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Sample records for polarization-based balanced heterodyne

  1. Polarization shaping in the mid-IR and polarization-based balanced heterodyne detection with application to 2D IR spectroscopy.

    PubMed

    Middleton, Chris T; Strasfeld, David B; Zanni, Martin T

    2009-08-17

    We demonstrate amplitude, phase and polarization shaping of femtosecond mid-IR pulses using a germanium acousto-optical modulator by independently shaping the frequency-dependent amplitudes and phases of two orthogonally polarized pulses which are then collinearly overlapped using a wire-grid polarizer. We use a feedback loop to set and stabilize the relative phase of the orthogonal pulses. We have also used a wire-grid polarizer to implement polarization-based balanced heterodyne detection for improved signal-to-noise of 2D IR spectra collected in a pump-probe geometry. Applications include coherent control of molecular vibrations and improvements in multidimensional IR spectroscopy.

  2. Optical heterodyne accelerometry: passively stabilized, fully balanced velocity interferometer system for any reflector

    SciTech Connect

    Buttler, William T.; Lamoreaux, Steven K.

    2010-08-10

    We formalize the physics of an optical heterodyne accelerometer that allows measurement of low and high velocities from material surfaces under high strain. The proposed apparatus incorporates currently common optical velocimetry techniques used in shock physics, with interferometric techniques developed to self-stabilize and passively balance interferometers in quantum cryptography. The result is a robust telecom-fiber-based velocimetry system insensitive to modal and frequency dispersion that should work well in the presence of decoherent scattering processes, such as from ejecta clouds and shocked surfaces.

  3. Quantum-limited operation of balanced mixer homodyne and heterodyne receivers

    NASA Astrophysics Data System (ADS)

    Machida, Susumu; Yamamoto, Yoshihisa

    1986-05-01

    In the GaAs semiconductor laser balanced mixer heterodyne receiver of Abbas and Chan (1983), the photocurrent fluctuation due to local oscillator wave intensity noise was suppressed, but the absolute quantum noise level calibration was not clarified. In this paper, the results of experimental calibration of the quantum noise level were obtained using two different methods: photocurrent spectral density measurement and photoelectron counting. The noise of a balanced mixer operation was confirmed to be truly quantum limited; the photocurrent fluctuation spectral density measured with a spectrum analyzer agreed with the quantum noise spectral density. The deviations from the absolute quantum noise level were within + or -0.02 dB. Complete suppression of local oscillator excess noise was demonstrated in the 0-1.5 GHz frequency region. Uses of balanced mixers for observing the squeezing phenomenon and quantum nondemolition measurement is mentioned.

  4. Polarization-based balanced detection for spectral-domain optical coherence tomography.

    PubMed

    Black, Adam J; Akkin, Taner

    2015-08-20

    We present a new design for spectral-domain optical coherence tomography that allows balanced detection using a single camera. The design uses polarization optics to encode the light in reference and sample arms. Two parallel and highly aligned spectra, which carry out-of-phase interference signals, in-phase common noise, and auto-interference terms, are focused on the camera, which performs the digital balanced detection for each wavelength. The optical system is characterized and tested for tissue imaging. Results demonstrate consistent signal gains in depth and suppression of DC and sample auto-interference. The design could be further amended for polarization-sensitive imaging and might demonstrate a market for manufacturing dual-line cameras with analog-balanced detection capability.

  5. Design of a full-dynamic-range balanced detection heterodyne gyroscope with common-path configuration.

    PubMed

    Lin, Chu-En; Yu, Chih-Jen; Chen, Chii-Chang

    2013-04-22

    In this article, we propose an optical heterodyne common-path gyroscope which has common-path configuration and full-dynamic range. Different from traditional non-common-path optical heterodyne technique such as Mach-Zehnder or Michelson interferometers, we use a two-frequency laser light source (TFLS) which can generate two orthogonally polarized light with a beat frequency has a common-path configuration. By use of phase measurement, this optical heterodyne gyroscope not only has the capability to overcome the drawback of the traditional interferometric fiber optic gyro: lack for full-dynamic range, but also eliminate the total polarization rotation caused by SMFs. Moreover, we also demonstrate the potential of miniaturizing this gyroscope as a chip device. Theoretically, if we assume that the wavelength of the laser light is 1550nm, the SMFs are 250m in length, and the radius of the fiber ring is 3.5cm, the bias stability is 0.872 deg/hr.

  6. A new balanced-path heterodyne I/Q-interferometer scheme for low environmental noise, high sensitivity phase measurements for both reflection and transmission geometry.

    PubMed

    Yoon, Seunghyun; Park, Youngkyu; Cho, Kyuman

    2013-09-09

    A new heterodyne interferometer scheme which has open accesses to both the geometrically balanced probe beam (PB) and reference beam (RB) paths, for which, depending on the nature of a specific sensing mechanism, a transmission geometry or a reflection geometry can be employed, is presented. We will show that, because of a small separation between the short length PB and RB running parallel to each other our newly proposed optical arrangement allows high rejection of unlocalized environmental perturbations. In fact, the geometrically balanced optical arrangement provides 19 dB rejection of any vibrations parallel to the direction of beam propagation, which cannot be achieved in a conventional interferometer scheme. Applications of this new interferometer scheme are discussed. As an example, we will show that our newly proposed interferometer scheme can be applied for high sensitivity measurements of concentration dependent refractive indexes in various solutions.

  7. Spatial heterodyne interferometry with polarization gratings.

    PubMed

    Kudenov, Michael W; Miskiewicz, Matthew N; Escuti, Michael J; Dereniak, Eustace L

    2012-11-01

    The implementation of a polarization-based spatial heterodyne interferometer (SHI) is described. While a conventional SHI uses a Michelson interferometer and diffraction gratings, our SHI exploits mechanically robust Wollaston prisms and polarization gratings. A theoretical model for the polarization SHI is provided and validated with data from our proof of concept experiments. This device is expected to provide a compact monolithic sensor for subangstrom resolution spectroscopy in remote sensing, biomedical imaging, and machine vision applications.

  8. Spatially-Heterodyned Holography

    DOEpatents

    Thomas, Clarence E [Knoxville, TN; Hanson, Gregory R [Clinton, TN

    2006-02-21

    A method of recording a spatially low-frequency heterodyne hologram, including spatially heterodyne fringes for Fourier analysis, includes: splitting a laser beam into a reference beam and an object beam; interacting the object beam with an object; focusing the reference beam and the object beam at a focal plane of a digital recorder to form a spatially low-frequency heterodyne hologram including spatially heterodyne fringes for Fourier analysis; digital recording the spatially low-frequency heterodyne hologram; Fourier transforming axes of the recorded spatially low-frequency heterodyne hologram including spatially heterodyne fringes in Fourier space to sit on top of a heterodyne carrier frequency defined by an angle between the reference beam and the object beam; cutting off signals around an origin; and performing an inverse Fourier transform.

  9. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1989-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

  10. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1990-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

  11. 30-micron heterodyne receiver

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor; Spears, David L.

    1987-01-01

    Advantages and constraints of remote measurements using heterodyne spectroscopy near 30 microns are discussed. The state of the art of wideband HgCdTe photomixers and PbSnSe diode-laser local oscillators being developed for FIR heterodyne receivers is described. The first compact 30-micron heterodyne radiometer was built, and initial results at 28-microns show about 2-percent mixer efficiency for a 500-MHz-bandwidth receiver. Factors limiting receiver performance are discussed, along with the projected sensitivity of new interdigitated-electrode HgCdTe photoconductor mixers being developed for operation up to 200 microns.

  12. An optical heterodyne densitometer

    NASA Technical Reports Server (NTRS)

    Migdall, A. L.; Zheng, Ying Cong; Hardis, J.; Snyder, J. J.

    1988-01-01

    Researchers are developing an optical heterodyne densitometer with the potential to measure optical density over an unprecedented dynamic range with high accuracy and sensitivity. This device uses a Mach-Zender interferometer configuration with heterodyne detection to make direct comparisons between optical and RF attenuators. Researchers expect to attain measurements of filter transmittance down to 10 to the minus 12th power with better than 1 percent uncertainty. In addition, they intend to extend the technique to the problem of measuring low levels of light scattering from reflective and transmissive optics.

  13. Submillimeter wave heterodyne receiver

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutam (Inventor); Manohara, Harish (Inventor); Siegel, Peter H. (Inventor); Ward, John (Inventor)

    2011-01-01

    In an embodiment, a submillimeter wave heterodyne receiver includes a finline ortho-mode transducer comprising thin tapered metallic fins deposited on a thin dielectric substrate to separate a vertically polarized electromagnetic mode from a horizontally polarized electromagnetic mode. Other embodiments are described and claimed.

  14. Heterodyne Interferometer Angle Metrology

    NASA Technical Reports Server (NTRS)

    Hahn, Inseob; Weilert, Mark A.; Wang, Xu; Goullioud, Renaud

    2010-01-01

    A compact, high-resolution angle measurement instrument has been developed that is based on a heterodyne interferometer. The common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer setup, an optical mask is used to sample the measurement laser beam reflecting back from a target surface. Angular rotations, around two orthogonal axes in a plane perpendicular to the measurement- beam propagation direction, are determined simultaneously from the relative displacement measurement of the target surface. The device is used in a tracking telescope system where pitch and yaw measurements of a flat mirror were simultaneously performed with a sensitivity of 0.1 nrad, per second, and a measuring range of 0.15 mrad at a working distance of an order of a meter. The nonlinearity of the device is also measured less than one percent over the measurement range.

  15. Infrared heterodyne spectroscopy in astronomy

    NASA Technical Reports Server (NTRS)

    Betz, A.

    1980-01-01

    A heterodyne spectrometer was constructed and applied to problems in infrared astronomical spectroscopy. The instrument offers distinct observational advantages for the detection and analysis of individual spectral lines at Doppler-limited resolution. Observations of carbon dioxide in planetary atmospheres and ammonia in circumstellar environments demonstrate the substantial role that infrared heterodyne techniques will play in the astronomical spectroscopy of the future.

  16. Heterodyne speckle velocimetry

    SciTech Connect

    Alaimo, M. D.; Magatti, D.; Ferri, F.; Potenza, M.A.C.

    2006-05-08

    We present a simple method for fluid velocimetry based on the velocity of the heterodyne speckles generated by tracking particles illuminated with coherent light. It works in real time and provides instantaneous two-dimensional velocity mappings in the direction orthogonal to the optical axis, independently of the particle concentration and size, also for subwavelength particles. It also provides the velocity distribution of the fluid over the entire sample thickness. The method has been quantitatively tested by using the motions of rigid diffusers and applied for mapping the flow of a confined fluid.

  17. Integrated heterodyne terahertz transceiver

    DOEpatents

    Lee, Mark; Wanke, Michael C.

    2009-06-23

    A heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on-chip with a Schottky diode mixer. An antenna connected to the Schottky diode receives a terahertz signal. The quantum cascade laser couples terahertz local oscillator power to the Schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal. The fully integrated transceiver optimizes power efficiency, sensitivity, compactness, and reliability. The transceiver can be used in compact, fieldable systems covering a wide variety of deployable applications not possible with existing technology.

  18. Integrated heterodyne terahertz transceiver

    DOEpatents

    Wanke, Michael C [Albuquerque, NM; Lee, Mark [Albuquerque, NM; Nordquist, Christopher D [Albuquerque, NM; Cich, Michael J [Albuquerque, NM

    2012-09-25

    A heterodyne terahertz transceiver comprises a quantum cascade laser that is integrated on-chip with a Schottky diode mixer. A terahertz signal can be received by an antenna connected to the mixer, an end facet or sidewall of the laser, or through a separate active section that can amplify the incident signal. The quantum cascade laser couples terahertz local oscillator power to the Schottky diode to mix with the received terahertz signal to provide an intermediate frequency output signal. The fully integrated transceiver optimizes power efficiency, sensitivity, compactness, and reliability. The transceiver can be used in compact, fieldable systems covering a wide variety of deployable applications not possible with existing technology.

  19. Digitally Enhanced Heterodyne Interferometry

    NASA Technical Reports Server (NTRS)

    Shaddock, Daniel; Ware, Brent; Lay, Oliver; Dubovitsky, Serge

    2010-01-01

    Spurious interference limits the performance of many interferometric measurements. Digitally enhanced interferometry (DEI) improves measurement sensitivity by augmenting conventional heterodyne interferometry with pseudo-random noise (PRN) code phase modulation. DEI effectively changes the measurement problem from one of hardware (optics, electronics), which may deteriorate over time, to one of software (modulation, digital signal processing), which does not. DEI isolates interferometric signals based on their delay. Interferometric signals are effectively time-tagged by phase-modulating the laser source with a PRN code. DEI improves measurement sensitivity by exploiting the autocorrelation properties of the PRN to isolate only the signal of interest and reject spurious interference. The properties of the PRN code determine the degree of isolation.

  20. White Light Heterodyne Interferometry SNR

    DTIC Science & Technology

    2015-04-09

    INTRODUCTION The subject of heterodyne interferometry, most successfully demonstrated for astronomy in the long- wave infrared (LWIR) at the...zero sun -like star puts out 4 × 107 photons/s/m2/nm at the surface of the earth at this wavelength, which corresponds to a power per unit bandwidth...MID- WAVE AND LONG- WAVE INFRARED While there is a significant penalty to the heterodyne approach in the visible through short- wave infrared (SWIR

  1. Dove prism heterodyne refractometer

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Chih; Lee, Chia-Yun; Chu, Kuan-Ho; Wu, Tsai-Chen

    2015-10-01

    In this study, we proposed an alternative method, integrating a Dove prism and precision circular heterodyne interferometry, for measuring the refractive index and concentration of sodium chloride and hydrogen peroxide solutions with low phase error. Due to the optical properties of the Dove prism, the test light undergoes total internal reflection (TIR) at the interface between the test sample and the prism. The light beam travels in and out of the Dove prism while maintaining the same direction. Therefore, only slight alignment is required, leading to only small errors in the phase and refractive index. In this study, the phase error, refractive index error, and resolution of the concentration are approximated to be 0.003°, 2×10-5, and 1×10-3 M, respectively. The proposed method has the advantages of a simple optical configuration, ease of operation, little alignment required, and high stability, and it allows for high-precision measurement of the refractive index and concentration of the liquid sample.

  2. Heterodyne systems and technology, part 1. [conferences

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Various aspects of optical heterodyning are considered. Topics covered heterodyning throughout the electromagnetic spectrum including detectors, local oscillators, tunable diode lasers, astronomical systems, and environmental sensors, with both active and passive systems represented.

  3. IR detectors - Heterodyne and direct

    NASA Technical Reports Server (NTRS)

    Spears, D. L.

    1983-01-01

    Recent developments in the area of wide-bandwidth infrared detectors, both for direct and heterodyne detection, are reviewed with emphasis on the differences and tradeoffs between photodiodes and photoconductors. In the direct-detection mode, where amplifier noise is an important consideration, the state-of-the-art detection noise equivalent power is approximated by 500 (B/10 MHz) pW. At short wavelengths (less than 1.7 micron), avalanche photodiodes offer superior performance, with a detection noise equivalent power of about 50 (B/10 MHz) pW. In heterodyne operation, near-ideal sensitivities of about 0.3 (B/10 MHz) pW have been achieved with 77K photodiodes. At 10 microns, HgCdTe photoconductors offer very good heterodyne performance at elevated temperatures: 2 (B/10 MHz) pW at 195 K and potentially 3 (B/10 MHz) pW at 250 K.

  4. Paired circularly polarized heterodyne ellipsometer

    SciTech Connect

    Yu, C.-J.; Lin, C.-E.; Yu, L.-P.; Chou, C

    2009-02-01

    We develop a paired circularly polarized heterodyne ellipsometer (PCPHE), in which a heterodyne interferometer based on a two-frequency circularly polarized laser beam is set up. It belongs to an amplitude-sensitive ellipsometer that is able to provide not only a wider dynamic range of polarization modulation frequency but also a higher detection sensitivity than that of a conventional photometric ellipsometer. A real-time and precise measurement of ellipsometric parameters, which demonstrated an accuracy of less than 1 nm on thickness measurement of SiO2 thin film deposited on silicon substrate, can be applied with the PCPHE.

  5. Concerning the Spatial Heterodyne Spectrometer

    SciTech Connect

    Lenzner, Matthias; Diels, Jean -Claude

    2016-01-22

    A modified Spatial Heterodyne Spectrometer (SHS) is used for measuring atomic emission spectra with high resolution. This device is basically a Fourier Transform Spectrometer, but the Fourier transform is taken in the directions perpendicular to the optical propagation and heterodyned around one preset wavelength. In recent descriptions of this device, one specific phenomenon - the tilt of the energy front of wave packets when diffracted from a grating - was neglected. This led to an overestimate of the resolving power of this spectrograph, especially in situations when the coherence length of the radiation under test is in the order of the effective aperture of the device. In conclusion, the limits of usability are shown here together with some measurements of known spectral lines.

  6. Concerning the Spatial Heterodyne Spectrometer

    DOE PAGES

    Lenzner, Matthias; Diels, Jean -Claude

    2016-01-22

    A modified Spatial Heterodyne Spectrometer (SHS) is used for measuring atomic emission spectra with high resolution. This device is basically a Fourier Transform Spectrometer, but the Fourier transform is taken in the directions perpendicular to the optical propagation and heterodyned around one preset wavelength. In recent descriptions of this device, one specific phenomenon - the tilt of the energy front of wave packets when diffracted from a grating - was neglected. This led to an overestimate of the resolving power of this spectrograph, especially in situations when the coherence length of the radiation under test is in the order ofmore » the effective aperture of the device. In conclusion, the limits of usability are shown here together with some measurements of known spectral lines.« less

  7. Scanning Terahertz Heterodyne Imaging Systems

    NASA Technical Reports Server (NTRS)

    Siegel, Peter; Dengler, Robert

    2007-01-01

    Scanning terahertz heterodyne imaging systems are now at an early stage of development. In a basic scanning terahertz heterodyne imaging system, (see Figure 1) two far-infrared lasers generate beams denoted the local-oscillator (LO) and signal that differ in frequency by an amount, denoted the intermediate frequency (IF), chosen to suit the application. The LO beam is sent directly to a mixer as one of two inputs. The signal beam is focused to a spot on or in the specimen. After transmission through or reflection from the specimen, the beams are focused to a spot on a terahertz mixer, which extracts the IF outputs. The specimen is mounted on a translation stage, by means of which the focal spot is scanned across the specimen to build up an image.

  8. Modified Phasemeter for a Heterodyne Laser Interferometer

    NASA Technical Reports Server (NTRS)

    Loya, Frank M.

    2010-01-01

    Modifications have been made in the design of instruments of the type described in "Digital Averaging Phasemeter for Heterodyne Interferometry". A phasemeter of this type measures the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. The phasemeter design lacked immunity to drift of the heterodyne frequency, was bandwidth-limited by computer bus architectures then in use, and was resolution-limited by the nature of field-programmable gate arrays (FPGAs) then available. The modifications have overcome these limitations and have afforded additional improvements in accuracy, speed, and modularity. The modifications are summarized.

  9. Robust terahertz self-heterodyne system using a phase noise compensation technique.

    PubMed

    Song, Hajun; Song, Jong-In

    2015-08-10

    We propose and demonstrate a robust terahertz self-heterodyne system using a phase noise compensation technique. Conventional terahertz self-heterodyne systems suffer from degraded phase noise performance due to phase noise of the laser sources. The proposed phase noise compensation technique uses an additional photodiode and a simple electric circuit to produce phase noise identical to that observed in the terahertz signal produced by the self-heterodyne system. The phase noise is subsequently subtracted from the terahertz signal produced by the self-heterodyne system using a lock-in amplifier. While the terahertz self-heterodyne system using a phase noise compensation technique offers improved phase noise performance, it also provides a reduced phase drift against ambient temperature variations. The terahertz self-heterodyne system using a phase noise compensation technique shows a phase noise of 0.67 degree in terms of a standard deviation value even without using overall delay balance control. It also shows a phase drift of as small as approximately 10 degrees in an open-to-air measurement condition without any strict temperature control.

  10. BALANCE

    DOEpatents

    Carmichael, H.

    1953-01-01

    A torsional-type analytical balance designed to arrive at its equilibrium point more quickly than previous balances is described. In order to prevent external heat sources creating air currents inside the balance casing that would reiard the attainment of equilibrium conditions, a relatively thick casing shaped as an inverted U is placed over the load support arms and the balance beam. This casing is of a metal of good thernnal conductivity characteristics, such as copper or aluminum, in order that heat applied to one portion of the balance is quickly conducted to all other sensitive areas, thus effectively preventing the fornnation of air currents caused by unequal heating of the balance.

  11. Two-wavelength spatial-heterodyne holography

    DOEpatents

    Hanson, Gregory R.; Bingham, Philip R.; Simpson, John T.; Karnowski, Thomas P.; Voelkl, Edgar

    2007-12-25

    Systems and methods are described for obtaining two-wavelength differential-phase holograms. A method includes determining a difference between a filtered analyzed recorded first spatially heterodyne hologram phase and a filtered analyzed recorded second spatially-heterodyned hologram phase.

  12. Heterodyne laser instantaneous frequency measurement system

    DOEpatents

    Wyeth, Richard W.; Johnson, Michael A.; Globig, Michael A.

    1990-01-01

    A heterodyne laser instantaneous frequency measurement system is disclosed. The system utilizes heterodyning of a pulsed laser beam with a continuous wave laser beam to form a beat signal. The beat signal is processed by a controller or computer which determines both the average frequency of the laser pulse and any changes or chirp of the frequency during the pulse.

  13. Heterodyne laser instantaneous frequency measurement system

    DOEpatents

    Wyeth, Richard W.; Johnson, Michael A.; Globig, Michael A.

    1989-01-01

    A heterodyne laser instantaneous frequency measurement system is disclosed. The system utilizes heterodyning of a pulsed laser beam with a continuous wave laser beam to form a beat signal. The beat signal is processed by a controller or computer which determines both the average frequency of the laser pulse and any changes or chirp of th frequency during the pulse.

  14. Berkeley heterodyne interferometer. [for IR stellar observations

    NASA Technical Reports Server (NTRS)

    Betz, A.

    1975-01-01

    A prototype heterodyne stellar interferometer has been built in order to demonstrate the feasibility of heterodyne techniques in measuring angular diameters of bright infrared stars. The first system tests were performed in December 1972. Attention is given to investigations concerning the possibility that optical air turbulence within the structure of the solar telescope employed can possibly destroy the phase coherence of the fringe signals.

  15. Laser heterodyne spectrometer for helioseismology

    NASA Technical Reports Server (NTRS)

    Glenar, D. A.; Deming, D.; Espenak, F.; Kostiuk, T.; Mumma, M. J.

    1986-01-01

    The technique of laser heterodyne spectroscopy has been applied to the measurement of solar oscillations. Coherent mixing of solar radiation with the output of a frequency-stabilized CO2 laser permits the measurement of fully resolved profiles of solar absorption lines with high spectral purity and excellent frequency stability. This technique has been used to measure OH pure rotation lines in the infrared solar spectrum. Power spectra of these line frequency measurements show the well-known 5-min oscillations as well as significant velocity power at shorter periods.

  16. Spatial heterodyne spectrometer for FLEX

    NASA Astrophysics Data System (ADS)

    Scott, Alan; Zheng, Sheng-Hai; Brown, Stephen; Bell, Andrew

    2007-10-01

    A spatial heterodyne spectrometer (SHS) has significant advantages for high spectral resolution imaging over narrow pre-selected bands compared to traditional solutions. Given comparable optical étendue at R~6500, a field-widened SHS will have a throughput-resolution product ~170 x larger than an air-spaced etalon spectrometer, and ~1000 x larger than a standard grating spectrometer. The monolithic glass Michelson design and lack of moving parts allows maximum stability of spectral calibration over the mission life. For these reasons, SHS offers considerable advantages for the core spectrometer instrument in the European Space Agency's (ESA) Fluorescence Explorer (FLEX) mission.

  17. Heterodyne lidar for chemical sensing

    SciTech Connect

    Oldenborg, R. C.; Tiee, J. J.; Shimada, T.; Wilson, C. W.; Remelius, D. K.; Fox, Jay; Swim, Cynthia

    2004-01-01

    The overall objective is to assess the detection performance of LWIR (long wavelength infrared) coherent Lidar systems that potentially possess enhanced effluent detection capabilities. Previous work conducted by Los Alamos has demonstrated that infrared DIfferential Absorption Lidar (DIAL) is capable of detecting chemicals in plumes from long standoff ranges. Our DIAL approach relied on the reflectivity of topographical targets to provide a strong return signal. With the inherent advantage of applying heterodyne transceivers to approach single-photon detection in LWIR, it is projected that marked improvements in detection range or in spatial coverage can be attained. In some cases, the added photon detection sensitivity could be utilized for sensing 'soft targets', such as atmospheric and threat aerosols where return signal strength is drastically reduced, as opposed to topographical targets. This would allow range resolved measurements and could lead to the mitigation of the limiting source of noise due to spectral/spatial/temporal variability of the ground scene. The ability to distinguish normal variations in the background from true chemical signatures is crucial to the further development of sensitive remote chemical sensing technologies. One main difficulty in demonstrating coherent DIAL detection is the development of suitable heterodyne transceivers that can achieve rapid multi-wavelength tuning required for obtaining spectral signature information. LANL has recently devised a novel multi-wavelength heterodyne transceiver concept that addresses this issue. A 5-KHz prototype coherent CO{sub 2} transceiver has been constructed and is being now used to help address important issues in remote CBW agent standoff detection. Laboratory measurements of signal-to-noise ratio (SNR) will be reported. Since the heterodyne detection scheme fundamentally has poor shot-to-shot signal statistics, in order to achieve sensitive detection limits, favorable averaging

  18. Infrared heterodyne spectroscopy of atmospheric ozone

    NASA Technical Reports Server (NTRS)

    Frerking, M. A.; Muehlner, D. J.

    1977-01-01

    The absorption spectrum of atmospheric ozone is measured within a 1/cm region at 1100/cm, using an IR heterodyne detector (spectrometer with CO2 local oscillator) developed for astronomical work. Absorption spectra obtained by passing radiation from the tunable diode laser through an absorption cell, heterodyne spectra of atmospheric ozone, and a predicted atmospheric spectrum are compared. Water vapor absorbing in the region of interest (1100/cm) is also considered. Preliminary results encourage the use of diode laser local oscillators in tunable heterodyne detector systems for spectroscopy of atmospheric ozone and remote high-resolution spectroscopy of atmospheric constituents and pollutants.

  19. Heterodyne 3D ghost imaging

    NASA Astrophysics Data System (ADS)

    Yang, Xu; Zhang, Yong; Yang, Chenghua; Xu, Lu; Wang, Qiang; Zhao, Yuan

    2016-06-01

    Conventional three dimensional (3D) ghost imaging measures range of target based on pulse fight time measurement method. Due to the limit of data acquisition system sampling rate, range resolution of the conventional 3D ghost imaging is usually low. In order to take off the effect of sampling rate to range resolution of 3D ghost imaging, a heterodyne 3D ghost imaging (HGI) system is presented in this study. The source of HGI is a continuous wave laser instead of pulse laser. Temporal correlation and spatial correlation of light are both utilized to obtain the range image of target. Through theory analysis and numerical simulations, it is demonstrated that HGI can obtain high range resolution image with low sampling rate.

  20. Heterodyne applications of tunable semiconductor diode lasers

    NASA Technical Reports Server (NTRS)

    Sidney, B. D.

    1983-01-01

    Infrared tunable diode lasers were developed in the 1960s and have been a valuable radiation source for high resolution laboratory and in situ spectroscopy. Use of Pb-salt Tunable Diode Lasers (TDL) in heterodyne applications impose stringent requirements on the TDL not normally required for laboratory spectroscopy. A review will be made of progress associated with TDLs in such heterodyne applications. Areas addressed will include such items as lifetime, operating temperature, and factors affecting excess noise. The review will emphasize the experience at Langley Research Center, but will include material from other users. The Langley information will include a description and current status of the Laser Heterodyne Spectrometer experiment and atmospheric solar absorption data obtained from a groundbased heterodyne system.

  1. A Heterodyne Interferometer For Testing Laser Diodes

    NASA Astrophysics Data System (ADS)

    1983-11-01

    A heterodyne, Mach-Zehnder interferometer system has been developed for testing the wavefront quality of laser diode collimator pens. The testing system is described and the problems associated with testing laser diodes are discussed.

  2. Balancing

    NASA Astrophysics Data System (ADS)

    Harteveld, Casper

    At many occasions we are asked to achieve a “balance” in our lives: when it comes, for example, to work and food. Balancing is crucial in game design as well as many have pointed out. In games with a meaningful purpose, however, balancing is remarkably different. It involves the balancing of three different worlds, the worlds of Reality, Meaning, and Play. From the experience of designing Levee Patroller, I observed that different types of tensions can come into existence that require balancing. It is possible to conceive of within-worlds dilemmas, between-worlds dilemmas, and trilemmas. The first, the within-world dilemmas, only take place within one of the worlds. We can think, for example, of a user interface problem which just relates to the world of Play. The second, the between-worlds dilemmas, have to do with a tension in which two worlds are predominantly involved. Choosing between a cartoon or a realistic style concerns, for instance, a tension between Reality and Play. Finally, the trilemmas are those in which all three worlds play an important role. For each of the types of tensions, I will give in this level a concrete example from the development of Levee Patroller. Although these examples come from just one game, I think the examples can be exemplary for other game development projects as they may represent stereotypical tensions. Therefore, to achieve harmony in any of these forthcoming games, it is worthwhile to study the struggles we had to deal with.

  3. Heterodyne effect in Hybrid CARS

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Zhang, Aihua; Zhi, Miaochan; Sokolov, Alexei; Welch, George; Scully, Marlan

    2009-10-01

    We study the interaction between the resonant Raman signal and non-Raman field, either the concomitant nonresonant four-wave-mixing (FWM) background or an applied external field, in our recently developed scheme of coherent Anti-Stokes Raman scattering, a hybrid CARS. Our technique combines instantaneous coherent excitation of several characteristic molecular vibrations with subsequent probing of these vibrations by an optimally shaped, time-delayed, narrowband laser pulse. This pulse configuration mitigates the non-resonant FWM background while maximizing the Raman-resonant signal, and allows rapid and highly specific detection even in the presence of multiple scattering. We apply this method to non-invasive monitoring of blood glucose levels. Under certain conditions we find that the measured signal is linearly proportional to the glucose concentration due to optical interference with the residual background light, which allows reliable detection of spectral signatures down to medically-relevant glucose levels. We also study the interference between the CARS field and an external field (the local oscillator) by controlling their relative phase and amplitude. This control allows direct observation of the real and imaginary components of the third-order nonlinear susceptibility (χ^(3)) of the sample. We demonstrate that the heterodyne method can be used to amplify the signal and thus increase detection sensitivity.

  4. RF spectrometers for heterodyne receivers

    NASA Technical Reports Server (NTRS)

    Buhl, D.; Mumma, M. J.

    1980-01-01

    Several types of spectrometers developed for radio astronomy receivers which utilize RF filters, multiple oscillators and mixers, digital autocorrelators and acoustic/optic devices are considered. The RF spectrometer developed at GSFC to provide wide bandwidths (greater than 1 GHz) as well as high resolution (5MHz) is described. The 128 channel filter bank is divided into high and low resolution sections. The high resolution section is tunable by providing a second mixer ahead of the filter bank. This is necessary because infrared receivers which use gas lasers as local oscillators are only tunable to specific laser frequencies. To compensate for astronomical Doppler shifts and molecule frequency differences a second local oscillator and mixer is needed. A diagram of the RF section of the filter bank is shown. The RF spectrometer is shown to be the best means of achieving ultra-wide bandwidths for infrared heterodyne receivers. For high resolution with a large number of channels, the acousto/optical spectrometer is the principle instrument, particularly for balloon or space flight applications.

  5. Analysis on optical heterodyne frequency error of full-field heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Li, Yang; Zhang, Wenxi; Wu, Zhou; Lv, Xiaoyu; Kong, Xinxin; Guo, Xiaoli

    2017-06-01

    The full-field heterodyne interferometric measurement technology is beginning better applied by employing low frequency heterodyne acousto-optical modulators instead of complex electro-mechanical scanning devices. The optical element surface could be directly acquired by synchronously detecting the received signal phases of each pixel, because standard matrix detector as CCD and CMOS cameras could be used in heterodyne interferometer. Instead of the traditional four-step phase shifting phase calculating, Fourier spectral analysis method is used for phase extracting which brings lower sensitivity to sources of uncertainty and higher measurement accuracy. In this paper, two types of full-field heterodyne interferometer are described whose advantages and disadvantages are also specified. Heterodyne interferometer has to combine two different frequency beams to produce interference, which brings a variety of optical heterodyne frequency errors. Frequency mixing error and beat frequency error are two different kinds of inescapable heterodyne frequency errors. In this paper, the effects of frequency mixing error to surface measurement are derived. The relationship between the phase extraction accuracy and the errors are calculated. :: The tolerance of the extinction ratio of polarization splitting prism and the signal-to-noise ratio of stray light is given. The error of phase extraction by Fourier analysis that caused by beat frequency shifting is derived and calculated. We also propose an improved phase extraction method based on spectrum correction. An amplitude ratio spectrum correction algorithm with using Hanning window is used to correct the heterodyne signal phase extraction. The simulation results show that this method can effectively suppress the degradation of phase extracting caused by beat frequency error and reduce the measurement uncertainty of full-field heterodyne interferometer.

  6. Ripplon scattering using grating heterodyne spectroscopy

    NASA Technical Reports Server (NTRS)

    Sirohi, R. S.; Edwards, R. V.; Mann, J. A., Jr.

    1980-01-01

    Heterodyne photon spectroscopy was used for the study of the viseo-elastic properties of the liquid interface by studying the scattering from thermal ripplons. A theory of a heterodyne apparatus based on a grating is presented, and the heterodyne condition is given in terms of the parameters of the experimental set-up. Emphasis was placed on the study of the instrumental function and its influence on the measurement data. The instrumental function is not always gaussian, but its functional form depends on the parameters of the experimental set-up. An algorithm is suggested to arrive at the center frequency and half width at half height of the spectrum from the noisy experimental data, and applied to the measurement data obtained from ethanol and water surfaces.

  7. Optical Heterodyne With Lower Phase Noise

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T.

    1994-01-01

    Proposed improvement enhances utility of optical-heterodyne apparatus used to generate radio signal at chosen frequency between 1 and 1,000 GHz. Two lasers injection-locked to third, mode-locked laser. Beat-frequency heterodyne output contains much less phase noise if generated from outputs of two independent lasers, and phase-coherent with reference signal. Potential applications include phased-array radar, fiber-optic communication systems, fiber-optic stabilized oscillators, and other applications involving conversions between optical and millimeter-wave signals.

  8. Laser heterodyne detection techniques. [for atmospheric monitoring applications

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.

    1976-01-01

    The principles of heterodyne radiometry are examined, taking into account thermal radiation, the Dicke microwave radiometer, photomixing in the infrared, and signal-to-noise considerations. The passive heterodyne radiometer is considered and a description is presented of heterodyne techniques in active monitoring systems. Attention is given to gas emissivities in the infrared, component requirements, experimental heterodyne detection of gases, a comparison of the passive heterodyne radiometer with the Michelson interferometer-spectrometer, airborne monitoring applications, turbulence effects on passive heterodyne radiometry, sensitivity improvements with heterodyning, atmosphere-induced degradation of bistatic system performance, pollutant detection experiments with a bistatic system, and the airborne laser absorption spectrometer. Future improvements in spectral flexibility are also discussed.

  9. Laser Metrology Heterodyne Phase-Locked Loop

    NASA Technical Reports Server (NTRS)

    Loya, Frank; Halverson, Peter

    2009-01-01

    A method reduces sensitivity to noise in a signal from a laser heterodyne interferometer. The phase-locked loop (PLL) removes glitches that occur in a zero-crossing detector s output [that can happen if the signal-to-noise ratio (SNR) of the heterodyne signal is low] by the use of an internal oscillator that produces a square-wave signal at a frequency that is inherently close to the heterodyne frequency. It also contains phase-locking circuits that lock the phase of the oscillator to the output of the zero-crossing detector. Because the PLL output is an oscillator signal, it is glitch-free. This enables the ability to make accurate phase measurements in spite of low SNR, creates an immunity to phase error caused by shifts in the heterodyne frequency (i.e. if the target moves causing Doppler shift), and maintains a valid phase even when the signal drops out for brief periods of time, such as when the laser is blocked by a stray object.

  10. Broadband Heterodyne SIS Spectrometer Prototype: First Results

    NASA Technical Reports Server (NTRS)

    Rice, F.; LeDuc, H.; Harris, A.; Hu, S.; Sumner, M.; Zmuidzinas, J.

    2004-01-01

    The broadband heterodyne SIS receiver system described elsewhere (reference 1) has been assembled and tested both in the laboratory and during two observing runs on the Cassegrain focus of the 10 meter telescope at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. Here we present a brief summary of the initial results.

  11. Digital Averaging Phasemeter for Heterodyne Interferometry

    NASA Technical Reports Server (NTRS)

    Johnson, Donald; Spero, Robert; Shaklan, Stuart; Halverson, Peter; Kuhnert, Andreas

    2004-01-01

    A digital averaging phasemeter has been built for measuring the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. This phasemeter performs well enough to enable interferometric measurements of distance with accuracy of the order of 100 pm and with the ability to track distance as it changes at a speed of as much as 50 cm/s. This phasemeter is unique in that it is a single, integral system capable of performing three major functions that, heretofore, have been performed by separate systems: (1) measurement of the fractional-cycle phase difference, (2) counting of multiple cycles of phase change, and (3) averaging of phase measurements over multiple cycles for improved resolution. This phasemeter also offers the advantage of making repeated measurements at a high rate: the phase is measured on every heterodyne cycle. Thus, for example, in measuring the relative phase of two signals having a heterodyne frequency of 10 kHz, the phasemeter would accumulate 10,000 measurements per second. At this high measurement rate, an accurate average phase determination can be made more quickly than is possible at a lower rate.

  12. Submillimeter local oscillators for spaceborne heterodyne applications

    NASA Technical Reports Server (NTRS)

    Petuchowski, S. J.; Durachta, J.

    1985-01-01

    Existing and prospective submillimeter local oscillator technologies are surveyed and compared with respect to criteria of suitability for application in spaceborne submillimeter heterodyne receivers as those proposed for the Large Deployable Reflector (LDR). Solid-state and plasma devices are considered in terms of fundamental limitations.

  13. HETERODYNE DETECTION IN OPTICAL COMMUNICATION TECHNIQUES

    DTIC Science & Technology

    difference frequency in the presence of incoherent noise. The use of heterodyne detection in optical communication , demultiplexing of channels, demodulation...of FM and AM, Doppler and displacement measurements, and stabilization of LASERs is discussed. The elements of an optical communication link are discussed: LASERs, modulators, transmission path, and detectors.

  14. Spatial-heterodyne interferometry for transmission (SHIFT) measurements

    DOEpatents

    Bingham, Philip R.; Hanson, Gregory R.; Tobin, Ken W.

    2006-10-10

    Systems and methods are described for spatial-heterodyne interferometry for transmission (SHIFT) measurements. A method includes digitally recording a spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis using a reference beam, and an object beam that is transmitted through an object that is at least partially translucent; Fourier analyzing the digitally recorded spatially-heterodyned hologram, by shifting an original origin of the digitally recorded spatially-heterodyned hologram to sit on top of a spatial-heterodyne carrier frequency defined by an angle between the reference beam and the object beam, to define an analyzed image; digitally filtering the analyzed image to cut off signals around the original origin to define a result; and performing an inverse Fourier transform on the result.

  15. A heterodyne interferometer for angle metrology.

    PubMed

    Hahn, Inseob; Weilert, M; Wang, X; Goullioud, R

    2010-04-01

    We have developed a compact, high-resolution, angle measurement instrument based on a heterodyne interferometer. Common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer set up, an optical mask is used to sample the laser beam reflecting back from four areas on a target surface. From the relative displacement measurements of the target surface areas, we can simultaneously determine angular rotations around two orthogonal axes in a plane perpendicular to the measurement beam propagation direction. The device is used in a testbed for a tracking telescope system where pitch and yaw angle measurements of a flat mirror are performed. Angle noise measurement of the device shows 0.1 nrad/square root of Hz at 1 Hz, at a working distance of 1 m. The operation range and nonlinearity of the device when used with a flat mirror is approximately +/-0.15 mrad, and 3 microrad rms, respectively.

  16. A heterodyne interferometer for angle metrology

    SciTech Connect

    Hahn, Inseob; Weilert, M.; Wang, X.; Goullioud, R.

    2010-04-15

    We have developed a compact, high-resolution, angle measurement instrument based on a heterodyne interferometer. Common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer set up, an optical mask is used to sample the laser beam reflecting back from four areas on a target surface. From the relative displacement measurements of the target surface areas, we can simultaneously determine angular rotations around two orthogonal axes in a plane perpendicular to the measurement beam propagation direction. The device is used in a testbed for a tracking telescope system where pitch and yaw angle measurements of a flat mirror are performed. Angle noise measurement of the device shows 0.1 nrad/{radical}(Hz) at 1 Hz, at a working distance of 1 m. The operation range and nonlinearity of the device when used with a flat mirror is approximately {+-}0.15 mrad, and 3 {mu}rad rms, respectively.

  17. Quantum limited heterodyne detection of spin noise

    NASA Astrophysics Data System (ADS)

    Cronenberger, S.; Scalbert, D.

    2016-09-01

    Spin noise spectroscopy is a powerful technique for studying spin relaxation in semiconductors. In this article, we propose an extension of this technique based on optical heterodyne detection of spin noise, which provides several key advantages compared to conventional spin noise spectroscopy: detection of high frequency spin noise not limited by detector bandwidth or sampling rates of digitizers, quantum limited sensitivity even in case of very weak probe power, and possible amplification of the spin noise signal. Heterodyne detection of spin noise is demonstrated on insulating n-doped GaAs. From measurements of spin noise spectra up to 0.4 Tesla, we determined the distribution of g-factors, Δg/g = 0.49%.

  18. Nanoscale defect detection by heterodyne interferometry

    SciTech Connect

    Lin Haoshan; Li Yuhe; Wang Dongsheng; Tong Xiaolei; Liu Mei

    2009-03-10

    We construct an instrument that facilitates the measurement of nanoscale defects. It is based on heterodyne interferometry with phase measurement that utilizes a polarizing beam splitter to form a measuring signal and an oscillating cantilever tip that acts as a scanning probe to get the measurement values of sample topography. The dependence of the tip displacement on the variation of tip-sample distance and the comb scanning of the sample topography are investigated by experiments. The results prove that the tip displacement increases and is enough to be discriminated in various positions where the sample is approached. The system has been successfully utilized to measure the defect characterization by measuring the pitch of the standard sample. The results also show that the heterodyne system has good repeatability, a large measurement range, and high accuracy, with a measurement stability of 0.5 nm.

  19. Ozone height profiles using laser heterodyne radiometer

    NASA Technical Reports Server (NTRS)

    Jain, S. L.

    1994-01-01

    The monitoring of vertical profiles of ozone and related minor constituents in the atmosphere are of great significance to understanding the complex interaction between atmospheric dynamics, chemistry and radiation budget. An ultra high spectral resolution tunable CO2 laser heterodyne radiometer has been designed, developed and set up at the National Physical Laboratory, New Delhi to obtain vertical profiles of various minor constituents the characteristic absorption lines in 9 to 11 micron spectral range. Due to its high spectral resolution the lines can be resolved completely and data obtained are inverted to get vertical profiles using an inversion technique developed by the author. In the present communication the salient features of the laser heterodyne system and the results obtained are discussed in detail.

  20. Stratospheric sounding by infrared heterodyne spectroscopy

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kunde, V. G.; Mumma, M. J.; Kostiuk, T.; Buhl, D.; Frerking, M. A.

    1978-01-01

    Intensity profiles of infrared spectral lines of stratospheric constituents can be fully resolved with a heterodyne spectrometer of sufficiently high resolution. The constituents' vertical distributions can then be evaluated accurately by analytic inversion of the measured line profiles. Estimates of the detection sensitivity of a heterodyne receiver are given in terms of minimum detectable volume mixing ratios of stratospheric constituents, indicating a large number of minor constituents which can be studied. Stratospheric spectral line shapes, and the resolution required to measure them are discussed in light of calculated synthetic line profiles for some stratospheric molecules in a model atmosphere. The inversion technique for evaluation of gas concentration profiles is briefly described and applications to synthetic lines of O3, CO2, CH4 and N2O are given.

  1. Study on the heterodyning scattering of retroreflective free-space optical communication with optical heterodyning.

    PubMed

    Jia, Honghui; Yin, Hongwei; Zhang, Hailiang; Wang, Xiaofeng; Chang, Shengli; Yang, Juncai

    2013-11-01

    Retroreflective free-space optical communication is important because of advantages such as small volume, low weight, and low power consumption. Link failure caused by bad weather conditions will occur because of the attenuated retroreflective signal and the increased scattering of the transmitted light. The scattering effect can be reduced because the physical properties (including polarization, wavefront, and phase) of the scattering signal are different from those of the retroreflective signal. The physical properties of the scattering signal are obtained using a polarization-sensitive Monte Carlo model, and the heterodyning scattering signal is obtained using heterodyning theory. Results show that, with optical heterodyning, the scattering effect is efficiently reduced, and advantages such as better adaptability to bad weather conditions, longer communication range, more compact transceiver design, larger covering area of the optical receiver, and easier target acquisition for the retromodulator than before can also be obtained.

  2. Wide-band heterodyne receiver development for effluent measurements

    SciTech Connect

    Hutchinson, D.P.; Richards, R.K.; Simpson, M.L.; Bennett, C.A.; Liu, H.C.; Buchanan, M.

    1998-05-01

    Oak Ridge National Laboratory (ORNL) has been developing advanced infrared heterodyne receivers for plasma diagnostics in fusion reactors for over 20 years. Passive heterodyne radiometry in the LWIR region of the spectrum has historically been restricted by HgCdTe (MCT) detector technology to receiver bandwidths of only 2 GHz. Given typical atmospheric line widths of approximately 3 GHz, a CO{sub 2} (or isotope) laser local oscillator with an average line spacing of 50 GHz, and an MCT detector, only chemical species whose absorptions fall directly on top of laser lines can be measured. Thus, with traditional narrow-band heterodyne radiometry, much of the LWIR spectrum is missed and the less complex direct detection DIAL has been the preferred technique in remote sensing applications. Wide-band heterodyne receivers offer significant improvements in remote measurement capability. Progress at the Institute for Microstructural Sciences (IMS) at National Research Council of Canada and at ORNL in wide-band quantum-well infrared photodetectors (QIPs) and receivers is significantly enhancing the bandwidth capabilities of heterodyne radiometers. ORNL recently made measurements in the lab using QWIPs developed at IMS that demonstrate heterodyne quantum efficiencies of 5% with a heterodyne bandwidth of 7 GHz. The path forward indicates that > 10% heterodyne quantum efficiencies and 30-GHz bandwidths are achievable with current QWIP technology. With a chopped, 30-GHz passive heterodyne receiver, a much larger portion of the LWIR spectrum can now be covered. One potential advantage of wide-band heterodyne receivers for effluent measurements is to dramatically reduce the number of laser lines needed to characterize and distinguish multiple chemical species of interest. In the following paper, the authors discuss this and other implications of these new technologies to the characterization of effluents using both passive heterodyne radiometry and thermo-luminescence.

