter-wheel assembly will have 8 positions that will be populated with 6 bandpass filters, a blank position, and a Grism that will consist of a three-element assembly to disperse the full field with an undeviated central wavelength for galaxy redshift surveys. All filter elements in the EW assembly will be made out of fused silica substrates (110 mm diameter) that will have the appropriate bandpass coatings according to the filter designations (Z087, Y106, J129, H158, F184, W149 and Grism). This paper presents and discusses the performance (including spectral transmission and reflectedtransmitted wavefront error measurements) of a subset of bandpass filter coating prototypes that are based on the WFC instrument filter compliment. The bandpass coating prototypes that are tested in this effort correspond to the Z087, W149, and Grism filter elements. These filter coatings have been procured from three different vendors to assess the most challenging aspects in terms of the in-band throughput, out of band rejection (including the cut-on and cutoff slopes), and the impact the wavefront error distortions of these filter coatings will have on the imaging performance of the de-field channel in the WFIRSTAFTA observatory.

  14. Performance of a Y-Ba-Cu-O superconducting filter/GaAs low noise amplifier hybrid circuit

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

    1992-01-01

    A superconducting 7.3 GHz two-pole microstrip bandpass filter and a GaAs low noise amplifier (LNA) were combined into a hybrid circuit and characterized at liquid nitrogen temperatures. This superconducting/seismology circuit's performance was compared to a gold filter/GaAs LNA hybrid circuit. The superconducting filter/GaAs LNA hybrid circuit showed higher gain and lower noise figure than its gold counterpart.

  15. Performance of a Y-Ba-Cu-O superconducting filter/GaAs low noise amplifier hybrid circuit

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Toncich, S. S.; Chorey, C. M.; Bonetti, R. R.; Williams, A. E.

    1992-01-01

    A superconducting 7.3 GHz two-pole microstrip bandpass filter and a GaAs low noise amplifier (LNA) were combined into an active circuit and characterized at liquid nitrogen temperatures. This superconducting/semiconducting circuit's performance was compared to a gold filter/GaAs LNA hybrid circuit. The superconducting filter/GaAs LNA hybrid circuit showed higher gain and lower noise figure than its gold counterpart.

  16. Development of filter exchangeable 3CCD camera for multispectral imaging acquisition

    NASA Astrophysics Data System (ADS)

    Lee, Hoyoung; Park, Soo Hyun; Kim, Moon S.; Noh, Sang Ha

    2012-05-01

    There are a lot of methods to acquire multispectral images. Dynamic band selective and area-scan multispectral camera has not developed yet. This research focused on development of a filter exchangeable 3CCD camera which is modified from the conventional 3CCD camera. The camera consists of F-mounted lens, image splitter without dichroic coating, three bandpass filters, three image sensors, filer exchangeable frame and electric circuit for parallel image signal processing. In addition firmware and application software have developed. Remarkable improvements compared to a conventional 3CCD camera are its redesigned image splitter and filter exchangeable frame. Computer simulation is required to visualize a pathway of ray inside of prism when redesigning image splitter. Then the dimensions of splitter are determined by computer simulation which has options of BK7 glass and non-dichroic coating. These properties have been considered to obtain full wavelength rays on all film planes. The image splitter is verified by two line lasers with narrow waveband. The filter exchangeable frame is designed to make swap bandpass filters without displacement change of image sensors on film plane. The developed 3CCD camera is evaluated to application of detection to scab and bruise on Fuji apple. As a result, filter exchangeable 3CCD camera could give meaningful functionality for various multispectral applications which need to exchange bandpass filter.

  17. A review of metal mesh filters

    NASA Astrophysics Data System (ADS)

    Ade, Peter A. R.; Pisano, Giampaolo; Tucker, Carole; Weaver, Samuel

    2006-06-01

    The Astronomical Instrumentation Group at Cardiff University has been developing metal mesh optical filters for more than 30 years, which are currently in use in many ground-, balloon- and space-based instruments. Here we review the current state of the art with respect to these quasi-optical components (low-pass, high-pass and band-pass filters, dichroics and beam-dividers) as developed for the FIR and sub-millimetre wavelength region. We compare performance data with various modelling tools (HFSS, transmission line theory or Floquet mode analysis). These models assist with our understanding of the behaviour of these filters when used at non-normal incidence or in the diffraction region of the grid structures. Interesting artefacts, such as the Wood anomalies and behaviour with S and P polarisations, which dictate the usage of these components in polarisation sensitive instruments, will be discussed.