  3. Error sources in deferred heterodyne moire deflectometry - An analytical study

    NASA Technical Reports Server (NTRS)

    Stricker, Josef

    1989-01-01

    The effects of the aperture size and shape of the photodetector and of the structure of the grating lines on the performance of deferred electronic heterodyne moire deflectometry are studied. It is shown that scanning of a moire fringe pattern parallel to an unshifted fringe yields periodical variations in the heterodyne phase and amplitude, which cause severe errors in the measurements.

  4. Sub-millimeter wave frequency heterodyne detector system

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

    2010-01-01

    The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

  5. Sub-millimeter wave frequency heterodyne detector system

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H. (Inventor); Dengler, Robert (Inventor); Mueller, Eric R. (Inventor)

    2009-01-01

    The present invention relates to sub-millimeter wave frequency heterodyne imaging systems. More specifically, the present invention relates to a sub-millimeter wave frequency heterodyne detector system for imaging the magnitude and phase of transmitted power through or reflected power off of mechanically scanned samples at sub-millimeter wave frequencies.

  6. Analysis of Optimum Heterodyne Receivers for Coherent Lidar Applications

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin

    2002-01-01

    A full analysis of the combined effects of all the noise sources of optical heterodyne receiver and the interaction between the competing control parameters of the receiver detector and pre-amplifier will be presented. This analysis provides the mean for true optimization of the coherent lidar receiver. The significance of the optimization of heterodyne receiver is shown for 2-micron coherent lidar.

  7. Error sources in deferred heterodyne moire deflectometry - An analytical study

    NASA Technical Reports Server (NTRS)

    Stricker, Josef

    1989-01-01

    The effects of the aperture size and shape of the photodetector and of the structure of the grating lines on the performance of deferred electronic heterodyne moire deflectometry are studied. It is shown that scanning of a moire fringe pattern parallel to an unshifted fringe yields periodical variations in the heterodyne phase and amplitude, which cause severe errors in the measurements.

  8. Measuring Cyclic Error in Laser Heterodyne Interferometers

    NASA Technical Reports Server (NTRS)

    Ryan, Daniel; Abramovici, Alexander; Zhao, Feng; Dekens, Frank; An, Xin; Azizi, Alireza; Chapsky, Jacob; Halverson, Peter

    2010-01-01

    An improved method and apparatus have been devised for measuring cyclic errors in the readouts of laser heterodyne interferometers that are configured and operated as displacement gauges. The cyclic errors arise as a consequence of mixing of spurious optical and electrical signals in beam launchers that are subsystems of such interferometers. The conventional approach to measurement of cyclic error involves phase measurements and yields values precise to within about 10 pm over air optical paths at laser wavelengths in the visible and near infrared. The present approach, which involves amplitude measurements instead of phase measurements, yields values precise to about .0.1 microns . about 100 times the precision of the conventional approach. In a displacement gauge of the type of interest here, the laser heterodyne interferometer is used to measure any change in distance along an optical axis between two corner-cube retroreflectors. One of the corner-cube retroreflectors is mounted on a piezoelectric transducer (see figure), which is used to introduce a low-frequency periodic displacement that can be measured by the gauges. The transducer is excited at a frequency of 9 Hz by a triangular waveform to generate a 9-Hz triangular-wave displacement having an amplitude of 25 microns. The displacement gives rise to both amplitude and phase modulation of the heterodyne signals in the gauges. The modulation includes cyclic error components, and the magnitude of the cyclic-error component of the phase modulation is what one needs to measure in order to determine the magnitude of the cyclic displacement error. The precision attainable in the conventional (phase measurement) approach to measuring cyclic error is limited because the phase measurements are af-

  9. Time-resolved, dual heterodyne phase collection transient grating spectroscopy

    NASA Astrophysics Data System (ADS)

    Dennett, Cody A.; Short, Michael P.

    2017-05-01

    The application of optical heterodyne detection for transient grating spectroscopy (TGS) using a fixed, binary phase mask often relies on taking the difference between signals captured at multiple heterodyne phases. To date, this has been accomplished by manually controlling the heterodyne phase between measurements with an optical flat. In this letter, an optical configuration is presented which allows for collection of TGS measurements at two heterodyne phases concurrently through the use of two independently phase controlled interrogation paths. This arrangement allows for complete, heterodyne amplified TGS measurements to be made in a manner not constrained by a mechanical actuation time. Measurements are instead constrained only by the desired signal-to-noise ratio. A temporal resolution of between 1 and 10 s, demonstrated here on single crystal metallic samples, will allow TGS experiments to be used as an in-situ, time-resolved monitoring technique for many material processing applications.

  10. Single-beam heterodyne FAST CARS microscopy.

    PubMed

    Shen, Yujie; Voronine, Dmitri V; Sokolov, Alexei V; Scully, Marlan O

    2016-09-19

    We demonstrate, for the first time, single-beam heterodyne FAST CARS imaging without data post-processing and with nonresonant background subtraction in a simple setup via the real-time piezo modulation of the probe delay. Our fast signal acquisition scheme does not require a spatial light modulator in the pulse shaper, and is suitable for high-resolution imaging and time-resolved dynamics. In addition, the spectral detection of the back-scattered FAST CARS signal is incorporated into the pulse shaper, allowing for a compact and more efficient design. Such epi-detection capability is demonstrated by imaging Si and MoS2 microstructures.

  11. Tunable Diode Laser Heterodyne Spectrophotometry of Ozone

    NASA Technical Reports Server (NTRS)

    Fogal, P. F.; McElroy, C. T.; Goldman, A.; Murcray, D. G.

    1988-01-01

    Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (less than 0.0005/ cm) solar spectra in the 9.6 micron ozone band. Observations have shown that a signal-to-noise ratio of 95 : 1 (35% of theoretical) for an integration time of 1/8 second can be achieved at a resolution of 0.0005 wavenumbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that. measured at the nearby National Oceanographic and Atmospheric Administration (NOAA) ozone monitoring facility in Boulder, Colorado.

  12. Next generation heterodyne array for JCMT

    NASA Astrophysics Data System (ADS)

    Chen, M.-T.; Dempsey, J.; Ho, P. T. P.; Friberg, P.; Bintley, D.; Walther, C.

    2016-07-01

    As part of the JCMT Future Instrumentation Project, the EAO looks to optimize the premier niche of the facility as the go-to telescope for fast, deep wide-field mapping of the universe at 345 GHz (850 um). The next generation heterodyne array for JCMT will be designed to provide deep ultra-fast mapping capabilities that takes advantage of the full field-of-view available to the telescope, and an array of 90 SIS mixers. This paper presents a preliminary design options and the critical science drivers for the project.

  13. Self-Heterodyne Laser-Spectrum Analyzer

    NASA Technical Reports Server (NTRS)

    Saif, Babak; Seery, Bernard D.

    1991-01-01

    Apparatus measures spectral widths of light emitted by GaAs or other narrow-linewidth diode lasers at wavelengths between 800 and 900 nm. Operating on quasi-homodyne of self-heterodyne principle, apparatus provides relatively high spectral resolution: measures spectral widths of order of 100 kHz. Fine spectral resolution of apparatus provides data relevant to use of AlGaAs diode lasers in such applications as coherent optical communication through free space and injection seeding of solid-state lasers. Also used to explore connections between lifetimes and spectral widths of diode lasers.

  14. Wideband heterodyne receiver for laser communication system

    NASA Technical Reports Server (NTRS)

    Flattau, T.; Lange, R. A.; Mellars, B.; Peyton, J.; Wolczok, J. M. (Inventor)

    1977-01-01

    A heterodyne receiver for laser communication is described which includes a front end having a cooled photomixer contained in a hermetically sealed spaced quality housing designed for wide bandwidth transmission. The photomixer is coupled through a wideband preamplifier to the receiver back end which includes a frequency tracking network and demodulating equipment. The receiver is capable of tracking a Doppler frequency shift of 750 MHz, positive or negative, and has an instantaneous intermediate frequency information bandwidth of 400 MHz. The receiver system is also capable of operating over a wide temperature range and is designed to be suitable for use in outer space communication.

  15. Heterodyne-Detected Dispersed Vibrational Echo Spectroscopy

    NASA Astrophysics Data System (ADS)

    Jones, Kevin C.; Ganim, Ziad; Tokmakoff, Andrei

    2009-11-01

    We develop heterodyned dispersed vibrational echo spectroscopy (HDVE) and demonstrate the new capabilities in biophysical applications. HDVE is a robust ultrafast technique that provides a characterization of the real and imaginary components of third-order nonlinear signals with high sensitivity and single-laser-shot capability and can be used to extract dispersed pump-probe and dispersed vibrational echo spectra. Four methods for acquiring HDVE phase and amplitude spectra were compared: Fourier transform spectral interferometry, a new phase modulation spectral interferometry technique, and combination schemes. These extraction techniques were demonstrated in the context of protein amide I spectroscopy. Experimental HDVE and heterodyned free induction decay amide I spectra were explicitly compared to conventional dispersed pump-probe, dispersed vibrational echo, and absorption spectra. The new capabilities of HDVE were demonstrated by acquiring single-shot spectra and melting curves of ubiquitin and concentration-dependent spectra of insulin suitable for extracting the binding constant for dimerization. The introduced techniques will prove particularly useful in transient experiments, studying irreversible reactions, and micromolar concentration studies of small proteins.

  16. Apparatus for direct-to-digital spatially-heterodyned holography

    DOEpatents

    Thomas, Clarence E.; Hanson, Gregory R.

    2006-12-12

    An apparatus operable to record a spatially low-frequency heterodyne hologram including spatially heterodyne fringes for Fourier analysis includes: a laser; a beamsplitter optically coupled to the laser; an object optically coupled to the beamsplitter; a focusing lens optically coupled to both the beamsplitter and the object; a digital recorder optically coupled to the focusing lens; and a computer that performs a Fourier transform, applies a digital filter, and performs an inverse Fourier transform. A reference beam and an object beam are focused by the focusing lens at a focal plane of the digital recorder to form a spatially low-frequency heterodyne hologram including spatially heterodyne fringes for Fourier analysis which is recorded by the digital recorder, and the computer transforms the recorded spatially low-frequency heterodyne hologram including spatially heterodyne fringes and shifts axes in Fourier space to sit on top of a heterodyne carrier frequency defined by an angle between the reference beam and the object beam and cuts off signals around an original origin before performing the inverse Fourier transform.

  17. SCATTERING OF LIGHT PULSES: Optical heterodyning study of the propagation dynamics of IR femtosecond laser pulses in a strongly scattering porous medium

    NASA Astrophysics Data System (ADS)

    Bestem'yanov, K. P.; Gordienko, Vyacheslav M.; Ivanov, Anatoliy A.; Konovalov, Aleksei N.; Podshivalov, Alexey A.

    2004-07-01

    A system is devised for optical heterodyning based on a femtosecond Cr:forsterite laser using a balance scheme for the laser noise compensation. The dependence of a heterodyne signal on the time delay is measured by detecting backscattered laser radiation from a strongly scattering porous object (a sheet of paper). It is found that the backscattered signal contains 'a long tail' with an exponential decay caused by multiple scattering. The exponent of the exponential is determined by the lifetime of photons in a scattering layer. The absorption and scattering coefficients for different types of paper are measured by the photon lifetime.

  18. Simplified coherent receiver with heterodyne detection of eight-channel 50 Gb/s PDM-QPSK WDM signal after 1040 km SMF-28 transmission.

    PubMed

    Zhang, Junwen; Dong, Ze; Yu, Jianjun; Chi, Nan; Tao, Li; Li, Xinying; Shao, Yufeng

    2012-10-01

    We propose and experimentally demonstrate a simplified coherent receiver based on heterodyne detection with only two balanced photodetectors and two analog-to-digital converters. The polarization diversity hybrid can be simplified relative to the conventional one. The detected intermediate frequency signals are first downconverted to baseband with inphase and quadrature separation. Using this scheme, we successfully demonstrated the eight-channel 50 Gb/s polarization division multiplexed quadrature phase shift keying WDM signal with heterodyne detection based on digital signal processing over 1040 km single-mode fiber 28 with erbium-doped fiber amplifier only amplification.

  19. Phase and frequency tracking considerations for heterodyne optical communications

    NASA Astrophysics Data System (ADS)

    Kaufmann, J. E.

    Heterodyne optical communications systems represent a potential for substantial performance improvement over direct detection systems. Certain difficulties can arise, however, in heterodyne systems, in connection with a frequency instability of the employed laser. In general, frequency or phase tracking will be needed at the receiver to avoid significant degradations in communications performance and requirements for increased transmitter power unless very stable lasers are available. The present investigation is concerned with receiver phase and frequency tracking schemes suitable for heterodyne PSK and MFSK (multilevel frequency-shift-keying) systems in a space communications context, although this work is also applicable to fiberoptic systems.

  20. Heterodyne spectroscopy of polariton spinor interactions

    NASA Astrophysics Data System (ADS)

    Takemura, N.; Trebaol, S.; Wouters, M.; Portella-Oberli, M. T.; Deveaud, B.

    2014-11-01

    We report on spinor polariton interactions in GaAs based microcavities. This investigation is carried out by means of heterodyne polarized pump-probe spectroscopy. We show the dependence of the energy renormalization of the lower and upper polariton resonances with cavity detuning for different polariton densities. We use the exciton-photon based Gross-Pitaevskii equation to model the experiment for both lower and upper polariton modes. The theoretical results reproduce qualitatively the experimental observations revealing the magnitude and sign of the parallel and antiparallel spin interaction strength. We evidence the strong influence of the biexciton resonance on the antiparallel spin polariton energy shift and provide the exciton-biexciton coupling constant. We derive our results in the lower polariton basis using the Gross-Pitaevskii equation, from which we express analytically the spinor polariton interactions and identify the clear role of the biexciton resonance.

  1. Ozone monitoring with an infrared heterodyne radiometer

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Seals, R. K., Jr.

    1977-01-01

    Measurements of the total burden and of the concentration-versus-altitude profiles of ozone have been made with a ground-based heterodyne radiometer at Pasadena, California. The measurements were made in the 9.5-micron wavelength region, where a strong ozone infrared absorption band exists. The radiometer measured solar absorption at selected wavelengths with a spectral resolution of 0.001 reciprocal centimeter, equivalent to the half-width of an ozone absorption line at the 10-millibar altitude level. A carbon dioxide laser served as the local oscillator. This technique can be used to gather important data on both tropospheric and stratospheric ozone, which are not readily accessible with other remote-sensing techniques.

  2. Submillimeter local oscillators for heterodyne spectroscopy

    NASA Technical Reports Server (NTRS)

    Danielewicz, E. J., Jr.

    1980-01-01

    The major technological innovations in continuous wave (CW) submillimeter sources which are specifically suitable for application as local oscillators in heterodyne systems are reviewed. A description of the various sources is given which underscores the general principles and operating features for each type of device. Particular emphasis is placed on CW optically pumped lasers, which have had a dramatic impact as widely available sources of narrow linewidth coherent radiation. The state-of-the-art is summarized for these lasers and performance data are presented for several local oscillator packages. Optically pumped lasers are then compared and contrasted with other competing sources such as backward wave oscillators, IMPATT diodes, and Josephson junctions. By comparing their advantages and limitations for use as local oscillators, the potential applications of these different sources are projected. The prospects for increased tunability, reliability, and scalability are briefly considered, and several novel techniques for generating partially tunable radiation using Schottky diode mixers or CW Raman lasers are highlighted.

  3. Far-Infrared Heterodyne Spectrometer for SOFIA

    NASA Technical Reports Server (NTRS)

    Betz, A. L.; Boreiko, R. T.

    1998-01-01

    This report summarizes work done under NASA Grant NAG2-1062 awarded to the University of Colorado. The project goal was to evaluate the scientific capabilities and technical requirements for a far-infrared heterodyne spectrometer suitable for the SOFIA Airborne Observatory, which is now being developed by NASA under contract to the Universities Space Research Association (USRA). The conclusions detailed below include our specific recommendations for astronomical observations, as well as our intended technical approach for reaching these scientific goals. These conclusions were presented to USRA in the form of a proposal to build this instrument. USRA subsequently awarded the University of Colorado a 3-year grant (USRA 8500-98-010) to develop the proposed Hot-Electron micro-Bolometer (HEB) mixer concept for high frequencies above 3 THz, as well as other semiconductor mixer technologies suitable for high sensitivity receivers in the 2-6 THz frequency band.

  4. Far-Infrared Heterodyne Spectrometer for Sofia

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1998-01-01

    The project goal was to evaluate the scientific capabilities and technical requirements for a far-infrared heterodyne spectrometer suitable for the SOFIA Airborne Observatory, which is now being developed by NASA under contract to the Universities Space Research Association (USRA). The conclusions detailed below include our specific recommendations for astronomical observations, as well as our intended technical approach for reaching these scientific goals. These conclusions were presented to USRA in the form of a proposal to build this instrument. USRA subsequently awarded the University of Colorado a 3-year grant to develop the proposed Hot-Electron micro-Bolometer (HEB) mixer concept for high frequencies above 3 THz, as well as other semiconductor mixer technologies suitable for high sensitivity receivers in the 2-6 THz frequency band.

  5. Homodyning and heterodyning the quantum phase

    NASA Technical Reports Server (NTRS)

    Dariano, Giacomo M.; Macchiavello, C.; Paris, M. G. A.

    1994-01-01

    The double-homodyne and the heterodyne detection schemes for phase shifts between two synchronous modes of the electromagnetic field are analyzed in the framework of quantum estimation theory. The probability operator-valued measures (POM's) of the detectors are evaluated and compared with the ideal one in the limit of strong local reference oscillator. The present operational approach leads to a reasonable definition of phase measurement, whose sensitivity is actually related to the output r.m.s. noise of the photodetector. We emphasize that the simple-homodyne scheme does not correspond to a proper phase-shift measurements as it is just a zero-point detector. The sensitivity of all detection schemes are optimized at fixed energy with respect to the input state of radiation. It is shown that the optimal sensitivity can be actually achieved using suited squeezed states.

  6. Absolute broadband calibration procedure for infrared heterodyne receivers

    SciTech Connect

    Bennett, C.A.; Richards, R.K.; Hutchinson, D.P.

    1988-08-15

    A dual-channel low-noise heterodyne receiver is presented as part of a development effort to build a carbon dioxide laser-based Thomson scattering alpha particle diagnostic for a burning plasma experiment./aip/

  7. Heterodyne technique in photoinduced force microscopy with photothermal effect

    NASA Astrophysics Data System (ADS)

    Yamanishi, J.; Naitoh, Y.; Li, Y. J.; Sugawara, Y.

    2017-03-01

    The heterodyne technique is used to detect short-range forces. Using the heterodyne technique, we demonstrate photoinduced force microscopy (PiFM) imaging and z-spectroscopy without the artifact of photothermal vibration. The rejection ratio was at least 99.975% under a high-scattering condition. In addition, the heterodyne technique employs the optimal amplitude at the first resonance frequency of the cantilever to detect the photoinduced force sensitively. According to our calculation, the optimal ratio of the amplitude to the distance between the dipole of the tip and that of the sample is 0.4448. The heterodyne technique can be employed to perform PiFM without the artifact by using the optimal amplitude.

  8. Heterodyne efficiency of a detection system for partially coherent beams.

    PubMed

    Salem, Mohamed; Rolland, Jannick P

    2010-05-01

    We consider the heterodyne efficiency as a measure of quality for a coherent detection system. The heterodyne efficiency reflects the matching between the received beam and the local oscillator beam on the detector surface, and one can use this property for the alignment of the system. In this paper we derive a general expression for the heterodyne efficiency of a detection system for beams at any state of coherence, assuming that the propagation directions for the two signals (the received signal and the locally generated one) are slightly different. We derive an analytical expression for the heterodyne efficiency when mixing coherently two partially coherent Gaussian Schell-model beams on a photodetector surface. Numerical examples are given for the variation in the heterodyne efficiency with the misalignment angle, the detector radius, and the parameters of the overlapping beams. We show that partially coherent beams, although they suffer more than coherent beams from a decrease in the heterodyne efficiency, are less affected than coherent beams by the misalignment of the detection system.

  9. Faster processing of multiple spatially-heterodyned direct to digital holograms

    DOEpatents

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN

    2008-09-09

    Systems and methods are described for faster processing of multiple spatially-heterodyned direct to digital holograms. A method includes of obtaining multiple spatially-heterodyned holograms, includes: digitally recording a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; digitally recording a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first object beam; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam; and applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result, wherein digitally recording the first spatially-heterodyned hologram is completed before digitally recording the second spatially-heterodyned hologram and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  10. Faster processing of multiple spatially-heterodyned direct to digital holograms

    DOEpatents

    Hanson, Gregory R.; Bingham, Philip R.

    2006-10-03

    Systems and methods are described for faster processing of multiple spatially-heterodyned direct to digital holograms. A method includes of obtaining multiple spatially-heterodyned holograms, includes: digitally recording a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; digitally recording a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first, object beam; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam; and applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result, wherein digitally recording the first spatially-heterodyned hologram is completed before digitally recording the second spatially-heterodyned hologram and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  11. Measuring Filter Transmittance Using Heterodyne Detection

    NASA Astrophysics Data System (ADS)

    Migdall, A. L.; Roop, B.; Xia, Gu Jun

    1991-01-01

    We use heterodyne detection to measure optical transmittance over an unprecedented dynamic range, with high accuracy and high sensitivity. Our set-up uses a Mach-Zehnder interferometer with acousto-optic frequency shifting to produce a 30 MHz frequency difference between the two light beams, resulting in a beat envelope on the interferometer output beam. We determine the optical transmittance of a filter by inserting it into one of the interferometer arms and measuring the change in amplitude of the optical beat signal. This method allows direct comparison between optical and RF attenuators, ultimately tying optical transmittance measurements to 30 MHz RF attenuation standards in an absolute way. Using this method, we have measured filters that cover 12 decades of transmittance. We discuss a recently developed instrument that improves the accuracy and dynamic range over which the optical-RF connection can be made. This instrument functions as a lock-in amplifier with a dynamic range of up to 180 dB. In addition, we extend the technique into the infrared at 10,6 μm, where we demonstrate that transmittances of filters at room temperature can be measured with a dynamic range of more than 11 decades.

  12. Broadband Infrared Heterodyne Spectrometer: Final Report

    SciTech Connect

    Stevens, C G; Cunningham, C T; Tringe, J W

    2010-12-16

    This report summarizes the most important results of our effort to develop a new class of infrared spectrometers based on a novel broadband heterodyne design. Our results indicate that this approach could lead to a near-room temperature operation with performance limited only by quantum noise carried by the incoming signal. Using a model quantum-well infrared photodetector (QWIP), we demonstrated key performance features of our approach. For example, we directly measured the beat frequency signal generated by superimposing local oscillator (LO) light of one frequency and signal light of another through a spectrograph, by injecting the LO light at a laterally displaced input location. In parallel with the development of this novel spectrometer, we modeled a new approach to reducing detector volume though plasmonic resonance effects. Since dark current scales directly with detector volume, this ''photon compression'' can directly lead to lower currents. Our calculations indicate that dark current can be reduced by up to two orders of magnitude in an optimized ''superlens'' structure. Taken together, our spectrometer and dark current reduction strategies provide a promising path toward room temperature operation of a mid-wave and possibly long-wave infrared spectrometer.

  13. Heterodyne method for high specificity gas detection.

    NASA Technical Reports Server (NTRS)

    Dimeff, J.; Donaldson, R. W.; Gunter, W. D., Jr.; Jaynes, D. N.; Margozzi, A. P.; Deboo, G. J.; Mcclatchie, E. A.; Williams, K. G.

    1971-01-01

    This paper describes a new technique for measuring trace quantities of gases. The technique involves the use of a reference cell (containing a known amount of the gas being sought) and a sample cell (containing an unknown amount of the same gas) wherein the gas densities are modulated. Light passing through the two cells in sequence is modulated in intensity at the vibrational-rotational lines characteristic of the absorption spectrum for the gas of interest. Since the absorption process is nonlinear, modulating the two absorption cells at two different frequencies gives rise to a heterodyning effect, which in turn introduces sum and difference frequencies in the detected signal. Measuring the ratio of the difference frequency signal for example, to the signal introduced by the reference cell provides a normalized measure of the amount of the gas in the sample cell. The readings produced are thereby independent of source intensity, window transparency, and detector sensitivity. Experimental evaluation of the technique suggests that it should be applicable to a wide range of gases, that it should be able to reject spurious signals due to unwanted gases, and that it should be sensitive to concentrations of the order of 10 to the minus 8th power when used with a sample cell of only 20 cm length.

  14. Comparison of direct and heterodyne detection optical intersatellite communication links

    NASA Technical Reports Server (NTRS)

    Chen, C. C.; Gardner, C. S.

    1987-01-01

    The performance of direct and heterodyne detection optical intersatellite communication links are evaluated and compared. It is shown that the performance of optical links is very sensitive to the pointing and tracking errors at the transmitter and receiver. In the presence of random pointing and tracking errors, optimal antenna gains exist that will minimize the required transmitter power. In addition to limiting the antenna gains, random pointing and tracking errors also impose a power penalty in the link budget. This power penalty is between 1.6 to 3 dB for a direct detection QPPM link, and 3 to 5 dB for a heterodyne QFSK system. For the heterodyne systems, the carrier phase noise presents another major factor of performance degradation that must be considered. In contrast, the loss due to synchronization error is small. The link budgets for direct and heterodyne detection systems are evaluated. It is shown that, for systems with large pointing and tracking errors, the link budget is dominated by the spatial tracking error, and the direct detection system shows a superior performance because it is less sensitive to the spatial tracking error. On the other hand, for systems with small pointing and tracking jitters, the antenna gains are in general limited by the launch cost, and suboptimal antenna gains are often used in practice. In which case, the heterodyne system has a slightly higher power margin because of higher receiver sensitivity.

  15. Design considerations for optical heterodyne receivers: A review

    NASA Technical Reports Server (NTRS)

    Degnan, J. J.

    1980-01-01

    The current state of knowledge concerning optical heterodyne receivers is reviewed. Following a discussion of noise processes in the heterodyne receiver and the manner in which sensitivity is increased through time integration of the detected signal, an expression for the mean square signal current is derived by mixing a coherent local oscillator with a partially coherent, quasimonochromatic source. Then the manner in which the IF signal calculation can be transferred to any convenient plane in the optical front end of the receiver is demonstrated. Using these techniques, a relatively simple equation is obtained for the coherently detected signal from an extended incoherent source and applied to the heterodyne detection of an extended thermal source and to the backscatter lidar problem where the antenna patterns of both the transmitter beam and heterodyne receiver must be taken into account. Finally, the detection of a coherent source is considered and, in particular, a distant point source such as a star or laser transmitter in a long range heterodyne communications system is discussed.

  16. Wideband Heterodyne QWIP Receiver Development for Thermonuclear Fusion Measurements

    SciTech Connect

    Bennett, C.A.; Buchanan, M.; Hutchinson, D.P.; Liu, H.C.; Richards, R.K.; Simpson, M.L.

    1998-11-01

    Oak Ridge National Laboratory (ORNL) has been developing heterodyne receivers for plasma diagnostic applications for over 20 years. One area of this work has been the development of a diagnostic system for the measurement of the energy of alpha particles created in a thermonuclear fusion reactor. These particles originate with an energy of 3.5 MeV and cool to the thermal energy of the plasma (around 15 keV) after several seconds. To measure the velocity distribution of these alpha particles, a Thomson scattering diagnostic is under development based on a high power CO{sub 2} laser at 10 microns with a heterodyne receiver. The Doppler shift generated by Thomson scattering of the alpha particles requires a wideband heterodyne receiver (greater than 10 GHz). Because Mercury-Cadimum-Telluride (MCT) detectors are limited to a bandwidth of approximately 2 GHz, a Quantum Well Infrared Photodetector (QWIP) detector was obtained from the National Research Council of Canada (NRC) and evaluated for its heterodyne performance using the heterodyne testing facility developed at ORNL.

  17. Doppler Asymmetric Spatial Heterodyne Spectroscopy (DASH): An Innovative Concept for Measuring Winds in Planetary Atmospheres

    DTIC Science & Technology

    2006-01-01

    Doppler Asymmetric Spatial Heterodyne Spectroscopy (DASH): An innovative concept for measuring winds in planetary atmospheres Christoph R...USA Keywords: Wind, atmospheric dynamics, Doppler imaging, Spatial Heterodyne Spectroscopy , Michelson Interferometer, planetary atmospheres...Heterodyne Spectroscopy (DASH): An innovative concept for measuring winds in planetary atmospheres 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  18. Velocity measurement by coherent x-ray heterodyning

    SciTech Connect

    Lhermitte, Julien R. M.; Rogers, Michael C.; Manet, Sabine; Sutton, Mark

    2017-01-01

    We present a small-angle coherent x-ray scattering technique used for measuring flow velocities in slow moving materials. The technique is an extension of X-ray Photon Correlation Spectroscopy (XPCS): It involves mixing the scattering from moving tracer particles with a static reference that heterodynes the signal. This acts to elongate temporal effects caused by flow in homodyne measurements, allowing for a more robust measurement of flow properties. Using coherent x-ray heterodyning, velocities ranging from 0.1 to 10 μm/s were measured for a viscous fluid pushed through a rectangular channel. We describe experimental protocols and theory for making these Poiseuille flow profile measurements and also develop the relevant theory for using heterodyne XPCS to measure velocities in uniform and Couette flows.

  19. Investigation of the quantum efficiency of optical heterodyne detectors

    NASA Technical Reports Server (NTRS)

    Batchman, T. E.

    1984-01-01

    The frequency response and quantum efficiency of optical photodetectors for heterodyne receivers is investigated. The measurements utilized two spectral lines from the output of two lasers as input to the photodetectors. These lines are easily measurable in power and frequency and hence serve as known inputs. By measuring the output current of the photodetector the quantum efficiency is determined as a function of frequency separation between the two input signals. An investigation of the theoretical basis and accuracy of this type of measurement relative to similar measurements utilizing risetime is undertaken. A theoretical study of the heterodyne process in photodetectors based on semiconductor physics is included so that higher bandwidth detectors may be designed. All measurements are made on commercially available detectors and manufacturers' specifications for normal photodetector operation are compared to the measured heterodyne characteristics.

  20. Velocity measurement by coherent x-ray heterodyning.

    PubMed

    Lhermitte, Julien R M; Rogers, Michael C; Manet, Sabine; Sutton, Mark

    2017-01-01

    We present a small-angle coherent x-ray scattering technique used for measuring flow velocities in slow moving materials. The technique is an extension of X-ray Photon Correlation Spectroscopy (XPCS): It involves mixing the scattering from moving tracer particles with a static reference that heterodynes the signal. This acts to elongate temporal effects caused by flow in homodyne measurements, allowing for a more robust measurement of flow properties. Using coherent x-ray heterodyning, velocities ranging from 0.1 to 10 μm/s were measured for a viscous fluid pushed through a rectangular channel. We describe experimental protocols and theory for making these Poiseuille flow profile measurements and also develop the relevant theory for using heterodyne XPCS to measure velocities in uniform and Couette flows.

  1. IQ quadrature demodulation algorithm used in heterodyne detection

    NASA Astrophysics Data System (ADS)

    Wang, Chunhui; Qu, Yang; Tang, Yajun Pang Tiantian

    2015-09-01

    In order to obtain better detection results of heterodyne, we used phase IQ quadrature demodulation algorithm to process the data which detected by laser heterodyne. Based on laser heterodyne interferometer, processing the data in the interferometer phase IQ quadrature demodulation algorithm from the signal to noise ratio, sampling rate, sampling rate, filter order and cutoff frequency, verify the effects of these system parameters to the phase precision, and choose the best parameters to obtain a better phase precision through experiment as: the signal to noise ratio is 25 dB, the IF signal frequency is 98.3 MHz, 98.5 MHz, 99.1 MHz, 99.5 MHz and 100 MHz, the sampling rate is 512-2048, the cutoff frequency and order of the filter are 0.11 and 40, respectively.

  2. Two-wavelength full-field heterodyne interferometric profilometry

    NASA Astrophysics Data System (ADS)

    Hsieh, Hung-Chih; Chen, Yen-Liang; Jian, Zhi-Chen; Wu, Wang-Tsung; Su, Der-Chin

    2009-02-01

    An alternative full-field interferometric profilometry is proposed by combining two-wavelength interferometry and heterodyne interferometry. A collimated heterodyne light is introduced into a modified Twyman-Green interferometer, the full-field interference signals are taken by a fast CMOS camera. The sampled intensities recorded by each pixel are fitted to derive a sinusoidal signal with the least-square sine wave fitting algorithm, and its phase can be obtained. Comparing the phase of the reference point, the relative phase of the pixel can be calculated. Next, the same measurement is made again at a different wavelength. The relative phase with respect to the effective wavelength can be calculated and the profile of the tested sample can be derived with the two-wavelength interferometric technique. Its validity is demonstrated. It has merits of both two-wavelength interferometry and heterodyne interferometry.

  3. Heterodyne detection with mismatch correction based on array detector

    NASA Astrophysics Data System (ADS)

    Dong, Hongzhou; Li, Guoqiang; Yang, Ruofu; Yang, Chunping; Ao, Mingwu

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  4. Heterodyne detection with mismatch correction base on array detector

    NASA Astrophysics Data System (ADS)

    Hongzhou, Dong; Guoqiang, Li; Ruofu, Yang; Chunping, Yang; Mingwu, Ao

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  5. Optical heterodyne measurement of cloud droplet size distributions.

    PubMed

    Gollub, J P; Chabay, L; Flygare, W H

    1973-12-01

    Optical heterodyne spectra of laser light quasi-elastically scattered by falling water droplets (1-10-micro radius) in a diffusion cloud chamber were used to determine the droplet size distribution. The rate of fall depends on radius in a known way, thus yielding a heterodyne spectrum manifesting a distribution of Doppler shifts. This spectrum, in conjunction with the calculated Mie scattering intensity as a function of droplet radius, provides a direct measure of the droplet size distribution for droplets large enough that Brownian motion is negligible. The experiments described in this paper demonstrate the technique and establish the potential for further more quantitative studies of size distributions.

  6. Widefield heterodyne interferometry using a custom CMOS modulated light camera.

    PubMed

    Patel, Rikesh; Achamfuo-Yeboah, Samuel; Light, Roger; Clark, Matt

    2011-11-21

    In this paper a method of taking widefield heterodyne interferograms using a prototype modulated light camera is described. This custom CMOS modulated light camera (MLC) uses analogue quadrature demodulation at each pixel to output the phase and amplitude of the modulated light as DC voltages. The heterodyne interference fringe patterns are generated using an acousto-optical frequency shifter (AOFS) in an arm of a Mach-Zehnder interferometer. Widefield images of fringe patterns acquired using the prototype MLC are presented. The phase can be measured to an accuracy of ±6.6°. The added value of this method to acquire widefield images are discussed along with the advantages.

  7. Integrated heterodyne interferometer with on-chip modulators and detectors.

    PubMed

    Cole, David B; Sorace-Agaskar, Cheryl; Moresco, Michele; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R

    2015-07-01

    We demonstrate, to our knowledge, the first on-chip heterodyne interferometer fabricated on a 300-mm CMOS compatible process that exhibits root-mean-square (RMS) position noise on the order of 2 nm. Measuring 1 mm by 6 mm, the interferometer is also, to our knowledge, the smallest heterodyne interferometer demonstrated to date and will surely impact numerous interferometric and metrology applications, including displacement measurement, laser Doppler velocimetry and vibrometry, Fourier transform spectroscopy, imaging, and light detection and ranging (LIDAR). Here we present preliminary results that demonstrate the displacement mode.

  8. First system experiments with a monolithically integrated tunable polarization diversity heterodyne receiver OEIC on InP

    NASA Astrophysics Data System (ADS)

    Hilbk, U.; Hermes, T.; Meissner, P.; Westphal, F. J.; Jacumeit, G.; Stenzel, R.; Unterboersch, G.

    1995-01-01

    System performance of an integrated polarization diversity heterodyne receiver optoelectronic IC (OEIC) is reported. The OEIC is monolithically integrated on InP. It includes a tunable 4 section DBR laser (quasi continuous tuning range 3.5 nm) and balanced photodiodes. The packaged OEIC is supplied with a fiber pigtail. Stable and polarization independent operation is achieved without any tendency for a bit error floor. The sensitivity at 1550.2 nm is -33.5 dBm at a bitrate of 140 Mbit/s. The performance of the OEIC based receiver is verified by operating in an experimental OFDM-TV distribution system with 4 channels.

  9. Thermal bifurcation in the upper solar photosphere inferred from heterodyne spectroscopy of OH rotational lines

    NASA Technical Reports Server (NTRS)

    Deming, D.; Hillman, J. J.; Kostiuk, T.; Mumma, M. J.; Zipoy, D. M.

    1984-01-01

    Low noise high spectral resolution observations of two pure rotation transitions of OH from the solar photosphere were obtained. The observations were obtained using the technique of optically null-balanced infrared heterodyne spectroscopy, and consist of center-to-limb line profiles of a v=1 and a v=0 transition near 12 microns. These lines should be formed in local thermodynamic equilibrium (LTE), and are diagnostics of the thermal structure of the upper photosphere. The v=0 R22 (24.5)e line strengthens at the solar limb, in contradiction to the predictions of current one dimensional photospheric models. Data for this line support a two dimensional model in which horizontal thermal fluctuations of order + or - 800K occur in the region Tau (sub 5000) approximately .001 to .01. This thermal bifurcation may be maintained by the presence of magnetic flux tubes, and may be related to the solar limb extensions observed in the 30 to 200 micron region.

  10. Laser/Heterodyne Measurement of Temperature and Salinity

    NASA Technical Reports Server (NTRS)

    Jobson, D. J.; Fales, C. L.; Katzberg, S. J.

    1982-01-01

    Proposed visible-light laser/heterodyne receiver would remotely measure temperature and salinity of subsurface water. Operation is based on acoustic/optical scattering of light by sound waves. Application of this concept is foreseen in current research on energy conversion from ocean currents produced by thermal gradients and on future marine remote-sensing program.

  11. A broadband, high-resolution spatial heterodyne spectrometer

    NASA Astrophysics Data System (ADS)

    Lawler, J. E.; Harlander, J.; Roesler, F. L.; Labby, Z.

    2009-05-01

    Design and performance parameters of a broadband, high-resolution spatial heterodyne spectrometer (SHS) with a transmitting beamsplitter are described. This Mark 1 SHS achieves more than a factor of five in continuous wavenumber coverage with a resolving power in hundreds of thousands. Progress toward an all reflection, broadband, high-resolution Mark 2 SHS is reported.

  12. An SIS Waveguide heterodyne Reciever for 600 GHz - 635 GHz

    NASA Technical Reports Server (NTRS)

    Salez, Morvan; Febvre, Pascal; McGrath, William R.; Bumble, Bruce; LeDuc, Henry G.

    1994-01-01

    A waveguide SIS heterodyne receiver using a Nb/A10xNb junction has been built for astronomical observations of molecular tranitions in the frequency range 600GHz - 635GHZ, and has been successfully used at the Caltech Submillimeter Observatory (CSO).

  13. Germanium:gallium photoconductors for far infrared heterodyne detection

    NASA Technical Reports Server (NTRS)

    Park, I. S.; Haller, E. E.; Grossman, E. N.; Watson, Dan M.

    1988-01-01

    Highly compensated Ge:Ga photoconductors for high bandwidth heterodyne detection have been fabricated and evaluated. Bandwidths up to 60 MHz have been achieved with a corresponding current responsivity of 0.01 A/W. The expected dependence of bandwidth on bias field is obtained. It is noted that increased bandwidth is obtained at the price of greater required local oscillator power.

  14. Heterodyne readout for read-write holographic memories

    NASA Technical Reports Server (NTRS)

    Mezrich, R. S.; Stewart, W. C.

    1973-01-01

    A heterodyne readout technique for read-write holographic memory systems that reconstruct a virtual image wavefront is described and demonstrated. The conventionally recorded hologram is illuminated simultaneously with a suitable combination of temporally modulated reference and modified object waves for readout. Best performance is obtained for temporal phase modulation. The coupling of the illuminating wavefronts by the hologram is analyzed.

  15. Laser/Heterodyne Measurement of Temperature and Salinity

    NASA Technical Reports Server (NTRS)

    Jobson, D. J.; Fales, C. L.; Katzberg, S. J.

    1982-01-01

    Proposed visible-light laser/heterodyne receiver would remotely measure temperature and salinity of subsurface water. Operation is based on acoustic/optical scattering of light by sound waves. Application of this concept is foreseen in current research on energy conversion from ocean currents produced by thermal gradients and on future marine remote-sensing program.

  16. Imaging doppler velocimeter with downward heterodyning in the optical domain

    DOEpatents

    Reu, Phillip L; Hansche, Bruce D

    2013-05-21

    In a Doppler velocimeter, the incoming Doppler-shifted beams are heterodyned to reduce their frequencies into the bandwidth of a digital camera. This permits the digital camera to produce at every sampling interval a complete two-dimensional array of pixel values. This sequence of pixel value arrays provides a velocity image of the target.

  17. A Spatial Heterodyne Spectrometer for Laboratory Astrophysics; First Interferogram

    NASA Technical Reports Server (NTRS)

    Lawler, J. E.; Labby, Z. E.; Roesler, F. L.; Harlander, J.

    2006-01-01

    A Spatial Heterodyne Spectrometer with broad spectral coverage across the VUV - UV region and with a high (> 500,000 ) spectral resolving power is being built for laboratory measurements of spectroscopic data including emission branching fractions, improved level energies, and hyperfine/isotopic parameters.

  18. Cryogenic 160-GHz MMIC Heterodyne Receiver Module

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene A.; Soria, Mary M.; Owen, Heather R.; Dawson, Douglas E.; Kangaslahti, Pekka P.; Gaier, Todd C.; Voll, Patricia; Lau, Judy; Sieth, Matt; Church, Sarah

    2011-01-01

    A cryogenic 160-GHz MMIC heterodyne receiver module has demonstrated a system noise temperature of 100 K or less at 166 GHz. This module builds upon work previously described in Development of a 150-GHz MMIC Module Prototype for Large-Scale CMB Radiation (NPO-47664), NASA Tech Briefs, Vol. 35, No. 8 (August 2011), p. 27. In the original module, the local oscillator signal was saturating the MMIC low-noise amplifiers (LNAs) with power. In order to suppress the local oscillator signal from reaching the MMIC LNAs, the W-band (75 110 GHz) signal had to be filtered out before reaching 140 170 GHz. A bandpass filter was developed to cover 120 170 GHz, using microstrip parallel-coupled lines to achieve the desired filter bandwidth, and ensure that the unwanted W-band local oscillator signal would be sufficiently suppressed. With the new bandpass filter, the entire receiver can work over the 140 180-GHz band, with a minimum system noise temperature of 460 K at 166 GHz. The module was tested cryogenically at 20 K ambient temperature, and it was found that the receiver had a noise temperature of 100 K over an 8-GHz bandwidth. The receiver module now includes a microstrip bandpass filter, which was designed to have a 3-dB bandwidth of approximately 120-170 GHz. The filter was fabricated on a 3-mil-thick alumina substrate. The filter design was based on a W-band filter design made at JPL and used in the QUIET (Q/U Imaging ExperimenT) radiometer modules. The W-band filter was scaled for a new center frequency of 150 GHz, and the microstrip segments were changed accordingly. Also, to decrease the bandwidth of the resulting scaled design, the center gaps between the microstrip lines were increased (by four micrometers in length) compared to the gaps near the edges. The use of the 150-GHz bandpass filter has enabled the receiver module to function well at room temperature. The system noise temperature was measured to be less than 600 K (at room temperature) from 154 to 168 GHz

  19. Single beam write and/or replay of spatial heterodyne holograms

    DOEpatents

    Thomas, Clarence E.; Hanson, Gregory R.

    2007-11-20

    A method of writing a spatially heterodyne hologram having spatially heterodyne fringes includes: passing a single write beam through a spatial light modulator that digitally modulates said single write beam; and focusing the single write beam at a focal plane of a lens to impose a holographic diffraction grating pattern on the photorefractive crystal, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein only said single write beam is incident on said photorefractive crystal without a reference beam. A method of replaying a spatially heterodyne hologram having spatially heterodyne fringes at a replay angle includes: illuminating a photorefractive crystal having a holographic diffraction grating with a beam from a laser at an illumination angle, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein a difference between said illumination angle and said replay angle defines a diffraction angle .alpha. that is a function of a plane wave mathematically added to original object wave phase and amplitude data of said spatially heterodyne hologram having spatially heterodyne fringes.

  20. Recording multiple spatially-heterodyned direct to digital holograms in one digital image

    DOEpatents

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN

    2008-03-25

    Systems and methods are described for recording multiple spatially-heterodyned direct to digital holograms in one digital image. A method includes digitally recording, at a first reference beam-object beam angle, a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram to sit on top of a first spatial-heterodyne carrier frequency defined by the first reference beam-object beam angle; digitally recording, at a second reference beam-object beam angle, a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram to sit on top of a second spatial-heterodyne carrier frequency defined by the second reference beam-object beam angle; applying a first digital filter to cut off signals around the first original origin and define a first result; performing a first inverse Fourier transform on the first result; applying a second digital filter to cut off signals around the second original origin and define a second result; and performing a second inverse Fourier transform on the second result, wherein the first reference beam-object beam angle is not equal to the second reference beam-object beam angle and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  1. A Deeper Look at the Fundamentals of Heterodyne Detection Requirements

    NASA Technical Reports Server (NTRS)

    Roychoudhuri, Chandrasekhar; Prasad, Narasimha S.

    2007-01-01

    We generally accept the experimentally observed criteria for heterodyne detections that the two waves that are mixed must (i) be collinear, (ii) have matched wave fronts and (iii) cannot be orthogonally polarized. We have not found in the literature adequate physical explanations for these requirements. The purpose of this paper is to find deeper physical understanding of the coherent heterodyne detection processes that could lead to better coherent laser radar system designs1. We find that there are a number of unresolved paradoxes in classical and quantum optics regarding the definitions and understanding of the "interference" and "coherence" properties of light, which are attributed as essentially due to inherent properties of the EM waves. A deeper exploration indicates that it is the various quantum mechanical properties of the detecting material dipoles that make light detectable (visible, or measurable) to us. Accordingly, all the properties that we generally attribute to only light, are in reality manifestations of collective properties of dipole-light interactions. "Interference" and "coherence" can be better understood in terms of this mutual interaction, followed by energy absorption by the dipoles from EM wave fields, manifesting in some measurable transformation of the detecting dipoles. Light beams do not interfere by themselves. The superposition effects due to light beams become manifest through the response characteristics of the detecting dipoles. In this paper, we will show some preliminary expe rimental results that clearly demonstrate that the heterodyning wave fronts have quantitative degradation in signal generation as the angle between them deviates from perfect collinearity. Subsequently, we will propose a hypothesis for this behavior. We will present experimental data establishing that the so called incoherent light can be detected through heterodyne mixing as long as the pulse length contained in the "incoherent" light is longer than the

  2. The Beauty and Limitations of 10 Micron Heterodyne Interferometry (ISI)

    NASA Technical Reports Server (NTRS)

    Danchi, William C.

    2003-01-01

    Until recently, heterodyne interferometry at 10 microns has been the only successful technique for stellar interferometry in the very difficult atmospheric window from 9-12 microns. For most of its operational lifetime the U.C. Berkeley Infrared Spatial Interferometer was a single-baseline two telescope (1.65 m aperture) system using CO2 lasers as local oscillators. This instrument was designed and constructed from 1983-1988, and first fringes were obtained at Mt. Wilson in June 1988. During the past few years, a third telescope was constructed and just recently the first closure phases were obtained at 11.15 microns. We discuss the history, physics and technology of heterodyne interferometry in the mid-infrared, and some key astronomical results that have come from this unique instrument.

  3. Coherent electromagnetic field imaging through Fourier transform heterodyne

    SciTech Connect

    Cooke, B.J.; Laubscher, B.E.; Olivas, N.L.; Goeller, R.M.; Cafferty, M.; Briles, S.D.; Galbraith, A.E. |; Grubler, A.C. |

    1998-12-31

    The authors present a detection process capable of directly imaging the transverse amplitude, phase, and if desired, Doppler shift of coherent electromagnetic fields. Based on coherent detection principles governing conventional heterodyned RADAR/LIDAR systems, Fourier Transform Heterodyne (FTH) incorporates transverse spatial encoding of the local oscillator for image capture. Appropriate selection of spatial encoding functions, or basis set, allows image retrieval by way of classic Fourier manipulations. Of practical interest: (1) imaging is accomplished on a single element detector requiring no additional scanning or moving components, and (2) a wide variety of appropriate spatial encoding functions exist that may be adaptively configured in real-time for applications requiring optimal detection. In this paper, they introduce the underlying principles governing FTH imaging, followed by demonstration of concept via a simple experimental setup based on a HeNe laser and a 69 element spatial phase modulator.

  4. Heterodyne moiré interferometry for measuring corneal surface profile

    NASA Astrophysics Data System (ADS)

    Chang, Wei-Yao; Chen, Kun-Huang; Chen, Der-Chin; Tseng, Jung-Kai; Chen, Shyan-Tarng; Sun, Han-Ying; Chen, Jing-Heng; Hsu, Ken Y.

    2014-03-01

    This study proposes an accurate method for reconstructing the corneal surface profile. By applying a constant velocity to the projection grating along the grating plane, a series of sampling points of the sinusoidal wave, which behaves in the manner of heterodyne interferometric signals, can be recorded using a CMOS camera. The phase distribution of the moiré fringes can then be obtained using the IEEE 1241 least-square sine fitting algorithm and two-dimensional (2D) phase unwrapping. Finally, the corneal surface profile can be reconstructed by substituting the phase distribution into a specially derived equation. To validate the proposed method, the corneal surface of a pig eyeball was measured. The measurement resolution was approximately 3.5 μm. Because of the introduction of the Talbot effect, the projection moiré method, and heterodyne interferometry, this approach provides the advantages of a simple optical setup, ease of operation, high stability, and high resolution.

  5. Spatial heterodyne spectrometer based on the Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Cai, Qisheng; Xiangli, Bin; Du, Shusong

    2015-11-01

    Spatial heterodyne spectroscopy (SHS) is a new kind of Fourier-transform spectroscopic technique capable of very high spectral resolution. In this paper, a spatial heterodyne spectrometer based on the Mach-Zehnder interferometer (MZ-SHS) is proposed. It is modified by replacing one mirror in the Mach-Zehnder interferometer with a diffraction grating. This technique retains many of the advantages of traditional SHS. Moreover, the spatial frequency of the interferogram is strictly linear with wavenumber. We describe the concept of the new MZ-SHS and elaborate the exact expression of the interferogram. Also, a design example and two kinds of imitated interferograms are presented in this paper. One is simulated in MATLAB and the other is generated in ZEMAX using ray tracing method. The retrieved spectra from these two interferograms show a good agreement with the theoretical results.

  6. Sensitivity limits of an infrared heterodyne spectrometer for astrophysical applications

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Mumma, M. J.; Kostiuk, T.; Buhl, D.

    1975-01-01

    A discussion and an evaluation of the degradation in sensitivity is given for a heterodyne spectrometer employing a HgCdTe photodiode mixer and tunable diode lasers. The minimum detectable source brightness is considered as a function of the mixer parameters, transmission coefficient of the beam splitter, and local oscillator emission powers. The degradation in the minimum detectable line source brightness which results from the bandwidth being a function of the line width is evaluated and plotted as a function of the wavelength and bandwidth for various temperature to mass ratios. It is shown that the minimum achievable degradation in the sensitivity of a practical astronomical heterodyne spectrometer is approximately 30. Estimates of signal-to-noise ratios with which infrared line emission from astronomical sources of interest may be detected are given.

  7. Phase-resolved ferromagnetic resonance using heterodyne detection method

    PubMed Central

    Yoon, Seungha; Liu, Jason; McMichael, Robert D.

    2016-01-01

    This paper describes a phase-resolved ferromagnetic resonance (FMR) measurement using a heterodyne method. Spin precession is driven by microwave fields and detected by 1550 nm laser light that is modulated at a frequency slightly shifted with respected to the FMR driving frequency. The evolving phase difference between the spin precession and the modulated light produces a slowly oscillating Kerr rotation signal with a phase equal to the precession phase plus a phase due to the path length difference between the excitation microwave signal and the optical signal. We estimate the accuracy of the precession phase measurement to be 0.1 rad. This heterodyne FMR detection method eliminates the need for field modulation and allows a stronger detection signal at higher intermediate frequency where the 1/f noise floor is reduced. PMID:27453957

  8. Development of trace gas detection instrumentation. [using the heterodyne principle

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Breadboard hardware was constructed to demonstrate detection of a gaseous species by the heterodyne principle. The characteristics of the component parts were investigated and preliminary measurements were made to establish the sensitivity and selectivity of the method for gas analysis of CO, CO2, and N2O. A prototype heterodyne gas analyzer was designed, built, and brought into operational condition. Performance parameters of the prototype analyzer were investigated and its sensitivity to CO2 measured. Further development was undertaken for both the optical bench and the electronic processor components. A three-gas prototype analyzer, capable of measuring the gases CO, CO2, and CH4 was also constructed and tested. Detailed descriptions of the work and results are presented.

  9. High sensitivity infrared 10.6 micrometer heterodyne receiver development

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The results are presented for a study on the design of an infrared 10.6-micrometer quantum-noise-limited optical receiver subsystem. Performance measurements of the HgCdTe photomixer preamplifier combination were carried out for photomixer temperatures up to 152 K and a photomixer frequency response of up to 420 MHz was obtained. Results of temperature and bias cycling of HgCdTe photomixers are reported. Design considerations for an operational 10.6 micrometer heterodyne receiver are presented. These consist of design data on required laser LO illumination, heat load levels for photomixer cooler, photomixer uniformity and the effects of photomixer impedance match on receiver sensitivity. Analysis and measurements of 10.6 micrometer heterodyne detection in an extrinsic photoconductive (p-type) HgCdTe photomixer are also presented.

  10. Probabilistic shaping for ROF system with heterodyne coherent detection

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Li, Xinying; Zhang, Ying; Xin, Xiangjun; Yu, Jianjun

    2017-05-01

    We investigate and compare the performance of normal and probabilistic shaping (PS) 16-ary quadrature amplitude modulation (16QAM) in a photonic vector millimeter-wave (mm-wave) signal generation system adopting heterodyne coherent detection. And we obtain a better bit-error ratio (BER) performance in the PS 16QAM scheme compared to the normal 16QAM scheme in the simulation. We also for the first time experimentally demonstrate the feasibility of PS-polarization-division-multiplexing 16QAM in a photonic vector mm-wave signal generation system employing heterodyne coherent detection. We obtain the same BER in PS and normal schemes with the PS scheme providing a higher bit rate. Then we experimentally carry out the performance investigation of PS in a 16QAM-modulated radio over fiber system with 40 m wireless transmission.

  11. Noise characteristics of heterodyne/homodyne frequency-domain measurements

    PubMed Central

    Kupinski, Matthew A.

    2012-01-01

    Abstract. We theoretically develop and experimentally validate the noise characteristics of heterodyne and/or homodyne measurements that are widely used in frequency-domain diffusive imaging. The mean and covariance of the modulated heterodyne output are derived by adapting the random amplification of a temporal point process. A multinomial selection rule is applied to the result of the temporal noise analysis to additionally model the spatial distribution of intensified photons measured by a charge-coupled device (CCD), which shows that the photon detection efficiency of CCD pixels plays an important role in the noise property of detected photons. The approach of using a multinomial probability law is validated from experimental results. Also, experimentally measured characteristics of means and variances of homodyne outputs are in agreement with the developed theory. The developed noise model can be applied to all photon amplification processes. PMID:22352646

  12. Infrared heterodyne receivers with IF responses approaching 5 GHz

    NASA Technical Reports Server (NTRS)

    Wolczok, J. M.; Peyton, B. J.

    1980-01-01

    Specialized coherent 10.6 micrometer infrared receivers were developed with infrared frequency responses approaching 5 GHz. Carbon dioxide lasers were employed for these applications because of their availability, stability, and high average power levels. Heterodyne receivers which employ extrinsic photoconductive Ge:Cu(Sb) mixers were developed for measurements of carbon dioxide laser scattering to determine: (1) the drive lower hybrid wave density fluctuations; and (2) the plasma ion temperature of the dense Tokamak plasmas.

  13. Heterodyne Interferometer for Triggering Gas-Puff PRSs

    DTIC Science & Technology

    2007-11-02

    completion of the Phase I effort. They are: "* Implement a heterodyne interferometer in a Michelson format using fiber optic components. "* Interface the...of single-mode fiber cable. These fibers represent the two legs of a Michelson interferometer . One fiber is terminated in a reflector and is the...independently through the same fiber to the interferometer head. They are subject to identical stresses and, therefore, incur identical phase noise which cancels

  14. Design of a sun tracker for a laser heterodyne spectrometer

    NASA Astrophysics Data System (ADS)

    Delahaigue, A.; Thiebeaux, C.; Courtois, D.; Le Corre, H.

    1988-01-01

    A sun tracker with a tracking precision of 0.001 degree has been developed for use with a high-resolution Laser Heterodyne Spectrometer. The mechanical and optical arrangement of the tracker are described in detail, in addition to the tracking software. The system was used to record ozone atmospheric spectra in the 10-micron region in March 1987. The analysis range is + or - 1220 MHz.

  15. Heterodyne spectroscopy with superconducting single-photon detector

    NASA Astrophysics Data System (ADS)

    Lobanov, Yu. V.; Shcherbatenko, M. L.; Semenov, A. V.; Kovalyuk, V. V.; Korneev, A. A.; Goltsman, G. N.

    2016-12-01

    We demonstrate successful operation of a Superconducting Single Photon Detector (SSPD) as the core element in a heterodyne receiver. Irradiating the SSPD by both a local oscillator power and signal power simultaneously, we observed beat signal at the intermediate frequency of a few MHz. Gain bandwidth was found to coincide with the detector single pulse width, where the latter depends on the detector kinetic inductance, determined by the superconducting nanowire length.

  16. Heterodyne photomixer spectrometer with receiver photomixer driven at different frequency than source photomixer

    DOEpatents

    Wanke, Michael C; Fortier, Kevin; Shaner, Eric A; Barrick, Todd A

    2013-07-09

    A heterodyne photomixer spectrometer comprises a receiver photomixer that is driven at a different frequency than the source photomixer, thereby maintaining the coherent nature of the detection, eliminating etalon effects, and providing not only the amplitude but also the phase of the received signal. The heterodyne technique can be applied where the source and receiver elements are components of a waveguide thereby forming an on-chip heterodyne spectrometer.

  17. Selected applications of photothermal and photoluminescence heterodyne techniques for process control in silicon wafer manufacturing

    NASA Astrophysics Data System (ADS)

    Ehlert, Andreas; Kerstan, Michael; Lundt, Holger; Huber, Anton; Helmreich, Dieter; Geiler, Hans-Dieter; Karge, Harald; Wagner, Matthias

    1997-02-01

    Two noncontact laser-based heterodyne techniques, photothermal heterodyne (PTH) and photoluminescence heterodyne (PLH), are introduced and applied to processing and quality control in silicon wafer manufacturing. The crystallographic characteristics of process-induced defects in silicon wafers are suitable for the application of PTH and PLH techniques, which are demonstrated on selected examples from different steps of silicon wafer production. Both PLH and PTH techniques meet the demand for nondestructive and on-line-suitable measurement in the semiconductor industry.

  18. Limitations for heterodyne detection of Brillouin scattered light

    SciTech Connect

    Allemeier, R.T.; Wagner, J.W.; Telschow, K.L.

    1995-01-01

    One means by which elastic properties of a material may be determined is measuring sound wave velocities in the material, from which elastic moduli of interest can be computed. Velocity can be measured by conventional piezoelectric transduction techniques, by applying laser ultrasonics, or by using Brillouin-scattering methods. Brillouin-scattering techniques for determining the sound wave velocity are particularly attractive since they are completely noninvasive. Only a probe beam of light is required since the thermal energy in the material provides the elastic motion. Heterodyne methods for detection of Brillouin-scattered light are considered one possible means to increase the speed of the scattered light frequency detection. Results of experiments with simulated Brillouin scattering suggest that heterodyne detection of the Brillouin-scattered light is feasible. Experiments to detect Brillouin-scattered light, with water as the scattering medium, were designed and interpreted using the results of the simulated scattering experiments. Overall, results showed that it is difficult to narrow the linewidth for Brillouin scattering to an acceptable level. The results given indicate that heterodyne detection of the Brillouin components requires detection bandwidths that are quite small, perhaps 10 Hz or lower. These small bandwidths can be routinely achieved using lock-in amplifier techniques.

  19. Towards an Imaging Mid-Infrared Heterodyne Spectrometer

    NASA Technical Reports Server (NTRS)

    Hewagama, T.; Aslam, S.; Jones, H.; Kostiuk, T.; Villanueva, G.; Roman, P.; Shaw, G. B.; Livengood, T.; Allen, J. E.

    2012-01-01

    We are developing a concept for a compact, low-mass, low-power, mid-infrared (MIR; 5- 12 microns) imaging heterodyne spectrometer that incorporates fiber optic coupling, Quantum Cascade Laser (QCL) local oscillator, photomixer array, and Radio Frequency Software Defined Readout (RFSDR) for spectral analysis. Planetary Decadal Surveys have highlighted the need for miniaturized, robust, low-mass, and minimal power remote sensing technologies for flight missions. The drive for miniaturization of remote sensing spectroscopy and radiometry techniques has been a continuing process. The advent of MIR fibers, and MEMS techniques for producing waveguides has proven to be an important recent advancement for miniaturization of infrared spectrometers. In conjunction with well-established photonics techniques, the miniaturization of spectrometers is transitioning from classic free space optical systems to waveguide/fiber-based structures for light transport and producing interference effects. By their very nature, these new devices are compact and lightweight. Mercury-Cadmium-Telluride (MCT) and Quantum Well Infrared Photodiodes (QWIP) arrays for heterodyne applications are also being developed. Bulky electronics is another barrier that precluded the extension of heterodyne systems into imaging applications, and our RFSDR will address this aspect.

  20. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  1. Spatial-temporal demodulation technique for heterodyne optical scanning holography

    NASA Astrophysics Data System (ADS)

    Liu, Jung-Ping; Luo, Dao-Zheng; Lu, Sheng-Hua

    2015-05-01

    In optical scanning holography (OSH), the object is raster scanned by a heterodyne fringe pattern. The light scattered from the object is detected by a photodetector. Traditionally, the photo-electric signal is demodulated by a dual-channel lock-in amplifier (LIA) to extract a complex hologram. The use of LIA complicates the detection module of the system and increases the cost, especially when the heterodyne frequency is high. In this paper, an alternative demodulation method called a spatial-temporal demodulation technique (STDT) is studied. In STDT, the photo-electric temporal signal is directly digitized as scanning lines. The spectrum of each scanning line is band-pass filtered to remove the zeroth-order term and the complex conjugate term. Finally, a complex hologram is obtained from the filtered spectrum. The first merit of STDT is that the phase of the demodulated complex hologram is insensitive to the modulation error. Thus it is easily applied to the applications of particle holography. Besides, the bandwidth of the zeroth-order term in STDT is narrow, which allows the system to be operated in a wide range of heterodyne frequency. This feature enables STDT-based OSH to be applied in low-cost and high-speed dynamic holographic imaging.

  2. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  3. Principles and Application of Heterodyne Scanning Tunnelling Spectroscopy

    PubMed Central

    Matsuyama, Eiji; Kondo, Takahiro; Oigawa, Haruhiro; Guo, Donghui; Nemoto, Shojiro; Nakamura, Junji

    2014-01-01

    Detection of the extremely weak signals in spectroscopy over an extremely wide frequency region is central to diverse sciences, including materials science, biology, astronomy and chemistry. Here we show a new type of atomic-scale spectroscopy, heterodyne scanning tunnelling spectroscopy (HSTS), which is based on the innovative application of the nonlinear heterodyne-mixing detection at the metal-insulator-metal (MIM) heterojunction of STM tip–vacuum–sample. The principle of HSTS is identical to that of the Atacama Large Millimeter Array (ALMA) space telescope in terms of using heterojunction for detecting extremely weak signals by converting from terahertz region to lower frequency regions. The MIM detector of ALMA, which is composed of niobium–titanium–nitride (NbTiN) tip-insulator-NbTiN, is very similar in shape and size to that of HSTS. We successfully detect a heterodyne beat signal f3 (= |f2 − f1|) and intermodulation distortion via tunnelling current by superimposing two different AC signals, f1 and f2, onto the DC tunnelling current at a highly oriented pyrolytic graphite (HOPG) surface. We then obtain spectra of the localized electronic states of HOPG by using f3. HSTS can be performed with a high resolution and over a wide energy range, including the terahertz range. PMID:25342108

  4. Laboratory Heterodyne Spectrometers Operating at 100 and 300 GHZ

    NASA Astrophysics Data System (ADS)

    Maßen, Jakob; Wehres, Nadine; Hermanns, Marius; Lewen, Frank; Heyne, Bettina; Endres, Christian; Graf, Urs; Honingh, Netty; Schlemmer, Stephan

    2017-06-01

    Two new laboratory heterodyne emission spectrometers are presented that are currently used for high-resolution rotational spectroscopy of complex organic molecules. The room temperature heterodyne receiver operating between 80-110 GHz, as well as the SIS heterodyne receiver operating between 270-370 GHz allow access to two very important frequency regimes, coinciding with Bands 3 and 7 of the ALMA (Atacama Large Millimeter Array) telescope. Taking advantage of recent progresses in the field of mm/submm technology, we build these two spectrometers using an XFFFTS (eXtended Fast Fourier Transform Spectrometer) for spectral acquisition. The instantaneous bandwidth is 2.5 GHz in a single sideband, spread over 32768 channels. Thus, the spectral resolution is about 76 kHz per channel and thus comparable to high resolution spectra from telescopes. Both receivers are operated in double sideband mode resulting in a total instantaneous bandwidth of 5 GHz. The system performances, in particular the noise temperatures and stabilities are presented. Proof-of-concept is demonstrated by showing spectra of methyl cyanide obtained with both spectrometers. While the transition frequencies for this molecule are very well known, intensities of those transitions can also be determined with high accuracy using our new instruments. This additional information shall be exploited in future measurements to improve spectral predictions for astronomical observations. Other future prospects concern the study of more complex organic species, such as ethyl cyanide. These aspects of the new instruments as well as limitations of the two distinct receivers will be discussed.

  5. Research on beam splitting prism in laser heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Fu, Xiu-hua; Xiong, Shi-fu; Kou, Yang; Pan, Yong-gang; Chen, Heng; Li, Zeng-yu; Zhang, Chuan-xin

    2014-08-01

    With the rapid development of optical testing technology, laser heterodyne interferometer has been used more and more widely. As the testing precision requirements continue to increase, the technical prism is an important component of heterodyne interference. The research utilizing thin film technology to improve optical performance of interferometer has been a new focus. In the article, based on the use requirements of interferometer beam splitting prism, select Ta2O5 and SiO2 as high and low refractive index materials respectively, deposit on substrate K9. With the help of TFCalc design software and Needle method, adopting electron gun evaporation and ion assisted deposition, the beam splitting prism is prepared successfully and the ratio of transmittance and reflectance for this beam splitting prism in 500~850 nm band, incident angle 45 degree is 8:2. After repeated tests, solved the difference problem of film deposition process parameters ,controlled thickness monitoring precision effectively and finally prepared the ideal beam splitting prism which is high adhesion and stable optics properties. The film the laser induced damage threshold and it meet the requirements of heterodyne interferometer for use.

  6. Heterodyne Doppler 1-micron lidar measurement of reduced effective telescope aperture due to atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Chan, Kin Pui; Killinger, Dennis K.; Sugimoto, Nobuo

    1991-01-01

    A pulsed Nd:YAG bistatic focused-beam lidar allowing simultaneous heterodyne and direct detection of the same lidar returns has been experimentally employed to ascertain the effect of atmospheric turbulence on heterodyne and direct-detection lidar at 1 micron, by measuring the average carrier-to-noise ratio and statistical fluctuation level in the return signals under various experimental and atmospheric conditions. Atmospheric turbulence is found capable of reducing the lidar receiver's effective telescope aperture and heterodyne detection efficiency. This observed effective-aperture limitation functionally resembles predictions based on the Clifford and Wandzura (1981) heterodyne wavefront detection theory.

  7. Modified heterodyne efficiency for coherent laser communication in the presence of polarization aberrations.

    PubMed

    Yang, Yufei; Yan, Changxiang; Hu, Chunhui; Wu, Congjun

    2017-04-03

    Heterodyne efficiency is referred as a measure of the quality for the coherent laser communication. The heterodyne efficiency not only reflects the matching of phase and amplitude between the received signal and the local oscillator, but also reveals the polarization matching between the two beams. Different from the common heterodyne efficiency, a revised heterodyne efficiency is proposed by considering the polarization aberrations of optical system. Based on the Polar and Pauli-Zernike decomposition algorithms, the effects of polarization aberrations on the output polarization states are analyzed and shown graphically. The variations of the heterodyne efficiency are investigated by including the separate component of polarization aberrations in mixing of two perfectly matched Gaussian beams. Depending on the modified heterodyne efficiency, an off-axis optical system with a periscopic scanner is modeled and used to discuss the variations of the heterodyne efficiency. A further investigation for three different coatings is accomplished to verify the effects the varied polarization aberrations have on the heterodyne efficiency. The analysis indicates that the modified heterodyne efficiency not only can provide a comprehensive description of the coherent detection system, but also can be used to evaluate and minimize the polarization aberrations of optical system.

  8. A polarization-based Thomson scattering technique for burning plasmas

    NASA Astrophysics Data System (ADS)

    Parke, E.; Mirnov, V. V.; Den Hartog, D. J.

    2014-02-01

    The traditional Thomson scattering diagnostic is based on measurement of the wavelength spectrum of scattered light, where electron temperature measurements are inferred from thermal broadening of the spectrum. At sufficiently high temperatures, especially those predicted for ITER and other burning plasmas, relativistic effects cause a change in the degree of polarization (P) of the scattered light; for fully polarized incident laser light, the scattered light becomes partially polarized. The resulting reduction of polarization is temperature dependent and has been proposed by other authors as a potential alternative to the traditional spectral decomposition technique. Following the previously developed Stokes vector approach, we analytically calculate the degree of polarization for incoherent Thomson scattering. For the first time, we obtain exact results valid for the full range of incident laser polarization states, scattering angles, and electron temperatures. While previous work focused only on linear polarization, we show that circularly polarized incident light optimizes the degree of depolarization for a wide range of temperatures relevant to burning plasmas. We discuss the feasibility of a polarization based Thomson scattering diagnostic for ITER-like plasmas with both linearly and circularly polarized light and compare to the traditional technique.

  9. The effects of polarization changes of stochastic electromagnetic beams on heterodyne detection in turbulence

    NASA Astrophysics Data System (ADS)

    Yan, Wang; Chengqiang, Li; Tingfeng, Wang; Heyong, Zhang; Jingjiang, Xie; Lisheng, Liu; Jin, Guo

    2016-11-01

    The performance of heterodyne systems is discussed for stochastic electromagnetic beams in turbulent atmospheres by introducing a turbulence spectrum of refractive-index fluctuations. Several analytic formulae for the heterodyne detection system are presented by employing the beam coherence polarization matrix of an electromagnetic Gaussian Schell-model beam. Based on the Tatarskii spectrum model, some numerical results are given for the variation of heterodyne efficiency with the misalignment angle, detector diameter, turbulence conditions and parameters of the overlapping beams. According to the numerical results, we find that the change in heterodyne efficiency is dependent on the initial polarization of the beams, and that a turbulent atmosphere degrades the heterodyne efficiency significantly for a lager detector diameter. The change in heterodyne efficiency in a turbulent atmosphere is basically the same as that in free space for a relatively short distance z s. However, the change in heterodyne efficiency is different for a sufficiently long distance. For the deterministic received signal and the detector, the performance of the heterodyne detection can be adjusted by controlling the local oscillator signal parameters.

  10. Packaged heterodyne source modules based on external cavity lasers for microwave applications

    NASA Astrophysics Data System (ADS)

    Chuyanov, Vadim; Kupershmidt, Vladimir; Kusnadi, Frans; Plaessmann, Henry; Ozcan, Meric

    2005-03-01

    External cavity lasers (ECL) based on semiconductor diode gain elements and Fiber Bragg Gratings (FBG) have been developed for Telecom (OC-48) nd Analog (CATV, QAM) applications. They possess very narrow linewidth (100 kHz) and exceptional wavelength stability. These qualities makes them attractive platform for implementation of heterodyne sources and Optical Phase Locked Loops (OPLL) for Microwave Photonics applications. We discuss two types of such heterodyne sources: heterodyne oscillator based on heterodyning of two ECL, and fixed frequency heterodyne oscillators based on ECL with FBG written in the polarization maintaining fiber. All two types of heterodyne sources were built based on industry standard 14-pin butterfly package. All of them exhibited excellent wavelength stability (less than 1 pm/mA and 1-2 pm/°C). Fixed frequency sources provided beat oscillation around 40 GHz. We present performance characteristics and measurement data on (linewidth, phase noise, heterodyne mixing, etc.) and discuss the merits of ECL use as heterodyne sources for Microwave Photonics applications.

  11. Atmospheric solar absorption measurements in the 9-11 micron region using a diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Hoell, J. M., Jr.

    1980-01-01

    A tunable diode laser heterodyne radiometer was developed for ground based measurements of atmospheric solar absorption spectra in the 9 to 12 micron spectral range. The performance and operating characteristics of this tunable infrared heterodyne radiometer (TIHR) is discussed along with recently measured heterodyne solar absorption spectra in the 10 to 11 micron spectral region.

  12. Potential sensitivities in frequency modulation and heterodyne amplitude modulation Kelvin probe force microscopes

    PubMed Central

    2013-01-01

    In this paper, the potential sensitivity in Kelvin probe force microscopy (KPFM) was investigated in frequency modulation (FM) and heterodyne amplitude modulation (AM) modes. We showed theoretically that the minimum detectable contact potential difference (CPD) in FM-KPFM is higher than in heterodyne AM-KPFM. We experimentally confirmed that the signal-to-noise ratio in FM-KPFM is lower than that in heterodyne AM-KPFM, which is due to the higher minimum detectable CPD dependence in FM-KPFM. We also compared the corrugations in the local contact potential difference on the surface of Ge (001), which shows atomic resolution in heterodyne AM-KPFM. In contrast, atomic resolution cannot be obtained in FM-KPFM under the same experimental conditions. The higher potential resolution in heterodyne AM-KPFM was attributed to the lower crosstalk and higher potential sensitivity between topographic and potential measurements. PMID:24350866

  13. Modeling the Effect of Optical System Aberrations on Coherent Lidar Heterodyne Efficiency

    NASA Technical Reports Server (NTRS)

    Chambers, Diana M.

    1997-01-01

    Signal-to-noise ratio of a coherent lidar is directly proportional to heterodyne efficiency, which is a measure of the mixing of the local oscillator and signal beams. Formulation of heterodyne efficiency is presented and then extended to include the primary, or Seidel, aberrations arising from optical systems. Animations of the intensity pattern for mixing of truncated Gaussian beams in the presence of Seidel aberrations are shown to illustrate the effect on heterodyne efficiency. Results showing the degradation of heterodyne efficiency with an increasing amount of Seidel aberration are given for the same Gaussian beams. This is further extended to predict the change in heterodyne efficiency of a coherent lidar as a result of its optical components by including aberration data derived from optical testing.

  14. Spatial-Heterodyne Interferometry For Reflection And Transm Ission (Shirt) Measurements

    DOEpatents

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN; Tobin, Ken W [Harriman, TN

    2006-02-14

    Systems and methods are described for spatial-heterodyne interferometry for reflection and transmission (SHIRT) measurements. A method includes digitally recording a first spatially-heterodyned hologram using a first reference beam and a first object beam; digitally recording a second spatially-heterodyned hologram using a second reference beam and a second object beam; Fourier analyzing the digitally recorded first spatially-heterodyned hologram to define a first analyzed image; Fourier analyzing the digitally recorded second spatially-heterodyned hologram to define a second analyzed image; digitally filtering the first analyzed image to define a first result; and digitally filtering the second analyzed image to define a second result; performing a first inverse Fourier transform on the first result, and performing a second inverse Fourier transform on the second result. The first object beam is transmitted through an object that is at least partially translucent, and the second object beam is reflected from the object.

  15. Optics and cryogenics for the 1.1 THz multi-pixel heterodyne receiver for APEX

    NASA Astrophysics Data System (ADS)

    Hurtado, Norma; Graf, Urs U.; Adams, Henning; Honingh, C. E.; Jacobs, Karl; Pütz, Patrick; Güsten, Rolf; Stutzki, Jürgen

    2014-08-01

    The 1.1 THz multi-pixel heterodyne receiver will be mounted in the Nasmyth A cabin of the 12 m APEX telescope on the Chajnantor plateau, 5000 meters altitude in northern Chile. The receiver will cover the spectral window of 1000 - 1080 GHz, where important spectral lines like CO 9-8 at 1036.9 GHz, a tracer of warm and dense gas and OH+ at 1033 GHz and NH+ at 1012.6 GHz, both important for the study of chemical networks in the ISM, are located. The multi-pixel receiver greatly enhances the science output under the difficult observing conditions in this frequency range. Two 9-pixel focal plane sub-arrays on orthogonal polarizations are installed in easily removable cartridges. We developed a new thermal link to connect the cartridges to the cryostat. Our thermal link is an all-metal design: aluminum and Invar. All the optics is fully reflective, thus avoiding the absorption and reflection losses of dielectric lenses and reducing standing waves in the receiver. To guaranty internal optics alignment, we employ a monolithic integrated optics approach for the cold optics and the Focal Plane Unit (FPU) optics modeled after the CHARM (Compact Heterodyne Array Receiver Module) concept. The receiver uses synthesizer-driven solid-state local oscillators (LO) and the mixers will be balanced SIS mixers, which are essentially based on the design of the on-chip balanced SIS mixers at 490 GHz developed in our institute. Singleended HEB mixers are used for the laboratory tests of the optics. The LO power distribution is accommodated behind the FPU optics. It is composed of the LO optics, which includes a collimating Fourier grating, and an LO distribution plate to supply LO signal to each of the 9 pixels of the sub-array. Different options for the LO coupling design and fabrication are being analyzed and will be based on in-house hybrid waveguide/planar technology. We summarize the receiver project with emphasis on the cryogenics and the optics and present laboratory test results

  16. Development of components for submillimeter wave heterodyne radiometers at JPL

    NASA Technical Reports Server (NTRS)

    Frerking, Margaret A.; Hunt, B. D.; Leduc, H. G.; Mcgrath, W. R.; Siegel, P. H.; Tolmunen, T.

    1990-01-01

    Components for the key elements of submillimeter wave heterodyne receivers are described. The devices and components are inherently space qualifiable having low power and mass needs and exhibiting robustness. Nb and NbN superconductor insulator superconductor (SIS) tunnel junctions are selected for the nonlinear mixing element because of their robustness. NbN exhibits a large superconducting bandgap, allowing operation in excess of 1500 GHz. Both waveguide mounts, for the lower frequencies and planar antenna mixer mounts for the higher frequency range, are used. Quasi-optical components are used for frequency multiplexing and combining.

  17. JCMT Science Archive: Advanced Heterodyne Data Products Pipeline

    NASA Astrophysics Data System (ADS)

    Jenness, T.; Cavanagh, B.; Economou, F.; Berry, D. S.

    2008-08-01

    The James Clerk Maxwell Telescope Science Archive (JSA), hosted by CADC, will contain reduced and calibrated data products from the ACSIS/HARP and SCUBA-2 instruments on JCMT and will support the JCMT Legacy Surveys. This paper describes the Advanced Data Products pipeline being developed for the JCMT heterodyne instrumentation suite. One of the goals is to generate clump catalogues, line catalogues and other advanced data products from these submillimetre data with the eventual aim of integrating these data into the Virtual Observatory. This paper describes the data reduction pipeline that will take calibrated data cubes and generate the advanced data products.

  18. Heterodyne interrogation system for TDM interferometric fiber optic sensors array

    NASA Astrophysics Data System (ADS)

    Fang, Gaosheng; Xu, Tuanwei; Li, Fang

    2015-04-01

    We proposed an interrogation system for time sequenced fiber optic sensors array based on the heterodyne detection and orthogonal demodulation techniques, where the sensors array is a kind of interferometric fiber optic sensors. The techniques are theoretically analyzed and experimentally demonstrated with recovering the sinusoid wave and triangle wave applied to the sensors. The system has a phase resolution about 1×10-4 rad/√Hz, the amplitude consistency and linearity of the demodulated results are 95.275% and 98.379%, respectively with single frequency event applied to the sensors.

  19. Spatial heterodyne spectroscopy - A novel interferometric technique for the FUV

    NASA Technical Reports Server (NTRS)

    Harlander, J.; Roesler, F. L.; Chakrabarti, S.

    1990-01-01

    The optical principles associated with spatial heterodyne spectroscopy (SHS) are described and the results of proof-of-concept tests performed in both the visible and the UV spectral regions are presented. A specific all-reflecting SHS configuration now being developed for high-resolution planetary Lyman-alpha studies is discussed. The expected performance of SHS systems is compared to that of conventional instrumentation in two cases: Venusian Ly-alpha measurements at high resolution from a sounding rocket and the velocity-resolved survey of the diffuse FUV interstellar medium emission from a Small Explorer class satellite.

  20. Study on avalanche photodiode influence on heterodyne laser interferometer linearity

    SciTech Connect

    Budzyn, Grzegorz Podzorny, Tomasz

    2016-06-28

    In the paper we analyze factors reducing the possible accuracy of the heterodyne laser interferometers. The analysis is performed for the avalanche-photodiode input stages but is in main points valid also for stages with other type of photodetectors. Instrumental error originating from optical, electronic and digital signal processing factors is taken into consideration. We stress factors which are critical and those which can be neglected at certain accuracy requirements. In the work we prove that it is possible to reduce errors of the laser instrument below 1 nm point for multiaxial APD based interferometers by precise control of incident optical power and the temperature of the photodiode.

  1. Novel phase measurement technique of the heterodyne laser interferometer

    SciTech Connect

    Choi, Hyunseung; Park, Kyihwan; La, Jongpil

    2005-09-15

    This article describes a novel phase measurement technique to increase the measurement velocity compared to the previous arc-tangent method in the heterodyne laser interferometer. The proposed method can reduce the calculation load because the pulse width modulation signal has a linear relation between the phase difference, while the nonlinear function such as arc tangent is required to demodulate the sinusoidal interferent signal. The brief analysis and measurement scheme of the system, and the experimental result using a Zeeman-stabilized He-Ne laser are presented. They demonstrate that the proposed phase measurement technique is proven to be three times faster and more robust than previous arc-tangent method.

  2. Optical heterodyne sensor using the Goos-Hänchen shift.

    PubMed

    Hashimoto, T; Yoshino, T

    1989-09-01

    A new sensing scheme, capable of measuring various quantities using the Goos-Häanchen shift in the polarization phase domain, is proposed. The phase retardation between s and p polarizations on total reflection is enhanced by using multiple reflections in a plane-parallel transparent plate. This phase shift can be sensitively and stably detected using an in-line heterodyne method. As an application of this method, a displacement sensor utilizing the deflection of a light beam by a lens is developed. This displacement sensor has a resolution of 60 nm over a dynamic range of 120 microm. Good agreement between theoretical and experimental results is shown.

  3. Free-Space Quantum Signatures Using Heterodyne Measurements

    NASA Astrophysics Data System (ADS)

    Croal, Callum; Peuntinger, Christian; Heim, Bettina; Khan, Imran; Marquardt, Christoph; Leuchs, Gerd; Wallden, Petros; Andersson, Erika; Korolkova, Natalia

    2016-09-01

    Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum mechanics to sign a classical message. Previous quantum signature schemes have used unambiguous quantum measurements. Such measurements, however, sometimes give no result, reducing the efficiency of the protocol. Here, we instead use heterodyne detection, which always gives a result, although there is always some uncertainty. We experimentally demonstrate feasibility in a real environment by distributing signature states through a noisy 1.6 km free-space channel. Our results show that continuous-variable heterodyne detection improves the signature rate for this type of scheme and therefore represents an interesting direction in the search for practical quantum signature schemes. For transmission values ranging from 100% to 10%, but otherwise assuming an ideal implementation with no other imperfections, the signature length is shorter by a factor of 2 to 10. As compared with previous relevant experimental realizations, the signature length in this implementation is several orders of magnitude shorter.

  4. Infrared heterodyne radiometer for airborne atmospheric transmittance measurements

    NASA Technical Reports Server (NTRS)

    Wolczok, J. M.; Lange, R. A.; Dinardo, A. J.

    1980-01-01

    An infrared heterodyne radiometer (IHR) was used to measure atmospheric transmittance at selected hydrogen fluoride (2.7 micrometer) and deuterium fluoride (3.8 micrometer) laser transitions. The IHR was installed aboard a KC-135 aircraft for an airborne atmospheric measurements program that used the sun as a backlighting source for the transmission measurements. The critical components are: a wideband indium antimonide (1nSb) photomixer, a CW HF/DF laser L0, a radiometric processor, and a 1900 K blackbody reference source. The measured heterodyne receiver sensitivity (NEP) is 1.3 x 10 to the -19th power W/Hz, which yields a calculated IHR temperature resolution accuracy of delta I sub S/-3 sub S = 0.005 for a source temperature of 1000 K and a total transmittance of 0.5. Measured atmospheric transmittance at several wavelengths and aircraft altitudes from 9.14 km (30,000 ft) to 13.72 km (45,000 ft) were obtained during the measurements program and have been compared with values predicted by the AFGL Atmospheric Line Parameter Compilation.

  5. Heterodyning Time Resolution Boosting for Velocimetry and Reflectivity Measurements

    SciTech Connect

    Erskine, D J

    2004-08-02

    A theoretical technique is described for boosting the temporal resolving power by several times, of detectors such as streak cameras in experiments that measure light reflected from or transmitted through a target, including velocity interferometer (VISAR) measurements. This is a means of effectively increasing the number of resolvable time bins in a streak camera record past the limit imposed by input slit width and blur on the output phosphor screen. The illumination intensity is modulated sinusoidally at a frequency similar to the limiting time response of the detector. A heterodyning effect beats the high frequency science signal down a lower frequency beat signal, which is recorded together with the conventional science signal. Using 3 separate illuminating channels having different phases, the beat term is separated algebraically from the conventional signal. By numerically reversing the heterodyning, and combining with the ordinary signal, the science signal can be reconstructed to better effective time resolution than the detector used alone. The effective time resolution can be approximately halved for a single modulation frequency, and further decreased inversely proportional to the number of independent modulation frequencies employed.

  6. Free-Space Quantum Signatures Using Heterodyne Measurements.

    PubMed

    Croal, Callum; Peuntinger, Christian; Heim, Bettina; Khan, Imran; Marquardt, Christoph; Leuchs, Gerd; Wallden, Petros; Andersson, Erika; Korolkova, Natalia

    2016-09-02

    Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum mechanics to sign a classical message. Previous quantum signature schemes have used unambiguous quantum measurements. Such measurements, however, sometimes give no result, reducing the efficiency of the protocol. Here, we instead use heterodyne detection, which always gives a result, although there is always some uncertainty. We experimentally demonstrate feasibility in a real environment by distributing signature states through a noisy 1.6 km free-space channel. Our results show that continuous-variable heterodyne detection improves the signature rate for this type of scheme and therefore represents an interesting direction in the search for practical quantum signature schemes. For transmission values ranging from 100% to 10%, but otherwise assuming an ideal implementation with no other imperfections, the signature length is shorter by a factor of 2 to 10. As compared with previous relevant experimental realizations, the signature length in this implementation is several orders of magnitude shorter.

  7. THIS: a tuneable heterodyne infrared spectrometer for SOFIA

    NASA Astrophysics Data System (ADS)

    Schieder, R.; Sonnabend, G.; Sornig, M.; Kroetz, P.; Stupar, D.

    2007-09-01

    The THIS instrument (Tuneable Heterodyne Infrared Spectrometer) is a versatile heterodyne receiver with a sensitivity close to theoretical prediction. It uses a Quantum Cascade Laser (QCL) as local oscillator and a HgCdTe photo-voltaic detector as mixer. The IF-spectrum is analyzed by means of a new broadband Acousto-Optical Spectrometer (AOS) with 3 GHz bandwidth and 1 MHz resolution. A dual sideband (DSB) system noise temperature has been measured with 2300 K at 10 μm wavelength, which is only 60% above the quantum limit. The stability of the system has been determined at an Allan variance minimum time of 50 seconds. Below this integration time the performance is purely radiometric. Also, the frequency stability has been measured with 1 MHz rms error within several hours. The quality of the instrument has been demonstrated by a few observing campaigns at the McMath-Pierce observatory on Kitt Peak. Measurements of Winds on Mars and Venus have been carried out and molecular line signals in sunspots have been detected. We propose to develop THIS as a second generation instrument for future astronomical observations on SOFIA.

  8. Optical heterodyne detection for cavity ring-down spectroscopy

    DOEpatents

    Levenson, Marc D.; Paldus, Barbara A.; Zare, Richard N.

    2000-07-25

    A cavity ring-down system for performing cavity ring-down spectroscopy (CRDS) using optical heterodyne detection of a ring-down wave E.sub.RD during a ring-down phase or a ring-up wave E.sub.RU during a ring up phase. The system sends a local oscillator wave E.sub.LO and a signal wave E.sub.SIGNAL to the cavity, preferably a ring resonator, and derives an interference signal from the combined local oscillator wave E.sub.LO and the ring-down wave E.sub.RD (or ring-up wave E.sub.RU). The local oscillator wave E.sub.LO has a first polarization and the ring-down wave E.sub.RD has a second polarization different from the first polarization. The system has a combining arrangement for combining or overlapping local oscillator wave E.sub.LO and the ring-down wave E.sub.RD at a photodetector, which receives the interference signal and generates a heterodyne current I.sub.H therefrom. Frequency and phase differences between the waves are adjustable.

  9. Non-Contact Photoacoustic Imaging Using a Commercial Heterodyne Interferometer.

    PubMed

    Tian, Chao; Feng, Ting; Wang, Cheng; Liu, Shengchun; Cheng, Qian; Oliver, David E; Wang, Xueding; Xu, Guan

    2016-12-01

    Most current photoacoustic imaging (PAI) systems employ piezoelectric transducers to receive photoacoustic signals, which requires coupling medium to facilitate photoacoustic wave propagation and are not favored in many applications. Here, we report an all-optical non-contact PAI system based on a commercial heterodyne interferometer working at 1550 nm. The interferometer remotely detects ultrasound-induced surface vibration and does not involve any physical contact with the sample. The theoretically predicated and experimentally measured noise equivalent detection limits of the optical sensor are about 4.5 and 810 Pa over 1.2 MHz bandwidth. Using a raster-scan PAI system equipped with the non-contact design, stereotactic boundaries of an artificial tumor in a pig brain were accurately delineated. The non-contact design also enables the tomographic PAI of biological tissue samples in a non-invasive manner. The preliminary results and analyses reveal that the heterodyne interferometer-based non-contact PAI system holds good potential in biomedical imaging.

  10. Detection method of nonlinearity errors by statistical signal analysis in heterodyne Michelson interferometer.

    PubMed

    Hu, Juju; Hu, Haijiang; Ji, Yinghua

    2010-03-15

    Periodic nonlinearity that ranges from tens of nanometers to a few nanometers in heterodyne interferometer limits its use in high accuracy measurement. A novel method is studied to detect the nonlinearity errors based on the electrical subdivision and the analysis method of statistical signal in heterodyne Michelson interferometer. Under the movement of micropositioning platform with the uniform velocity, the method can detect the nonlinearity errors by using the regression analysis and Jackknife estimation. Based on the analysis of the simulations, the method can estimate the influence of nonlinearity errors and other noises for the dimensions measurement in heterodyne Michelson interferometer.

  11. Heterodyne Interferometry in InfraRed at OCA-Calern Observatory in the seventies

    NASA Astrophysics Data System (ADS)

    Gay, J.; Rabbia, Y.

    2014-04-01

    We report on various works carried four decades ago, so as to develop Heterodyne Interferometry in InfraRed (10 μm) at Calern Observatory (OCA, France), by building an experiment, whose the acronym "SOIRDETE" means "Synthese d'Ouverture en InfraRouge par Detection hETErodyne". Scientific and technical contexts by this time are recalled, as well as basic principles of heterodyne interferometry. The preliminary works and the SOIRDETE experiment are briefly described. Short comments are given in conclusion regarding the difficulties which have prevented the full success of the SOIRDETE experiment.

  12. Note: Periodic error measurement in heterodyne interferometers using a subpicometer accuracy Fabry-Perot interferometer.