  18. Disk filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  19. Disk filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  20. An R-peak detection method that uses an SVD filter and a search back system.

    PubMed

    Jung, Woo-Hyuk; Lee, Sang-Goog

    2012-12-01

    In this paper, we present a method for detecting the R-peak of an ECG signal by using an singular value decomposition (SVD) filter and a search back system. The ECG signal was detected in two phases: the pre-processing phase and the decision phase. The pre-processing phase consisted of the stages for the SVD filter, Butterworth High Pass Filter (HPF), moving average (MA), and squaring, whereas the decision phase consisted of a single stage that detected the R-peak. In the pre-processing phase, the SVD filter removed noise while the Butterworth HPF eliminated baseline wander. The MA removed the remaining noise of the signal that had gone through the SVD filter to make the signal smooth, and squaring played a role in strengthening the signal. In the decision phase, the threshold was used to set the interval before detecting the R-peak. When the latest R-R interval (RRI), suggested by Hamilton et al., was greater than 150% of the previous RRI, the method of detecting the R-peak in such an interval was modified to be 150% or greater than the smallest interval of the two most latest RRIs. When the modified search back system was used, the error rate of the peak detection decreased to 0.29%, compared to 1.34% when the modified search back system was not used. Consequently, the sensitivity was 99.47%, the positive predictivity was 99.47%, and the detection error was 1.05%. Furthermore, the quality of the signal in data with a substantial amount of noise was improved, and thus, the R-peak was detected effectively. PMID:22922087

  1. Simulator spectral characterization using balloon calibrated solar cells with narrow band pass filters

    NASA Technical Reports Server (NTRS)

    Goodelle, G. S.; Brooks, G. R.; Seaman, C. H.

    1981-01-01

    The development and implementation of an instrument for spectral measurement of solar simulators for testing solar cell characteristics is reported. The device was constructed for detecting changes in solar simulator behavior and for comparing simulator spectral irradiance to solar AM0 output. It consists of a standard solar cell equipped with a band pass filter narrow enough so that, when flown on a balloon to sufficient altitude along with sufficient numbers of cells, each equipped with filters of different bandpass ratings, the entire spectral response of the standard cell can be determined. Measured short circuit currents from the balloon flights thus produce cell devices which, when exposed to solar simulator light, have a current which does or does not respond as observed under actual AM0 conditions. Improvements of the filtered cells in terms of finer bandpass filter tuning and measurement of temperature coefficients are indicated.

  2. Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures.

    PubMed

    Horie, Yu; Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Faraon, Andrei

    2016-05-30

    We propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-Pérot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250nm around λ = 1550nm (Δλ/λ = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwiched metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling. PMID:27410093

  3. Wide bandwidth and high resolution planar filter array based on DBR-metasurface-DBR structures

    NASA Astrophysics Data System (ADS)

    Horie, Yu; Arbabi, Amir; Arbabi, Ehsan; Kamali, Seyedeh Mahsa; Faraon, Andrei

    2016-05-01

    We propose and experimentally demonstrate a planar array of optical bandpass filters composed of low loss dielectric metasurface layers sandwiched between two distributed Bragg reflectors (DBRs). The two DBRs form a Fabry-P\\'erot resonator whose center wavelength is controlled by the design of the transmissive metasurface layer which functions as a phase shifting element. We demonstrate an array of bandpass filters with spatially varying center wavelengths covering a wide range of operation wavelengths of 250 nm around {\\lambda} = 1550 nm ({\\Delta}{\\lambda}/{\\lambda} = 16%). The center wavelengths of each filter are independently controlled only by changing the in-plane geometry of the sandwiched metasurfaces, and the experimentally measured quality factors are larger than 700. The demonstrated filter array can be directly integrated on top of photodetector arrays to realize on-chip high-resolution spectrometers with free-space coupling.

  4. Photonic aided bandpass sampling in coherent phase modulated radio-over-fiber links

    NASA Astrophysics Data System (ADS)

    Cao, Minghua; Li, Jianqiang; Dai, Jian; Dai, Yitang; Yin, Feifei; Zhou, Yue; Xu, Kun

    2016-06-01

    We have experimentally presented a digital coherent receiver employing photonic aided bandpass sampling technology for phase-modulated radio-over-fiber (RoF) links. An optical intensity modulator (IM) is utilized as the bandpass sampler which performs encoded on-off keyed pulse sequence on the optical local oscillator. Quaternary Phase Shift Keying (QPSK) modulated data signal with 20 MHz bandwidth at 5.2 GHz, 10.2 GHz and 15.2 GHz RF carrier frequency is experimentally demonstrated to be successfully detected by using balanced photodiodes (BPDs) with only 800 MHz analog bandwidth. It demonstrates that the required analog bandwidth of BPDs and ADCs can be dramatically reduced in a direct sampled coherent RoF communications system.