    PubMed

    Zhu, Minhao; Wei, Haoyun; Wu, Xuejian; Li, Yan

    2014-08-01

    Periodic error is the major problem that limits the accuracy of heterodyne interferometry. A traceable system for periodic error measurement is developed based on a nonlinearity free Fabry-Perot (F-P) interferometer. The displacement accuracy of the F-P interferometer is 0.49 pm at 80 ms averaging time, with the measurement results referenced to an optical frequency comb. Experimental comparison between the F-P interferometer and a commercial heterodyne interferometer is carried out and it shows that the first harmonic periodic error dominates in the commercial heterodyne interferometer with an error amplitude of 4.64 nm.

  13. Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Siller, Brian; Mills, Andrew; Porambo, Michael; McCall, Benjamin

    2011-06-01

    The technique of Cavity Enhanced Velocity Modulation Spectroscopy (CEVMS) has recently been developed. By demodulating the detector signal at twice the plasma modulation frequency (2f), the velocity-modulated ionic absorption signal can be extracted. Although the concentration-modulated excited neutral molecules are also observed at 2f, the ion and neutral signals can be distinguished and separated with phase-sensitive demodulation. The optical cavity provides two major benefits. It increases both the optical path length and the intracavity laser power by a factor of 2×Finesse/π. The multipass advantage allows for much longer path length than was previously possible with unidirectional multipass White cells. The power enhancement combined with perfectly overlapped counterpropagating beams within the cavity allows for sub-Doppler spectroscopy. Although CEVMS showed much potential, its sensitivity was ultimately limited by electronic noise from the plasma interfering with the cavity-locking electronics. We have further improved upon CEVMS by combining it with Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy (NICE-OHMS). The laser is frequency modulated at precisely an integer multiple of the free spectral range of the optical cavity; this allows the heterodyne sidebands to be coupled into the optical cavity. Heterodyne detection of the cavity leak-out is immune to noise in the laser-cavity lock, and 2f demodulation further decreases electronic noise in the system and retains ion-neutral discrimination. The additional level of modulation beyond ordinary CEVMS has the added advantage of enabling the observation of both absorption and dispersion signals simultaneously by using two RF mixers, each driving its own lock-in amplifier. In a single scan, four distinct signals can be obtained: absorption and dispersion for ions and excited neutrals. The technique has been demonstrated in the near-IR for N_2^+. B. M. Siller, A. A. Mills and B. J. Mc

  14. Airborne Astronomy with a 150 microns - 400 microns Heterodyne Spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1995-01-01

    This report summarizes work done under NASA Grant NAG2-753 awarded to the University of Colorado. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory, and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved. Detections of particular note have been the 370 micron line of neutral atomic carbon, the 158 micron transition of ionized carbon, many of the high-J rotational lines of CO-12 and CO-13 between J=9-8 and J=22-21, the 119 micron and 163 micron rotational lines of OH, the 219 micron ground-state rotational line of H2D(+), and the 63 micron fine structure line of neutral atomic oxygen. All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6) thereby allowing accurate line shapes and Doppler velocities to be measured.

  15. Digital Phase Meter for a Laser Heterodyne Interferometer

    NASA Technical Reports Server (NTRS)

    Loya, Frank

    2008-01-01

    The Digital Phase Meter is based on a modified phase-locked loop. When phase alignment between the reference input and the phase-shifted metrological input is achieved, the loop locks and the phase shift of the digital phase shifter equals the phase difference that one seeks to measure. This digital phase meter is being developed for incorporation into a laser heterodyne interferometer in a metrological apparatus, but could also be adapted to other uses. Relative to prior phase meters of similar capability, including digital ones, this digital phase meter is smaller, less complex, and less expensive. The phase meter has been constructed and tested in the form of a field-programmable gate array (FPGA).

  16. Mid-infrared heterodyne interferometry with the Infrared Spatial Interferometer

    NASA Astrophysics Data System (ADS)

    Wishnow, E. H.

    2014-04-01

    The Infrared Spatial Interferometer (ISI) is a three telescope array located at Mt. Wilson. It is a unique mid-IR system that uses heterodyne detection with CO2 lasers as local oscillators. Mid-IR measurements of red supergiant stars and Asymptotic Giant Branch stars have been conducted for about 20 years. The ISI provides precision measurements of stellar sizes and asymmetries, and also measurements of the dust shells surrounding these stars. We have observed changes of these quantities over time periods of weeks to decades. A new high-speed digital spectrometer-correlator has recently been built. It will provide a new capability to measure stellar visibilities on-and-off individual molecular spectral lines. These spectro-interferometric measurements will help determine the nature of extended stellar atmospheres.

  17. Heterodyne Hall effect in a two-dimensional electron gas

    NASA Astrophysics Data System (ADS)

    Oka, Takashi; Bucciantini, Leda

    2016-10-01

    We study the hitherto unaddressed phenomenon of the quantum Hall effect with a magnetic and electric field oscillating in time with resonant frequencies. This phenomenon highlights an example of a heterodyne device with the magnetic field acting as a driving force, and it is analyzed in detail in its classical and quantum versions using Floquet theory. A bulk current flowing perpendicularly to the applied electric field is found, with a frequency shifted by integer multiples of the driving frequency. When the ratio of the cyclotron and driving frequency takes special values, the electron's classical trajectory forms a loop and the effective mass diverges, while in the quantum case we find an analog of the Landau quantization. A possible realization using metamaterial plasmonics is discussed.

  18. Heterodyne x-ray diffuse scattering from coherent phonons

    DOE PAGES

    Kozina, M.; Trigo, M.; Chollet, M.; ...

    2017-08-10

    Here in this paper, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibrium, where inelastic x-ray scattering is proportional to the phonon occupation, we show that the scattering is proportional to the phonon amplitude for coherent states. The wavevectors of the observed phonons extend beyond the excitation wavevector. The nanoparticles break the discrete translational symmetry of the lattice, enabling the generation of large wavevector coherent phonons. Elastic scattering of x-ray photons frommore » the nanoparticles provides a reference for heterodyne mixing, yielding signals proportional to the phonon amplitude.« less

  19. Analysis and System Design Framework for Infrared Spatial Heterodyne Spectrometers

    SciTech Connect

    Cooke, B.J.; Smith, B.W.; Laubscher, B.E.; Villeneuve, P.V.; Briles, S.D.

    1999-04-05

    The authors present a preliminary analysis and design framework developed for the evaluation and optimization of infrared, Imaging Spatial Heterodyne Spectrometer (SHS) electro-optic systems. Commensurate with conventional interferometric spectrometers, SHS modeling requires an integrated analysis environment for rigorous evaluation of system error propagation due to detection process, detection noise, system motion, retrieval algorithm and calibration algorithm. The analysis tools provide for optimization of critical system parameters and components including : (1) optical aperture, f-number, and spectral transmission, (2) SHS interferometer grating and Littrow parameters, and (3) image plane requirements as well as cold shield, optical filtering, and focal-plane dimensions, pixel dimensions and quantum efficiency, (4) SHS spatial and temporal sampling parameters, and (5) retrieval and calibration algorithm issues.

  20. Diffraction effects and special advantages in electronic heterodyne moire deflectometry

    NASA Technical Reports Server (NTRS)

    Stricker, J.

    1986-01-01

    Effects of diffraction on the performance of electronic heterodyne readout of moire fringes are investigated. The sensitivity, accuracy, and resolution of the system are calculated, and it is shown that these features are significantly improved compared with the conventional intensity moire readout technique. The sensitivity of the system can be tripled without changing the distance between gratings. The system was evaluated experimentally by measuring the refractive-index derivatives of a weak phase object consisting of a large KD(asterisk)P crystal. Effects of nonlinear fringe modulation were studied both theoretically and experimentally. It is shown that in this case the electronic phase is not linearly related to the fringe shift, and calibration of the system is necessary.

  1. Transmission Raman Measurements Using a Spatial Heterodyne Raman Spectrometer (SHRS).

    PubMed

    Strange, K Alicia; Paul, Kelly C; Angel, S Michael

    2017-02-01

    A spatial heterodyne Raman spectrometer (SHRS) was used to measure transmission Raman spectra of highly scattering compounds. Transmission Raman spectral intensities of ibuprofen were only 2.4 times lower in intensity than backscatter Raman spectra. The throughput was about eight times higher than an f/1.8 dispersive spectrometer, and the width of the area viewed was found to be seven to nine times higher, using 50.8 mm and 250 mm focal length collection lenses. However, the signal-to-noise (S/N) ratio was two times lower for the SHRS than the f/1.8 dispersive spectrometer, apparently due to high levels of stray light.

  2. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.; Spears, D.

    1978-01-01

    A stratospheric ozone absorption line in the 10 micron band was measured and resolved completely, using an infrared heterodyne spectrometer with a spectral resolution of 5 MHz. The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectra line profile. The absolute total column density was 0.32 plus or minus 0.02 cm-atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) - (7,1,7) O3 line center frequency was found to be 1043.1772 plus or minus 0.00033 cm/1 or 420 plus or minus 10 MHz higher than the P(24) CO2 laser line frequency.

  3. A THz heterodyne instrument for biomedical imaging applications

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H.

    2004-01-01

    An ultra-wide-dynamic-range heterodyne imaging system operating at 2.5 THz is described. The instrument employs room temperature Schottky barrier diode mixers and far infrared gas laser sources developed for NASA space applications. A dynamic range of over 100dB at fixed intermediate frequencies has been realized. Amplitude/phase tracking circuitry results in stability of 0.02 dB and +-2 degrees of phase. The system is being employed to characterize biological (human and animal derived tissues) and a variety of materials of interest to NASA. This talk will describe the instrument and some of the early imaging experiments on everything from mouse tail to aerogel.

  4. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.; Spears, D.

    1978-01-01

    A stratospheric ozone absorption line in the 10 micron band was measured and resolved completely, using an infrared heterodyne spectrometer with a spectral resolution of 5 MHz. The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectra line profile. The absolute total column density was 0.32 plus or minus 0.02 cm-atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) - (7,1,7) O3 line center frequency was found to be 1043.1772 plus or minus 0.00033 cm/1 or 420 plus or minus 10 MHz higher than the P(24) CO2 laser line frequency.

  5. Subsurface contrast due to friction in heterodyne force microscopy

    NASA Astrophysics Data System (ADS)

    Verbiest, G. J.; Oosterkamp, T. H.; Rost, M. J.

    2017-02-01

    The nondestructive imaging of subsurface structures on the nanometer scale has been a long-standing desire in both science and industry. A few impressive images were published so far that demonstrate the general feasibility by combining ultrasound with an atomic force microscope. From different excitation schemes, heterodyne force microscopy seems to be the most promising candidate delivering the highest contrast and resolution. However, the physical contrast mechanism is unknown, thereby preventing any quantitative analysis of samples. Here we show that friction at material boundaries within the sample is responsible for the contrast formation. This result is obtained by performing a full quantitative analysis, in which we compare our experimentally observed contrasts with simulations and calculations. Surprisingly, we can rule out all other generally believed responsible mechanisms, like Rayleigh scattering, sample (visco)elasticity, damping of the ultrasonic tip motion, and ultrasound attenuation. Our analytical description paves the way for quantitative subsurface-AFM imaging.

  6. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.

    1978-01-01

    A stratospheric ozone absorption line in the 10 microns band was measured and resolved completely, using an infrared heterodyne spectrometer with spectral resolution of 5 MHz (0.000167 cm to -1 power). The vertical concentration profile of stratospheric ozone was obtained through an analytical inversion of the measured spectral line profile. The absolute total column density was 0.34 cm atm with a peak mixing ratio occurring at approximately 24 km. The (7,1,6) to (7,1,7) O3 line center frequency was found to be 1043.1775 + or - 0.00033 cm to toe -1 power, or 430 + or - 10 MHz higher than the P(24) CO2 laser line frequency.

  7. Airborne Astronomy with a 150 micron - 400 micron Heterodyne Spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1995-01-01

    This report summarizes work done under NASA Grant NAG2-753 awarded to the University of Colorado. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory, and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved. Detections of particular note have been the 370 micron line of neutral atomic carbon, the 158 micron transition of ionized carbon, many of the high-J rotational lines of CO-12 and CO-13 between J=9-8 and J=22-21, the 119 micron and 163 micron rotational lines of OH, the 219 micron ground-state rotational line of H2D(+), and the 63 microns fine structure line of neutral atomic oxygen. All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6), thereby allowing accurate line shapes and Doppler velocities to be measured.

  8. A THz heterodyne instrument for biomedical imaging applications

    NASA Technical Reports Server (NTRS)

    Siegel, Peter H.

    2004-01-01

    An ultra-wide-dynamic-range heterodyne imaging system operating at 2.5 THz is described. The instrument employs room temperature Schottky barrier diode mixers and far infrared gas laser sources developed for NASA space applications. A dynamic range of over 100dB at fixed intermediate frequencies has been realized. Amplitude/phase tracking circuitry results in stability of 0.02 dB and +-2 degrees of phase. The system is being employed to characterize biological (human and animal derived tissues) and a variety of materials of interest to NASA. This talk will describe the instrument and some of the early imaging experiments on everything from mouse tail to aerogel.

  9. Diffraction effects and special advantages in electronic heterodyne moire deflectometry

    NASA Technical Reports Server (NTRS)

    Stricker, J.

    1986-01-01

    Effects of diffraction on the performance of electronic heterodyne readout of moire fringes are investigated. The sensitivity, accuracy, and resolution of the system are calculated, and it is shown that these features are significantly improved compared with the conventional intensity moire readout technique. The sensitivity of the system can be tripled without changing the distance between gratings. The system was evaluated experimentally by measuring the refractive-index derivatives of a weak phase object consisting of a large KD(asterisk)P crystal. Effects of nonlinear fringe modulation were studied both theoretically and experimentally. It is shown that in this case the electronic phase is not linearly related to the fringe shift, and calibration of the system is necessary.

  10. High resolution heterodyne interferometer without detectable periodic nonlinearity.

    PubMed

    Joo, Ki-Nam; Ellis, Jonathan D; Buice, Eric S; Spronck, Jo W; Schmidt, Robert H Munnig

    2010-01-18

    A high resolution heterodyne laser interferometer without periodic nonlinearity for linear displacement measurements is described. It uses two spatially separated beams with an offset frequency and an interferometer configuration which has no mixed states to prevent polarization mixing. In this research, a simple interferometer configuration for both retroreflector and plane mirror targets which are both applicable to industrial applications was developed. Experimental results show there is no detectable periodic nonlinearity for both of the retro-reflector interferometer and plane mirror interferometer to the noise level of 20 pm. Additionally, the optical configuration has the benefit of doubling the measurement resolution when compared to its respective traditional counterparts. Because of non-symmetry in the plane mirror interferometer, a differential plane mirror interferometer to reduce the thermal error is also discussed.

  11. Monitoring atmospheric pollutants with a heterodyne radiometer transmitter-receiver

    NASA Technical Reports Server (NTRS)

    Menzies, R. T. (Inventor)

    1973-01-01

    The presence of selected atmospheric pollutants can be determined by transmitting an infrared beam of proper wavelength through the atmosphere, and detecting the reflections of the transmitted beam with a heterodyne radiometer transmitter-receiver using part of the laser beam as a local oscillator. The particular pollutant and its absorption line strength to be measured are selected by the laser beam wave length. When the round-trip path for the light is known or measured, concentration can be determined. Since pressure (altitude) will affect the shape of the molecular absorption line of a pollutant, tuning the laser through a range of frequencies, which includes a part of the absorption line of the pollutant of interest, yields pollutant altitude data from which the altitude and altitude profile is determined.

  12. Airborne astronomy with a 150 micrometer - 500 micrometer heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Betz, A. L.

    1991-01-01

    This report summarizes work done under NASA Grant NAG2-254 awarded to the University of California. The project goal was to build a far-infrared heterodyne spectrometer for NASA's Kuiper Airborne Observatory (KAO), and to use this instrument to observe atomic and molecular spectral lines from the interstellar medium. This goal was successfully achieved; the spectrometer is now in routine use aboard the KAO. Detections of particular note have been the 370 micrometers line of neutral atomic carbon, the 158 micrometers transition of ionized carbon, many of the high-J rotational lines of 12CO and 13CO between J=9-8 and J=22-21, the 119 micron ground-state rotational line of OH, and the 219 micron ground-state rotational line of H2D(+). All of these lines were observed at spectral resolutions exceeding 1 part in 10(exp 6), thereby allowing accurate line shapes and Doppler velocities to be measured.

  13. Spatial Heterodyne Imager for Mesospheric Radicals on STPSat-1

    NASA Astrophysics Data System (ADS)

    Englert, Christoph R.; Stevens, Michael H.; Siskind, David E.; Harlander, John M.; Roesler, Frederick L.

    2010-10-01

    The Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER) was a high-resolution, near ultraviolet spectrometer that imaged the Earth's limb for 2.5 years between March 2007 and October 2009. The instrument used the Spatial Heterodyne Spectroscopy technique for the first time on a satellite and successfully demonstrated its capabilities. SHIMMER measured the solar resonance fluorescence of the OH A2Σ+-X2Π (0, 0) band around 309 nm, which allows the retrieval of mesospheric OH density profiles. It also measured the Rayleigh scattered background from the clear atmosphere and solar scattering from polar mesospheric cloud particles. We present details on the SHIMMER mission, the payload design, and the data analysis. A comparison between SHIMMER and concurrent Microwave Limb Sounder OH data shows good agreement between 60 and 90 km altitude for several latitudes and seasons. We also find good agreement of the SHIMMER OH densities and standard photochemical model calculations between 60 and 80 km. We find no evidence of a 25%-35% mesospheric OH deficit, previously reported using Middle Atmosphere High-Resolution Spectrograph Investigation (MAHRSI) OH data. However, independent analysis of Rayleigh scattered background signals observed by SHIMMER and MAHRSI under similar lighting conditions revealed that MAHRSI radiances are systematically smaller than SHIMMER radiances by 24%. Although this difference is well outside of the combined uncertainties for both experiments, the agreement of SHIMMER OH with Microwave Limb Sounder OH and standard photochemistry results, together with our Rayleigh scattering comparison, suggests an unidentified MAHRSI calibration problem that effectively eliminates the mesospheric OH deficit reported using MAHRSI observations.

  14. Heterodyne efficiency for a coherent laser radar with diffuse or aerosol targets

    NASA Technical Reports Server (NTRS)

    Frehlich, R. G.

    1993-01-01

    The performance of a Coherent Laser Radar is determined by the statistics of the coherent Doppler signal. The heterodyne efficiency is an excellent indication of performance because it is an absolute measure of beam alignment and is independent of the transmitter power, the target backscatter coefficient, the atmospheric attenuation, and the detector quantum efficiency and gain. The theoretical calculation of heterodyne efficiency for an optimal monostatic lidar with a circular aperture and Gaussian transmit laser is presented including beam misalignment in the far-field and near-field regimes. The statistical behavior of estimates of the heterodyne efficiency using a calibration hard target are considered. For space based applications, a biased estimate of heterodyne efficiency is proposed that removes the variability due to the random surface return but retains the sensitivity to misalignment. Physical insight is provided by simulation of the fields on the detector surface. The required detector calibration is also discussed.

  15. Investigation of heterodyne performance of quantum-well detectors. Final report

    SciTech Connect

    Simpson, M.L.; Hutchinson, D.P.; Calabretta, J.

    1994-09-23

    The purpose of this Cooperative Research and Development Agreement (CRADA) between Martin Marietta Energy Systems Inc., (Contractor) and Martin Marietta Electronic Missles (Participant) is the determination of the heterodyne characteristics of quantum-well detectors. The Participant has developed a quantum-well infrared imaging video detector with very low light level characteristics. A further improvement in low-level infrared detection could be achieved if this device can be operated in the coherent or heterodyne mode. A major program in the Physics Division of Oak Ridge National Laboratory (ORNL) presently uses individual heterodyne infrared detectors in a system under development for fusion diagnostics. An imaging infrared heterodyne detector would represent a major breakthrough in this area and would have major implications for other plasma diagnostic programs. The Participant is also studying the application of this device in the area of laser radar.

  16. Phase-sensitive optical time-domain reflectometry with heterodyne demodulation

    NASA Astrophysics Data System (ADS)

    He, Xiangge; Liu, Fei; Qin, Mengzhe; Cao, Shan; Gu, Lijuan; Zheng, Xiaoping; Zhang, Min

    2017-04-01

    A phase-sensitive optical time-domain reflectometry (Φ-OTDR) system using dual heterodyne pulses combined with heterodyne demodulation is proposed. The theory of this system is analyzed. The experimental results show that this system can achieve a very large dynamic range with a frequency range of 50 Hz to 25 kHz and an amplitude range of 0.9 rad to 73 rad. At the same time, multi vibrations at different locations can also be well detected.

  17. Simulated electronic heterodyne recording and processing of pulsed-laser holograms

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1979-01-01

    The electronic recording of pulsed-laser holograms is proposed. The polarization sensitivity of each resolution element of the detector is controlled independently to add an arbitrary phase to the image waves. This method which can be used to simulate heterodyne recording and to process three-dimensional optical images, is based on a similar method for heterodyne recording and processing of continuous-wave holograms.

  18. Conclusions from the discussions on observational results of heterodyne spectroscopy in astronomy

    NASA Technical Reports Server (NTRS)

    Mumma, M.

    1975-01-01

    Experimental results in astronomy obtained with the aid of infrared heterodyne detection techniques are considered, taking into account the detection of thermal emission with no dispersion at the intermediate frequency and observations involving molecular line detection. The tuning range of a heterodyne spectrometer and of a Fourier transform spectrometer is considered and attention is given to the selection of the appropriate technique for a specific investigative problem.-

  19. Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

    NASA Astrophysics Data System (ADS)

    dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [

    F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)
    ], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

  20. Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

    SciTech Connect

    Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell'Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

  1. A 2 THz Heterodyne Array Receiver for SOFIA

    NASA Technical Reports Server (NTRS)

    Walker, Christopher K.

    1996-01-01

    We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approx. 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the FIR portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galaxy evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (greater than or equal to 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. The quality of the waveguide structure is far better than that obtainable using any other fabrication technique. The beam

  2. Balance Problems

    MedlinePlus

    ... version of this page please turn Javascript on. Balance Problems About Balance Problems Have you ever felt dizzy, lightheaded, or ... dizziness problem during the past year. Why Good Balance is Important Having good balance means being able ...

  3. Silicon photonic transceiver circuit for high-speed polarization-based discrete variable quantum key distribution

    SciTech Connect

    Cai, Hong; Long, Christopher M.; DeRose, Christopher T.; Boynton, Nicholas; Urayama, Junji; Camacho, Ryan; Pomerene, Andrew; Starbuck, Andrew L.; Trotter, Douglas C.; Davids, Paul S.; Lentine, Anthony L.

    2017-01-01

    We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.

  4. THIS: A Next Generation Tuneable Heterodyne Infrared Spectrometer for SOFIA

    NASA Technical Reports Server (NTRS)

    Sonnabend, Guido; Wirtz, Daniel; Schieder, Rudolf

    2004-01-01

    A new infrared heterodyne instrument has been developed which allows the use of both tuneable diode lasers (TDL) and quantum cascade lasers (QCL) as local oscillators (LO). The current frequency tuning range of our system extends from 900 to 1100/cm depending on the availability of lasers but is planned to be extended to 600/cm soon. The IF-bandwidth is 1.4 GHz using an acousto-optical spectrometer (AOS). The frequency resolution and stability of the system is approximately 10(exp 7). Currently, mercury-cadmium-telluride (MCT) detectors are used as mixers while new devices like quantum-well-infrared-photodetectors (QWIP) and hot-electron-bolometers (HEB) are investigated. The IF-bandwidth can be extended to about 3 GHz by using a new broadband acousto-optical spectrometer presently under development. The instrument is fully transportable and can be attached to any infrared or optical telescope. The semiconductor laser is stabilized to a Fabry-Perot ring-resonator, which is also used as an efficient diplexer to superimpose the local-oscillator and the signal radiation. As a first step measurements of trace gases in Earth's atmosphere and non-LTE emission from Venus' atmosphere were carried out as well as observations of molecular features in sunspots. Further astronomical observations from ground-based telescopes and the airborne observatory SOFIA are planned for the future. Of particular interest are molecules without a permanent dipole moment like H2, CH4, C2H2 etc.

  5. Heterodyne Stabilization for the Laser Interferometer Space Antenna (LISA)

    NASA Astrophysics Data System (ADS)

    Eichholz, Johannes; Hochman, Steven; Preston, Alix; Mueller, Guido

    2010-10-01

    LISA is a joint NASA/ESA space mission to detect gravitational waves from 0.1 mHz to 1 Hz generated e.g. by super-massive black hole mergers. Three spacecraft move in a triangular constellation on a heliocentric orbit. Their distances are monitored interferometrically with laser links. LISA detects fluctuations of the 5 million km arm lengths on a picometer scale. The requirement for the frequency stability of the lasers is 141 Hz/μHz. I will present a new stabilization scheme based on heterodyne interferometry. It requires less components than the currently envisioned Pound Drever Hall technique and can easily be integrated into LISA's interferometry measurement system. The two lasers of each spacecraft are injected into the same optical cavity. Near resonance, the phase of the reflected light is sensitive to frequency fluctuations. The second, off-resonant beam can be used to lock the primary laser to the cavity resonance. I will discuss this technique and present experimental results. This work is supported by NASA Contract #00078244 and NASA Grant NNX08AG75G.

  6. Fourier transform methods applied to an optical heterodyne profilometer

    NASA Astrophysics Data System (ADS)

    Beltrán-González, A.; García-Torales, G.; Martínez-Ponce, G.

    2013-11-01

    In this work, theory and experiment describe the performance of a surface profile measurement device based on optical heterodyne interferometry are presented. The object and reference beams propagating through the interferometer are obtained by single-pass through an acousto-optic modulator. The diffraction orders 0 and the Doppler-shifted +1 (object and reference beams, respectively) are manipulated to propagate collinearly towards the interferometer output where a fast photodetector is placed to collect the irradiance. The modulated optical signal is Fourier transformed using a data acquisition card and RF communications software. The peak centered at the acousto-optic frequency in the power spectrum is filtered and averaged. The irregularities on the surface of the reflective sample are proportional to the height of this peak. The profile of a reflective blazed grating has been sketched by translating laterally the sample using a nanopositioning system. Experimental results are compared to the measurement done with a scanning electron microscope. There has been found a good agreement between both methods.

  7. A heterodyne interferometer for high-performance industrial metrology

    NASA Astrophysics Data System (ADS)

    Schuldt, Thilo; Gohlke, Martin; Weise, Dennis; Johann, Ulrich; Peters, Achim; Braxmaier, Claus

    2008-11-01

    We developed a compact, fiber-coupled heterodyne interferometer for translation and tilt metrology. Noise levels below 5 pm/√Hz in translation and below 10 nrad/√Hz in tilt measurement, both for frequencies above 10-2 Hz, were demonstrated in lab experiments. While this setup was developed with respect to the LISA (Laser Interferometer Space Antenna) space mission current activities focus on its adaptation for dimensional characterization of ultra-stable materials and industrial metrology. The interferometer is used in high-accuracy dilatometry measuring the coefficient of thermal expansion (CTE) of dimensionally highly stable materials such as carbon-fiber reinforced plastic (CFRP) and Zerodur. The facility offers the possibility to measure the CTE with an accuracy better 10-8/K. We also develop a very compact and quasi-monolithic sensor head utilizing ultra-low expansion glass material which is the basis for a future space-qualifiable interferometer setup and serves as a prototype for a sensor head used in industrial environment. For high resolution 3D profilometry and surface property measurements (i. e. roughness, evenness and roundness), a low-noise (<=1nm/√ Hz) actuator will be implemented which enables a scan of the measurement beam over the surface under investigation.

  8. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.

    1978-01-01

    Measurements of a stratospheric ozone concentration profile are made by detecting infrared absorption lines with a heterodyne spectrometer. The infrared spectrometer is based on a line-by-line tunable CO2 lasers, a liquid-nitrogen cooled HgCdTe photomixer, and a 64-channel spectral line receiver. The infrared radiation from the source is mixed with local-oscillator radiation. The difference frequency signal in a bandwidth above and below the local-oscillator frequency is detected. The intensity in each sideband is found by subtracting sideband contributions. It is found that absolute total column density is 0.32 plus or minus 0.02 cm-atm with a peak mixing ratio at about 24 km. The (7,1,6)-(7,1,7) O3 line center frequency is identified as 1043.1772/cm. Future work will involve a number of ozone absorption lines and measurements of diurnal variation. Completely resolved stratospheric lines may be inverted to yield concentration profiles of trace constituents and stratospheric gases.

  9. A simple and versatile phase detector for heterodyne interferometers

    NASA Astrophysics Data System (ADS)

    Mlynek, A.; Faugel, H.; Eixenberger, H.; Pautasso, G.; Sellmair, G.

    2017-02-01

    The measurement of the relative phase of two sinusoidal electrical signals is a frequently encountered task in heterodyne interferometry, but also occurs in many other applications. Especially in interferometry, multi-radian detectors are often required, which track the temporal evolution of the phase difference and are able to register phase changes that exceed 2π. While a large variety of solutions to this problem is already known, we present an alternative approach, which pre-processes the signals with simple analog circuitry and digitizes two resulting voltages with an analog-to-digital converter (ADC), whose sampling frequency can be far below the frequency of the sinusoidal signals. Phase reconstruction is finally carried out by software. The main advantage of this approach is its simplicity, using only few low-cost hardware components and a standard 2-channel ADC with low performance requirements. We present an application on the two-color interferometer of the ASDEX Upgrade tokamak, where the relative phase of 40 MHz sinusoids is measured.

  10. A compact high-sensitivity heterodyne interferometer for industrial metrology

    NASA Astrophysics Data System (ADS)

    Schuldt, Thilo; Gohlke, Martin; Weise, Dennis; Peters, Achim; Johann, Ulrich; Braxmaier, Claus

    2008-04-01

    For translation and tilt metrology, we developed a compact fiber-coupled polarizing heterodyne interferometer which is based on a highly symmetric design where both, measurement and reference beam have similar optical pathlengths and the same frequency and polarization. The method of differential wavefront sensing is implemented for tilt measurement. With this setup we reached noise levels below 5 pm/square root of Hz; Hz in translation and below 10 nrad/square root of Hz; in tilt measurement, both for frequencies above 10-2 Hz. While this setup is developed with respect to the requirements of the LISA (Laser Interferometer Space Antenna) space mission, we here present the current status of its adoption to industrial applications. We currently design a very compact and quasi-monolithic setup of the interferometer sensor head based on ultra-low expansion glass material. The resulting compact and robust sensor head can be used for nano-positioning control. We also plan to implement a scan of the measurement beam over the surface under investigation enabling high resolution 3D profilometry and surface property measurements (i. e. roughness, evenness and roundness). The dedicated low-noise (<=1nm/square root of Hz) piezo-electric actuator in the measurement beam of the interferometer will be realized using integrated micro-system technology and can either be implemented in one or two dimensions.

  11. Stratospheric ozone measurement with an infrared heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Kostiuk, T.; Mumma, M. J.; Buhl, D.; Kunde, V. G.; Brown, L. W.

    1978-01-01

    Measurements of a stratospheric ozone concentration profile are made by detecting infrared absorption lines with a heterodyne spectrometer. The infrared spectrometer is based on a line-by-line tunable CO2 lasers, a liquid-nitrogen cooled HgCdTe photomixer, and a 64-channel spectral line receiver. The infrared radiation from the source is mixed with local-oscillator radiation. The difference frequency signal in a bandwidth above and below the local-oscillator frequency is detected. The intensity in each sideband is found by subtracting sideband contributions. It is found that absolute total column density is 0.32 plus or minus 0.02 cm-atm with a peak mixing ratio at about 24 km. The (7,1,6)-(7,1,7) O3 line center frequency is identified as 1043.1772/cm. Future work will involve a number of ozone absorption lines and measurements of diurnal variation. Completely resolved stratospheric lines may be inverted to yield concentration profiles of trace constituents and stratospheric gases.

  12. Seedless Laser Velocimetry Using Heterodyne Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Balla, R. Jeffrey; Herring, G. C.; Jenkins, Luther N.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    A need exists for a seedless equivalent of laser Doppler velocimetry (LDV) for use in low-turbulence or supersonic flows or elsewhere where seeding is undesirable or impractical. A compact laser velocimeter using heterodyne non-resonant laser-induced thermal acoustics (LITA) to measure a single component of velocity is described. Neither molecular (e.g. NO2) nor particulate seed is added to the flow. In non-resonant LITA two beams split from a short-pulse pump laser are crossed; interference produces two counterpropagating sound waves by electrostriction. A CW probe laser incident on the sound waves at the proper angle is directed towards a detector. Measurement of the beating between the Doppler-shifted light and a highly attenuated portion of the probe beam allows determination of one component of flow velocity, speed of sound, and temperature. The sound waves essentially take the place of the particulate seed used in LDV. The velocimeter was used to study the flow behind a rearward-facing step in NASA Langley Research Center's Basic Aerodynamics Research Tunnel. Comparison is made with pitot-static probe data in the freestream over the range 0 m/s - 55 m/s. Comparison with LDV is made in the recirculation region behind the step and in a well-developed boundary layer in front of the step. Good agreement is found in all cases.

  13. Investigation of moderately turbid suspensions by heterodyne near field scattering.

    PubMed

    Escobedo-Sánchez, M A; Rojas-Ochoa, L F; Laurati, M; Egelhaaf, S U

    2017-08-03

    Light scattering has proven to be a very powerful technique to characterize soft matter systems. However, many samples are turbid and hence suffer from multiple scattering which can affect the signal considerably. Multiple scattering can be reduced by diluting the sample or changing the solvent, but often this alters the sample and hence is precluded. Here we study the dynamics of a model system. In particular, we investigate the effects of moderate multiple scattering on small-angle heterodyne near field scattering (HNFS). Varying the particle concentration and size we change the degree of multiple scattering, which is quantified by the transmission of light. In dependence of the degree of multiple scattering, we analyze the statistical properties of the HNFS signal, which is the difference between two intensity patterns separated by a delay time. The distribution of intensity differences follows a Gaussian distribution if single scattering dominates and a Laplace distribution in the presence of extreme multiple scattering. We also investigate the effects of multiple scattering on the measured intermediate scattering function and the hydrodynamic radius of the particles. Reliable data are obtained for sample transmissions down to about 0.7. This is confirmed by a comparison with results from a far field cross-correlation instrument that suppresses multiple scattering contributions. Therefore, HNFS represents a technically simple but powerful method to investigate samples that are moderately multiple scattering.

  14. Preliminary submillimeter spectroscopic measurements using a submillimeter heterodyne radiometer

    NASA Technical Reports Server (NTRS)

    Safren, H. G.; Stabnow, W. R.; Bufton, J. L.; Peruso, C. J.; Rossey, C. E.; Walker, H. E.

    1982-01-01

    A submillimeter heterodyne radiometer uses a submillimeter laser, pumped by a CO2 laser, as a local oscillator and a room temperature Schottky barrier diode as the first IF mixer. The radiometer can resolve spectral lines in the submillimeter region of the spectrum (arising from pure rotational molecular transitions) to within 0.3 MHz, using acousto-optic spectrum analyzer which measures the power spectrum by simultaneously sampling 0.3 MHz wide channels over a 100 MHz bandwidth spanning the line. Preliminary observations of eight spectral lines of H2O2, CO, NH3 and H2O, all lying in the 434-524 micrometer wavelength range are described. All eight lines were observed using two local oscillator frequencies obtained by operating the submillimeter laser with either methyl fluoride (CH3F) or formic acid (HCOOH) as the lasing gas. Sample calculations of line parameters from the observed data show good agreement with established values. One development goal is the size and weight reduction of the package to make it suitable for balloon or shuttle experiments to detect trace gases in the upper atmosphere.

  15. High-resolution optical fiber heterodyne interferometer for measuring displacement

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Wang, Jia; Cao, Mang; Li, Dacheng

    1990-07-01

    Many Methods have been developed to .easure displace.ent with high accuracy, for exap1e, with a dual frequency laser interferometer (AC interferometer) and an classic interferoseter (DC interferoeter) which use a stabilized laser and fringe counter, and an AC interfero.eter has ore advantage over the DC one. An AC interfero.eter with a Zee.an laser can get a high resolution, in the order of nanoMeters, but its resolution extension liRited by nonlinear relation between phase and displace.ent which caused by the two-frequency coRponents in interferoaeter[1]. Because the fundaaental length scale of the interferometer is the wavelength of the light source in the air. The accuracy of an interferoeter is li.ited by the operating envireaent, teRperature, husidity, pressure, etc. because the aiRs of interferoseters expose in the air. A high resolution optical fiber heterodyne interfermeter is described in the paper.

  16. Short term frequency stability measurement for narrow linewidth laser by time domain self-heterodyne method

    NASA Astrophysics Data System (ADS)

    Lu, Lidong; Sun, Xiaoyan; Bu, Xiande; Li, Binglin

    2016-11-01

    Based on the time delay self-heterodyne method to measure the laser linewidth, the short-term linewidth variation of a narrow linewidth laser is experimentally studied and analyzed, and then a time domain self-heterodyne method is proposed to measure the short-term frequency stability of narrow linewidth laser. The Rayleigh backscattering frequency of a pulsed light propagating in an optical fiber with length of 100km is used as the local oscillation frequency with relatively long time duration to measure the frequency variation of the narrow linewidth laser. By heterodyne between the laser frequency and the local oscillation frequency, the variation of the laser frequency is presented in the heterodyne radio frequency (IF). Then the time domain data of the heterodyne IF are extracted by an oscilloscope and through short time Fourier transform the frequency from the laser in different time segments is obtained. Experimental results demonstrate that for narrow linewidth laser its frequency in short-term is randomly fluctuating with a range less than triple of the laser linewidth. The measurement and evaluation of laser short-term frequency stability benefits the application of narrow linewidth lasers in distributed optical fiber sensing area.

  17. Coherent summation of spatially distorted Doppler lidar signals using a two-dimensional heterodyne detector array

    NASA Technical Reports Server (NTRS)

    Chan, Kin Pui; Killinger, Dennis K.

    1992-01-01

    We have investigated the improvement in the signal-to-noise ratio for a coherent Doppler lidar through the use of a multi-element heterodyne detector array. Such an array enables the spatial summation of atmospheric refractive turbulence induced speckles, and time varying target speckles. Our recent experiments have shown that the non-coherent summation of the lidar signals from a heterodyne detector array can enhance the heterodyne mixing efficiency and thus the signal-to-noise ratio. In this paper, we expand this work to include the coherent summation of array signals. The digitized heterodyne signals were stored in a personal computer. Fast Fourier transforms were performed on both the non-coherent and coherent summations of the detector array signals. It was found that the coherent summation greatly enhanced the accuracy in the Doppler frequency estimate. A theoretical analysis was performed and indicated good agreement with experimental results. We have also applied these results to the more general lidar applications including atmospheric wind sensing, and have found that in most lidar applications the Doppler frequency estimate is increased through the use of the heterodyne detector array.

  18. Heterodyne efficiency of a coherent free-space optical communication model through atmospheric turbulence.

    PubMed

    Ren, Yongxiong; Dang, Anhong; Liu, Ling; Guo, Hong

    2012-10-20

    The heterodyne efficiency of a coherent free-space optical (FSO) communication model under the effects of atmospheric turbulence and misalignment is studied in this paper. To be more general, both the transmitted beam and local oscillator beam are assumed to be partially coherent based on the Gaussian Schell model (GSM). By using the derived analytical form of the cross-spectral function of a GSM beam propagating through atmospheric turbulence, a closed-form expression of heterodyne efficiency is derived, assuming that the propagation directions for the transmitted and local oscillator beams are slightly different. Then the impacts of atmospheric turbulence, configuration of the two beams (namely, beam radius and spatial coherence width), detector radius, and misalignment angle over heterodyne efficiency are examined. Numerical results suggest that the beam radius of the two overlapping beams can be optimized to achieve a maximum heterodyne efficiency according to the turbulence conditions and the detector radius. It is also found that atmospheric turbulence conditions will significantly degrade the efficiency of heterodyne detection, and compared to fully coherent beams, partially coherent beams are less sensitive to the changes in turbulence conditions and more robust against misalignment at the receiver.

  19. Quantum secure direct communication protocol with blind polarization bases and particles' transmitting order

    NASA Astrophysics Data System (ADS)

    Song, Jie; Zhu, Ai-Dong; Zhang, Shou

    2007-03-01

    This paper presents a modified secure direct communication protocol by using the blind polarization bases and particles' random transmitting order. In our protocol, a sender (Alice) encodes secret messages by rotating a random polarization angle of particle and then the receiver (Bob) sends back these particles as a random sequence. This ensures the security of communication.

  20. A 2 THz Heterodyne Array Receiver for SOFIA

    NASA Technical Reports Server (NTRS)

    Walker, Christopher K.

    1998-01-01

    We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approx. 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the FIR portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galaxy evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (greater than or equal to 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. Figure 1 is a photograph of the 2 THz double feedhorn structure designed and constructed under the auspices of this grant

  1. Tunable diode laser heterodyne spectrometer for remote observations near 8 microns

    NASA Technical Reports Server (NTRS)

    Glenar, D. A.; Kostiuk, T.; Jennings, D. E.; Buhl, D.; Mumma, M. J.

    1982-01-01

    Infrared heterodyne spectroscopy is a passive technique employing coherent optical detection for the study of spectral features in remote sources. It employs optical components such as mirrors and lenses normally associated with incoherent optics, but because of it's coherent nature, it offers the advantages of ultrahigh spectral resolving power, high frequency precision, and diffraction limited field-of-view. Attention is given to the development of an ultrahigh resolution diode laser heterodyne spectrometer for observational and laboratory use. The instrument is designed for operation in the spectral range from 7.5 to 8.5 microns. A PbSe tuneable diode laser (TDL) is employed as local oscillator. A closed-cycle cooler is employed to keep the oscillator at operating temperatures in the range from 12 to 60 K. Attention is given to factors determining the TDL heterodyne sensitivity, the spectrometer design, and a survey of 8 micron observations, SiO could be detected in the sunspot spectrum.

  2. Signal averaging limitations in heterodyne- and direct-detection laser remote sensing measurements

    NASA Technical Reports Server (NTRS)

    Menyuk, N.; Killinger, D. K.; Menyuk, C. R.

    1983-01-01

    The improvement in measurement uncertainty brought about by the averaging of increasing numbers of pulse return signals in both heterodyne- and direct-detection lidar systems is investigated. A theoretical analysis is presented which shows the standard deviation of the mean measurement to decrease as the inverse square root of the number of measurements, except in the presence of temporal correlation. Experimental measurements based on a dual-hybrid-TEA CO2 laser differential absorption lidar system are reported which demonstrate that the actual reduction in the standard deviation of the mean in both heterodyne- and direct-detection systems is much slower than the inverse square-root dependence predicted for uncorrelated signals, but is in agreement with predictions in the event of temporal correlation. Results thus favor the use of direct detection at relatively short range where the lower limit of the standard deviation of the mean is about 2 percent, but advantages of heterodyne detection at longer ranges are noted.

  3. Fiber-optic delay-line stabilization of heterodyne optical signal generator and method using same

    NASA Technical Reports Server (NTRS)

    Logan, Ronald T. (Inventor)

    1997-01-01

    The present invention is a laser heterodyne frequency generator system with a stabilizer for use in the microwave and millimeter-wave frequency ranges utilizing a photonic mixer as a photonic phase detector in a stable optical fiber delay-line. Phase and frequency fluctuations of the heterodyne laser signal generators are stabilized at microwave and millimeter wave frequencies by a delay line system operating as a frequency discriminator. The present invention is free from amplifier and mixer 1/.function. noise at microwave and millimeter-wave frequencies that typically limit phase noise performance in electronic cavity stabilized electronic oscillators. Thus, 1/.function. noise due to conventional mixers is eliminated and stable optical heterodyne generation of electrical signals is achieved.

  4. A dual-heterodyne laser interferometer for simultaneous measurement of linear and angular displacements.

    PubMed

    Yan, Hao; Duan, Hui-Zong; Li, Lin-Tao; Liang, Yu-Rong; Luo, Jun; Yeh, Hsien-Chi

    2015-12-01

    Picometer laser interferometry is an essential tool for ultra-precision measurements in frontier scientific research and advanced manufacturing. In this paper, we present a dual-heterodyne laser interferometer for simultaneously measuring linear and angular displacements with resolutions of picometer and nanoradian, respectively. The phase measurement method is based on cross-correlation analysis and realized by a PXI-bus data acquisition system. By implementing a dual-heterodyne interferometer with a highly symmetric optical configuration, low frequency noises caused by the environmental fluctuations can be suppressed to very low levels via common-mode noise rejection. Experimental results for the dual-heterodyne interferometer configuration presented demonstrate that the noise levels of the linear and angular displacement measurements are approximately 1 pm/Hz(1/2) and 0.5 nrad/Hz(1/2) at 1 Hz.

  5. Heterodyne Spectroscopy in the Thermal Infrared Region: A Window on Physics and Chemistry

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor

    2004-01-01

    The thermal infrared region contains molecular bands of many of the most important species in gaseous astronomical sources. True shapes and frequencies of emission and absorption spectral lines from these constituents of planetary and stellar atmospheres contain unique information on local temperature and abundance distribution, non-thermal effects, composition, local dynamics and winds. Heterodyne spectroscopy in the thermal infrared can remotely measure true line shapes in relatively cool and thin regions and enable the retrieval of detailed information about local physics and chemistry. The concept and techniques for heterodyne detection will be discussed including examples of thermal infrared photomixers and instrumentation used in studies of several astronomical sources. Use of heterodyne detection to study non-LTE phenomena, planetary aurora, minor planetary species and gas velocities (winds) will be discussed. A discussion of future technological developments and relation to space flight missions will be addressed.

  6. Mode beating and heterodyning of monolithically integrated semiconductor ring lasers

    NASA Astrophysics Data System (ADS)

    Liu, Chiyu

    Monolithically integrated semiconductor ring lasers (SRLs) are attractive optical sources for optoelectronic integrated circuits (OEICs) because they do not require any feedback elements, do not have parts exposed to external ambient, and can operate in a traveling-wave mode. They are promising candidates for wavelength filtering, unidirectional traveling-wave operation, and multiplexing/demultiplexing applications. Ring lasers can also be used as ultrashort pulse generators using various mode-locking schemes and as active gyro components. However, the SRL is a very complicated dynamic system, which requires more investigations to understand the performance regarding details of the design and fabrication. As a part of NASA-supported project "Monolithically Integrated Semiconductor Ring Laser Gyro for Space Applications", this dissertation research was focused on design and characterization of a novel monolithically integrated rotation sensor based on two large-size independent SRLs. Numerical modeling based on the beam propagation method (BPM) was used to design the fabrication parameters for the single-mode ridge-waveguide ring cavity and directional coupler waveguides. The mode internal coupling in single lateral-mode laser diodes with InGaAs/GaAs material system was investigated by optical experiments and numerical modeling. To gain the understanding of the SRL performance, optical and electrical characterization was performed on fabricated SRLs. Particular emphasis was placed on the study of optical and radio frequency (RF) beating spectra of longitudinal modes of ring lasers. RF measurements provide high accuracy in the diagnosis of laser oscillation parameters by purely electronic means, particularly in the measurement of the group index and its dependence on current and temperature. Theoretical analysis based on the effective index method provides good agreement between the experimental data and numerical calculations. Finally, optical heterodyning spectra

  7. New Wavenumber Calibration Tables From Heterodyne Frequency Measurements

    PubMed Central

    Maki, Arthur G.; Wells, Joseph S.

    1992-01-01

    This new calibration atlas is based on frequency rather than wavelength calibration techniques for absolute references. Since a limited number of absolute frequency measurements is possible, additional data from alternate methodology are used for difference frequency measurements within each band investigated by the frequency measurements techniques. Data from these complementary techniques include the best Fourier transform measurements available. Included in the text relating to the atlas are a description of the heterodyne frequency measurement techniques and details of the analysis, including the Hamiltonians and least-squares-fitting and calculation. Also included are other relevant considerations such as intensities and lincshape parameters. A 390-entry bibliography which contains all data sources used and a subsequent section on errors conclude the text portion. The primary calibration molecules are the linear triatomics, carbonyl sulfide and nitrous oxide, which cover portions of the infrared spectrum ranging from 488 to 3120 cm−1. Some gaps in the coverage afforded by OCS and N2O are partially covered by NO, CO, and CS2. An additional region from 4000 to 4400 cm−1 is also included. The tabular portion of the atlas is too lengthy to include in an archival journal. Furthermore, different users have different requirements for such an atlas. In an effort to satisfy most users, we have made two different options available. The first is NIST Special Publication 821, which has a spectral map/facing table format. The spectral maps (as well as the facing tables) are calculated from molecular constants derived for the work. A complete list of all of the molecular transitions that went into making the maps is too long (perhaps by a factor of 4 or 5) to include in the facing tables. The second option for those not interested in maps (or perhaps to supplement Special Publication 821) is the complete list (tables-only) which is available in computerized format as

  8. Balance Problems

    MedlinePlus

    ... our e-newsletter! Aging & Health A to Z Balance Problems Basic Facts & Information What are Balance Problems? Having good balance means being able to ... Only then can you “keep your balance.” Why Balance is Important Your feelings of dizziness may last ...

  9. V-groove diffraction grating for use in an FUV spatial heterodyne interferometer

    NASA Technical Reports Server (NTRS)

    Cotton, Daniel M.; Bach, Bernie; Bush, Brett C.; Chakrabarti, Supriya

    1991-01-01

    A need has arisen for efficient, blazed, symmetric gratings for use as beam splitters in far and extreme ultraviolet interferometers. In particular, the development of an all-reflection, far ultraviolet spatial heterodyne interferometer can benefit tremendously from such a grating. To fulfill this need, we have manufactured a mechanically ruled grating with a V-groove profile blazed for H Lyman-alpha at 1216 A. We present the grating performance at Lyman-alpha in the context of its application to the spatial heterodyne interferometer.

  10. Selection of the tagged photons by off axis heterodyne holography in ultrasound-modulated optical tomography

    NASA Astrophysics Data System (ADS)

    Gross, M.

    2017-03-01

    Ultrasound-modulated optical tomography (UOT) is a technique that images optical contrast deep inside scattering media. Heterodyne holography is a promising tool able to detect the UOT tagged photons with high efficiency. In this work, we describe theoretically the detection of the tagged photon in heterodyne holography based UOT, show how to filter the untagged photon, and discuss the effect of shot noise. The discussion considers also speckle decorrelation. We show that optimal detection sensitivity can be reached, if the frame exposure time of the camera used to perform the holographic detection is of the order of the decorrelation time.

  11. V-groove diffraction grating for use in an FUV spatial heterodyne interferometer

    NASA Technical Reports Server (NTRS)

    Cotton, Daniel M.; Bach, Bernie; Bush, Brett C.; Chakrabarti, Supriya

    1991-01-01

    A need has arisen for efficient, blazed, symmetric gratings for use as beam splitters in far and extreme ultraviolet interferometers. In particular, the development of an all-reflection, far ultraviolet spatial heterodyne interferometer can benefit tremendously from such a grating. To fulfill this need, we have manufactured a mechanically ruled grating with a V-groove profile blazed for H Lyman-alpha at 1216 A. We present the grating performance at Lyman-alpha in the context of its application to the spatial heterodyne interferometer.

  12. Mid-infrared photothermal heterodyne spectroscopy in a liquid crystal using a quantum cascade laser

    PubMed Central

    Mërtiri, Alket; Jeys, Thomas; Liberman, Vladimir; Hong, M. K.; Mertz, Jerome; Altug, Hatice; Erramilli, Shyamsunder

    2012-01-01

    We report a technique to measure the mid-infrared photothermal response induced by a tunable quantum cascade laser in the neat liquid crystal 4-octyl-4′-cyanobiphenyl (8CB), without any intercalated dye. Heterodyne detection using a Ti:sapphire laser of the response in the solid, smectic, nematic and isotropic liquid crystal phases allows direct detection of a weak mid-infrared normal mode absorption using an inexpensive photodetector. At high pump power in the nematic phase, we observe an interesting peak splitting in the photothermal response. Tunable lasers that can access still stronger modes will facilitate photothermal heterodyne mid-infrared vibrational spectroscopy. PMID:22912508

  13. Methods, compositions and kits for imaging cells and tissues using nanoparticles and spatial frequency heterodyne imaging

    DOEpatents

    Rose-Petruck, Christoph; Wands, Jack R.; Rand, Danielle; Derdak, Zoltan; Ortiz, Vivian

    2016-04-19

    Methods, compositions, systems, devices and kits are provided herein for preparing and using a nanoparticle composition and spatial frequency heterodyne imaging for visualizing cells or tissues. In various embodiments, the nanoparticle composition includes at least one of: a nanoparticle, a polymer layer, and a binding agent, such that the polymer layer coats the nanoparticle and is for example a polyethylene glycol, a polyelectrolyte, an anionic polymer, or a cationic polymer, and such that the binding agent that specifically binds the cells or the tissue. Methods, compositions, systems, devices and kits are provided for identifying potential therapeutic agents in a model using the nanoparticle composition and spatial frequency heterodyne imaging.

  14. Clutter isolation and cardiac monitoring using harmonic doppler radar with heterodyne receiver and passive RF tags.

    PubMed

    Singh, Aditya; Lubecke, Victor

    2010-01-01

    A harmonic radar employing the use of harmonic passive RF tags can be successfully used to isolate the human respiration from environmental clutter. This paper describes the successful use of heterodyne receiver architecture with Doppler radar to track the heart-rate of a human being using passive body-worn harmonic tags in presence of a controlled noise generator at distances up to 120 cm. The heterodyne system results have been compared with those of a conventional Doppler radar for cardiopulmonary monitoring that fails to isolate the noise from heart-rate in presence of a noise source.

  15. Measurement of in-plane displacement by wavelength-modulated heterodyne speckle interferometry.

    PubMed

    Lee, Ju-Yi; Lu, Ming-Pei; Lin, Kun-Yi; Huang, Szu-Han

    2012-03-10

    The use of wavelength-modulated light incorporated into an optical-path-difference speckle interferometer is demonstrated as a heterodyne technique for measuring the in-plane displacement of a rough object. The in-plane displacement can be determined from the measured phase variation of the heterodyne speckle signal. We also improved the optical configuration to create a high-contrast interference pattern. Experimental results reveal that the proposed method can detect displacement up to a long range of 220 μm and displacement variation down to the nanometer range. Moreover, the sensitivity can reach up to 0.8°/nm. The performance of the system is discussed.

  16. Evaluation of periodgrams as a tool to study spectral densities of heterodyne signals

    NASA Astrophysics Data System (ADS)

    Alvarado, Jose Manuel; Stern, Catalina

    2002-11-01

    The use of periodgrams as a tool to study heterodyne signals is evaluated. The heterodyne signal carries information about density fluctuations from light scattered by a turbulent jet. The goal of the analysis is to be able to separate the information about density fluctuations of acoustics origin (peaked at about 2 MHz) from fluctuations in the density due to entropy irregularities (wide peak centered at the origin). There are frequency regions where both overlap. Various methods are compared: Bartlett, Welch, Yule-Walker, Burg and others. (To be presented in Spanish.)

  17. Scanning heterodyne Kerr-effect microscope for imaging of magnetic tracks

    NASA Astrophysics Data System (ADS)

    Protopopov, Vladimir V.; Lee, Sukwon; Kwon, Youngkun; Cho, Sunghoon; Kim, Hyuk; Chae, Jonggyn

    2006-07-01

    Design and performance of a new type of Kerr microscope based on heterodyne cross-polarized technique is presented. Weak depolarization of the probe beam due to longitudinal magneto-optical Kerr effect is detected by means of heterodyne mixing of the two cross-polarized and frequency shifted waves generated by Zeeman-type He-Ne laser. In comparison with the traditional homodyne method the proposed technique has better sensitivity and spatial resolution. Experimental results of imaging service magnetic tracks on real samples of magnetic disks are presented, showing better contrast and spatial resolution with respect to the images obtained from commercial devices available in the market.

  18. Usefulness of the infrared heterodyne radiometer in remote sensing of atmospheric pollutants.

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Shumate, M. S.

    1971-01-01

    The application of narrow-band optical receivers to the problem of sensing atmospheric pollution is discussed. The emission/absorption lines of many major atmospheric pollutant molecules overlap the operating frequency bands of CO2 laser and CO laser heterodyne receivers. Several remote pollution sensing systems which are based upon utilization of these spectral overlaps are described, and an analysis of their potential is presented. The possibility of using other lasers (e.g.: the PbSnTe tunable diode laser) as local oscillators is also considered. Results of laboratory experiments with a CO2 laser heterodyne radiometer are presented.

  19. Balance Problems

    MedlinePlus

    ... often, it could be a sign of a balance problem. Balance problems can make you feel unsteady. You may ... related injuries, such as a hip fracture. Some balance problems are due to problems in the inner ...

  20. Multi-mode heterodyned 5th-order infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Leger, Joel D.; Varner, Clyde; Rubtsov, Igor V.

    2016-10-01

    Fifth-order multidimensional infrared spectroscopy with heterodyned detection was carried out in the three-beam dual-frequency configuration. Numerous 5th-order cross peaks were detected for the 4-azidobutyrate-N-hydroxysuccinimide ester compound in solution involving several vibrational modes ranging in frequency from 1045 to 2100 cm-1. Cross peaks involving overtones (2X/Z) and combination bands (XY/Z) among the tags, modes X and Y excited by the first two mid-IR laser pulses, and the reporter, modes Z excited by the third laser pulse, were acquired and the factors affecting the amplitude of 5th-order cross peaks are discussed. The 5th-order cross peaks were detected among modes that are spatially close (a few bonds apart) as well as for modes spatially separated by ca. 12 Å (eight bonds apart). In both cases, the waiting time dependences for the 3rd and 5th order cross peaks were found to be different. In particular, the waiting time at which the cross-peak maximum is reached, the decay time, and the value of a plateau at large waiting times were all differing strongly. The differences are explained by reduced sensitivity of the 5th-order signals to modes coupled weakly to the reporter mode and different relaxation dynamics involving overtone state of the tag. The ability of the 5th-order peaks to single out the modes coupled strongly to the reporter can help identifying specific energy relaxation and transport pathways, which will be useful for understanding energy transport dynamics in molecules. The absorptive 5th-order cross peaks were constructed which report on three-point correlation functions. It is shown that in addition to the triple-frequency correlation functions, a correlation of the frequencies with the mode coupling (anharmonicity) can be naturally measured by the 5th-order spectroscopy. The current limit for detecting 5th-order signals was estimated at the level of 1 × 10-3 in reduced anharmonicity, which is determined by the corresponding two

  1. Great circle solution to polarization-based quantum communication (QC) in optical fiber

    DOEpatents

    Nordholt, Jane Elizabeth; Peterson, Charles Glen; Newell, Raymond Thorson; Hughes, Richard John

    2016-03-15

    Birefringence in optical fibers is compensated by applying polarization modulation at a receiver. Polarization modulation is applied so that a transmitted optical signal has states of polarization (SOPs) that are equally spaced on the Poincare sphere. Fiber birefringence encountered in propagation between a transmitter and a receiver rotates the great circle on the Poincare sphere that represents the polarization bases used for modulation. By adjusting received polarizations, polarization components of the received optical signal can be directed to corresponding detectors for decoding, regardless of the magnitude and orientation of the fiber birefringence. A transmitter can be configured to transmit in conjugate polarization bases whose SOPs can be represented as equidistant points on a great circle so that the received SOPs are mapped to equidistant points on a great circle and routed to corresponding detectors.

  2. Simultaneous separation of hydrophobic and polar bases using a silica hydride stationary phase.

    PubMed

    Yang, Yuanzhong; Matyska, Maria T; Boysen, Reinhard I; Pesek, Joseph J; Hearn, Milton T W

    2013-04-01

    In this study, the retention behavior of selected hydrophobic and polar bases on a minimally modified silica hydride phase was investigated. From these results and the associated retention plots, significant differences in the chromatographic dependencies of these two classes of basic compounds were evident. The polar bases exhibited strong retention with mobile phases of high organic solvent content, but displayed weak retention with mobile phases of high water content. In contrast, the hydrophobic bases showed "U-shape" retention dependencies, indicative of the interplay of both RP and normal-phase retention characteristics. These studies have demonstrated that hydrophobic and polar bases can be simultaneously separated on the same column either under typical RP-like or aqueous normal-phase-like conditions, respectively, with distinctive selectivity. Finally, the effects of temperature on the RP and aqueous normal phase modality of separations with these analytes were investigated, where discrete changes in retention behavior were also observed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Engineering of Condensed Matter Nuclear Physics: Heterodyne Behavior in Condensed Matter Nuclear Systems

    NASA Astrophysics Data System (ADS)

    Swartz, Mitchell R.

    2007-03-01

    Previously, we reported methods to semi-quantitatively measure and control tardive thermal power (TTP) which develops long after the termination of electric input power in condensed matter high-deuteron-flux Phusor devices providing (Pt/D2O/Pd; 0.5 cm^3) peak excess power ratios circa 2.30+/-.84 ^2^,^3. Now we report one method to improve excess energy using heterodyned CMN systems using both normal and TTD operation - heterodyne operation (that is, ` hetero ' for other, and ` dyne ' for power). By augmenting the conventional excess energy produced by CMN active systems (normal operation) with the additional energy (``other power'') resulting from the time integral of TTP (``heat after death''), the net time-integrated excess energy (output energy beyond that applied as the input energy) is greater than we have previously reported^2 and may be maximized using TTD drive techniques^1. Initial experiments of heterodyned active samples, capable of excess heat operation at the optimal operating point, have yielded excess energy increases of up to four times beyond that obtained without heterodyned operation. M.R. Swartz, Bull. of the APS, 50, #1, part 2, 1203 (2005). M.R.Swartz, Proc ICCF10, 29-44; 45-54, and 213-226 (2006).

  4. Airborne far-infrared heterodyne remote sensing of stratospheric oh: a feasibility study

    SciTech Connect

    Miller, S,; Birk, M.; Schreier, F.; Hausamann, D. )

    1992-01-01

    The hydroxyl radical OH is one of the most important, but least investigated, atmospheric species. For an improved understanding of its strong involvement in stratospheric chemistry, more data is needed which provides concentrations of OH and related species at any latitude, longitude, season and day of time. This requirement can not be fulfilled by existing stratospheric sensors. Balloon-borne sensors provide data up to 40 km, yet they are subject to the typical restrictions for balloon operation, while airborne in-situ measurements are limited by the maximum altitude of the aircraft. In this study it is shown, that an airborne Far Infrared heterodyne receiver is able to meet the need for a versatile stratospheric OH sensor. Based on both the high spectral resolution and sensitivity of heterodyne receivers and the availability of airborne heterodyne technology it will be shown that this instrument is capable of retrieving data with the greatly expanded spatial and temporal coverage required. When operated on a standard aircraft at an altitude of 12 km, the heterodyne receiver can retrieve concentration profiles from above the flight altitude with a typical altitude resolution of 5 to 7 km.

  5. Camera-Based Lock-in and Heterodyne Carrierographic Photoluminescence Imaging of Crystalline Silicon Wafers

    NASA Astrophysics Data System (ADS)

    Sun, Q. M.; Melnikov, A.; Mandelis, A.

    2015-06-01

    Carrierographic (spectrally gated photoluminescence) imaging of a crystalline silicon wafer using an InGaAs camera and two spread super-bandgap illumination laser beams is introduced in both low-frequency lock-in and high-frequency heterodyne modes. Lock-in carrierographic images of the wafer up to 400 Hz modulation frequency are presented. To overcome the frame rate and exposure time limitations of the camera, a heterodyne method is employed for high-frequency carrierographic imaging which results in high-resolution near-subsurface information. The feasibility of the method is guaranteed by the typical superlinearity behavior of photoluminescence, which allows one to construct a slow enough beat frequency component from nonlinear mixing of two high frequencies. Intensity-scan measurements were carried out with a conventional single-element InGaAs detector photocarrier radiometry system, and the nonlinearity exponent of the wafer was found to be around 1.7. Heterodyne images of the wafer up to 4 kHz have been obtained and qualitatively analyzed. With the help of the complementary lock-in and heterodyne modes, camera-based carrierographic imaging in a wide frequency range has been realized for fundamental research and industrial applications toward in-line nondestructive testing of semiconductor materials and devices.

  6. Spatial frequency response of an optical heterodyne receiver. [transfer function analysis

    NASA Technical Reports Server (NTRS)

    Fales, C. L.; Robinson, D. M.

    1980-01-01

    The principles of transfer function analysis are applied to a passive optical heterodyne receiver to obtain the modulation transfer function (MTF). MTF calculations are performed based on an optical platform which is imaging vertically varying profiles at worst case shuttle orbit altitudes. An analysis of the derogatory effects of sampling (aliasing) and central obscurations on both resolution and heterodyne efficiency is given. It is found that the cascading property of MTF analysis must be carefully applied since the coherent transfer function of the optical receiver and that due to the local oscillator-detector combination are not separable but are related by the convolution of their products. Application of these results to the specific case of a space-lab type optical heterodyne receiver shows that resolutions of the order of 1.5-2.0 Km are possible for worst-case type orbital scenarios. Further, comparison of obscured-type receivers (e.g., Cassegrains) with unobscured receivers shows that both resolution and efficiency are severely degraded in an obscured-type receiver and consequently should not be used for a passive heterodyne detection scheme.

  7. Synthetic Array Heterodyne Detection: Developments within the Caliope CO{sub 2} DIAL Program

    SciTech Connect

    Rehse, S.J.; Strauss, E.M.

    1995-09-01

    A new technique, Synthetic Array Heterodyne Detection, offers a wider field of view and improved signal to noise for coherent DIAL systems by reducing speckle interference. We have implemented a synthetic multi-pixel array using a CO{sub 2} laser on a single element HgCdTe photodiode.

  8. LASER BEAMS: Laser heterodyning of Gaussian beams with partial spatial coherence

    NASA Astrophysics Data System (ADS)

    Kozin, G. I.; Kuznetsov, A. P.; Lebedinskii, M. O.

    2005-05-01

    The characteristics of Gaussian beams with partial spatial coherence are considered theoretically. The conditions for efficient recording of laser radiation reflected from scattering surfaces upon laser heterodyning and intracavity radiation reception are analysed. Recommendations on the use of projecting telescopic systems are given. Theoretical conclusions are confirmed experimentally.

  9. SURVEY OF OPTICAL VELOCIMETRY EXPERIMENTS - APPLICATIONS OF PDV, A HETERODYNE VELOCIMETER

    SciTech Connect

    HOLTKAMP, DAVID B.

    2007-02-12

    Optical velocimetry has been an important experimental diagnostic for many experiments. Recent improvements to heterodyne techniques have resulted in compact, inexpensive and high performance velocimetry measurement systems. We report on developments and improvements in this area and illustrate the performance of Photon Doppler Velocimetry (PDV) by showing several experimental examples.

  10. Heterodyne holography with full control of both the signal and reference arms.

    PubMed

    Gross, Michel

    2016-01-20

    Heterodyne holography is a variant of phase-shifting holography in which the reference and signal arms are controlled by acousto-optic modulators. In this review paper, we will briefly describe the method and its properties, and we will illustrate its advantages in experimental applications.

  11. Deriving eigenmode excitation spectrum of synthetic photonic lattices by means of optical heterodyning

    NASA Astrophysics Data System (ADS)

    Tikan, A. M.; Vatnik, I. D.; Churkin, D. V.; Sukhorukov, A. A.

    2017-02-01

    A method based on optical heterodyning is proposed for measuring relative optical phases of pulses circulating in synthetic photonic lattices (SPL). The knowledge of the phases can be further used for qualitative reconstruction of an eigenmode excitation spectrum in the SPL.

  12. Tunable diode laser heterodyne radiometer measurement of atmospheric absorption of solar radiation

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Copeland, G. E.

    1980-01-01

    A tunable infrared heterodyne radiometer (TIHR) which uses a diode laser as the local oscillator is described as well as methods for the evaluation of the excess noise characteristics of the tunable diode laser. Preliminary atmospheric absorption data taken with the TIHR are presented and show the capability of the TIHR for making the highest resolution atmospheric measurements to date.

  13. Study of Planetary Atmospheres by High Resolution Mid-Infrared Heterodyne Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sornig, M.; Sonnabend, G.; Krotz, P.; Stupar, D.; Schieder, R.; Fast, K. E.; Livengood, T. A.; Hewagama, T.; Kostiuk, T.

    Infrared heterodyne spectroscopy offers the capability of very high spectral resolving power (greater than 107 ) combined with relatively high sensitivity compared to mid-infrared direct detection techniques extrapolated to heterodyne resolving power. This high spectral and spatial resolution enables unique high sensitivity studies of the physical and chemical processes in planetary atmospheres through measurement of the true line shapes and frequencies of fundamental transitions of atmospheric molecular species. Two IR heterodyne systems presently are used for astronomical studies. One is the Cologne Tunable Heterodyne Infrared Spectrometer (THIS ) [1]. The other instrument is the NASA Goddard Space Flight Center Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) [2]. The accessible wavelength range of these instruments is constrained by the laser technology employed in the local oscillator and available deterctor/mixers. Current technology with HgCdTe detectors limits the operating range to 7-12 µm for THIS, using quantum cascade lasers, and 9-12 µm for HIPWAC, using CO2 gas lasers. The high spectral resolution and frequency precision of heterodyne detection enables the measurement of fully resolved absorption and emission line shapes of atmospheric species such as CO2 , C2 H6 , O3 , C2 H4 , CH4 , which contain information on the regions of their formation. Analysis of line shapes of well-mixed species retrieves constraints on temperature profiles such as by using C2 H6 spectra on Jupiter and Titan or CO2 on Mars and Venus. Photochemistry on Mars can be probed by direct measurement of lines of O3 , an important tracer of such processes. 1 Atmospheric dynamics in planetary atmospheres can be detected by observing molecular lines Doppler-shifted due to winds such as on Venus, Titan and. Less than 1 MHz Doppler shift (<10 m/s winds) can be detected with this technique using high signal-to-noise ratio data. Results from such measurements with

  14. THz Direct Detector and Heterodyne Receiver Arrays in Silicon Nanoscale Technologies

    NASA Astrophysics Data System (ADS)

    Grzyb, Janusz; Pfeiffer, Ullrich

    2015-10-01

    The main scope of this paper is to address various implementation aspects of THz detector arrays in the nanoscale silicon technologies operating at room temperatures. This includes the operation of single detectors, detectors operated in parallel (arrays), and arrays of detectors operated in a video-camera mode with an internal reset to support continuous-wave illumination without the need to synchronize the source with the camera (no lock-in receiver required). A systematic overview of the main advantages and limitations in using silicon technologies for THz applications is given. The on-chip antenna design challenges and co-design aspects with the active circuitry are thoroughly analyzed for broadband detector/receiver operation. A summary of the state-of-the-art arrays of broadband THz direct detectors based on two different operation principles is presented. The first is based on the non-quasistatic resistive mixing process in a MOSFET channel, whereas the other relies on the THz signal rectification by nonlinearity of the base-emitter junction in a high-speed SiGe heterojunction bipolar transistor (HBT). For the MOSFET detector arrays implemented in a 65 nm bulk CMOS technology, a state-of-the-art optical noise equivalent power (NEP) of 14 pW/ at 720 GHz was measured, whereas for the HBT detector arrays in a 0.25 μm SiGe process technology, an optical NEP of 47 pW/ at 700 GHz was found. Based on the implemented 1k-pixel CMOS camera with an average power consumption of 2.5 μW/pixel, various design aspects specific to video-mode operation are outlined and co-integration issues with the readout circuitry are analyzed. Furthermore, a single-chip 2 × 2 array of heterodyne receivers for multi-color active imaging in a 160-1000 GHz band is presented with a well-balanced NEP across the operation bandwidth ranging from 0.1 to 0.24 fW/Hz (44.1-47.8 dB single-sideband NF) and an instantaneous IF bandwidth of 10 GHz. In its present implementation, the receiver RF

  15. Retrieval of atmospheric ozone profiles from an infrared quantum cascade laser heterodyne radiometer: results and analysis.

    PubMed

    Weidmann, Damien; Reburn, William J; Smith, Kevin M

    2007-10-10

    Following the recent development of a ground-based prototype quantum cascade laser heterodyne radiometer operating in the midinfrared, atmospheric ozone profile retrievals from a solar occultation measurement campaign performed at the Rutherford Appleton Laboratory on 21 September 2006 are presented. Retrieval is based on the optimal estimation method. High resolution (0.0073 cm(-1)) atmospheric spectra recorded by the laser heterodyne radiometer and covering a microwindow (1033.8-1034.5 cm(-1)) optimized for atmospheric ozone measurements were used as measurement vectors. As part of the evaluation of this novel instrument, a comprehensive analysis of the retrievals is presented, demonstrating the high potential of quantum cascade laser heterodyne radiometry for atmospheric sounding. Vertical resolutions of 2 km near the ground and about 3 km in the stratosphere were obtained. The information content of the retrieval was found to be up to 48 bits, which is much higher than any other passive ground-based instrument. Frequency mismatches of several absorption peaks between the forward model and experimental spectra have been observed and significantly contribute to the retrieval noise error in the upper-troposphere lower-stratosphere region. Retrieved ozone vertical profiles were compared to ozonesonde data recorded at similar latitudes. The agreement is generally excellent except for the 20 to 25 km peak in ozone concentration, where ozonesonde data were found to be 20% lower than the amount retrieved from the laser heterodyne radiometer spectra. Quantum cascade laser based heterodyne radiometry in the midinfrared has been demonstrated to provide high spectral resolution and unprecedented vertical resolution for a passive sounder in a highly compact and mechanically simple package.

  16. A novel white-light interferometry using low differential-frequency heterodyne system

    NASA Astrophysics Data System (ADS)

    Kong, Xinxin; Xiangli, Bin; Zhang, Wenxi; Wu, Zhou; Li, Yang; Lv, Xiaoyu

    2017-06-01

    The optical surface profiler offers fast non-contact and high-precision 3D metrology for complex surface features, which are widely used in the field of precision machining manufacturing. The optical surface profiler traditionally adopts the white light interference (WLI) technique which mainly includes optical interference system and high-precision displacement stage. The accuracy of the displacement table determines the longitudinal resolution of the instrument. In this paper, a novel WLI technique is proposed, i.e. full-field heterodyne WLI, which combines common displacement stage, low differential-frequency heterodyne system and optical interferometry system. The low differential-frequency heterodyne system generates heterodyne signal in the range of laser coherence length. By using the digital phase shift in substitution for the mechanical phase shift, the vertical resolution increases from the sub-nanometer level to the sub-angstrom level. Due to the low difference frequency technique, the common area array detector acquisition is available. A fixed displacement stage position obtains a set of three-dimensional data cubes. Through Fourier-Transform process of the time series data, the initial phase of each pixel at a specific heterodyne frequency is calculated and transformed into surface height information. By using phase unwrapping, the object surface profile can be restored within the laser coherence length. Through digital phase-shifting, phase extraction technology replaces the intensity extraction technology, the moving distance of the displacement can be calibrated with high precision. Thus it can achieve a large range of high-precision contour measurement and reduce the cost of the instrument.

  17. Introducing tunable special heterodyne spectrometers in cometary studies

    NASA Astrophysics Data System (ADS)

    Hosseini, S.; Harris, W.

    2014-07-01

    Cometary remote sensing, in many cases, depends on measurement of fine spectral features from targets covering relatively large angular areas on the sky. The range of studies in cometary science is highly diverse. Size scales and perspectives vary dramatically, with opportunities for both Earth-based and in situ studies. Many characteristics of comets, such as coma dynamics, outflow/escape, radiative transfer, and isotopic ratios, are best addressed with high-resolving-power studies that integrate a large FOV. In addition, it is of great importance to obtain high-resolution data to resolve small Doppler shifts, fine structure, line shapes, and atomic multiplets/molecular bands. However, more detection is not enough, because the coma is inherently active; it can manifest substantial variation both temporally and spatially. As a result, we must combine a study of the target's global evolution parallel to the ability to measure with some spatial fidelity across the FOV and to map its variation in time. This combination of requirements is a challenge that modern instrumental approaches are limited in their ability to meet. One method for addressing these needs is through the use of a broadly tunable all-reflective Special Heterodyne Spectrometer (SHS). SHS instruments are common-path two-beam Fourier-transform spectrometers that produce 2-D spatial interference patterns without the requirement for moving parts. The utility of SHS comes from its combination of a wide input acceptance angle (0.5--1°), high resolving power (of order ˜ 10^5), compact format, high dynamic range, and relaxed optical tolerances compared with other interferometer designs. This combination makes them extremely useful for velocity-resolved observations of wide field targets from both small and large telescopes. We have constructed a tunable SHS, Khayyam, at fixed focal plane of the Coudé Auxiliary Telescope (CAT) at Mt. Hamilton. The CAT provides a test case for on-axis use of SHS, and the

  18. Integrated Heterodyne MOEMS for detection of low intensity signals

    NASA Astrophysics Data System (ADS)

    Elman, Noel M.; Krylov, Slava; Sternheim, Marek; Shacham-Diamand, Yosi

    2006-01-01

    A novel MEMS-based modulation scheme is presented as a method to enhance the signal-to-noise ratio (SNR) of silicon photodiodes adapted for the detection of light-emitting bio-reporter signals. Photodiodes are an attractive photodetector choice because they are VLSI compatible, easily miniaturized, highly scalable, and inexpensive. Silicon photodiodes exhibit a wide response range extending from the ultraviolet (UV) to the near infrared (IR) part of the spectrum, which in principle is appropriate for sensing low intensity optical signals. Silicon photodiodes, however, exhibit limited sensitivity to optical dc signals, as the magnitude of the low frequency noise is comparable to signal magnitude. Optical modulation prior to photodetection overcomes the inherent low frequency noise of photodetectors and system detection circuits. The enhancement scheme is based on a design of high frequency optical modulators that operate in the 1-2 kHz range in order to overcome the low frequency spectral noise. We have denominated this MEMS-based scheme Integrated Heterodyne Optical System (IHOS). The modulation efficiency of the proposed architecture can reach up to 50 percent. In order to implement the MOEMS optical modulators, a new two-mask fabrication process was developed that combines high-aspect ratio and low aspect ratio structures at the same device layer (aspect ratio is defined as a ratio between the structure height to its width). Long stroke electrostatic combdrive actuators integrated with folded flexures (high aspect-ratio) were fabricated together to drive large aperture shutters (low aspect ratio). We have denominated this process MASIS (Multiple Aspect Ratio Structural Integration). Under resonant excitation at approximately 1 kHz, MOEMS modulators demonstrated maximum displacement of about 40 microns at an actuation voltage of 15 V peak in air, and 3.5 V peak in vacuum (8 mTorr). Results of analytical solutions and finite element analysis (FEA) simulations are

  19. Dual-Polarization, Sideband-Separating, Balanced Receiver for 1.5 THz

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Goutman; Ward, John; Manohara, Harish; Siegel, Peter

    2009-01-01

    A proposed heterodyne receiver would be capable of detecting electromagnetic radiation in both of two orthogonal linear polarizations, separating sidebands, and providing balanced outputs in a frequency band centered at 1.5 THz with a fractional bandwidth greater than 40 percent. Dual polarization, sideband-separating, and balanced-output receivers are well-known and have been used extensively at frequencies up to about 100 GHz; and there was an earlier proposal for such a receiver for frequencies up to 900 GHz. However, the present proposal represents the first realistic design concept for such a receiver capable of operating above 1 THz. The proposed receiver is intended to be a prototype of mass-producible receiver units, operating at frequencies up to 6 THz, that would be incorporated into highly sensitive heterodyne array instruments to be used in astronomical spectroscopic and imaging studies.

  20. The polarization-based collimated beam combiner and the proposed NOVA fringe tracker (NFT) for the VLTI

    NASA Astrophysics Data System (ADS)

    Meisner, Jeffrey A.; Jaffe, Walter J.; Le Poole, Rudolf S.; Pereira, Silvania F.; Quirrenbach, Andreas; Raban, David; Vosteen, Amir

    2010-07-01

    The Polarization-Based Collimated Beam Combiner efficiently produces pairwise interference between beams from multiple telescopes. An important feature is achieving "Photometric Symmetry" whereby interference measurements have no first-order sensitivity to wavefront perturbations (or photometric variations following spatial filtering) which otherwise entail visibility measurements with increased error, bias, and nonlinearity in phase determination. Among other proposed applications, this topology has been chosen as the basis for the design of the NOVA Fringe Tracker (NFT), a proposed 4 or 6 telescope second-generation fringe tracker for the VLTI. The NFT takes advantage of the photometric symmetry thus achieved making it capable of tracking on stars resolved beyond the first visibility null, as well as interfering a telescope beam with one which is 20 times brighter, a design goal set by ESO. By not requiring OPD modulation for interferometric detection, the detector exposure time can be increased without performance reduction due to time skew nor is sensitivity reduced by removing optical power for photometric monitoring, and use of two-phase interferometric detection saves one half of the photons being diverted for detection of the other two (mainly) unused quadrature phases. The topology is also proposed for visibility measuring interferometers with configurations proposed for the achievement of balanced quadrature or 3-phase interferometric detection. A laboratory demonstration confirms >>100:1 rejection of photometric crosstalk in a fringe tracking configuration where atmospheric OPD fluctuations were simulated using a hair dryer. Tracking with a 30:1 intensity ratio between the incoming beams was performed while rejecting large introduced photometric fluctuations.

  1. Optical polarization based logic functions (XOR or XNOR) with nonlinear Gallium nitride nanoslab.

    PubMed

    Bovino, F A; Larciprete, M C; Giardina, M; Belardini, A; Centini, M; Sibilia, C; Bertolotti, M; Passaseo, A; Tasco, V

    2009-10-26

    We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. The polarization of the noncollinear generated beam is a function of the polarization of both pump beams, thus we experimentally investigated all possible polarization combinations, evidencing that only some of them are allowed and that the nonlinear interaction of optical signals behaves as a polarization based XOR. The experimental results show the peculiarity of the nonlinear optical response associated with noncollinear excitation, and are explained using the expression for the effective second order optical nonlinearity in noncollinear scheme.

  2. Atmospheric solar absorption measurements in the 9 to 11 mu m region using a diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Hoell, J. M., Jr.

    1980-01-01

    A tunable diode laser heterodyne radiometer was developed for ground-based measurements of atmospheric solar absorption spectra in the 8 to 12 microns spectral range. The performance and operating characteristics of this Tunable Infrared Heterodyne Radiometer (TIHR) are discussed along with atmospheric solar absorption spectra of HNO3, O3, CO2, and H2O in the 9 to 11 microns spectral region.

  3. Detrimental Effect Elimination of Laser Frequency Instability in Brillouin Optical Time Domain Reflectometer by Using Self-Heterodyne Detection

    PubMed Central

    Li, Yongqian; Li, Xiaojuan; An, Qi; Zhang, Lixin

    2017-01-01

    A useful method for eliminating the detrimental effect of laser frequency instability on Brillouin signals by employing the self-heterodyne detection of Rayleigh and Brillouin scattering is presented. From the analysis of Brillouin scattering spectra from fibers with different lengths measured by heterodyne detection, the maximum usable pulse width immune to laser frequency instability is obtained to be about 4 µs in a self-heterodyne detection Brillouin optical time domain reflectometer (BOTDR) system using a broad-band laser with low frequency stability. Applying the self-heterodyne detection of Rayleigh and Brillouin scattering in BOTDR system, we successfully demonstrate that the detrimental effect of laser frequency instability on Brillouin signals can be eliminated effectively. Employing the broad-band laser modulated by a 130-ns wide pulse driven electro-optic modulator, the observed maximum errors in temperatures measured by the local heterodyne and self-heterodyne detection BOTDR systems are 7.9 °C and 1.2 °C, respectively. PMID:28335508

  4. Detrimental Effect Elimination of Laser Frequency Instability in Brillouin Optical Time Domain Reflectometer by Using Self-Heterodyne Detection.

    PubMed

    Li, Yongqian; Li, Xiaojuan; An, Qi; Zhang, Lixin

    2017-03-20

    A useful method for eliminating the detrimental effect of laser frequency instability on Brillouin signals by employing the self-heterodyne detection of Rayleigh and Brillouin scattering is presented. From the analysis of Brillouin scattering spectra from fibers with different lengths measured by heterodyne detection, the maximum usable pulse width immune to laser frequency instability is obtained to be about 4 µs in a self-heterodyne detection Brillouin optical time domain reflectometer (BOTDR) system using a broad-band laser with low frequency stability. Applying the self-heterodyne detection of Rayleigh and Brillouin scattering in BOTDR system, we successfully demonstrate that the detrimental effect of laser frequency instability on Brillouin signals can be eliminated effectively. Employing the broad-band laser modulated by a 130-ns wide pulse driven electro-optic modulator, the observed maximum errors in temperatures measured by the local heterodyne and self-heterodyne detection BOTDR systems are 7.9 °C and 1.2 °C, respectively.

  5. Source self-mixing in the detection of extended incoherent sources. [in optical heterodyne radiometry

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1975-01-01

    We consider the self-beating of incoherent light from an extended source at a wideband photomixer. The intermediate frequency mean squared current is found to be proportional to the product of the direct detected source power and the power within the IF bandpass about the optical frequency and within the heterodyne field of view. Thus the ratio of the heterodyne signal to self-beating power is proportional to the ratio of local oscillator power to direct detected power. This ratio is usually large for systems employing efficient local oscillators that generate shot-noise-limited operation. In less efficient systems, such as those employing tunable diode lasers, the effects of self-mixing may be significant.

  6. High-resolution multi-heterodyne spectroscopy based on Fabry-Perot quantum cascade lasers

    SciTech Connect

    Wang, Yin; Wang, Wen; Wysocki, Gerard; Soskind, Michael G.

    2014-01-20

    In this Letter, we present a method of performing broadband mid-infrared spectroscopy with conventional, free-running, continuous wave Fabry-Perot quantum cascade lasers (FP-QCLs). The measurement method is based on multi-heterodyne down-conversion of optical signals. The sample transmission spectrum probed by one multi-mode FP-QCL is down-converted to the radio-frequency domain through an optical multi-heterodyne process using a second FP-QCL as the local oscillator. Both a broadband multi-mode spectral measurement as well as high-resolution (∼15 MHz) spectroscopy of molecular absorption are demonstrated and show great potential for development of high performance FP-laser-based spectrometers for chemical sensing.

  7. Voltage tunable differential heterodyne spectroscopy in the far-infrared with Josephson junctions

    NASA Technical Reports Server (NTRS)

    Ulrich, B. T.

    1978-01-01

    The basic methods of differential heterodyne spectroscopy with Josephson junctions are described. A technique is outlined for bridging the gap between a local oscillator frequency and a signal frequency through the use of a voltage-tunable internal oscillation frequency in a Josephson junction structure. It is shown that an intermediate frequency can be converted to a conveniently low frequency by double frequency conversion carried out directly in a Josephson junction. The expected conversion efficiency is estimated qualitatively. Experiments are discussed in which the differential heterodyne frequency-conversion technique was demonstrated at a wavelength of 0.4 mm and a voltage-tunable oscillation in a double Josephson junction structure was observed, with oscillation line widths as narrow as 0.5 Hz, for a resistance of 3.3 nanohms and an estimated inductance of the order of 1 nH.

  8. Heterodyne interferometry method for calibration of a Soleil-Babinet compensator.

    PubMed

    Zhang, Wenjing; Zhang, Zhiwei

    2016-05-20

    A method based on the common-path heterodyne interferometer system is proposed for the calibration of a Soleil-Babinet compensator. In this heterodyne interferometer system, which consists of two acousto-optic modulators, the compensator being calibrated is inserted into the signal path. By using the reference beam as the benchmark and a lock-in amplifier (SR844) as the phase retardation collector, retardations of 0 and λ (one wavelength) can be located accurately, and an arbitrary retardation between 0 and λ can also be measured accurately and continuously. By fitting a straight line to the experimental data, we obtained a linear correlation coefficient (R) of 0.995, which indicates that this system is capable of linear phase detection. The experimental results demonstrate determination accuracies of 0.212° and 0.26° and measurement precisions of 0.054° and 0.608° for retardations of 0 and λ, respectively.

  9. A 10 micron laser heterodyne spectrometer for remote detection of trace gases

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.; Kostiuk, T.; Buhl, D.

    1978-01-01

    Infrared heterodyne spectroscopy provides a means of measuring the intensity profiles of individual rotation-vibration spectral lines with high sensitivity. Considerable effort has been expended on optimizing these instruments for remote measurements of gases in planetary atmospheres with the result that present-generation spectrometers are beginning to provide new and startling results on the planets. The fundamental principles of laser heterodyne spectroscopy are discussed. Detailed considerations of the optical design and the electronic design of the spectral-line receiver are given. Representative results obtained with this spectrometer are discussed, including precision frequency measurements of NH3 (nu-2) lines, detection of auroral emission from Jupiter, and measurements of terrestrial O3 and CO2.

  10. A Miniaturized Laser Heterodyne Radiometer for Greenhouse Gas Measurements in the Atmospheric Column

    NASA Technical Reports Server (NTRS)

    Steel, Emily Wilson

    2015-01-01

    Laser Heterodyne Radiometry is a technique adapted from radio receiver technology has been used to measure trace gases in the atmosphere since the 1960s.By leveraging advances in the telecommunications industry, it has been possible to miniaturize this technology.The mini-LHR (Miniaturized Laser Heterodyne Radiometer) has been under development at NASA Goddard Space flight Center since 2009. This sun-viewing instrument measures carbon dioxide and methane in the atmospheric column and operates in tandem with an AERONET sun photometer producing a simultaneous measure of aerosols. The mini-LHR has been extensively field tested in a range of locations ranging in the continental US as well as Alaska and Hawaii and now operates autonomously with sensitivities of approximately 0.2 ppmv and approximately10 ppbv, for carbon dioxide and methane respectively, for 10 averaged scans under clear sky conditions.

  11. Application of tunable diode lasers as local oscillators in an Infrared Heterodyne Radiometer (IHR)

    NASA Technical Reports Server (NTRS)

    Savage, M. G.; Augeri, R. C.; Peyton, B. J.

    1979-01-01

    The utility of diode lasers as local oscillators (LOs) in a heterodyne receiver application was investigated. The CW power, spectral tunability, spectral stability, and spatial intensity distribution of the TDL outputs were measured. A tunable diode laser LO was incorporated into a laboratory Dicke-switched infrared heterodyne setup and used to measure radiometer sensitivity as well as spectroscopic characteristics of selected absorption lines of ammonia. The test results on one of the two tunable diode lasers are emphasized in an attempt to provide a comprehensive data package which may be useful for future planning purposes. The second tunable diode laser exhibits characteristics similar to the fully tested TDL with the exception that some changes in its performance characteristics as it was temperature cycled between room temperature and the operating temperature of approximately 50K occurred.

  12. Inversion technique for IR heterodyne sounding of stratospheric constituents from space platforms

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Shapiro, G. L.; Alvarez, J. M.

    1981-01-01

    The techniques which have been employed for inversion of IR heterodyne measurements for remote sounding of stratospheric trace constituents usually rely on either geometric effects based on limb-scan observations (i.e., onion peel techniques) or spectral effects by using weighting functions corresponding to different frequencies of an IR spectral line. An experimental approach and inversion technique are discussed which optimize the retrieval of concentration profiles by combining the geometric and the spectral effects in an IR heterodyne receiver. The results of inversions of some synthetic CIO spectral lines corresponding to solar occultation limb scans of the stratosphere are presented, indicating considerable improvement in the accuracy of the retrieved profiles. The effects of noise on the accuracy of retrievals are discussed for realistic situations.

  13. Some n-p (Hg,Cd)Te photodiodes for 8-14 micrometer heterodyne applications

    NASA Technical Reports Server (NTRS)

    Shanley, J. F.; Flanagan, C. T.

    1980-01-01

    The results describing the dc and CO2 laser heterodyne characteristics of a three element photodiode array and single element and four element photodiode arrays are presented. The measured data shows that the n(+)-p configuration is capable of achieving bandwidths of 475 to 725 MHz and noise equivalent powers of 3.2 x 10 to the minus 20th power W/Hz at 77 K and 1.0 x 10 to the minus 19th power W/Hz at 145 K. The n(+)-n(-)-p photodiodes exhibited wide bandwidths (approximately 2.0 GHz) and fairly good effective heterodyne quantum efficiencies (approximately 13-30 percent at 2.0 GHz). Noise equivalent powers ranging from 1.44 x 10 to the minus 19th power W/Hz to 6.23 x 10 to the minus 20th power W/Hz were measured at 2.0 GHz.

  14. Bulk and integrated acousto-optic spectrometers for molecular astronomy with heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    A survey of acousto-optic spectrometers for molecular astronomy is presented, noting a technique of combining the acoustic bending of a collimated coherent light beam with a Bragg cell followed by an array of sensitive photodetectors. This acousto-optic spectrometer has a large bandwidth, a large number of channels, high resolution, and is energy efficient. Receiver development has concentrated on high-frequency heterodyne systems for the study of the chemical composition of the interstellar medium. RF spectrometers employing acousto-optic diffraction cells are described. Acousto-optic techniques have been suggested for applications to electronic warfare, electronic countermeasures and electronic support systems. Plans to use integrated optics for the further miniaturization of acousto-optic spectrometers are described. Bulk acousto-optic spectrometers with 300 MHz and 1 GHz bandwidths are being developed for use in the back-end of high-frequency heterodyne receivers for astronomical research.

  15. A 4.7THz heterodyne receiver for a balloon borne telescope

    NASA Astrophysics Data System (ADS)

    Hayton, D. J.; Kloosterman, J. L.; Ren, Y.; Kao, T. Y.; Gao, J. R.; Klapwijk, T. M.; Hu, Q.; Walker, C. K.; Reno, J. L.