  5. Computer-aided design of millimeter-wave E-plane filters

    NASA Astrophysics Data System (ADS)

    Shih, Y.-C.; Itoh, T.; Bui, L. Q.

    1983-02-01

    A computer-aided design (CAD) algorithm has been developed for a class of E-plane bandpass filters. The analysis portion of the algorithm is based on the residue-calculus technique and a generalized scattering parameter method. It is mathematically exact and numerically very efficient. Filters designed with this method have been fabricated and tested in Ka-band. Good agreement with design has been obtained.

  6. Water Filters

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Aquaspace H2OME Guardian Water Filter, available through Western Water International, Inc., reduces lead in water supplies. The filter is mounted on the faucet and the filter cartridge is placed in the "dead space" between sink and wall. This filter is one of several new filtration devices using the Aquaspace compound filter media, which combines company developed and NASA technology. Aquaspace filters are used in industrial, commercial, residential, and recreational environments as well as by developing nations where water is highly contaminated.

  7. Digital linearization of multi-carrier RF link with photonic bandpass sampling.

    PubMed

    Dai, Yitang; Liang, Xiaodong; Yin, Feifei; Zhou, Yue; Zhang, Junyi; Yu, Lan; Li, Jianqiang; Xu, Kun

    2015-09-01

    Due to the capacity in simultaneously down-converting and receiving ultra-wideband, multi-carrier radio frequency (RF) or microwave signals, the photonic bandpass sampling has found more and more applications in multi-carrier communication, frequency-agile coherent radar, compressive sensing, etc. The nonlinear transfer during the electronics-to-optics conversion results in distortions, which are bandpass sampled and frequency-folded within the first Nyquist zone, together with the target signals. Because of the multi-octave-span operation, all nonlinearities must be considered besides the usually-concerned third-order inter-modulation distortion (IMD3). We show theoretically that a photonic bandpass sampling link is equivalent to a baseband digital nonlinear link, and then propose a corresponding linearization scheme for the output signal. Such digital linearization is capable of suppressing all types of distortions. Both numerical and experimental examples are demonstrated, where all of the 3rd-order nonlinearities, including the internal and external IMD3, the cross modulation, and 3rd-order harmonics, are well eliminated. PMID:26368420

  8. Biological Filters.

    ERIC Educational Resources Information Center

    Klemetson, S. L.

    1978-01-01

    Presents the 1978 literature review of wastewater treatment. The review is concerned with biological filters, and it covers: (1) trickling filters; (2) rotating biological contractors; and (3) miscellaneous reactors. A list of 14 references is also presented. (HM)

  9. Metallic Filters

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Filtration technology originated in a mid 1960's NASA study. The results were distributed to the filter industry, an HR Textron responded, using the study as a departure for the development of 421 Filter Media. The HR system is composed of ultrafine steel fibers metallurgically bonded and compressed so that the pore structure is locked in place. The filters are used to filter polyesters, plastics, to remove hydrocarbon streams, etc. Several major companies use the product in chemical applications, pollution control, etc.

  10. Measuring Redshifts of Emission-line Galaxies Using Ramp Filters

    NASA Astrophysics Data System (ADS)

    Lesser, Ryan William; Bohman, John; McNeff, Mathew; Holden, Marcus; Moody, Joseph; Joner, Michael D.; Barnes, Jonathan

    2016-01-01

    Photometric redshifts are routinely obtained for galaxies without emission using broadband photometry. It is possible in theory to derive reasonably accurate (< 200 km/sec) photometric redshift values for emission-line objects using "ramp" filters with a linearly increasing/decreasing transmission through the bandpass. To test this idea we have obtained a set of filters tuned for isolating H-alpha at a redshift range of 0-10,000 km/sec. These filters consist of two that vary close to linearly in transmission, have opposite slope, and cover the wavelength range from 655nm - 685nm, plus a Stromgren y and 697nm filter to measure the continuum. Redshifts are derived from the ratio of the ramp filters indices after the continuum has been subtracted out. We are finishing the process of obtaining photometric data on a set of about 100 galaxies with known redshift to calibrate the technique and will report on our results.