    2014-07-01

    We report on the performance of a high sensitivity 4.7 THz heterodyne receiver based on a NbN hot electron bolometer mixer and a quantum cascade laser (QCL) as local oscillator. The receiver is developed to observe the astronomically important neutral atomic oxygen [OI] line at 4.7448 THz on a balloon based telescope. The single-line frequency control and improved beam pattern of QCL have taken advantage of a third-order distributed feedback structure. We measured a double sideband receiver noise temperature (Trec(DSB)) of 815 K, which is ~ 7 times the quantum noise limit (hν/2kB). An Allan time of 15 s at an effective noise fluctuation bandwidth of 18 MHz is demonstrated. Heterodyne performance was further supported by a measured methanol line spectrum around 4.7 THz.

  16. Heterodyne receiver at 2.5 THz with quantum cascade laser and hot electron bolometric mixer

    NASA Astrophysics Data System (ADS)

    Hübers, H.-W.; Pavlov, S. G.; Richter, H.; Semenov, A. D.; Mahler, L.; Tredicucci, A.; Beere, H. E.; Ritchie, D. A.

    2006-06-01

    Quantum cascade lasers (QCLs) operating at 2.5 THz have been used for gas phase spectroscopy and as local oscillator in a heterodyne receiver. One QCL has a Fabry-Perot resonator while the other has a distributed feedback resonator. The linewidth and frequency tunability of both QCLs have been investigated by either mixing two modes of the QCL or by mixing the emission from the QCL with the emission from a 2.5 THz gas laser. The frequency tunability as well as the linewidth is sufficient for Doppler limited spectroscopy of methanol gas. The QCLs have been used successfully as local oscillators in a heterodyne receiver. Noise temperature measurements with a hot electron bolometer and a QCL yielded the same result as with a gas laser as local oscillator.

  17. Imaging and target detection with a heterodyne-reception optical radar.

    PubMed

    Shapiro, J H; Capron, B A; Harney, R C

    1981-10-01

    A mathematical system model for a compact heterodyne-reception infrared radar is developed. This model incorporates the statistical effects of propagation through atmospheric turbulence, target speckle and glint, and heterodyne-reception shot noise. It is used to find the image signal-to-noise ratio of a matched-filter envelope-detector receiver and the target detection probability of the optimum likelihood ratio processor. For realistic parameter values it is shown that turbulence-induced beam spreading and coherence loss may be neglected. Target speckle and atmospheric scintillation, however, present serious limitations on single-frame imaging and target-detection performance. Experimental turbulence strength measurements are reviewed, and selected results are used in sample performance calculations for a realistic infrared radar.

  18. Waveform measurement technique for phase/frequency-modulated lights based on self-heterodyne interferometry.

    PubMed

    Tsuchida, Hidemi

    2017-03-06

    A novel technique is proposed and demonstrated for measuring the temporal waveforms of phase/frequency-modulated lights based on self-heterodyne interferometry with a delay time much shorter than the modulation period and on the unwrapped phase detection of heterodyne beat signals with real-time vector signal analysis. The technique makes use of an approximated relationship between the beat signal phase and the instantaneous frequency of modulated lights. The results of waveform measurements are presented for directly frequency-modulated and externally phase-modulated lights, which have been commonly employed for FWCW-LIDAR and serrodyne frequency translation, respectively. The temporal waveforms of triangular modulation are successfully measured with a frequency deviation as large as 15 GHz and the detailed investigation is presented on the deviation of measured waveform from ideal ones.

  19. Improved optical pulse heterodyne demodulation scheme for fiber-optic interferometric sensors

    NASA Astrophysics Data System (ADS)

    Lai, Haiqiang; Wang, Jianfei; Tu, Xiaobo; Meng, Zhou

    2015-10-01

    An improved optical pulse heterodyne demodulation scheme for fiber-optic interferometric sensors is demonstrated. This scheme uses two series-connected Acoustic-optic modulators (AOMs) as intensity modulator and frequency shifter respectively. Compared to the traditional optical heterodyne demodulation structure, this scheme eliminates the polarization-induced signal fading and the noise floor is lowered for using the Michelson-configuration delay structure and Faraday rotation mirrors (FRMs) in the optic architecture of system. At the same time, the architecture of this scheme is not complicated and can be used to complex a large sensor array. Experimental results show that the phase noise floor of this demodulation scheme is flat and reaches -99dB/sqrt(Hz) at frequencies above 300 Hz.

  20. Current ways and means for reduction or elimination of periodic nonlinearity in heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Chen, Peng; Hu, Peng-cheng; Ding, Xue-mei; Tan, Jiu-bin

    2015-02-01

    This paper reviews ways and means used for reduction or elimination of periodic nonlinearity in heterodyne interferometers. The periodic nonlinearity resulting from polarization mixing or frequency mixing in heterodyne interferometers was modeled into one expression, which included the initial polarization state of the laser source, the rotational alignment of the beam splitter along with different transmission coefficients for polarization states and the rotational misalignment of a receiving polarizer. Three compensation techniques, measuring two orthogonal output signals, Lissajous Compensation and Chu-Ray Algorithm, are described and discussed for reduction of periodic nonlinearity. These algorithms needed at least one fringe of motion or a constant velocity sweep to properly correct the motion. And five types of two spatially separated beam interferometer configurations are described and discussed for elimination of periodic nonlinearity to a picometer level. It is concluded that the main disadvantage of these configurations was their complex architecture with unbalanced long beam paths.

  1. Three-dimensional shape measurement of small object based on tri-frequency heterodyne method

    NASA Astrophysics Data System (ADS)

    Liu, Shouqi; Feng, Wei; Zhang, Qican; Liu, Yuankun

    2015-08-01

    Among temporal phase unwrapping methods based on structured light projection, tri-frequency heterodyne method, with the merits of less projected fringe, high precision and high reliability, has become a practical method in objects three-dimensional (3D) shape measurement. In this paper, a 3D shape measuring system was developed with a digital micromirror device (DMD) and synchronously trigged CCD camera. The 3D shape of a measured object was reconstructed from the deformed fringe patterns based on tri-frequency heterodyne method. The practical experiments were carried on some coins, and the results show that the system can restore their 3D shape on the tested partition with an accuracy of microns. This measurement system is prominent in 3D shape measurement of small or tiny objects, sample testing, and many other application fields.

  2. Frequency locking of a field-widened Michelson interferometer based on optimal multi-harmonics heterodyning.

    PubMed

    Cheng, Zhongtao; Liu, Dong; Zhou, Yudi; Yang, Yongying; Luo, Jing; Zhang, Yupeng; Shen, Yibing; Liu, Chong; Bai, Jian; Wang, Kaiwei; Su, Lin; Yang, Liming

    2016-09-01

    A general resonant frequency locking scheme for a field-widened Michelson interferometer (FWMI), which is intended as a spectral discriminator in a high-spectral-resolution lidar, is proposed based on optimal multi-harmonics heterodyning. By transferring the energy of a reference laser to multi-harmonics of different orders generated by optimal electro-optic phase modulation, the heterodyne signal of these multi-harmonics through the FWMI can reveal the resonant frequency drift of the interferometer very sensitively within a large frequency range. This approach can overcome the locking difficulty induced by the low finesse of the FWMI, thus contributing to excellent locking accuracy and lock acquisition range without any constraint on the interferometer itself. The theoretical and experimental results are presented to verify the performance of this scheme.

  3. Bulk and integrated acousto-optic spectrometers for molecular astronomy with heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Chin, G.; Buhl, D.; Florez, J. M.

    1981-01-01

    A survey of acousto-optic spectrometers for molecular astronomy is presented, noting a technique of combining the acoustic bending of a collimated coherent light beam with a Bragg cell followed by an array of sensitive photodetectors. This acousto-optic spectrometer has a large bandwidth, a large number of channels, high resolution, and is energy efficient. Receiver development has concentrated on high-frequency heterodyne systems for the study of the chemical composition of the interstellar medium. RF spectrometers employing acousto-optic diffraction cells are described. Acousto-optic techniques have been suggested for applications to electronic warfare, electronic countermeasures and electronic support systems. Plans to use integrated optics for the further miniaturization of acousto-optic spectrometers are described. Bulk acousto-optic spectrometers with 300 MHz and 1 GHz bandwidths are being developed for use in the back-end of high-frequency heterodyne receivers for astronomical research.

  4. Two-wavelength laser-diode heterodyne interferometry with one phasemeter

    NASA Astrophysics Data System (ADS)

    Onodera, Ribun; Ishii, Yukihiro

    1995-12-01

    A two-wavelength laser-diode interferometer that is based on heterodyne detection with one phasemeter has been constructed. Two laser diodes are frequency modulated by mutually inverted sawtooth currents on an unbalanced interferometer. One can measure the tested phase at a synthetic wavelength from the sum of the interference beat signals by synchronizing them with the modulation frequency. The experimental result presented shows a phase-measurement range with a 4.7- mu m synthetic wavelength.

  5. Air pollution - Remote detection of several pollutant gases with a laser heterodyne radiometer

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.; Shumate, M. S.

    1974-01-01

    An infrared heterodyne radiometer with a spectral resolution of 0.04 reciprocal centimeters has been used to remotely detect samples of ozone, sulfur dioxide, ammonia, and ethylene at room temperature, and samples of nitric oxide at 390 K. Each gas was observed in a background of nitrogen or oxygen at atmospheric pressure. Sensitivities to some of these gases are adequate for detection of ambient concentrations as low as a few parts per billion.

  6. Security of Y-00 under heterodyne measurement and fast correlation attack

    NASA Astrophysics Data System (ADS)

    Donnet, Stéphane; Thangaraj, Andrew; Bloch, Matthieu; Cussey, Johann; Merolla, Jean-Marc; Larger, Laurent

    2006-08-01

    We provide a security analysis of the Y-00 protocol under heterodyne measurement and correlation attack. We show that the secrecy of the data encryption scheme is extremely sensitive to the running-key generation process. In many situations our simple attack succeeds in recovering the initial shared secret key. Our simulation results suggest that a truly secure implementation of the protocol should take into account the effective key generation method.

  7. Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Betz, A. L.; Johnson, M. A.; Mclaren, R. A.; Sutton, E. C.

    1975-01-01

    Strong 10 micrometer line emission from (C-12)(O-16)2 in the upper atmosphere of Venus was detected by heterodyne techniques. Observations of the absolute Doppler shift of the emission features indicate mean zonal wind velocities less than 10 m/sec in the upper atmosphere near the equator. No evidence was found of the 100 m/sec wind velocity implied by the apparent 4-day rotation period of ultraviolet cloud features.

  8. Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Betz, A. L.; Johnson, M. A.; Mclaren, R. A.; Sutton, E. C.

    1976-01-01

    Strong 10-micron line emission from (C-12)(O-16)2 in the upper atmosphere of Venus has been detected by heterodyne techniques. Observations of the absolute Doppler shift of the emission features indicated mean zonal wind velocities less than 10 m/s in the upper atmosphere near the equator. No evidence was found for the 100-m/s wind velocity implied by the apparent four-day rotation period of ultraviolet cloud features.

  9. Heterodyne detection of CO2 emission lines and wind velocities in the atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Betz, A. L.; Johnson, M. A.; Mclaren, R. A.; Sutton, E. C.

    1975-01-01

    Strong 10 micrometer line emission from (c-12)(o-16)2 in the upper atmosphere of Venus was detected by heterodyne techniques. Observations of the absolute Doppler shift of the emission features indicate mean zonal wind velocities less than 10 m/sec in the upper atmosphere near the equator. No evidence was found of the 100 m/sec wind velocity implied by the apparent 4-day rotation period of ultraviolet cloud features.

  10. Development of a slab waveguide spatial heterodyne spectrometer for remote sensing

    NASA Astrophysics Data System (ADS)

    Florjańczyk, Miroslaw; Cheben, Pavel; Janz, Siegfried; Lamontagne, Boris; Lapointe, Jean; Scott, Alan; Solheim, Brian; Xu, Dan-Xia

    2010-02-01

    We present development of a compact, robust, waveguide Fourier-transform microspectrometer for high-resolution and high-throughput spectroscopy in space-based applications. The prototype device is being developed to monitor water vapor in the atmosphere from a micro-satellite platform. The instrument is based on a unique slab waveguide spatial heterodyne spectrometer (SHS) chip fabricated at the National Research Council Canada in silicon-on-insulator (SOI) technology.

  11. Study of LPG-assisted fibre modal Michelson interferometers with coherence addressing and heterodyne interrogation

    NASA Astrophysics Data System (ADS)

    Caldas, P.; Araújo, F.; Ferreira, L. A.; Rego, G.; Marques, M. B.; Santos, J. L.

    2007-07-01

    In this work, the LPG-assisted fibre Michelson modal interferometer is studied as a sensing structure for environmental refractive index, temperature and liquid level when coherence addressing and heterodyne interrogation are considered. The effects on measurand sensitivity of the order of the cladding mode excited by the LPG, of the degree of etching of the sensing fibre and of the fibre type used are investigated.

  12. Method of vibration analysis using holographic interferometry and heterodyne optical detection

    NASA Technical Reports Server (NTRS)

    Vlad, V. I.; Maurer, J.; Popa, D.

    1974-01-01

    A method of studying thin plate vibrations with the aid of a laser beam is discussed. Through a suitable combination of time-average holographic interferometry, real-time holographic interferometry, and heterodyne optical detection, it is possible to obtain complete information on the vibration parameters of modes, amplitudes, frequencies, and phases. The method has the advantage of three dimensional global observation, noncontact, and high precision measurements.

  13. Absolute intensity calibration of the 32-channel heterodyne radiometer on experimental advanced superconducting tokamak

    SciTech Connect

    Liu, X.; Zhao, H. L.; Liu, Y. Li, E. Z.; Han, X.; Ti, A.; Hu, L. Q.; Zhang, X. D.; Domier, C. W.; Luhmann, N. C.

    2014-09-15

    This paper presents the results of the in situ absolute intensity calibration for the 32-channel heterodyne radiometer on the experimental advanced superconducting tokamak. The hot/cold load method is adopted, and the coherent averaging technique is employed to improve the signal to noise ratio. Measured spectra and electron temperature profiles are compared with those from an independent calibrated Michelson interferometer, and there is a relatively good agreement between the results from the two different systems.

  14. Rapid-tuning device for CO/sub 2/ heterodyne detection lidar

    SciTech Connect

    Fox, J. A.; Gautier, C. R.; Ahl, J. L.

    1989-07-01

    A device for rapid-tuning cw, /ital Q/-switched lasers for a CO/sub 2/ heterodyne detection lidar is presented. It is shown that it is possible to utilize galvanometer-driven mirrors to rapidly switch wavelengths over randomly selected lasing transitions in the 9--11 /mu/m portion of the spectrum. Both a transmitter and a local oscillator are simultaneously switched between transitions while still achieving the frequency stability typically required for a coherent lidar system.

  15. Range accuracy of photon heterodyne detection with laser pulse based on Geiger-mode APD.

    PubMed

    Luo, Hanjun; Yuan, XiuHua; Zeng, Yanan

    2013-08-12

    In this paper, we propose a combined system of heterodyne detection with laser pulse and photon counting based on Geiger-mode avalanche photodiode (GM-APD) that is designed to achieve the range of remote non-cooperative target. Based on the heterodyne principle and assuming that the creation of primary electrons in GM-APD is Poisson-distributed, the range accuracy model is established. The factors that influence the range accuracy, namely pulse width, echo intensity, local oscillator (LO) intensity, noise, echo position, and beat frequency, are discussed. The results show that these six factors have significant influence on the range accuracy when the echo intensity is extremely weak. In case that the primary electrons of the echo signal are beyond 4, the pulse width and echo intensity are the main influence factors. It is also shown that the stronger echo intensity, narrower pulse width, low noise, large echo position, and small beat frequency produce higher range accuracy in a pulsed photon heterodyne detection system based on GM-APD.

  16. Ground-based prototype quantum cascade laser heterodyne radiometer for atmospheric studies

    NASA Astrophysics Data System (ADS)

    Weidmann, D.; Reburn, W. J.; Smith, K. M.

    2007-07-01

    The advent of quantum cascade lasers has provided matured continuously tunable solid state laser sources emitting from mid-infrared to terahertz wavelengths. Such sources, used as local oscillators, offer the practical prospect of aircraft, high altitude platform, and satellite deployment of compact and shot noise limited heterodyne radiometers for Earth observation and astronomy. A ground-based prototype of a quantum cascade laser heterodyne radiometer operating in the mid-infrared has been developed and is presented. The instrument design and concepts are described, together with evaluation of the instrument in the laboratory and during field measurements of atmospheric ozone. In this study the best performance achieved by the prototype quantum cascade laser heterodyne radiometer was a signal-to-noise ratio of three times the theoretical shot-noise limit. The prototype has allowed the main sources of excess noise to be identified as residual optical feedback in the local oscillator optical path and a lack of mechanical and thermal stability in the local oscillator collimation system. Instrument improvements are currently being implemented and enhanced performance is expected in the near future.

  17. Improved synthetic-heterodyne Michelson interferometer vibrometer using phase and gain control feedback.

    PubMed

    Galeti, José Henrique; Kitano, Cláudio; Connelly, Michael J

    2015-12-10

    Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity measurement using interferometric sensors as it can provide an output signal which is immune to interferometric drift. With the advent of cost effective, high-speed real-time signal processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In conventional synthetic-heterodyne demodulation schemes, to obtain the dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a new synthetic-heterodyne demodulation method is described leading to an expression for the dynamic displacement and velocity of the object under test that is significantly less sensitive to the received optical power. In addition, the application of two independent phase and gain feedback loops is used to compensate for the nonideal gain and phase response of the anti-aliasing filter required for the signal acquisition of the received wideband interferometer signal. The efficacy of the improved system is demonstrated by measuring the displacement sensitivity frequency response and linearity of a Piezoelectric Mirror-Shifter (PMS) over a range of 200 Hz-9 kHz. In addition, the system is used to measure the response of the PMS to triangular and impulse type stimuli. The experimental results show excellent agreement with measurements taken using two independent industry standard calibration methods.

  18. Cryogen-free heterodyne-enhanced mid-infrared Faraday rotation spectrometer

    PubMed Central

    Wang, Yin; Nikodem, Michal; Wysocki, Gerard

    2013-01-01

    A new detection method for Faraday rotation spectra of paramagnetic molecular species is presented. Near shot-noise limited performance in the mid-infrared is demonstrated using a heterodyne enhanced Faraday rotation spectroscopy (H-FRS) system without any cryogenic cooling. Theoretical analysis is performed to estimate the ultimate sensitivity to polarization rotation for both heterodyne and conventional FRS. Sensing of nitric oxide (NO) has been performed with an H-FRS system based on thermoelectrically cooled 5.24 μm quantum cascade laser (QCL) and a mercury-cadmium-telluride photodetector. The QCL relative intensity noise that dominates at low frequencies is largely avoided by performing the heterodyne detection in radio frequency range. H-FRS exhibits a total noise level of only 3.7 times the fundamental shot noise. The achieved sensitivity to polarization rotation of 1.8 × 10−8 rad/Hz1/2 is only 5.6 times higher than the ultimate theoretical sensitivity limit estimated for this system. The path- and bandwidth-normalized NO detection limit of 3.1 ppbv-m/Hz1/2 was achieved using the R(17/2) transition of NO at 1906.73 cm−1. PMID:23388967

  19. Deferred electronic heterodyne moire deflectometry: A method for transient density fields measurement

    NASA Technical Reports Server (NTRS)

    Stricker, Josef

    1989-01-01

    Effects of spherical aberrations of the mirror used in the moire system on the angular resolution of the system are investigated. It is shown that the spherical aberrations may reduce significantly the performance of the conventional moire deflectometer. However, due to the heterodyne procedure, this is not the case with the heterodyne moire system. A moire system with a constant speed moving grating is demonstrated. It is shown that the system readout is linear and the system does not need calibration. In addition, the repeatability of the measurements is improved in this system as compared to the sinusoidally moving grating setup. The problem of the photographic plates alignment is solved by using a mechanical system in which the plate is held firmly throughout the experiment and accurately replaced after removing for photographic processing. The effect of a circular detector's aperture size on readout was tested. It is shown that the spatial phase variations, observed when scanning along a straight moire fringe, may considerably be reduced. At present we may say that both the on-line and the deferred heterodyne moire techniques may reliably be used. The errors of phase readings are 1 deg and 5 deg for the on-line and deferred methods. The total error due to subtraction of two readings at each position is, therefore, 1.4 deg and 7 deg, respectively. Further research for improving the deferred system is suggested.

  20. Common mode noise rejection properties of amplitude and phase noise in a heterodyne interferometer.

    PubMed

    Hechenblaikner, Gerald

    2013-05-01

    High precision metrology systems based on heterodyne interferometry can measure the position and attitude of objects to accuracies of picometer and nanorad, respectively. A frequently found feature of the general system design is the subtraction of a reference phase from the phase of the position interferometer, which suppresses low frequency common mode amplitude and phase fluctuations occurring in volatile optical path sections shared by both the position and reference interferometer. Spectral components of the noise at frequencies around or higher than the heterodyne frequency, however, are generally transmitted into the measurement band and may limit the measurement accuracy. Detailed analytical calculations complemented with Monte Carlo simulations show that high frequency noise components may also be entirely suppressed, depending on the relative difference of measurement and reference phase, which may be exploited by corresponding design provisions. While these results are applicable to any heterodyne interferometer with certain design characteristics, specific calculations and related discussions are given for the example of the optical metrology system of the LISA Pathfinder mission to space.

  1. Method for measuring the refractive index distribution of a GRIN lens with heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Hsieh, H. C.; Chen, Y. L.; Wu, W. T.; Su, D. C.

    2009-06-01

    Based on the Fresnel's equations and the heterodyne interferometry, an alternative method for measuring the refractive index distribution of a GRIN lens is presented. A light coming from the heterodyne light source passes through a quarterwave plate and is incident on the tested GRIN lens. The reflected light passes through an analyzer and an imaging lens; finally it enters a CMOS camera. The interference signals produced by the components of the s- and the p-polarizations are recorded and they are sent to a personal computer to be analyzed. In order to measure the absolute phases of the interference signals accurately, a special condition is chosen. Then, the interference signals become a group of periodic sinusoidal segments, and each segment has an initial phase ψ with the information of the refractive index. Consequently, the estimated data of ψ are substituted into the special equations derived from Fresnel's equations, and the refractive index distribution of the GRIN lens can be obtained. Because of its common-path optical configuration, this method has both merits of the common-path interferometry and the heterodyne interferometry. In addition, the phase can be measured without reference signals.

  2. Development and performance of a laser heterodyne spectrometer using tunable semiconductor lasers as local oscillators

    NASA Technical Reports Server (NTRS)

    Glenar, D.; Kostiuk, T.; Jennings, D. E.; Mumma, M. J.

    1980-01-01

    A diode laser based IR heterodyne spectrometer for laboratory and field use was developed for high efficiency operation between 7.5 and 8.5 microns. The local oscillator is a PbSSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed cycle cooler. The laser output frequency is controlled and stabilized using a high precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. Single laser modes are selected by a grating placed in the local oscillator beam. The system employs reflecting optics throughout to minimize losses from internal reflection and absorption, and to eliminate chromatic effects. Spectral analysis of the diode laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the infrared spectral regions over which useful heterodyne operation can be achieved. System performance has been studied by making heterodyne measurements of etalon fringes and several Freon 13 (CF3Cl) absorption lines against a laboratory blackbody source. Preliminary field tests have also been performed using the Sun as a source.

  3. Broadband mid-infrared and THz chemical detection with quantum cascade laser multi-heterodyne spectrometers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Westberg, Jonas; Sterczewski, Lukasz A.; Patrick, Link; Wysocki, Gerard

    2017-05-01

    Majority of chemical species of interest in security and safety applications (e.g. explosives) have complex molecular structures that produce unresolved rotational-vibrational spectroscopic signatures in the mid-infrared. This requires spectroscopic techniques that can provide broadband coverage in the mid-IR region to target broadband absorbers and high resolution to address small molecules that exhibit well-resolved spectral lines. On the other hand, many broadband mid-IR absorbers exhibit well-resolved rotational components in the THz spectral region. Thus, development of spectroscopic sensing technologies that can address both spectral regions is of great importance. Here we demonstrate recent progress towards broadband high-resolution spectroscopic sensing applications with Fabry-Perot quantum cascade lasers (QCLs) and frequency combs using multi-heterodyne spectroscopy (MHS) techniques. In this paper, we will present spectroscopic sensing of large and small molecules in the mid-IR region using QCLs operating at 8.5µm. An example high-resolution, broadband MHS of ammonia (small molecule) and isobutane (broadband absorber) at atmospheric pressure in the 1165-1190 cm^-1 range will be discussed. We have developed a balanced MHS system for mitigation of the laser intensity fluctuations. Absorption spectroscopy as well as dispersion spectroscopy with minimum fractional absorption down to 10^-4/Hz1/2 and fast spectral acquisition capabilities down to 10 µs/spectrum range will be demonstrated. In order to mitigate the shortcomings of the limited chemical selectivity in the mid-IR, THz QCL based spectrometer is currently under development to provide spectral de-congestion and thus significantly improve chemical identification. Preliminary characterization of the performance of THZ QCL combs for the THz QCL-MHS will be presented.

  4. Broadband and high-efficiency circular polarizer based on planar-helix chiral metamaterials

    NASA Astrophysics Data System (ADS)

    Wang, Jiang; Shen, Zhongxiang; Wu, Wen

    2017-09-01

    We reveal a broadband and high-efficiency circular polarizer based on chiral metamaterials composed of an array of planar helices, which can effectively reject the incident left-hand circularly polarized (LCP) wave, while allowing the right-hand circularly polarized (RCP) wave to pass through it. The physical mechanism of the proposed circular polarizer is explained with the aid of the current distributions under the excitations of LCP and RCP waves. Microwave experiments are performed to verify this idea, and measured results are in good agreement with the numerical ones. Experimental results show that a fractional bandwidth of 75.6% for the transmittance of the LCP wave lower than 0.2 can be obtained. Moreover, the proposed circular polarizer exhibits a high transmittance of over 0.9 for the RCP incident wave and a high circular polarization selection efficiency of over 0.95. The proposed circular polarizer will be potentially very useful for satellite and optical communications.

  5. Polarizer based upon a plasmonic resonant thin layer on a squeezed photonic crystal fiber.

    PubMed

    Khaleque, Abdul; Hattori, Haroldo T

    2015-03-20

    In this article, a polarizer based on surface plasmon resonance in a squeezed rectangular lattice is analyzed through a full-vector finite-element method solver. The device allows one state of polarization (e.g., y-polarized mode) to propagate through the fiber while the other state (x-polarized mode) is heavily attenuated: the modal losses for the x- and y-polarized modes are 1221 dB/cm and 1.6 dB/cm, respectively, at the wavelength of 1310 nm. Given the high differential attenuation between the two orthogonal polarization modes, the device could be used as a compact polarizer with potential applications in sensing, communications, and other areas.

  6. Perfect dual-band circular polarizer based on twisted split-ring structure asymmetric chiral metamaterial.

    PubMed

    Cheng, Yongzhi; Gong, Rongzhou; Cheng, Zhengze; Nie, Yan

    2014-09-01

    A near-perfect dual-band circular polarizer based on bilayer twisted, single split-ring resonator structure asymmetric chiral metamaterial was proposed and investigated. The simple bilayer structure with a 90° twisted angle allows for equalizing the orthogonal components of the electric field at the output interface with a 90° phase difference for a y-polarized wave propagating along the backward (-z) direction. It is found that right- and left-hand circular polarization are realized in transmissions at 7.8 and 10.1 GHz, respectively. Experiments agree well with numerical simulations, which exhibit that the polarization extinction ratio is more than 30 dB at the resonant frequencies. Further, the simple design also can be operated at the terahertz range by scaling down the geometrical parameters of the unit cell.

  7. Polarization-based material classification technique using passive millimeter-wave polarimetric imagery.

    PubMed

    Hu, Fei; Cheng, Yayun; Gui, Liangqi; Wu, Liang; Zhang, Xinyi; Peng, Xiaohui; Su, Jinlong

    2016-11-01

    The polarization properties of thermal millimeter-wave emission capture inherent information of objects, e.g., material composition, shape, and surface features. In this paper, a polarization-based material-classification technique using passive millimeter-wave polarimetric imagery is presented. Linear polarization ratio (LPR) is created to be a new feature discriminator that is sensitive to material type and to remove the reflected ambient radiation effect. The LPR characteristics of several common natural and artificial materials are investigated by theoretical and experimental analysis. Based on a priori information about LPR characteristics, the optimal range of incident angle and the classification criterion are discussed. Simulation and measurement results indicate that the presented classification technique is effective for distinguishing between metals and dielectrics. This technique suggests possible applications for outdoor metal target detection in open scenes.

  8. Laser Balancing

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Mechanical Technology, Incorporated developed a fully automatic laser machining process that allows more precise balancing removes metal faster, eliminates excess metal removal and other operator induced inaccuracies, and provides significant reduction in balancing time. Manufacturing costs are reduced as a result.

  9. Laser Balancing

    NASA Astrophysics Data System (ADS)

    1981-01-01

    Mechanical Technology, Incorporated developed a fully automatic laser machining process that allows more precise balancing removes metal faster, eliminates excess metal removal and other operator induced inaccuracies, and provides significant reduction in balancing time. Manufacturing costs are reduced as a result.

  10. Apparatus and method for heterodyne-generated two-dimensional detector array using a single element detector

    DOEpatents

    Strauss, C.E.

    1997-11-18

    Apparatus and method are disclosed for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO{sub 2} laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart. 4 figs.

  11. Apparatus and method for heterodyne-generated two-dimensional detector array using a single element detector

    DOEpatents

    Strauss, Charlie E.

    1997-01-01

    Apparatus and method for heterodyne-generated, two-dimensional detector array using a single detector. Synthetic-array heterodyne detection, permits a single-element optical detector to behave as though it were divided into an array of separate heterodyne detector elements. A fifteen-element synthetic array has successfully been experimentally realized on a single-element detector, permitting all of the array elements to be read out continuously and in parallel from one electrical connection. A CO.sub.2 laser and a single-element HgCdTe photodiode are employed. A different heterodyne local oscillator frequency is incident upon the spatially resolvable regions of the detector surface. Thus, different regions are mapped to different heterodyne beat frequencies. One can determine where the photons were incident on the detector surface even though a single electrical connection to the detector is used. This also prevents the destructive interference that occurs when multiple speckles are imaged (similar to spatial diversity), In coherent LIDAR this permits a larger field of view. An acoustooptic modulator generates the local oscillator frequencies and can achieve adequate spatial separation of optical frequencies of the order of a megahertz apart.

  12. Long-term stabilization of a heterodyne metrology interferometer down to a noise level of 20 pm over an hour.

    PubMed

    Niwa, Yoshito; Arai, Koji; Ueda, Akitoshi; Sakagami, Masaaki; Gouda, Naoteru; Kobayashi, Yukiyasu; Yamada, Yoshiyuki; Yano, Taihei

    2009-11-10

    A heterodyne metrology interferometer was stabilized down to a noise level of 20 picometers (pm) as a root-mean-square (RMS) value integrated between 0.3 mHz and 1 Hz. This noise level was achieved by employing active and passive interferometer stabilization techniques. The heterodyne interferometer was built on a 50 mm square ultralow expansion glass plate in order to reduce an optical path length change caused by temperature variation. An optical configuration of the interferometer is a Mach-Zehnder interferometer with a design as symmetric as possible so that a detection signal can be insensitive to homogeneous thermal expansion of the glass plate. The heterodyne frequency is actively controlled in order to suppress residual noises caused by optical path length changes outside of the glass plate as well as phase fluctuations of the heterodyne frequency source. Our stabilization scheme is considered useful in achieving the 20 pm noise level without a stable heterodyne frequency source, as well as temperature stabilization around a whole apparatus. This interferometer can be used in precise metrology applications, such as characterization of deformation for satellite optical components against thermal exposure.

  13. Long-term stabilization of a heterodyne metrology interferometer down to a noise level of 20 pm over an hour

    SciTech Connect

    Niwa, Yoshito; Arai, Koji; Ueda, Akitoshi; Sakagami, Masaaki; Gouda, Naoteru; Kobayashi, Yukiyasu; Yamada, Yoshiyuki; Yano, Taihei

    2009-11-10

    A heterodyne metrology interferometer was stabilized down to a noise level of 20 picometers (pm) as a root-mean-square (RMS) value integrated between 0.3 mHz and 1 Hz. This noise level was achieved by employing active and passive interferometer stabilization techniques. The heterodyne interferometer was built on a 50 mm square ultralow expansion glass plate in order to reduce an optical path length change caused by temperature variation. An optical configuration of the interferometer is a Mach-Zehnder interferometer with a design as symmetric as possible so that a detection signal can be insensitive to homogeneous thermal expansion of the glass plate. The heterodyne frequency is actively controlled in order to suppress residual noises caused by optical path length changes outside of the glass plate as well as phase fluctuations of the heterodyne frequency source. Our stabilization scheme is considered useful in achieving the 20 pm noise level without a stable heterodyne frequency source, as well as temperature stabilization around a whole apparatus. This interferometer can be used in precise metrology applications, such as characterization of deformation for satellite optical components against thermal exposure.

  14. Scanning balanced-path homodyne I/Q-interferometer scheme and its applications.

    PubMed

    Eang, Seang Hor; Yoon, Seunghyun; Park, Jun Gyu; Cho, Kyuman

    2015-06-01

    The balanced-path scheme of a heterodyne interferometer proposed by Yoon et al. has been applied to the scanning homodyne I/Q-interferometer. This provides an 11-dB improvement on common vibration rejection over the heterodyne scheme and, thereby, allows high sensitivity and high stability phase and amplitude measurements for high-speed scanning interferometer applications. It is shown that our new scanning interferometer scheme is very useful for diagnosing a sample that requires complex analysis. As an example, our new scanning interferometer scheme has been applied for obtaining phase and amplitude images of the protein biochip samples prepared by using the sandwich ELISA. The amplitude images are used for diagnosing homogeneity of the sample, while the phase images are used for measuring the phase difference between samples treated with different concentrations of IL-5.

  15. Extinction-ratio-independent electrical method for measuring chirp parameters of Mach-Zehnder modulators using frequency-shifted heterodyne.

    PubMed

    Zhang, Shangjian; Wang, Heng; Zou, Xinhai; Zhang, Yali; Lu, Rongguo; Liu, Yong

    2015-06-15

    An extinction-ratio-independent electrical method is proposed for measuring chirp parameters of Mach-Zehnder electric-optic intensity modulators based on frequency-shifted optical heterodyne. The method utilizes the electrical spectrum analysis of the heterodyne products between the intensity modulated optical signal and the frequency-shifted optical carrier, and achieves the intrinsic chirp parameters measurement at microwave region with high-frequency resolution and wide-frequency range for the Mach-Zehnder modulator with a finite extinction ratio. Moreover, the proposed method avoids calibrating the responsivity fluctuation of the photodiode in spite of the involved photodetection. Chirp parameters as a function of modulation frequency are experimentally measured and compared to those with the conventional optical spectrum analysis method. Our method enables an extinction-ratio-independent and calibration-free electrical measurement of Mach-Zehnder intensity modulators by using the high-resolution frequency-shifted heterodyne technique.

  16. Balancing Acts

    MedlinePlus

    ... a new type of balance therapy using computerized, virtual reality. UPMC associate professor Susan Whitney, Ph.D., developed ... a virtual grocery store in the university's Medical Virtual Reality Center. Patients walk on a treadmill and safely ...

  17. Ground Based Observation of Isotopic Oxygen in the Martian Atmosphere Using Infrared Heterodyne Spectroscopy

    NASA Technical Reports Server (NTRS)

    Smith, R. L.; Kostiuk, T.; Livengood, T. A.; Fast, K. E.; Hewagama, T.; Delgado, J. D.; Sonnabend, G.

    2010-01-01

    Infrared heterodyne spectra of isotopic CO2 in the Martian atmosphere were obtained using the Goddard Heterodyne Instrument for Planetary Wind and Composition, HIPWAC, which was interfaced with the 3-meter telescope at the NASA Infrared Telescope Facility- Spectra were colle cted at a resolution of lambda/delta lambda=10(exp 7). Absorption fea tures of the CO2 isotopologues have been identified from which isotop ic ratios of oxygen have been determined. The isotopic ratios O-17/O -16 and O-18/O-16 in the Martian atmosphere can be related to Martian atmospheric evolution and can be compared to isotopic ratios of oxyg en in the Earth's atmosphere. Isotopic carbon and oxygen are importa nt constraints on any theory for the erosion of the Martian primordia l atmosphere and the interaction between the atmosphere and surface o r subsurface chemical reservoirs. This investigation explored the pr esent abundance of the stable isotopes of oxygen in Mars' atmospheric carbon dioxide by measuring rovibrational line absorption in isotop ic species of CO2 using groundbased infrared heterodyne spectroscopy in the vicinity of the 9.6 micron and 10.6 micron CO2 lasing bands. T he target transitions during this observation were O-18 C-12 O-16 as well as O-178 C-12 O-16 and O-16 C-113 O-16 at higher resolving power of lambda/delta lambda=10(exp 7) and with high signal-to-noise ratio (longer integration time) in order to fully characterize the absorpt ion line profiles. The fully-resolved lineshape of both the strong n ormal-isotope and the weak isotopic CO2 lines were measured simultane ously in a single spectrum.

  18. The development of a heterodyne velocimeter system for use in sub-microsecond time regimes

    NASA Astrophysics Data System (ADS)

    Bowden, M. D.; Maisey, M. P.

    2007-09-01

    Recent advances over the last five years in high-speed digitizing oscilloscopes and high-bandwidth photodiodes, driven primarily by the telecommunications industry, have enabled the development of a new type of interferometer for measuring high velocities, such as those found in detonics experiments. The heterodyne velocimeter can be visualized as a fiber-based Michelson interferometer. The beam from a single-mode fiber laser at 1550 nm is passed through a circulator, acting to separate bi-directional light. The beam is then reflected via free-space optics from the surface of interest, and then focused back into the same fiber. This reflected light is mixed with an approximately equal amount of non-reflected light, and the resulting interference is recorded using a high-bandwidth photodiode and oscilloscope. In contrast to more traditional velocimetry techniques such as VISAR, only a single data channel is required per probe. The uses of heterodyne velocimetry have, to date, been primarily in the multi-microsecond time regime, i.e. explosively driven metal plates. In this paper, we present a four-channel, ultra-high bandwidth system designed for use in the sub-microsecond time regime, and present the results obtained from laser-driven flyer plates traveling in excess of 3 km s -1. We have developed analysis software suited to use in this time regime, where a relatively small displacement is recorded. The original heterodyne velocimeter relied on back-reflectance from the probe to obtain the non-reflected light. This limits both the flexibility of the system and the efficiency of the probes. We have overcome this issue by introducing a beam splitter into the system prior to the circulator. This allows the probing system to be designed for maximum efficiency, and we are then able to tune the non-reflected light on a shot-to-shot basis.

  19. Michelson interferometer vibrometer using self-correcting synthetic-heterodyne demodulation.

    PubMed

    Connelly, Michael J; Galeti, José Henrique; Kitano, Cláudio

    2015-06-20

    Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity detection in interferometric sensors, as it can provide an output signal that is immune to interferometric drift. With the advent of cost-effective, high-speed real-time signal-processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In synthetic heterodyne, to obtain the actual dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a method is described for determining the former and setting the Bessel function argument to a set value, which ensures maximum sensitivity. Conventional synthetic-heterodyne demodulation requires the use of two in-phase local oscillators; however, the relative phase of these oscillators relative to the interferometric signal is unknown. It is shown that, by using two additional quadrature local oscillators, a demodulated signal can be obtained that is independent of this phase difference. The experimental interferometer is a Michelson configuration using a visible single-mode laser, whose current is sinusoidally modulated at a frequency of 20 kHz. The detected interferometer output is acquired using a 250 kHz analog-to-digital converter and processed in real time. The system is used to measure the displacement sensitivity frequency response and linearity of a piezoelectric mirror shifter over a range of 500 Hz to 10 kHz. The experimental results show good agreement with two data-obtained independent techniques: the signal coincidence and denominated n-commuted Pernick method.

  20. Complete all-optical processing polarization-based binary logic gates and optical processors.

    PubMed

    Zaghloul, Y A; Zaghloul, A R M

    2006-10-16

    We present a complete all-optical-processing polarization-based binary-logic system, by which any logic gate or processor can be implemented. Following the new polarization-based logic presented in [Opt. Express 14, 7253 (2006)], we develop a new parallel processing technique that allows for the creation of all-optical-processing gates that produce a unique output either logic 1 or 0 only once in a truth table, and those that do not. This representation allows for the implementation of simple unforced OR, AND, XOR, XNOR, inverter, and more importantly NAND and NOR gates that can be used independently to represent any Boolean expression or function. In addition, the concept of a generalized gate is presented which opens the door for reconfigurable optical processors and programmable optical logic gates. Furthermore, the new design is completely compatible with the old one presented in [Opt. Express 14, 7253 (2006)], and with current semiconductor based devices. The gates can be cascaded, where the information is always on the laser beam. The polarization of the beam, and not its intensity, carries the information. The new methodology allows for the creation of multiple-input-multiple-output processors that implement, by itself, any Boolean function, such as specialized or non-specialized microprocessors. Three all-optical architectures are presented: orthoparallel optical logic architecture for all known and unknown binary gates, singlebranch architecture for only XOR and XNOR gates, and the railroad (RR) architecture for polarization optical processors (POP). All the control inputs are applied simultaneously leading to a single time lag which leads to a very-fast and glitch-immune POP. A simple and easy-to-follow step-by-step algorithm is provided for the POP, and design reduction methodologies are briefly discussed. The algorithm lends itself systematically to software programming and computer-assisted design. As examples, designs of all binary gates, multiple

  1. Complete all-optical processing polarization-based binary logic gates and optical processors

    NASA Astrophysics Data System (ADS)

    Zaghloul, Y. A.; Zaghloul, A. R. M.

    2006-10-01

    We present a complete all-optical-processing polarization-based binary-logic system, by which any logic gate or processor can be implemented. Following the new polarization-based logic presented in [Opt. Express 14, 7253 (2006)], we develop a new parallel processing technique that allows for the creation of all-optical-processing gates that produce a unique output either logic 1 or 0 only once in a truth table, and those that do not. This representation allows for the implementation of simple unforced OR, AND, XOR, XNOR, inverter, and more importantly NAND and NOR gates that can be used independently to represent any Boolean expression or function. In addition, the concept of a generalized gate is presented which opens the door for reconfigurable optical processors and programmable optical logic gates. Furthermore, the new design is completely compatible with the old one presented in [Opt. Express 14, 7253 (2006)], and with current semiconductor based devices. The gates can be cascaded, where the information is always on the laser beam. The polarization of the beam, and not its intensity, carries the information. The new methodology allows for the creation of multiple-input-multiple-output processors that implement, by itself, any Boolean function, such as specialized or non-specialized microprocessors. Three all-optical architectures are presented: orthoparallel optical logic architecture for all known and unknown binary gates, singlebranch architecture for only XOR and XNOR gates, and the railroad (RR) architecture for polarization optical processors (POP). All the control inputs are applied simultaneously leading to a single time lag which leads to a very-fast and glitch-immune POP. A simple and easy-to-follow step-by-step algorithm is provided for the POP, and design reduction methodologies are briefly discussed. The algorithm lends itself systematically to software programming and computer-assisted design. As examples, designs of all binary gates, multiple

  2. [Study on the Technology of the 4.4 μm Mid-Infrared Laser Heterodyne Spectrum].

    PubMed

    Tan, Tu; Cao, Zhen-song; Wang, Gui-shi; Wang, Lei; Liu, Kun; Huang, Yin-bo; Chen Wei-dong; Gao, Wei-ming

    2015-06-01

    In this paper, first time as our knowledge, we describe the development and performance evaluation of a 4.4 μm external cavity quantum cascade laser based laser heterodyne radiometer. Laser heterodyne spectroscopy is a high sensitive laser spectroscopy technique which offers the potential to develop a compact ground or satellite based radiometer for Earth observation and astronomy. An external cavity quantum cascade laser operating at 4. 4 μm, with output power up to 180 mW and narrow line width was used as a local oscillation. The external cavity quantum cascade laser offers wide spectral tuning range, it is tunable from 4.38 to 4.52 μm with model hop free and can be used for simultaneous detections of CO2, CO and N2 O. A blackbody was used as a signal radiation source. Development and fundamental theory of Laser heterodyne spectroscopy was described. The performance of the developed Laser heterodyne radiometer was evaluated by measuring of CO2 spectral at different pressures. Analyses results showed that a signal-to-noise ratio of 86 was achieved which was less than the theoretical value of 287. The spectral resolution of the developed Laser heterodyne spectroscopy is about 0.007 8 cm(-1) which could meet the requirement of high resolution spectroscopy measurement in the case of Doppler linewidth. The experiment showed that middle Infrared laser heterodyne spectroscopy system had high signal-to-noise ratio and spectral resolution, and had broad application prospect in high precision measurement of atmospheric greenhouse gas concentration and vertical profile.

  3. Heterodyne interferometry for the detection of elastic waves: a tutorial and open-hardware project

    NASA Astrophysics Data System (ADS)

    Hitchman, Sam; van Wijk, Kasper; Broderick, Neil; Adam, Ludmila

    2015-05-01

    Non-contacting acoustic and ultrasonic measurements are of interest in applications ranging from nondestructive evaluation to rock physics and medical imaging. The fundamental workings of the detector—the interferometer—are easily explained in undergraduate physics courses, but practical implementations are dominated by specialized, and commercial, devices. We present a robust and relatively inexpensive detector, which consists of a heterodyne interferometer and phase locked loop frequency demodulator, as an open-source alternative. We illustrate the broadband capabilities with the detection of ultrasonic waves in a mudstone sample, and low-frequency (100 Hz) vibrations of a piston.

  4. A terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer.

    SciTech Connect

    Klaassen, T. O.; Hajenius, M.; Adam, A. J. L.; Klapwijk, T. M.; Baryshev, A.; Kumar, Sushil; Baselmans, J. J. A.; Hu, Qing; Yang, Z. Q.; Hovenier, J. N.; Williams, Benjamin S.; Gao, J. R.; Reno, John Louis

    2005-03-01

    We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above 2 THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8 THz as local oscillator. We measure a double sideband receiver noise temperature of 1400 K at 2.8 THz and 4.2 K, and find that the free-running QCL has sufficient power stability for a practical receiver, demonstrating an unprecedented combination of sensitivity and stability.

  5. A re-evaluation of laser heterodyne radiometer ClO measurements. [for stratospheric chemistry studies

    NASA Technical Reports Server (NTRS)

    Menzies, R. T.

    1983-01-01

    Previously reported measurements of stratospheric ClO using a balloon-borne laser heterodyne radiometer, launched from Palestine, Texas, are re-evaluated as a result of recent spectroscopic data. A spectral feature which was observed during September, 1978 and November, 1979 flights was incorrectly identified as a ClO absorption line, while a second feature observed during the latter flight with somewhat limited sensitivity is now believed to be due to ClO. This new interpretation results in a measured ClO profile which falls off more rapidly with decreasing altitude than the previous results indicated.

  6. Space position measurement using long-path heterodyne interferometer with optical frequency comb.

    PubMed

    Wang, Xiaonan; Takahashi, Satoru; Takamasu, Kiyoshi; Matsumoto, Hirokazu

    2012-01-30

    A heterodyne interference system was developed for position measurement. A stabilized optical-frequency comb is used as the laser source. The preliminary experiment to measure a distance of 22.478 m shows a drift of 1.6 μm in 20 minutes after the temperature compensation. Comparison and frequency shift experiments have been done for a distance of about 7.493 m. The experimental results show that the drift is mainly caused by environmental condition changes and the vibration of the table and floor also has some effects. It was verified that the absolute distance measurement can be realized by fringe scanning and frequency-shifting methods.

  7. On the theory of optical heterodyne polarization interferometry of originally isotropic media

    SciTech Connect

    Gancheryonok, I.I.; Zhavrid, P.G.

    1995-12-01

    We present a consistent theoretical analysis of optical heterodyne polarization interferometry (OHPI) of originally isotropic media with colinear interacting waves (the pump-probe arrangement) within the framework of third-order nonlinear susceptibility. Our analysis is based on the formalism of Mueller matrices and Stokes vector-parameters. The following generalizations are made: the analysis is carried out for completely polarized pumping radiation with arbitrary polarization and a linearly polarized or completely depolarized probing beam, and the detected OHPI signal is calculated taking into account effects of second order in the excitation light intensity and linear absorption of the interacting beams. 12 refs., 2 figs.

  8. Determination of thermoelastic material properties by differential heterodyne detection of impulsive stimulated thermal scattering.

    PubMed

    Verstraeten, B; Sermeus, J; Salenbien, R; Fivez, J; Shkerdin, G; Glorieux, C

    2015-06-01

    The underlying working principle of detecting impulsive stimulated scattering signals in a differential configuration of heterodyne diffraction detection is unraveled by involving optical scattering theory. The feasibility of the method for the thermoelastic characterization of coating-substrate systems is demonstrated on the basis of simulated data containing typical levels of noise. Besides the classical analysis of the photoacoustic part of the signals, which involves fitting surface acoustic wave dispersion curves, the photothermal part of the signals is analyzed by introducing thermal wave dispersion curves to represent and interpret their grating wavelength dependence. The intrinsic possibilities and limitations of both inverse problems are quantified by making use of least and most squares analysis.

  9. First results from the Spatial Heterodyne Imager for Mesospheric Radicals (SHIMMER): Diurnal variation of mesospheric hydroxyl

    NASA Astrophysics Data System (ADS)

    Englert, Christoph R.; Stevens, Michael H.; Siskind, David E.; Harlander, John M.; Roesler, Fred L.; Pickett, Herbert M.; von Savigny, Christian; Kochenash, Andrew J.

    2008-10-01

    We present the first SHIMMER observations of the diurnal variation of mesospheric hydroxyl (OH). We compare our data with Aura Microwave Limb Sounder (MLS) observations at about 13h local time near 55°N and find very good agreement. This validates the Spatial Heterodyne Spectroscopy technique for space-borne optical remote sensing applications. We extend our analysis to other local times, not observed by MLS, for latitudes near 55°N in the summer of 2007. At 74 km, we find excellent agreement with a photochemical model, but above 76 km, significant model/data differences in the shape of the OH diurnal variation are observed.

  10. X-ray spatial frequency heterodyne imaging of protein-based nanobubble contrast agents

    PubMed Central

    Rand, Danielle; Uchida, Masaki; Douglas, Trevor; Rose-Petruck, Christoph

    2014-01-01

    Spatial Frequency Heterodyne Imaging (SFHI) is a novel x-ray scatter imaging technique that utilizes nanoparticle contrast agents. The enhanced sensitivity of this new technique relative to traditional absorption-based x-ray radiography makes it promising for applications in biomedical and materials imaging. Although previous studies on SFHI have utilized only metal nanoparticle contrast agents, we show that nanomaterials with a much lower electron density are also suitable. We prepared protein-based “nanobubble” contrast agents that are comprised of protein cage architectures filled with gas. Results show that these nanobubbles provide contrast in SFHI comparable to that of gold nanoparticles of similar size. PMID:25321797

  11. Remote Sensing of Methane in the Martian Atmosphere using Infrared Laser Heterodyne Radiometry

    NASA Astrophysics Data System (ADS)

    Passmore, R. L.; Bowles, N. E.; Weidmann, D.; Smith, K.

    2011-12-01

    In the last few years, several research teams have reported the detection of methane in the atmosphere of Mars, measuring 10 ppb on average [1][2][3]. The source of the methane is still unknown, but its identification is important as its presence could imply a biological origin. However, the detection limits of current instruments lie below the requirements for an unambiguous determination of concentration mapping and distribution. We investigate the viability of detecting methane in the Martian atmosphere via a high sensitivity remote sensing technique known as passive mid-infrared laser heterodyne radiometry. Although heterodyne spectroscopy is not a new idea, recent advancements in local oscillator technology [4] offer the possibility of significant instrument miniaturisation relevant to space deployment. We present our current work on a laser heterodyne radiometer (LHR) which involves adapting an existing 10 μm laser breadboard design, which was used with much success to study stratospheric ozone [5], to operate at 7.7 μm in order to target the ν4 fundamental band of methane. The core of the LHR consists of a distributed-feedback quantum cascade laser (QCL) operating in continuous-wave mode, which acts as the local oscillator. QCLs are ideal local oscillators for this type of instrument as they emit with high spectral purity and the necessary optical power in the mid-infrared region where characteristic spectral lines of interest lie. Atmospheric modelling of the Martian atmosphere and instrument sensitivity studies enabled simulated methane spectral features to be studied in detail, which subsequently determined the focus for experimental efforts in the laboratory. Testing of the LHR was initially carried out on small gas cells containing pure methane gas, but in order to test the instrument more rigorously for atmospheric studies a larger gas cell was constructed that approximates the Martian atmosphere in the laboratory. Trace quantities of methane were

  12. Coherent Φ-OTDR based on polarization-diversity integrated coherent receiver and heterodyne detection

    NASA Astrophysics Data System (ADS)

    Yan, Qizhong; Tian, Ming; Li, Xiang; Yang, Qi; Xu, Yimin

    2017-04-01

    We demonstrate a novel distributed optical fiber sensor system based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). Both the phase and the amplitude of the Rayleigh scattering (RS) light can be demodulated based on I/Q demodulation and heterodyne detection using commercial available 100G integrated coherent receiver (ICR). The polarization fading problem in Φ -OTDR can be avoided by considering the RS signal from both polarizations. The dynamic strain sensing with a sensing range of 9.8 km and a spatial resolution of 15 m is experimentally demonstrated.

  13. A 16-channel heterodyne electron cyclotron emission radiometer on J-TEXT.

    PubMed

    Yang, Z J; Phillips, P E; Zhuang, G; Xiao, J S; Huang, H; Rowan, W L; Wang, Z J

    2012-10-01

    To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94-125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.

  14. A 16-channel heterodyne electron cyclotron emission radiometer on J-TEXT

    SciTech Connect

    Yang, Z. J.; Zhuang, G.; Xiao, J. S.; Wang, Z. J.; Phillips, P. E.; Huang, H.; Rowan, W. L.

    2012-10-15

    To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94-125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.

  15. Circularly polarized optical heterodyne interferometer for optical activity measurement of a quartz crystal.

    PubMed

    Chou, Chien; Kuo, Wen-Chuan; Han, Chien-Yuan

    2003-09-01

    Phase retardation between two orthogonal circularly polarized light waves that propagate in an optical active medium is proportional to its optical activity. The measurement of optical activity of a quartz depolarizer in terms of the phase difference of two orthogonal circularly polarized waves is proposed. A circularly polarized optical heterodyne interferometer with a Zeeman laser to measure the optical activity of a quartz crystal is demonstrated experimentally. The accuracy of the measurement is discussed. In addition, the effect of elliptical polarization and nonorthogonality of linearly polarized light waves of a Zeeman laser on the optical activity measurement is analyzed.

  16. Atmospheric turbulence-induced signal fades on optical heterodyne communication links

    NASA Astrophysics Data System (ADS)

    Winick, K. A.

    1986-06-01

    The three basic atmospheric propagation effects, absorption, scattering, and turbulence, are reviewed. A simulation approach is then developed to determine signal fade probability distributions on heterodyne-detected satellite links which operate through naturally occurring atmospheric turbulence. The calculations are performed on both angle-tracked and nonangle-tracked downlinks, and on uplinks, with and without adaptive optics. Turbulence-induced degradations in communication performance are determined using signal fade probability distributions, and it is shown that the average signal fade can be a poor measure of the performance degradation.

  17. A network of heterodyne laser interferometers for monitoring and control of large ring-lasers

    NASA Astrophysics Data System (ADS)

    Donazzan, Alberto; Naletto, Giampiero; Pelizzo, Maria G.; Cuccato, Davide; Beghi, Alessandro; Ortolan, Antonello; Belfi, Jacopo; Bosi, Filippo; Simonelli, Andreino; Beverini, Nicolò; Carelli, Giorgio; Maccioni, Enrico; Santagata, Rosa; Porzio, Alberto; Tartaglia, Angelo; Di Virgilio, Angela

    2016-08-01

    The sensitivity achieved by large ring-laser gyroscopes will make it possible to detect faint relativistic effects related to the rotation of the Earth's mass. This task requires a strict control of the ring cavity geometry (shape and orientation), which can be performed by a novel network of portable heterodyne interferometers, capable of measuring the absolute distance betweeen two retro-reflectors with a nominal accuracy better than 1nm. First steps have been taken towards the realization of this device and a starting prototype of distance gauge is under development and test.

  18. X-ray spatial frequency heterodyne imaging of protein-based nanobubble contrast agents.

    PubMed

    Rand, Danielle; Uchida, Masaki; Douglas, Trevor; Rose-Petruck, Christoph

    2014-09-22

    Spatial Frequency Heterodyne Imaging (SFHI) is a novel x-ray scatter imaging technique that utilizes nanoparticle contrast agents. The enhanced sensitivity of this new technique relative to traditional absorption-based x-ray radiography makes it promising for applications in biomedical and materials imaging. Although previous studies on SFHI have utilized only metal nanoparticle contrast agents, we show that nanomaterials with a much lower electron density are also suitable. We prepared protein-based "nanobubble" contrast agents that are comprised of protein cage architectures filled with gas. Results show that these nanobubbles provide contrast in SFHI comparable to that of gold nanoparticles of similar size.

  19. Parallel heterodyne detection of dynamic light-scattering spectra from gold nanoparticles diffusing in viscous fluids.

    PubMed

    Atlan, Michael; Desbiolles, Pierre; Gross, Michel; Coppey-Moisan, Maïté

    2010-03-01

    We developed a microscope intended to probe, using a parallel heterodyne receiver, the fluctuation spectrum of light quasi-elastically scattered by gold nanoparticles diffusing in viscous fluids. The cutoff frequencies of the recorded spectra scale up linearly with those expected from single-scattering formalism in a wide range of dynamic viscosities (1 to 15 times water viscosity at room temperature). Our scheme enables ensemble-averaged optical fluctuations measurements over multispeckle recordings in low light, at temporal frequencies up to 10 kHz, with a 12 Hz framerate array detector.

  20. Bandpass filtering of moving-object laser heterodyne-signals by finite apertures.

    PubMed

    Leader, J C

    1978-04-15

    Expressions for the frequency power spectral density and power spectral density SNR of a heterodyne detection system are derived assuming the signal radiation field results from a laser illuminated, moving rough object. The calculated spectral density is attenuated at large spectral spread frequencies (resulting from target rotation) by averaging of the high spatial frequency speckle pattern by the finite extent (aperture) of the local oscillator field. Optimum signal detection is obtained only at the Doppler shifted frequency. Spatial anisotropy of the radiation field mutual coherence function precludes exact calculations for arbitrary local oscillator field distributions.

  1. A novel heterodyne displacement interferometer with no detectable periodic nonlinearity and optical resolution doubling

    SciTech Connect

    Joo, K; Ellis, J D; Buice, E S; Spronck, J W; Munnig Schmidt, R H

    2010-02-05

    This paper describes a novel heterodyne laser interferometer with no significant periodic nonlinearity for linear displacement measurements. Moreover, the optical configurations have the benefit of doubling the measurement resolution when compared to its respective traditional counterparts. Experimental results show no discernable periodic nonlinearity for a retro-reflector interferometer and plane mirror interferometer configurations with a noise level below 20 pm. The incoming laser beams of the interferometers are achieved by utilizing two single mode optical fibers. To determine the stability of the optical fiber couplers a fiber delivery prototype was also built and tested.

  2. Design and construction of a coelostat for heterodyne measurements at a wavelength of 10 micrometer

    NASA Astrophysics Data System (ADS)

    Strzoda, Rainer

    1987-01-01

    A heliostat was designed and built as carrier for a 10 micrometer IR heterodyne spectrometer for transmission measurements in the Earth atmosphere for investigations of solar oscillations. The high wavelength resolution allows the determination of line profiles and transition frequencies with high precision. A series of highly resolved ozone absorption spectra lead to the vertical ozone distribution, in good agreement with reference measurements. An improvement of the results is expected after a more precise determination of ozone spectroscopic data from laboratory measurements. The measurement uncertainties are still too high to determine a frequency spectrum of solar oscillations.

  3. High-accuracy thickness measurement of a transparent plate with the heterodyne central fringe identification technique

    SciTech Connect

    Wu, Wang-Tsung; Hsieh, Hung-Chih; Chang, Wei-Yao; Chen, Yen-Liang; Su, Der-Chin

    2011-07-20

    In a modified Twyman-Green interferometer, the optical path variation is measured with the heterodyne central fringe identification technique, as the light beam is focused by a displaced microscopic objective on the front/rear surface of the test transparent plate. The optical path length variation is then measured similarly after the test plate is removed. The geometrical thickness of the test plate can be calculated under the consideration of dispersion effect. This method has a wide measurable range and a high accuracy in the measurable range.

  4. High-accuracy thickness measurement of a transparent plate with the heterodyne central fringe identification technique.

    PubMed

    Wu, Wang-Tsung; Hsieh, Hung-Chih; Chang, Wei-Yao; Chen, Yen-Liang; Su, Der-Chin

    2011-07-20

    In a modified Twyman-Green interferometer, the optical path variation is measured with the heterodyne central fringe identification technique, as the light beam is focused by a displaced microscopic objective on the front/rear surface of the test transparent plate. The optical path length variation is then measured similarly after the test plate is removed. The geometrical thickness of the test plate can be calculated under the consideration of dispersion effect. This method has a wide measurable range and a high accuracy in the measurable range.

  5. High-accuracy thickness measurement of a transparent plate with the heterodyne central fringe identification technique

    NASA Astrophysics Data System (ADS)

    Wu, Wang-Tsung; Hsieh, Hung-Chih; Chang, Wei-Yao; Chen, Yen-Liang; Su, Der-Chin

    2011-07-01

    In a modified Twyman--Green interferometer, the optical path variation is measured with the heterodyne central fringe identification technique, as the light beam is focused by a displaced microscopic objective on the front/rear surface of the test transparent plate. The optical path length variation is then measured similarly after the test plate is removed. The geometrical thickness of the test plate can be calculated under the consideration of dispersion effect. This method has a wide measurable range and a high accuracy in the measurable range.

  6. Characterization and calibration of 8-channel E-band heterodyne radiometer system for SST-1 tokamak.

    PubMed

    Siju, Varsha; Kumar, Dharmendra; Shukla, Praveena; Pathak, S K

    2014-05-01

    An 8-channel E-band heterodyne radiometer system (74-86 GHz) is designed, characterized, and calibrated to measure the radial electron temperature profile by measuring Electron Cyclotron Emission spectrum at SST-1 Tokamak. The developed radiometer has a noise equivalent temperature of 1 eV and sensitivity of 5 × 10(9) V/W. In order to precisely measure the absolute value of electron temperature, a calibration measurement of the radiometer system is performed using hot-cold Dicke switch method, which confirms the system linearity.

  7. Common-Path Heterodyne Laser-Induced Thermal Acoustics for Seedless Laser Velocimetry

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Herring, G. C.; Balla, R. Jeffrey; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    We demonstrate the use of a novel technique for the detection of heterodyne laser-induced thermal acoustics signals, which allows the construction of a highly stable seedless laser velocimeter. A common-path configuration is combined with quadrature detection to provide flow direction, greatly improve robustness to misalignment and vibration, and give reliable velocity measurement at low flow velocities. Comparison with Pitot tube measurements in the freestream of a wind tunnel shows root-mean-square errors of 0.67 m/s over the velocity range 0.55 m/s.

  8. Laser heterodyne interferometer for simultaneous measuring displacement and angle based on the Faraday effect.

    PubMed

    Zhang, Enzheng; Hao, Qun; Chen, Benyong; Yan, Liping; Liu, Yanna

    2014-10-20

    A laser heterodyne interferometer for simultaneous measuring displacement and angle based on the Faraday effect is proposed. The optical configuration of the proposed interferometer is designed and the mathematic model for measuring displacement and angle is established. The influences of the translational, lateral and rotational movements of the measuring reflector on displacement and angle measurement are analyzed in detail. The experimental setup based on the proposed interferometer was constructed and a series of experiments of angle comparison and simultaneous measuring displacement and angle were performed to verify the feasibility of the proposed interferometer for precision displacement and angle measurement.

  9. Imaging through obscurants with a heterodyne detection-based ladar system

    NASA Astrophysics Data System (ADS)

    Reibel, Randy R.; Roos, Peter A.; Kaylor, Brant M.; Berg, Trenton J.; Curry, James R.

    2014-06-01

    Bridger Photonics has been researching and developing a ladar system based on heterodyne detection for imaging through brownout and other DVEs. There are several advantages that an FMCW ladar system provides compared to direct detect pulsed time-of-flight systems including: 1) Higher average powers, 2) Single photon sensitive while remaining tolerant to strong return signals, 3) Doppler sensitivity for clutter removal, and 4) More flexible system for sensing during various stages of flight. In this paper, we provide a review of our sensor, discuss lessons learned during various DVE tests, and show our latest 3D imagery.

  10. Characterization and calibration of 8-channel E-band heterodyne radiometer system for SST-1 tokamak

    SciTech Connect

    Siju, Varsha; Kumar, Dharmendra; Shukla, Praveena; Pathak, S. K.

    2014-05-15

    An 8-channel E-band heterodyne radiometer system (74–86 GHz) is designed, characterized, and calibrated to measure the radial electron temperature profile by measuring Electron Cyclotron Emission spectrum at SST-1 Tokamak. The developed radiometer has a noise equivalent temperature of 1 eV and sensitivity of 5 × 10{sup 9} V/W. In order to precisely measure the absolute value of electron temperature, a calibration measurement of the radiometer system is performed using hot-cold Dicke switch method, which confirms the system linearity.

  11. Electronic frequency modulation for the increase of maximum measurable velocity in a heterodyne laser interferometer

    SciTech Connect

    Choi, Hyunseung; La, Jongpil; Park, Kyihwan

    2006-10-15

    A Zeeman-type He-Ne laser is frequently used as a heterodyne laser due to the simple construction and the small loss of a light. However, the low beat frequency of the Zeeman-type laser limits the maximum measurable velocity. In this article, an electronic frequency modulation algorithm is proposed to overcome the drawback of the low velocity measurement capability by increasing the beat frequency electronically. The brief analysis, the measurement scheme of the proposed algorithm, and the experimental results are presented. It is demonstrated that the proposed algorithm is proven to enhance the maximum measurable velocity.

  12. Comment on "Heterodyne Lidar Returns in the Turbulent Atmosphere: Performance Evaluation of Simulated Systems"

    NASA Technical Reports Server (NTRS)

    Frehlich, Rod; Kavaya, Michael J.

    2000-01-01

    The explanation for the difference between simulation and the zero-order theory for heterodyne lidar returns in a turbulent atmosphere proposed by Belmonte and Rye is incorrect. The theoretical expansion is not developed under a square- law-structure function approximation (random wedge atmosphere). Agreement between the simulations and the zero-order term of the theoretical expansion is produced for the limit of statistically independent paths (bi-static operation with large transmitter-receiver separation) when the simulations correctly include the large-scale gradients of the turbulent atmosphere.

  13. Spatially and frequency-resolved monitoring of intradie capacitive coupling by heterodyne excitation infrared lock-in thermography

    NASA Astrophysics Data System (ADS)

    León, J.; Perpiñà, X.; Altet, J.; Vellvehi, M.; Jordà, X.

    2013-02-01

    This paper combines the infrared lock-in thermography (IR-LIT) and heterodyne excitation techniques to detect high-frequency capacitive currents due to intradie electrical coupling between microelectronic devices or more complex systems. Modulating the excitation with the heterodyne approach, we drive devices or complex systems with high frequency electrical signals in such a way that they behave as low frequency heat sources, modulating their temperature field at a frequency detectable by an IR-LIT system. This approach is analytically studied and extended to a bi-dimensional scenario, showing that the thermal information at low frequency depends on the electrical characteristics of the sample at high frequency.

  14. Khayyam: progress and prospects of coupling a spatial heterodyne spectrometer (SHS) to a Cassegrain telescope for optical interferometry

    NASA Astrophysics Data System (ADS)

    Hosseini, Sona; Harris, Walter

    2016-08-01

    In the temporal study of faint, extended sources at high resolving power, Spatial Heterodyne Spectrometer (SHS) can offer significant advantages about conventional dispersive grating spectrometers. We describe here a four-year continuous progress in Mt. Hamilton, Lick Observatory, toward development of a prototype reflective Spacial Heterodyne Spectrometer, Khayyam, instrument-telescope configuration to combine all of the capabilities necessary to obtain high resolving power visible band spectra of diffuse targets from small aperture on-axis telescopes where significant observing time can be obtained. We will discuss the design considerations going into this new system, installation, testing of the interferometer-telescope combination, the technical challenges and procedures moving forward.

  15. A broadband RF continuously variable time delay device. [using Bragg cell and optical heterodyne technology for signal processing

    NASA Technical Reports Server (NTRS)

    Freyre, F. W.

    1981-01-01

    A method for implementation of continuously variable time delay of broadband RF signals is described. The method uses Bragg Cell and optical heterodyne technology. The signal to be delayed is applied to the Bragg Cell acoustic transducer, and the delay time is the acoustic transit time from this transducer to the incident light beam. By translating the light beam, the delay is varied. Expressions describing the Bragg Cell diffraction, lens Fourier transformation, and the optical heterodyne processes are developed. Specifications for the variable delay including bandwidth, range of delay, and insertion loss are provided. Applications include radar signal processing, spread spectrum intercept, radar ECM, and adaptive array antenna processing.

  16. Coherent summation of spatially distorted laser Doppler signals by using a two-dimensional heterodyne detector array

    NASA Technical Reports Server (NTRS)

    Chan, Kin P.; Killinger, Dennis K.

    1992-01-01

    Phase-sensitive coherent summation of individual heterodyne detector array signals was demonstrated for the enhanced detection of spatially distorted laser Doppler returns. With the use of a 2 x 2 heterodyne detector array, the phase and amplitude of a time-varying speckle pattern was detected, and the signal-to-noise ratio of the Doppler shift estimate was shown to be improved by a factor of 2, depending on the extent of spatial coherence loss. These results are shown to agree with a first-order analysis and indicate the advantage of coherent summation for both short-range laser Doppler velocimetry and long-range atmospheric coherent lidar.

  17. Chirped pulse heterodyne for optimal beat note detection between a frequency comb and a continuous wave laser.

    PubMed

    Deschênes, Jean-Daniel; Genest, Jérôme

    2015-04-06

    Chirped pulse heterodyne is proposed to maximize the signal-to-noise ratio (SNR) when measuring the beat note between an optical frequency comb and a continuous wave (CW) laser. The noise model reveals that all the comb power within the largest possible detection bandwidth can be used to increase the SNR. The chirped comb/CW interference experiment is shown to be equivalent to CW/CW interference, using the comb's spectrally available power. The approach can also greatly alleviate dynamic range issues when detected pulsed heterodyne signals. A beat note SNR of 68.3 dB in a 100 kHz bandwidth is achieved.

  18. Wavelength shift tolerance of a heterodyne detection scheme for cost-efficient DWDM-PON / 60 GHz wireless integration

    NASA Astrophysics Data System (ADS)

    Medeiros, M. C. R.; Thakur, M. P.; Mikroulis, S.; Mitchell, J. E.

    2015-01-01

    Radio-over-fiber systems employing remote antenna units (RAUs) based on coherent optical heterodyne detection of two phase uncorrelated lasers and envelope detection have been recently demonstrated. By using two uncorrelated lasers, this system concept allows simple implementation that can additionally be improved, if thermally uncooled lasers are used. Although such asynchronous receiver design is mildly affected by the laser phase noise, it suffers from the wavelength drift that occurs between the uncooled laser sources. Also, there are performance penalties due to high laser line-width when complex modulation formats are used for transmission. In this work, we analyze the performance of heterodyne based optical receivers, using OOK and multilevel modulation.

  19. Composite film polarizer based on the oriented assembly of electrospun nanofibers.

    PubMed

    Hu, Zhongliang; Ma, Zhijun; Peng, Mingying; He, Xin; Zhang, Hang; Li, Yang; Qiu, Jianrong

    2016-04-01

    Polarizers are widely applied in antiglare glasses, planner displays, photography filters and optical communications, etc. In this investigation, we propose a new strategy for the preparation of a flexible film polarizer based on the electrospinning technique. An aligned assembly of polyvinyl acetate (PVA) nanofibers was electrospun and collected by a fast-rotating drum, then soaked in polymethyl methacrylate (PMMA) solution and dried thoroughly to obtain a transparent PVA-PMMA composite film polarizer. The morphology, structure and optical performance of the PVA nanofibers and the film polarizers were characterized with a scanning electron microscope, UV-vis-IR spectrometer and polarized Raman spectra, etc. The PVA-PMMA film polarizer demonstrated efficient polarizing activity toward visible and near-infrared light, while keeping fair transparency in the range of 400-1400 nm. Due to the protection from the hydrophobic PMMA matrix, the PVA-PMMA film polarizers show high moisture resistance, making it applicable in a humid environment. Considering the scalability and versatility of the strategy employed here, the PVA-PMMA film polarizer prepared could replace the conventional film polarizers in a wide range of applications.

  20. Composite film polarizer based on the oriented assembly of electrospun nanofibers

    NASA Astrophysics Data System (ADS)

    Hu, Zhongliang; Ma, Zhijun; Peng, Mingying; He, Xin; Zhang, Hang; Li, Yang; Qiu, Jianrong

    2016-04-01

    Polarizers are widely applied in antiglare glasses, planner displays, photography filters and optical communications, etc. In this investigation, we propose a new strategy for the preparation of a flexible film polarizer based on the electrospinning technique. An aligned assembly of polyvinyl acetate (PVA) nanofibers was electrospun and collected by a fast-rotating drum, then soaked in polymethyl methacrylate (PMMA) solution and dried thoroughly to obtain a transparent PVA-PMMA composite film polarizer. The morphology, structure and optical performance of the PVA nanofibers and the film polarizers were characterized with a scanning electron microscope, UV-vis-IR spectrometer and polarized Raman spectra, etc. The PVA-PMMA film polarizer demonstrated efficient polarizing activity toward visible and near-infrared light, while keeping fair transparency in the range of 400-1400 nm. Due to the protection from the hydrophobic PMMA matrix, the PVA-PMMA film polarizers show high moisture resistance, making it applicable in a humid environment. Considering the scalability and versatility of the strategy employed here, the PVA-PMMA film polarizer prepared could replace the conventional film polarizers in a wide range of applications.

  1. Polarization-based index of refraction and reflection angle estimation for remote sensing applications.

    PubMed

    Thilak, Vimal; Voelz, David G; Creusere, Charles D

    2007-10-20

    A passive-polarization-based imaging system records the polarization state of light reflected by objects that are illuminated with an unpolarized and generally uncontrolled source. Such systems can be useful in many remote sensing applications including target detection, object segmentation, and material classification. We present a method to jointly estimate the complex index of refraction and the reflection angle (reflected zenith angle) of a target from multiple measurements collected by a passive polarimeter. An expression for the degree of polarization is derived from the microfacet polarimetric bidirectional reflectance model for the case of scattering in the plane of incidence. Using this expression, we develop a nonlinear least-squares estimation algorithm for extracting an apparent index of refraction and the reflection angle from a set of polarization measurements collected from multiple source positions. Computer simulation results show that the estimation accuracy generally improves with an increasing number of source position measurements. Laboratory results indicate that the proposed method is effective for recovering the reflection angle and that the estimated index of refraction provides a feature vector that is robust to the reflection angle.

  2. Compact broadband polarizer based on shallowly-etched silicon-on-insulator ridge optical waveguides.

    PubMed

    Dai, Daoxin; Wang, Zhi; Julian, Nick; Bowers, John E

    2010-12-20

    A new way to make broadband polarizers on silicon-on-insulator (SOI) waveguides is proposed, analyzed and characterized. The characteristics of the eigenmodes in a shallowly-etched SOI ridge optical waveguide are analyzed by using a full-vectorial finite-different method (FV-FDM) mode solver. The theoretical calculation shows that the loss of TE fundamental mode could be made very low while at the same time the TM fundamental mode has very large leakage loss, which is strongly dependent on the trench width. The leakage loss of the TM fundamental mode changes quasi-periodically as the trench width w(tr) varies. The formula of the period ∆w(tr) is given. By utilizing the huge polarization dependent loss of this kind of waveguide, a compact and simple optical polarizer based on a straight waveguide was demonstrated. The polarizer is fabricated on a 700 nm-thick SOI wafer and then characterized by using a free-space optical system. The measured extinction ratio is as high as 25 dB over a 100 nm wavelength range for a 1 mm-long polarizer.

  3. Polarization-based optical imaging and processing techniques with application to the cancer diagnostics

    NASA Astrophysics Data System (ADS)

    Liu, Gang L.; Li, Yanfang; Cameron, Brent D.

    2002-06-01

    In this investigation, a polarization-based imaging system is developed and described that measures the two-dimensional effective backscattering Mueller matrix of a sample in near real-time. As is well known, a Mueller matrix can provide considerable information on the makeup and optical characteristics of a sample and also directly describes how the sample transforms an incident light beam. The ability to measure the two-dimensional Mueller matrix of a biological sample, therefore, can provide considerable information on the sample composition as well as the potential to reveal significant structural information that normally would not be visible through standard imaging techniques. Additional information can also be obtained through the application of image-processing, decomposition, and reconstruction techniques that operate directly on the 2D Mueller matrix. Using the developed system, it is shown how the induction of internal strain within the sample coupled with image reconstruction and decomposition techniques can further improve image contrast and aid in the detection of boundaries between tissues of different biomechanical and structural properties. The studies presented were performed with both rat tissue and a melanoma-based tissue culture. The results demonstrate how these techniques could provide information that may be of diagnostic value in the physical detection of malignant lesion boundaries.

  4. Development of a P-I-N HgCdTe photomixer for laser heterodyne spectrometry

    NASA Technical Reports Server (NTRS)

    Bratt, Peter R.

    1987-01-01

    An improved HgCdTe photomixer technology was demonstrated employing a p-i-n photodiode structure. The i-region was near intrinsic n-type HgCdTe; the n-region was formed by B+ ion implantation; and the p-region was formed either by a shallow Au diffusion or by a Pt Schottky barrier. Experimental devices in a back-side illuminated mesa diode configuration were fabricated, tested, and delivered. The best photomixer was packaged in a 24-hour LN2 dewar along with a cooled GaAs FET preamplifier. Testing was performed by mixing black-body radiation with a CO2 laser beam and measuring the IF signal, noise, and signal-to-noise ratio in the GHz frequency range. Signal bandwidth for this photomixer was 1.3 GHz. The heterodyne NEP was 4.4 x 10 to the -20 W/Hz out to 1 GHz increasing to 8.6 x 10 to the -10 W/Hz at 2 GHz. Other photomixers delivered on this program had heterodyne NEPs at 1 GHz ranging from 8 x 10 to the -20 to 4.4 x 10 to the -19 W/Hz and NEP bandwidths from 2 to 4 GHz.

  5. Femtosecond Heterodyne Transient Grating Spectroscopic Studies of Intramolecular Charge Transfer Character of Peridinin and Peridinin Analogs

    NASA Astrophysics Data System (ADS)

    Bishop, Michael; Khosravi, Soroush; Obaid, Razib; Whitelock, Hope; Carroll, Ann Marie; Lafountain, Amy; Frank, Harry; Beck, Warren; Gibson, George; Berrah, Nora

    2016-05-01

    The peridinin chlorophyll-a protein is a light harvesting complex found in several species of dinoflagellates. Peridinin absorbs strongly in the mid-visible spectral region and, despite the lack of a strong permanent dipole moment in its lowest energy excited state, is able to transfer excitation energy quickly and efficiently to chlorophyll-a. It is believed that the high efficiency arises from the development of intramolecular charge-transfer (ICT) character upon photoexcitation. Recently, heterodyne transient grating spectroscopy has been used to study the ultrafast (<50 fs) dynamics of β carotene and peridinin. The studies show evidence for a structurally displaced intermediate in both cases and strong ICT character in the case of peridinin, but up to now the work has not provided appropriate control experiments. The present experiments examine peridinin and two peridinin analogs, S1-peridinin and S2-peridinin. S1-peridinin is reported to have greatly diminished ICT character, and S2-peridinin is reported to have little-or-no ICT character. Heterodyne transient grating data will be presented and provide a more unambiguous characterization spectral and kinetic properties associated with the peridinin ICT state. Funded by the DoE-BES, Grant No. DE-SC0012376.

  6. Micromachined Millimeter- and Submillimeter-wave SIS Heterodyne Receivers for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Hu, Qing

    1997-01-01

    This is a progress report for the second year of a NASA-sponsored project. The report discusses the design and fabrication of micromachined Superconductor Insulator Superconductor (SIS) heterodyne receivers with integrated tuning elements. These receivers tune out the functional capacitance at desired frequencies, resulting in less noise, lower temperatures and broader bandwidths. The report also discusses the design and fabrication of the first monolithic 3x3 focal-plane arrays for a frequency range of 170-210 GHz. Also addressed is the construction of a 9-channel bias and read-out system, as well as the redesign of the IF connections to reduce cross talk between SIS junctions, which become significant a frequency of 1.5 GHz IF. Uniformity of the junction arrays were measured and antenna beam patterns of several array elements under operating conditions also were measured. Finally, video and heterodyne responses of our focal-plane arrays were measured as well. Attached is a paper on: 'Development of a 170-210 GHz 3x3 micromachined SIS imaging array'.

  7. Development of a Doppler Asymmetric Spatial Heterodyne Spectrometer for Measuring Upper Atmospheric Winds

    NASA Astrophysics Data System (ADS)

    Babcock, D. D.; Harlander, J.; Englert, C. R.; Roesler, F. L.; Pedersen, T. R.; Feldman, R.

    2009-12-01

    The global distribution of upper atmospheric winds is one of the most important data products currently unavailable to the upper atmospheric and space community due to the difficulty of making such measurements from space platforms. We discuss recent progress in increasing the technical readiness level of a Doppler Asymmetric Spatial Heterodyne (DASH) spectrometer for the measurement of upper atmospheric winds. A space flight prototype instrument is in the process of being built and tested to show DASH can successfully measure simulated Doppler winds in a space like environment. DASH is a modified Spatial Heterodyne Spectrometer (SHS), a relatively new type of Fourier transform spectrometer (FTS) which requires no scanning mechanical components, can be built in a compact monolithic configuration, and achieves the same throughput as the best FTS instruments currently known. The main advantages of the DASH optical technique are its robustness, relatively compact size, and ability to measure multiple emission lines (including calibration lines) simultaneously, thus making it an ideal candidate instrument for future Aeronomy space flight missions.

  8. An Extremely Wide Bandwidth, Low-Noise SIS Heterodyne Receiver Design for Millimeter and Submillimeter Observations

    NASA Technical Reports Server (NTRS)

    Sumner, Matthew; Blain, Andrew; Harris, Andrew; Hu, Robert; Rice, Frank; LeDuc, H. G.; Weinreb, Sander; Zmuidzinas, Jonas

    2002-01-01

    Millimeter and submillimeter heterodyne receivers using state-of-the-art SIS detectors are capable of extremely large instantaneous bandwidths with noise temperatures within a few Kelvin of the quantum limit. We present the design for a broadband, sensitive, heterodyne spectrometer under development for the Caltech Submillimeter Observatory (CSO). The 180-300 GHz double-sideband design uses a single SIS device excited by a full bandwidth, fixed-tuned waveguide probe on a silicon substrate. The IF output frequency (limited by the MMIC low noise IF preamplifier) is 6-18 GHz, providing an instantaneous RF bandwidth of 24 GHz (double-sideband). The SIS mixer conversion loss should be no more than 1-2 dB with mixer noise temperatures across the band within 10 K of the quantum limit. The single-sideband receiver noise temperature goal is 70 K. The wide instantaneous bandwidth and low noise will result in an instrument capable of a variety of important astrophysical observations beyond the capabilities of current instruments. Lab testing of the receiver will begin in the summer of 2002, and the first use on the CSO should occur in the spring of 2003.

  9. Spectral line inversion for sounding of stratospheric minor constituents by infrared heterodyne technique from balloon altitudes

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Shapiro, G. L.; Allario, F.; Alvarez, J. M.

    1981-01-01

    A combination of two different techniques for the inversion of infrared laser heterodyne measurements of tenuous gases in the stratosphere by solar occulation is presented which incorporates the advantages of each technique. An experimental approach and inversion technique are developed which optimize the retrieval of concentration profiles by incorporating the onion peel collection scheme into the spectral inversion technique. A description of an infrared heterodyne spectrometer and the mode of observations for solar occulation measurement is presented, and the results of inversions of some synthetic ClO spectral lines corresponding to solar occulation limb-scans of the stratosphere are examined. A comparison between the new techniques and one of the current techniques indicates that considerable improvement in the accuracy of the retrieved profiles can be achieved. It is found that noise affects the accuracy of both techniques but not in a straightforward manner since there is interaction between the noise level, noise propagation through inversion, and the number of scans leading to an optimum retrieval.

  10. Tunable diode-laser heterodyne spectrometer for remote observations near 8 microns

    NASA Technical Reports Server (NTRS)

    Glenar, D.; Kostiuk, T.; Jennings, D. E.; Buhl, D.; Mumma, M. J.

    1982-01-01

    A diode-laser-based, ultrahigh resolution IR heterodyne spectrometer for laboratory and field use has been developed for operation between 7.5 and 8.5 microns. The local oscillator is a PbSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed-cycle cooler. The laser output frequency is controlled and stabilized using a high-precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. The system largely employs reflecting optics to minimize losses from internal reflection and absorption and to eliminate chromatic effects. Spectral analysis of the diode-laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the IR spectral regions over which useful heterodyne operation can be achieved. Observations have been made of atmospheric N2O, O3, and CH4 between 1170 and 1200/cm, using both a single-frequency swept IF channel and a 64-channel RF spectral line receiver with a total IF coverage of 1600 MHz.

  11. Performance limitations of a free-space optical communication satellite network owing to vibrations: heterodyne detection.

    PubMed

    Arnon, S; Rotman, S R; Kopeika, N S

    1998-09-20

    Free-space optical communication between satellites in a distributed network can permit high data rates of communication between different places on Earth. To establish optical communication between any two satellites requires that the line of sight of their optics be aligned during the entire communication time. Because of the large distance between the satellites and the alignment accuracy required, the pointing from one satellite to another is complicated because of vibrations of the pointing system caused by two fundamental stochastic mechanisms: tracking noise created by the electro-optic tracker and vibrations derived from mechanical components. Vibration of the transmitter beam in the receiver plane causes a decrease in the received optical power. Vibrations of the receiver telescope relative to the received beam decrease the heterodyne mixing efficiency. These two factors increase the bit-error rate of a coherent detection network. We derive simple mathematical models of the network bit-error rate versus the system parameters and the transmitter and receiver vibration statistics. An example of a practical optical heterodyne free-space satellite optical communication network is presented. From this research it is clear that even low-amplitude vibration of the satellite-pointing systems dramatically decreases network performance.

  12. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

    NASA Astrophysics Data System (ADS)

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-03-01

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach.

  13. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers.

    PubMed

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-03-17

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach.

  14. Detection of nonlinear distortions in the vibration of acoustically driven mechanical systems using heterodyne vibrometry

    NASA Astrophysics Data System (ADS)

    Aerts, J. R. M.; Dirckx, J. J. J.; Pintelon, R.

    2008-06-01

    Recently, a measurement set-up was presented to detect small nonlinear distortions in the vibration of acoustically driven mechanical systems. A speaker generates a specially designed multisine excitation signal that drives the vibration of a test object. The generated sound pressure is measured with a probe microphone in front of the test object, and an heterodyne vibrometer measures the corresponding vibration. Due to the high degree of linearity of the heterodyne technique, very small nonlinear distortions can be detected. In this paper the set-up is used to verify whether small nonlinear distortions are present in the vibration of the middle ear system, which is classically considered to be a completely linear system. In vitro measurements on the right ear of an adult male gerbil proved that nonlinear distortions are present in the vibration of the tympanic membrane. Similar results were seen in measurements on the left ear. The influence of post-mortem changes on the nonlinear behaviour of the middle ear was verified in a number of successive measurements. These indicated that the nonlinear behaviour of the middle ear decreases in time.

  15. Detonation Wave Profiles in Plastic Bonded Explosives Measured using 1550 nm Heterodyne Velocimetry

    NASA Astrophysics Data System (ADS)

    Gustavsen, Rick

    2009-06-01

    We have measured detonation wave profiles in several triaminotrinitrobenzene (TATB) and cyclotetramethylene tetranitramine (HMX or octogen) based plastic bonded explosives using 1550 nm Heterodyne Velocimetry. (Heterodyne Velocimetry is also called Photon Doppler Velocimetry or PDV.) Planar detonations were produced by impacting the explosive with projectiles launched in a gas gun. Particle velocity wave profiles were measured at the mirror/interface of the explosive and either a LiF or PMMA window. Mirrors consisted of either a thin vapor deposited aluminum layer, or a 6 micron thick aluminum foil. Focusing and collimating light collection probes were used. Time-Frequency-Analysis of the fringe data was carried out using both Wavelet and Short-Time-Fourier-Transform (STFT) methods. With clean fringe data, good profiles can be obtained with a 1 ns full width half maximum (FWHM) analysis window (STFT) or about 3 to 4 oscillations in the wavelet. Some profiles, however, have a noisy character which is correlated with intensity fluctuations in the raw fringe data. Wave profiles show a ZND reaction zone structure with a single reaction in the HMX based explosives and both fast and slow reactions in the TATB based explosives.

  16. Real-time high-resolution heterodyne-based measurements of spectral dynamics in fibre lasers

    PubMed Central

    Sugavanam, Srikanth; Fabbri, Simon; Le, Son Thai; Lobach, Ivan; Kablukov, Sergey; Khorev, Serge; Churkin, Dmitry

    2016-01-01

    Conventional tools for measurement of laser spectra (e.g. optical spectrum analysers) capture data averaged over a considerable time period. However, the generation spectrum of many laser types may involve spectral dynamics whose relatively fast time scale is determined by their cavity round trip period, calling for instrumentation featuring both high temporal and spectral resolution. Such real-time spectral characterisation becomes particularly challenging if the laser pulses are long, or they have continuous or quasi-continuous wave radiation components. Here we combine optical heterodyning with a technique of spatio-temporal intensity measurements that allows the characterisation of such complex sources. Fast, round-trip-resolved spectral dynamics of cavity-based systems in real-time are obtained, with temporal resolution of one cavity round trip and frequency resolution defined by its inverse (85 ns and 24 MHz respectively are demonstrated). We also show how under certain conditions for quasi-continuous wave sources, the spectral resolution could be further increased by a factor of 100 by direct extraction of phase information from the heterodyned dynamics or by using double time scales within the spectrogram approach. PMID:26984634

  17. Realization of heterodyne acquisition and tracking with diode lasers at lambda of 1.55 micron

    NASA Astrophysics Data System (ADS)

    Hueber, Martin F.; Leeb, Walter R.; Scholtz, Arpad L.

    1991-05-01

    We designed, realized, and tested a laboratory model of an optical intersatellite link employing InGaAs DFB semiconductor lasers operating at a wavelength of 1.55 micron. Heterodyne sensing was used for both the spatial acquisition and the spatial tracking processes. During the acquisition process spiral scanning of the transmitter area of uncertainty is performed. For each spatial search position the local oscillator laser is swept through a predefined frequency uncertainty range until the beat signal appears at the desired intermediate frequency (IF = 700 MHz). A heterodyne quadrant detector was realized by using a four-sided reflecting pyramid to split the superimposed beam. During tracking, the microcomputer reads the tracking sensor output signals, calculates the required antenna correction, and feeds the appropriate signals to the beam steering unit. Thus we realized a digital tracking loop, whereas the intermediate frequency is stabilized by means of an analog control loop. The typical tracking error measured for various system conditions amounts to less than 1/20 of the FOV, i.e. less than +/- 25 microrad.

  18. A heterodyne interferometer with periodic nonlinearities smaller than ±10 pm

    NASA Astrophysics Data System (ADS)

    Weichert, C.; Köchert, P.; Köning, R.; Flügge, J.; Andreas, B.; Kuetgens, U.; Yacoot, A.

    2012-09-01

    The PTB developed a new optical heterodyne interferometer in the context of the European joint research project ‘Nanotrace’. A new optical concept using plane-parallel plates and spatially separated input beams to minimize the periodic nonlinearities was realized. Furthermore, the interferometer has the resolution of a double-path interferometer, compensates for possible angle variations between the mirrors and the interferometer optics and offers a minimal path difference between the reference and the measurement arm. Additionally, a new heterodyne phase evaluation based on an analogue to digital converter board with embedded field programmable gate arrays was developed, providing a high-resolving capability in the single-digit picometre range. The nonlinearities were characterized by a comparison with an x-ray interferometer, over a measurement range of 2.2 periods of the optical interferometer. Assuming an error-free x-ray interferometer, the nonlinearities are considered to be the deviation of the measured displacement from a best-fit line. For the proposed interferometer, nonlinearities smaller than ±10 pm were observed without any quadrature fringe correction.

  19. Monolithically integrated heterodyne optical phase-lock loop with RF XOR phase detector.

    PubMed

    Steed, Robert J; Pozzi, Francesca; Fice, Martyn J; Renaud, Cyril C; Rogers, David C; Lealman, Ian F; Moodie, David G; Cannard, Paul J; Lynch, Colm; Johnston, Lilianne; Robertson, Michael J; Cronin, Richard; Pavlovic, Leon; Naglic, Luka; Vidmar, Matjaz; Seeds, Alwyn J

    2011-10-10

    We present results for an heterodyne optical phase-lock loop (OPLL), monolithically integrated on InP with external phase detector and loop filter, which phase locks the integrated laser to an external source, for offset frequencies tuneable between 0.6 GHz and 6.1 GHz. The integrated semiconductor laser emits at 1553 nm with 1.1 MHz linewidth, while the external laser has a linewidth less than 150 kHz. To achieve high quality phase locking with lasers of these linewidths, the loop delay has been made less than 1.8 ns. Monolithic integration reduces the optical path delay between the laser and photodiode to less than 20 ps. The electronic part of the OPLL was implemented using a custom-designed feedback circuit with a propagation delay of ~1 ns and an open-loop bandwidth greater than 1 GHz. The heterodyne signal between the locked slave laser and master laser has phase noise below -90 dBc/Hz for frequency offsets greater than 20 kHz and a phase error variance in 10 GHz bandwidth of 0.04 rad2.

  20. Using the Heterodyne Method to Measure Velocities on Shock Physics Experiments

    NASA Astrophysics Data System (ADS)

    Strand, Oliver

    2007-06-01

    Velocimetry is an important diagnostic for shock physics experiments. Velocities for these types of experiments can be in the kilometer-per-second range. We have developed a new velocimetry diagnostic for use on shock physics experiments that is based upon the heterodyne method. This diagnostic is easily assembled from commercially available parts developed for the telecommunication industry. The entire system uses single mode fibers to transport the signals from the laser to the probes and back to the detectors. We mix the Doppler-shifted light from the moving surface with non-shifted light from the laser itself to generate a beat signal at the detector. For this system using 1550 nm lasers, a velocity of 1 km/s generates a beat signal of 1.29 GHz. The detectors and the digitizers must have high-bandwidth capabilities to faithfully follow the beat waveform to allow a determination of the frequency as a function of time. Our current system has a maximum velocity capability of over 5 km/s. This paper will describe the heterodyne velocimeter and will present some of the data that has been taken with it. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory, under contract No. W-7405-Eng-48.

  1. Balance System

    NASA Technical Reports Server (NTRS)

    1988-01-01

    TherEx Inc.'s AT-1 Computerized Ataxiameter precisely evaluates posture and balance disturbances that commonly accompany neurological and musculoskeletal disorders. Complete system includes two-strain gauged footplates, signal conditioning circuitry, a computer monitor, printer and a stand-alone tiltable balance platform. AT-1 serves as assessment tool, treatment monitor, and rehabilitation training device. It allows clinician to document quantitatively the outcome of treatment and analyze data over time to develop outcome standards for several classifications of patients. It can evaluate specifically the effects of surgery, drug treatment, physical therapy or prosthetic devices.

  2. Balancing Eggs

    ERIC Educational Resources Information Center

    Mills, Allan

    2014-01-01

    Theory predicts that an egg-shaped body should rest in stable equilibrium when on its side, balance vertically in metastable equilibrium on its broad end and be completely unstable on its narrow end. A homogeneous solid egg made from wood, clay or plastic behaves in this way, but a real egg will not stand on either end. It is shown that this…

  3. Balancing Eggs

    ERIC Educational Resources Information Center

    Mills, Allan

    2014-01-01

    Theory predicts that an egg-shaped body should rest in stable equilibrium when on its side, balance vertically in metastable equilibrium on its broad end and be completely unstable on its narrow end. A homogeneous solid egg made from wood, clay or plastic behaves in this way, but a real egg will not stand on either end. It is shown that this…

  4. Spatial heterodyne interferometry of VY Canis Major's, alpha Orionis, alpha Scorpii, and R leonis at 11 microns

    NASA Technical Reports Server (NTRS)

    Sutton, E. C.; Storey, J. W. V.; Betz, A. L.; Townes, C. H.; Spears, D. L.

    1977-01-01

    Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec.

  5. Digital balanced detection for fast optical computerized tomography

    NASA Astrophysics Data System (ADS)

    Hafiz, Rehan; Ozanyan, Krikor B.

    2006-10-01

    Analogue Balanced Photo-detection has found extensive usage in high- sensitivity small signal applications e.g. coherent heterodyne detection. It is particularly effective for laser intensity noise removal. Nevertheless, the high cost of the commercially available analogue systems makes them unsuitable for multi-channel applications, such as fast tomography. In this paper a flexible, scalable, inexpensive and compact solution for multi channel digital balanced detection is presented. The proposed system has two components: an analogue front-end, comprising a differential photodiode amplifier for minimizing the external interference noise, and a digital balanced noise remover. The latter component initially calculates a balancing factor (BF) from the average power ratio of the signal and reference photocurrents, measured with the object removed from the signal path. Three digital balancing algorithms (DBAx) are considered for subsequent processing. In DBA1, BF is directly used in real-time ratiometric calculations. In DBA2, the BF is adjusted in real time by monitoring the window-averaged power of the received photocurrents. In DBA3, first the baseline is removed using differentiation and then ratiometric detection is performed. Using the digital alternative only one measurement of the reference beam is necessary for single-source, multi-channel detection systems. The data from multiple channels are processed in parallel by pipelined hardware, configured as a state machine. The proposed system leads to a fast optical computerized tomography system using digital balanced detection.

  6. Balance (or Vestibular) Rehabilitation

    MedlinePlus

    ... the Public / Hearing and Balance Balance (or Vestibular) Rehabilitation Audiologic (hearing), balance, and medical diagnostic tests help ... whether you are a candidate for vestibular (balance) rehabilitation. Vestibular rehabilitation is an individualized balance retraining exercise ...

  7. Laser Heterodyne Radiometer for Sensitive Detection of CO2 and CH4

    NASA Technical Reports Server (NTRS)

    Wilson, Emily L.; Miller, J. Houston

    2011-01-01

    We propose to develop an inexpensive, miniaturized, passive laser heterodyne radiometer (LHR) using commercially available telecommunications laser components to measure two significant carbon cycle gases in the atmospheric column: carbon dioxide (CO2) and methane (CH4). This instrument would operate in tandem with the passive aerosol sensor currently used in AERONET (an established network of more than 450 ground aerosol monitoring instruments worldwide). Because aerosols induce a radiative effect that influences terrestrial carbon exchange, simultaneous detection of aerosols with these key carbon cycle gases offers a uniquely comprehensive measurement approach that supports the Decadal Survey. Laser heterodyne radiometry is a technique for detecting weak signals that was adapted from radio receiver technology. In a radio receiver, a weak input signal from a radio antenna is mixed with a stronger local oscillator signal. The mixed signal (beat note, or intermediate frequency) has a frequency equal to the difference between the input signal and the local oscillator. The intermediate frequency is amplified and sent to a detector that extracts the audio from the signal. In a laser heterodyne radiometer, the weak input signal is light that has undergone absorption by a trace gas. The local oscillator is a laser at a near-by frequency - in this case a low-cost distributed feedback (DFB) telecommunications laser. These two light waves are superimposed in either a beamsplitter or in a fiber coupler (as is the case in this design). The signals are mixed in the detector, and the RF beat frequency is extracted. Changes in concentration of the trace gas are realized through analyzing changes in the beat frequency amplitude. A schematic of the progression of the LHR development project is shown in the figure below. At the center (within the dashed line), light from the local oscillator is superimposed upon light that has undergone absorption by a trace gas, in a single mode

  8. High Resolution Infrared Heterodyne Spectroscopy: Ethylene bands at 10.5 MU m.

    NASA Astrophysics Data System (ADS)

    Morozhenko, V.; Kostiuk, T.; Buhl, D.; Hewagama, T.; Livengood, T. A.; Kollyukh, A.

    1998-09-01

    Heterodyne Spectroscopy can make a significant contribution to remote studies of planetary atmospheres and other gaseous astronomical objects. Infrared heterodyne investigations of planetary atmospheres permit the determination of their composition, distribution of pressure and temperature with altitude, and the investigation of local physics and chemistry. This method is especially important for the investigation of atmospheric dynamics. It has a high spectral resolution ( lambda /Delta lambda ~ 10(7) ), which makes it possible to remotely determine the direction and speed of winds with an accuracy 2 m/s (J.Goldstein et al., 1991). However, in order to retrieve the atmospheric parameters from atmospheric line measurements, it is important to know the molecular parameters of the lines being measured. Ethylene (C_2H_4) is an important hydrocarbon present in atmospheres of Jupiter, Saturn, and Titan (e.g., T.Kostiuk et al., 1993). It is a product of methane chemistry in the stratospheres of these planets and has a complicated spectrum in the middle IR region. This makes it a very interesting and usable probe of physical-dynamical properties of these atmospheres. In this report we present initial results of laboratory investigations of absorption lines of ethylene in the nu_4 , nu {_7} and nu_ {10} bands near 10.5 mu m. The measurements were made using a laboratory infrared heterodyne spectrometer with the ethylene gas at temperatures 293-297K and pressures 0.05-50 Torr. Parameters of more than 150 lines were measured relative to lines in the P and R branches of the (12) CO_2 laser and in the P branch of the (14) CO_2 laser. Absolute frequencies of the stronger lines were determined to +/- 5.3*10(-5) cm(-1) . Their intensities were determined to ~10%. The dependence of the line width on pressure was determined. Comparison of our results with other experimental and theoretical results (J. Hillman et al.,1998) will be discussed. V.Morozhenko acknowledges support under

  9. Balanced Can

    NASA Astrophysics Data System (ADS)

    Shakerin, Said

    2013-12-01

    The ordinary 12-oz beverage cans in the figures below are not held up with any props or glue. The bottom of such cans is stepped at its circumference for better stacking. When this kind of can is tilted, as shown in Fig. 1, the outside corners of the step touch the surface beneath, providing an effective contact about 1 cm wide. Because the contact is relatively wide and the geometry is symmetrical, it is easy to balance an empty can by simply adding an appropriate amount of water so that the overall center of mass is located directly above the contact. In fact, any amount of water between about 40 and 210 mL will work. A computational animation of this trick by Sijia Liang and Bruce Atwood that shows center of mass as a function of amount of added water is available at http://demonstrations.wolfram.com. Once there, search "balancing can."

  10. Airplane Balance

    NASA Technical Reports Server (NTRS)

    Huguet, L

    1921-01-01

    The authors argue that the center of gravity has a preponderating influence on the longitudinal stability of an airplane in flight, but that manufacturers, although aware of this influence, are still content to apply empirical rules to the balancing of their airplanes instead of conducting wind tunnel tests. The author examines the following points: 1) longitudinal stability, in flight, of a glider with coinciding centers; 2) the influence exercised on the stability of flight by the position of the axis of thrust with respect to the center of gravity and the whole of the glider; 3) the stability on the ground before taking off, and the influence of the position of the landing gear. 4) the influence of the elements of the glider on the balance, the possibility of sometimes correcting defective balance, and the valuable information given on this point by wind tunnel tests; 5) and a brief examination of the equilibrium of power in horizontal flight, where the conditions of stability peculiar to this kind of flight are added to previously existing conditions of the stability of the glider, and interfere in fixing the safety limits of certain evolutions.

  11. W-band Heterodyne Receiver Module with 27 K Noise Temperature

    NASA Technical Reports Server (NTRS)

    Gawande, R.; Reeves, R.; Cleary, K.; Readhead, A. C.; Gaier, T.; Kangaslahti, P.; Samoska, L.; Church, S.; Sieth, M.; Voll, P.; Harris, A.; Lai, R.; Sarkozy, S.

    2012-01-01

    We present noise temperature and gain measurements of a W-band heterodyne module populated with MMIC LNAs designed and fabricated using 35nm InP HEMT process. The module has a WR-10 waveguide input. GPPO connectors are used for the LO input and the I and and Q IF outputs. The module is tested at both ambient (300 K) and cryogenic (25 K) temperatures. At 25 K physical temperature, the module has a noise temperature in the range of 27-45 K over the frequency band of 75-111 GHz. The module gain varies between 15 dB and 27 dB. The band-averaged module noise temperature of 350 K and 33 K were measured over 80-110 GHz for the physical temperature of 300 K and 25 K, respectively. The resulting cooling factor is 10.6.

  12. An empirical correction for moderate multiple scattering in super-heterodyne light scattering.

    PubMed

    Botin, Denis; Mapa, Ludmila Marotta; Schweinfurth, Holger; Sieber, Bastian; Wittenberg, Christopher; Palberg, Thomas

    2017-05-28

    Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.

  13. Scanning laser differential-heterodyne interferometer for flying-height measurement.

    PubMed

    Ngoi, B K; Venkatakrishnan, K; Tan, B

    2000-02-01

    With conventional optical interferometry flying-height testing, a stationary measurement beam and a two-axis moving stage are used to measure slider-disk spacing at different points on the slider. Pitch angle or roll angle is calculated on the basis of the measurement results. We report on a scanning differential-heterodyne interferometer, which measures the continuous flying-height variation along the edge of a slider with two continuously scanning laser beams. Pitch angle or roll angle can be obtained directly from the scanning measurement. The system can also measure points individually to obtain the absolute flying height at different locations on the slider. Experiments were performed to demonstrate the concept of scanning measurement. The flying-height variation along the slider edge was measured by continuous scan and by point-to-point moving. The measurement results from continuous scan coincided with those of conventional methods.

  14. A Low-noise Micromachined Millimeter-Wave Heterodyne Mixer using Nb Superconducting Tunnel Junctions

    NASA Technical Reports Server (NTRS)

    DeLange, Gert; Jacobson, Brian R.; Hu, Qing

    1996-01-01

    A heterodyne mixer with a micromachined horn antenna and a superconductor-insulator-superconductor (SIS) tunnel junction as mixing element is tested in the W-band (75-115 GHz) frequency range. Micromachined integrated horn antennas consist of a dipole antenna suspended on a thin Si3N4 dielectric membrane inside a pyramidal cavity etched in silicon. The mixer performance is optimized by using a backing plane behind the dipole antenna to tune out the capacitance of the tunnel junction. The lowest receiver noise temperature of 30 +/- 3 K (without any correction) is measured at 106 GHz with a 3-dB bandwidth of 8 GHz. This sensitivity is comparable to the state-of-the-art waveguide and quasi-optical SIS receivers, showing the potential use of micromachined horn antennas in imaging arrays.

  15. Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

    NASA Technical Reports Server (NTRS)

    Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.

    2013-01-01

    We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

  16. An upgraded 32-channel heterodyne electron cyclotron emission radiometer on Tore Supra

    SciTech Connect

    Segui, J.L.; Molina, D.; Giruzzi, G.; Goniche, M.; Huysmans, G.; Maget, P.; Ottaviani, M.

    2005-12-15

    A 32-channel, 1 GHz spaced heterodyne radiometer is used on the Tore Supra tokamak to measure electron cyclotron emission (ECE) in the frequency range 78-110 GHz for the ordinary mode (O:E parallel B,k perpendicular B) and 94-126 GHz for the extraordinary mode (X:E perpendicular B,k perpendicular B). The radial resolution is essentially limited by ECE relativistic effects, depending on electron temperature and density, and not by the channels' frequency spacing. The time resolution depends on the acquisition scheme: the system allows for both 1 ms and 10 {mu}s acquisition. For example, this leads to precise electron temperature mapping during MHD activity. First experimental results obtained with this upgraded 32-channel radiometer are presented.

  17. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device

    PubMed Central

    Heywood, Sarah L.; Glavin, Boris A.; Beardsley, Ryan P.; Akimov, Andrey V.; Carr, Michael W.; Norman, James; Norton, Philip C.; Prime, Brian; Priestley, Nigel; Kent, Anthony J.

    2016-01-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1–12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies. PMID:27477841

  18. Terahertz Radiation Heterodyne Detector Using Two-Dimensional Electron Gas in a GaN Heterostructure

    NASA Technical Reports Server (NTRS)

    Karasik, Boris S.; Gill, John J.; Mehdi, Imran; Crawford, Timothy J.; Sergeev, Andrei V.; Mitin, Vladimir V.

    2012-01-01

    High-resolution submillimeter/terahertz spectroscopy is important for studying atmospheric and interstellar molecular gaseous species. It typically uses heterodyne receivers where an unknown (weak) signal is mixed with a strong signal from the local oscillator (LO) operating at a slightly different frequency. The non-linear mixer devices for this frequency range are unique and are not off-the-shelf commercial products. Three types of THz mixers are commonly used: Schottky diode, superconducting hot-electron bolometer (HEB), and superconductor-insulation-superconductor (SIS) junction. A HEB mixer based on the two-dimensional electron gas (2DEG) formed at the interface of two slightly dissimilar semiconductors was developed. This mixer can operate at temperatures between 100 and 300 K, and thus can be used with just passive radiative cooling available even on small spacecraft.

  19. Heterodyning technique to improve performance of delta-sigma-based beamformers.

    PubMed

    Freeman, S R; Quick, M K; Morin, M A; Anderson, R C; Desilets, C S; Linnenbrink, T E; O'Donnell, M

    1999-01-01

    Delta-sigma (DeltaSigma) modulators can implement a simpler digital ultrasound beamformer than can traditional architectures based on multi-bit analog-to-digital converters (A/D). The signal-to-noise ratio (SNR) of the DeltaSigma modulators, however, suffers from limited oversampling ratios. To improve the SNR of each channel, a mixing signal heterodynes narrowband signals to lower frequencies where the baseband DeltaSigma modulator performs better. Noise figure analyses are presented that illustrate the effectiveness of this technique in improving noise performance. Also, spectral Doppler and color flow simulations are presented that realistically emulate a 32 channel oversampled beamformer and compare these results with traditional and ideal systems.

  20. A 2 Thz Schottky Solid-State Heterodyne Receiver for Atmospheric Studies

    NASA Technical Reports Server (NTRS)

    Treuttel, Jeanne; Schlecht, Erich; Siles, Jose; Lee, Choonsup; Lin, Robert; Thomas, Bertrand; Gonzalez-Olvero, David; Yee, Jeng-Hwa; Wu, Dong; Mehdi, Imran

    2016-01-01

    Obtaining temperature, pressure, and composition profiles along with wind velocities in the Earth's thermosphere/ionosphere system is a key NASA goal for understanding our planet. We report on the status of a technology development effort to build an all-solid-state heterodyne receiver at 2.06 terahertz that will allow the measurement of the 2.06 terahertz [OI] line for altitudes greater than 100 kilometers. The receiver front end features low-parasitic Schottky diode mixer chips that are driven by a local oscillator (LO) source using Schottky diode based multipliers. The multiplier chain consists of a 38 gigahertz oscillator followed by a set of three cascaded triplers at 114 gigahertz, 343 gigahertz and 1.03 terahertz.

  1. Potential of a superconducting photon counter for heterodyne detection at the telecommunication wavelength

    NASA Astrophysics Data System (ADS)

    Shcherbatenko, M.; Lobanov, Y.; Semenov, A.; Kovalyuk, V.; Korneev, A.; Ozhegov, R.; Kazakov, A.; Voronov, B. M.; Goltsman, G. N.

    2016-12-01

    Here, we report on successful operation of a NbN thin film superconducting nanowire single-photon detector (SNSPD) in a coherent mode (as a mixer) at the telecommunication wavelength of 1550 nm. Providing the Local Oscillator power of the order of a few picowatts, we were practically able to reach the quantum noise limited sensitivity. The intermediate frequency gain bandwidth was limited by the spectral band of single-photon response pulse of the detector, which is proportional to the detector size. We observed gain bandwidth of 65 MHz and 140 MHz for 7x7 um^2 and 3x3 um^2 devices respectively. Tiny amount of the required Local Oscillator power and wide gain and noise bandwidths along with the needless of any Low Noise Amplification opens possibility for a photon counting heterodyne-born megapixel array development.

  2. Design and simulated performance of a CARS spectrometer for dynamic temperature measurements using electronic heterodyning

    NASA Technical Reports Server (NTRS)

    Deen, M. Jamal; Thompson, E. D.

    1989-01-01

    A new design for generating CARS signals and for the detection and processing of these signals is presented and evaluated. The design is based on electronic heterodyning of the CARS spectrum of nitrogen at two selected narrowband frequencies, ratioing the resulting signal strengths, and comparing this ratio with a theoretically derived temperature scale. A reference cell is incorporated into the design for system calibration and for accurate temperature measurements. The spectrometer is found capable of measuring temperature in the submillisecond time scale with an accuracy of 10 percent in the 1000-2000 K temperature range. A typical result using the Hg(x)Cd(1-x)Te photomixer for T = 1500 K, Delta T = 50 K is a SNR of 21 dB and a data collection rate of 300 Hz.

  3. Automated control and data acquisition for a tunable diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Shull, T. S.; Rinsland, P. L.

    1983-01-01

    This paper describes the hardware and software design, development, and implementation of the control and data electronics of a laser heterodyne spectrometer instrument being built at NASA Langley Research Center for a technology demonstration. Functional partitioning, applied at all levels of hardware and software, has been found to provide expedient design, development, and testing of the instrument. The instrument is composed of distributed microprocessor-based units. A master/slave protocol is presented which can be simulated by a terminal for unit checkout. All but one of the units are implemented using a set of core boards, plus unique boards where necessary. This design has led to reduced hardware development, reduced parts inventory, and replication of software modules, while providing the flexibility needed for a development instrument. The development tools and documentation guidelines are discussed.

  4. Optical Spatial Heterodyned Interferometry for Inspection of Micro-Electro-Mechanical Systems

    SciTech Connect

    Tobin Jr, Kenneth William; Bingham, Philip R; Price, Jeffery R

    2005-01-01

    Interferometric imaging has the potential to extend the usefulness of optical microscopes by encoding small phase shifts that reveal information about topology and materials. At the Oak Ridge National Laboratory (ORNL), we have developed an optical Spatial Heterodyne Interferometry (SHI) method that captures reflection images containing both phase and amplitude information at a high rate of speed. By measuring the phase of a wavefront reflected off or transmitted through a surface, the relative surface heights and some materials properties can be measured. In this paper we briefly review our historical application of SHI in the semiconductor industry, but the focus is on new research to adapt this technology to the inspection of MEMS devices, in particular to the characterization of motion elements such as microcantilevers and deformable mirror arrays.

  5. Multichannel optical-fibre heterodyne interferometer for ultrasound detection of partial discharges in power transformers

    NASA Astrophysics Data System (ADS)

    Posada, J. E.; Garcia-Souto, J. A.; Rubio-Serrano, J.

    2013-09-01

    A multichannel interferometric system is proposed for the ultrasonic detection of partial discharges using intrinsic optical fibre sensors that may be immersed in oil. It is based on a heterodyne scheme which drives at least four sensor heads in order to localize the source of the acoustic emissions. Proper design of the sensing head improves its sensitivity through magnification and reaches a compact encapsulated probe able to be installed within power transformers. The optoelectronic implementation and the experimental tests are presented to optimize the resolution (4 channels—4 mrad). In addition, the results of ultrasound measurements at 150 kHz with an optical fibre sensor immersed in water in an acoustic test bench are shown, in which a resolution better than 10 Pa was obtained. Finally, the set-up for three-phase power transformers is demonstrated and characterized to detect and locate the source of acoustic emissions.

  6. 1.6 THz heterodyne receiver for the far infrared space telescope

    NASA Astrophysics Data System (ADS)

    Cherednichenko, S.; Kroug, M.; Merkel, H.; Khosropanah, P.; Adam, A.; Kollberg, E.; Loudkov, D.; Gol'Tsman, G.; Voronov, B.; Richter, H.; Huebers, H.-W.

    2002-08-01

    A low noise heterodyne receiver is being developed for the terahertz range using a phonon-cooled hot-electron bolometric mixer based on 3.5 nm thick superconducting NbN film. In the 1-2 GHz intermediate frequency band the double-sideband receiver noise temperature was 450 K at 0.6 THz, 700 K at 1.6 THz and 1100 K at 2.5 THz. In the 3-8 GHz IF band the lowest receiver noise temperature was 700 K at 0.6 THz, 1500 K at 1.6 THz and 3000 K at 2.5 THz while it increased by a factor of 3 towards 8 GHz.

  7. The effect of patch potentials in Casimir force measurements determined by heterodyne Kelvin probe force microscopy.

    PubMed

    Garrett, Joseph L; Somers, David; Munday, Jeremy N

    2015-06-03

    Measurements of the Casimir force require the elimination of the electrostatic force between the surfaces. However, due to electrostatic patch potentials, the voltage required to minimize the total force may not be sufficient to completely nullify the electrostatic interaction. Thus, these surface potential variations cause an additional force, which can obscure the Casimir force signal. In this paper, we inspect the spatially varying surface potential of e-beamed, sputtered, sputtered and annealed, and template stripped gold surfaces with Heterodyne amplitude modulated Kelvin probe force microscopy (HAM-KPFM). It is demonstrated that HAM-KPFM improves the spatial resolution of surface potential measurements compared to amplitude modulated Kelvin probe force microscopy. We find that patch potentials vary depending on sample preparation, and that the calculated pressure can be similar to the pressure difference between Casimir force calculations employing the plasma and Drude models.

  8. Heterodyne spectrophotometry of ozone in the 9.6-micron band using a tunable diode laser

    NASA Technical Reports Server (NTRS)

    Mcelroy, C. T.; Goldman, A.; Fogal, P. F.; Murcray, D. G.

    1990-01-01

    Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (0.0003/cm) solar spectra in the 9.6-micron ozone band. Observations have shown that a signal-to-noise ratio of 120:1 (about 30 percent of theoretical) for an integration time of 1/8 s can be achieved at a resolution of 0.0013 wave numbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that measured at the nearby NOAA ozone monitoring facility in Boulder, Colorado. Line positions for several ozone lines in the spectral region 996-997/cm are reported. Recent improvements have produced a signal-to-noise ratio of 95:1 (about 40 percent of theoretical) at 0.0003/cm and extended the range of wavelengths which can be observed.

  9. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device.

    PubMed

    Heywood, Sarah L; Glavin, Boris A; Beardsley, Ryan P; Akimov, Andrey V; Carr, Michael W; Norman, James; Norton, Philip C; Prime, Brian; Priestley, Nigel; Kent, Anthony J

    2016-08-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1-12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

  10. Synchronous high speed multi-point velocity profile measurement by heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Hou, Xueqin; Xiao, Wen; Chen, Zonghui; Qin, Xiaodong; Pan, Feng

    2017-02-01

    This paper presents a synchronous multipoint velocity profile measurement system, which acquires the vibration velocities as well as images of vibrating objects by combining optical heterodyne interferometry and a high-speed CMOS-DVR camera. The high-speed CMOS-DVR camera records a sequence of images of the vibrating object. Then, by extracting and processing multiple pixels at the same time, a digital demodulation technique is implemented to simultaneously acquire the vibrating velocity of the target from the recorded sequences of images. This method is validated with an experiment. A piezoelectric ceramic plate with standard vibration characteristics is used as the vibrating target, which is driven by a standard sinusoidal signal.

  11. Laser heterodyne interferometric signal processing method based on rising edge locking with high frequency clock signal.

    PubMed

    Zhang, Enzheng; Chen, Benyong; Yan, Liping; Yang, Tao; Hao, Qun; Dong, Wenjun; Li, Chaorong

    2013-02-25

    A novel phase measurement method composed of the rising-edge locked signal processing and the digital frequency mixing is proposed for laser heterodyne interferometer. The rising-edge locked signal processing, which employs a high frequency clock signal to lock the rising-edges of the reference and measurement signals, not only can improve the steepness of the rising-edge, but also can eliminate the error counting caused by multi-rising-edge phenomenon in fringe counting. The digital frequency mixing is realized by mixing the digital interference signal with a digital base signal that is different from conventional frequency mixing with analogue signals. These signal processing can improve the measurement accuracy and enhance anti-interference and measurement stability. The principle and implementation of the method are described in detail. An experimental setup was constructed and a series of experiments verified the feasibility of the method in large displacement measurement with high speed and nanometer resolution.

  12. Ultrafast chirped optical waveform recorder using referenced heterodyning and a time microscope

    DOEpatents

    Bennett, Corey Vincent [Livermore, CA

    2011-11-22

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  13. Ultrafast chirped optical waveform recording using referenced heterodyning and a time microscope

    DOEpatents

    Bennett, Corey Vincent

    2010-06-15

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  14. Development of a Multi-axis Heterodyne Interferometry system for LISA

    NASA Astrophysics Data System (ADS)

    Fulda, Paul; Thorpe, James

    2017-01-01

    Precision laser interferometric readout of test mass position and angle is one of the key technologies enabling a space-based gravitational wave mission such as LISA. At Goddard Space Flight Center we are developing a test-bed to demonstrate a Multi-Axis Heterodyne Interferometry (MAHI) system capable of meeting the measurement, range of motion and noise requirements for the short-arm measurement (test-mass to spacecraft) of LISA. Crucially, this system will use an optical design, photoreceivers and phase measurement systems which are also suitable for the long-arm measurement (spacecraft to spacecraft), thus reducing mission complexity. We will report on the progress of the MAHI system development, including preliminary measurements from a table-top prototype MAHI system.

  15. Absolute distance measurement using frequency-sweeping heterodyne interferometer calibrated by an optical frequency comb.

    PubMed

    Wu, Xuejian; Wei, Haoyun; Zhang, Hongyuan; Ren, Libing; Li, Yan; Zhang, Jitao

    2013-04-01

    We present a frequency-sweeping heterodyne interferometer to measure an absolute distance based on a frequency-tunable diode laser calibrated by an optical frequency comb (OFC) and an interferometric phase measurement system. The laser frequency-sweeping process is calibrated by the OFC within a range of 200 GHz and an accuracy of 1.3 kHz, which brings about a precise temporal synthetic wavelength of 1.499 mm. The interferometric phase measurement system consisting of the analog signal processing circuit and the digital phase meter achieves a phase difference resolution better than 0.1 deg. As the laser frequency is sweeping, the absolute distance can be determined by measuring the phase difference variation of the interference signals. In the laboratory condition, our experimental scheme realizes micrometer accuracy over meter distance.

  16. Measuring the thermal expansion coefficient of the carbon fiber optical tube by heterodyne laser interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; He, Wenjun; Zhang, Lei; Zhao, Xuan; Tian, Yuqi

    2016-11-01

    In This paper, we present an experimental design of measuring thermal expansion coefficient of the carbon fiber optical tube based on the heterodyne laser interferometry. In the course of the experiment, the error caused by the temperature changes of the external environment was considered, and the compensation is carried out. The data of the experiment was recorded and analyzed. The curve of the thermal expansion coefficient of the carbon fiber optical tube was close. The measurement of the thermal expansion coefficient was finished within a small range of temperature changes. The thermal expansion coefficient of the carbon fiber optical tube was 6 0.78 x 10-5m/ ° C - × , which was consistent with the experience value. Athermalization for the supporting structure of the Cassette optical system was designed according to the results of the experiment.

  17. MASTER: A Triple Heterodyne Receiver for Astronomy in the Millimetre and Submillimetre Domain

    NASA Astrophysics Data System (ADS)

    Battistelli, E.; Zannoni, M.; Boella, G.; Gervasi, M.; Passerini, A.; Sironi, G.; Andreone, D.; Brunetti, L.; Lacquaniti, V.; Maggi, S.; Steni, R.; Natale, E.; Thorpe, J. R.

    A progress report of the MASTER project is presented here. MASTER is a system of three heterodyne receivers based on SIS (superconductor-insulator-superconductor) tunnel junction mixers. In our instrument these mixers will allow direct down-conversion from 94, 225, and 345 to 1.5GHz, the IF where the signal will be detected. This instrument, coupled to a 2-4m telescope like the one proposed for the DOME C base in Antarctica and in conjunction with an Acusto Optical Spectrometer, can be used to detect emission lines associated with molecular clouds in the interstellar medium. The current status of a 94GHz receiver, the prototype of MASTER, will be presented too. The study of the optical coupling between the receiver and MITO telescope in the Italian Alps will also be described.

  18. Measurement of the absolute wavefront curvature radius in a heterodyne interferometer.

    PubMed

    Hechenblaikner, Gerald

    2010-09-01

    We present an analytical derivation of the coupling parameter relating the angle between two interfering beams in a heterodyne interferometer to the differential phase signals detected by a quadrant photodiode. This technique, also referred to as differential wavefront sensing, is commonly used in space-based gravitational wave detectors to determine the attitude of a test mass in one of the interferometer arms from the quadrant diode signals. Successive approximations to the analytical expression are made to simplify the investigation of parameter dependencies. Motivated by our findings, we propose what we believe to be a new measurement method to accurately determine the absolute wavefront curvature of a single measurement beam. We also investigate the change in the coupling parameter when the interferometer "test mirror" is moved from its nominal position, an effect which mediates the coupling of mirror displacement noise into differential phase measurements.

  19. A laser interferometer for measuring straightness and its position based on heterodyne interferometry

    SciTech Connect

    Chen Benyong; Zhang Enzheng; Yan Liping; Li Chaorong; Tang Wuhua; Feng Qibo

    2009-11-15

    Not only the magnitude but also the position of straightness errors are of concern to users. However, current laser interferometers used for measuring straightness seldom give the relative position of the straightness error. To solve this problem, a laser interferometer for measuring straightness and its position based on heterodyne interferometry is proposed. The optical configuration of the interferometer is designed and the measurement principle is analyzed theoretically. Two experiments were carried out. The first experiment verifies the validity and repeatability of the interferometer by measuring a linear stage. Also, the second one for measuring a flexure-hinge stage demonstrates that the interferometer is capable of nanometer measurement accuracy. These results show that this interferometer has advantages of simultaneously measuring straightness error and the relative position with high precision, and a compact structure.

  20. Imaging system for low-density plasma by heterodyne interferometer with fan beam microwave

    NASA Astrophysics Data System (ADS)

    Ito, H.; Yugami, N.; Nishida, Y.; Sakai, W.

    2002-12-01

    A microwave imaging system based on a heterodyne interferometer has been developed to measure the spatial distribution of the plasma density without introducing any direct disturbance to the plasma by employing a diode array scattering technique. The imaging system with the use of a fan beam microwave for a radar system demonstrates the principle of the technique by placing finite-size dielectric phantoms instead of the plasma between the horn antenna and the diode antenna array. Experimental results show that very good image of the objects can be reconstructed and the system is equivalent to popularly known multichannel imaging system. As a result, it is possible to make simple, low-cost, and compact microwave interferometer for measuring the spatial distribution of the plasma density.

  1. Remote sensing of atmospheric winds using speckleturbulence interaction, a CO(2) laser, and optical heterodyne detection.

    PubMed

    Holmes, J F; Amzajerdian, F; Gudimetla, R V; Hunt, J M

    1988-06-15

    Speckle-turbulence interaction can be utilized to measure the vector wind in a plane perpendicular to the line of sight from a laser transmitter to a target. A continuous wave source of around 1 W and operating at 10.6 microm, in conjunction with an optical heterodyne receiver, has been used to measure atmospheric winds along horizontal paths. A theoretical basis, the experimental apparatus, processing techniques, and experimental results are presented. The technique has been demonstrated for remote sensing of atmospheric winds along horizontal paths but also has potential for global remote sensing of atmospheric winds and for onboard wind shear detection systems for aircraft. The results show that rms accuracies of the order of 0.5 m/s are possible with averaging times as short as 2 s.

  2. Highly integrated optical heterodyne phase-locked loop with phase/frequency detection.

    PubMed

    Lu, Mingzhi; Park, Hyunchul; Bloch, Eli; Sivananthan, Abirami; Bhardwaj, Ashish; Griffith, Zach; Johansson, Leif A; Rodwell, Mark J; Coldren, Larry A

    2012-04-23

    A highly-integrated optical phase-locked loop with a phase/frequency detector and a single-sideband mixer (SSBM) has been proposed and demonstrated for the first time. A photonic integrated circuit (PIC) has been designed, fabricated and tested, together with an electronic IC (EIC). The PIC integrates a widely-tunable sampled-grating distributed-Bragg-reflector laser, an optical 90 degree hybrid and four high-speed photodetectors on the InGaAsP/InP platform. The EIC adds a single-sideband mixer, and a digital phase/frequency detector, to provide single-sideband heterodyne locking from -9 GHz to 7.5 GHz. The loop bandwith is 400 MHz.

  3. Thermal phase lag heterodyne infrared imaging for current tracking in radio frequency integrated circuits

    NASA Astrophysics Data System (ADS)

    Perpiñà, X.; León, J.; Altet, J.; Vellvehi, M.; Reverter, F.; Barajas, E.; Jordà, X.

    2017-02-01

    With thermal phase lag measurements, current paths are tracked in a Class A radio frequency (RF) power amplifier at 2 GHz. The amplifier is heterodynally driven at 440 MHz and 2 GHz, and its resulting thermal field was inspected, respectively, at 1013 and 113 Hz with an infrared lock-in thermography system. The phase lag maps evidence with a higher sensitivity than thermal amplitude measurements an input-output loop due to a substrate capacitive coupling. This limits the amplifier's performance, raising the power consumption in certain components. Other information relative to local power consumption and amplifier operation is also inferred. This approach allows the local non-invasive testing of integrated systems regardless of their operating frequency.

  4. Design and simulated performance of a CARS spectrometer for dynamic temperature measurements using electronic heterodyning

    NASA Technical Reports Server (NTRS)

    Deen, M. Jamal; Thompson, E. D.

    1989-01-01

    A new design for generating CARS signals and for the detection and processing of these signals is presented and evaluated. The design is based on electronic heterodyning of the CARS spectrum of nitrogen at two selected narrowband frequencies, ratioing the resulting signal strengths, and comparing this ratio with a theoretically derived temperature scale. A reference cell is incorporated into the design for system calibration and for accurate temperature measurements. The spectrometer is found capable of measuring temperature in the submillisecond time scale with an accuracy of 10 percent in the 1000-2000 K temperature range. A typical result using the Hg(x)Cd(1-x)Te photomixer for T = 1500 K, Delta T = 50 K is a SNR of 21 dB and a data collection rate of 300 Hz.

  5. A W-Band Heterodyne FMCW Radar Based on TX IQ-Modulation

    NASA Astrophysics Data System (ADS)

    Feger, Reinhard; Wagner, Christoph; Stelzer, Andreas

    2011-08-01

    In this paper a method to realize a heterodyne frequency-modulated continuous-wave (FMCW) radar is presented. The proposed principle relies on the use of an inphase/quadrature (IQ)-modulator as single-sideband-mixer to shift the frequency of the FMCW-output away from dc. Since in any IQ-modulator phase and amplitude imbalances occur, the effect of these imbalances will be investigated by deriving the corresponding signal model. Based on this analysis, a method to compensate the imbalances by a predistortion of the modulation signal will be derived. The presented method does not require special test signals or additional hardware, but relies on a standard FMCW measurement onto a calibration target. A prototype radar system was built and used in test measurements to verify the proposed principle. The measurement results show that a suppression of unwanted signal components caused by IQ-imbalances better than 45 dB is achievable.

  6. The effect of patch potentials in Casimir force measurements determined by heterodyne Kelvin probe force microscopy

    NASA Astrophysics Data System (ADS)

    Garrett, Joseph L.; Somers, David; Munday, Jeremy N.

    2015-06-01

    Measurements of the Casimir force require the elimination of the electrostatic force between the surfaces. However, due to electrostatic patch potentials, the voltage required to minimize the total force may not be sufficient to completely nullify the electrostatic interaction. Thus, these surface potential variations cause an additional force, which can obscure the Casimir force signal. In this paper, we inspect the spatially varying surface potential of e-beamed, sputtered, sputtered and annealed, and template stripped gold surfaces with Heterodyne amplitude modulated Kelvin probe force microscopy (HAM-KPFM). It is demonstrated that HAM-KPFM improves the spatial resolution of surface potential measurements compared to amplitude modulated Kelvin probe force microscopy. We find that patch potentials vary depending on sample preparation, and that the calculated pressure can be similar to the pressure difference between Casimir force calculations employing the plasma and Drude models.

  7. Improving Spectral Results Using Row-by-Row Fourier Transform of Spatial Heterodyne Raman Spectrometer Interferogram.

    PubMed

    Barnett, Patrick D; Strange, K Alicia; Angel, S Michael

    2016-12-12

    This work describes a method of applying the Fourier transform to the two-dimensional Fizeau fringe patterns generated by the spatial heterodyne Raman spectrometer (SHRS), a dispersive interferometer, to correct the effects of certain types of optical alignment errors. In the SHRS, certain types of optical misalignments result in wavelength-dependent and wavelength-independent rotations of the fringe pattern on the detector. We describe here a simple correction technique that can be used in post-processing, by applying the Fourier transform in a row-by-row manner. This allows the user to be more forgiving of fringe alignment and allows for a reduction in the mechanical complexity of the SHRS.

  8. High-speed high-resolution heterodyne interferometer using a laser with low beat frequency.

    PubMed

    Diao, Xiaofei; Hu, Pengcheng; Xue, Zi; Kang, Yanhui

    2016-01-01

    A high-speed high-resolution heterodyne interferometer using a laser with low beat frequency is developed. The interferometer has two spatially separated parallel beams with different frequencies. Two interference signals with opposite Doppler shift are optically generated by the interferometric optics. The measurement electronics uses two identical phasemeters for the two opposite interference signals. The two interference signals are selectively used according to the speed of the target, which makes sure that the Doppler shift of the selected signal is always positive, so that the measurable speed is no longer limited by the beat frequency of the laser source. Experimental results show that the measurement resolution is 0.62 nm. The measurable speed can exceed the restriction determined by the beat frequency. Compared with a commercial interferometer, the displacement difference is less than 40 nm in a travel range of 900 mm.

  9. Development of long wavelength semiconductor diode lasers near 28 microns for use in infrared heterodyne spectrometers

    NASA Technical Reports Server (NTRS)

    Linden, K. J.

    1984-01-01

    The development of tunable diode lasers operating in the 28 micrometers spectral region for use in infrared heterodyne spectrometers is reported. A process capable of yielding lasers emitting 500 micron W of multimode power, 112 micron W in a true single mode and true single mode operation at laser currents of up to 35% above threshold was developed. Results were obtained from narrow mesastripe (20 micrometer wide) short cavity (120 micrometer length) laser configurations. Six stripe geometry lasers, with a variety of cavity widths and lengths were delivered. The techniques to fabricate such devices was obtained and the long term reliability of such lasers by reproducible electrical and optical output characteristics fabrication from lasers are demonstrated.

  10. Micromachined Millimeter- and Submillimeter-Wave SIS Heterodyne Receivers for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Hu, Qing

    1998-01-01

    A heterodyne mixer with a micromachined horn antenna and a superconductor -insulator-superconductor (SIS) tunnel junction as mixing element is tested in the W-band (75-115 GHz) frequency range. Micromachined integrated horn antennas consist of a dipole antenna suspended on a thin Si3N4 dielectric membrane inside a pyramidal cavity etched in silicon. The mixer performance is optimized by using a backing plane behind the dipole antenna to tune out the capacitance of the tunnel junction. The lowest receiver noise temperature of 30+/-3 K without any correction) is measured at 106 GHz with a 3-dB bandwidth of 8 GHz. This sensitivity is comparable to the state-of-the-art waveguide and quasi-optical SIS receivers, showing the potential use of micromachined horn antennas in imaging arrays.

  11. An empirical correction for moderate multiple scattering in super-heterodyne light scattering

    NASA Astrophysics Data System (ADS)

    Botin, Denis; Mapa, Ludmila Marotta; Schweinfurth, Holger; Sieber, Bastian; Wittenberg, Christopher; Palberg, Thomas

    2017-05-01

    Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.

  12. Heterodyne coherent anti-Stokes Raman scattering by the phase control of its intrinsic background

    SciTech Connect

    Wang Xi; Wang Kai; Welch, George R.; Sokolov, Alexei V.

    2011-08-15

    We demonstrate the use of femtosecond laser pulse shaping for precise control of the interference between the coherent anti-Stokes Raman scattering (CARS) signal and the coherent nonresonant background generated within the same sample volume. Our technique is similar to heterodyne detection with the coherent background playing the role of the local oscillator field. In our experiment, we first apply two ultrashort (near-transform-limited) femtosecond pump and Stokes laser pulses to excite coherent molecular oscillations within a sample. After a short and controllable delay, we then apply a laser pulse that scatters off of these oscillations to produce the CARS signal. By making fine adjustments to the probe field spectral profile, we vary the relative phase between the Raman-resonant signal and the nonresonant background, and we observe a varying spectral interference pattern. These controlled variations of the measured pattern reveal the phase information within the Raman spectrum.

  13. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device

    NASA Astrophysics Data System (ADS)

    Heywood, Sarah L.; Glavin, Boris A.; Beardsley, Ryan P.; Akimov, Andrey V.; Carr, Michael W.; Norman, James; Norton, Philip C.; Prime, Brian; Priestley, Nigel; Kent, Anthony J.

    2016-08-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1–12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

  14. Determination of thermoelastic material properties by differential heterodyne detection of impulsive stimulated thermal scattering

    PubMed Central

    Verstraeten, B.; Sermeus, J.; Salenbien, R.; Fivez, J.; Shkerdin, G.; Glorieux, C.

    2015-01-01

    The underlying working principle of detecting impulsive stimulated scattering signals in a differential configuration of heterodyne diffraction detection is unraveled by involving optical scattering theory. The feasibility of the method for the thermoelastic characterization of coating-substrate systems is demonstrated on the basis of simulated data containing typical levels of noise. Besides the classical analysis of the photoacoustic part of the signals, which involves fitting surface acoustic wave dispersion curves, the photothermal part of the signals is analyzed by introducing thermal wave dispersion curves to represent and interpret their grating wavelength dependence. The intrinsic possibilities and limitations of both inverse problems are quantified by making use of least and most squares analysis. PMID:26236643

  15. Automated control and data acquisition for a tunable diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Shull, T. S.; Rinsland, P. L.

    1983-01-01

    This paper describes the hardware and software design, development, and implementation of the control and data electronics of a laser heterodyne spectrometer instrument being built at NASA Langley Research Center for a technology demonstration. Functional partitioning, applied at all levels of hardware and software, has been found to provide expedient design, development, and testing of the instrument. The instrument is composed of distributed microprocessor-based units. A master/slave protocol is presented which can be simulated by a terminal for unit checkout. All but one of the units are implemented using a set of core boards, plus unique boards where necessary. This design has led to reduced hardware development, reduced parts inventory, and replication of software modules, while providing the flexibility needed for a development instrument. The development tools and documentation guidelines are discussed.

  16. Using Infrared Laser Heterodyne Radiometry to Search for Methane in the Atmosphere of Mars

    NASA Astrophysics Data System (ADS)

    Passmore, Richard; Bowles, Neil; Weidmann, Damien; Smith, Kevin

    2010-05-01

    Introduction Methane has been detected in the atmosphere of Mars by several research teams in the last few years. Ground-based observations [1][2] and space-based instruments (e.g. the Planetary Fourier Transform spectrometer on Mars Express [3]) have reported low levels of methane gas (approximately 10 ppb) in the Martian atmosphere. Methane detection is important as its presence could imply a biological origin, and Martian methane sources are still unknown. However, current methane concentration measurements are at instruments' lower limits of detection. The viability of remote sensing using infrared laser heterodyne radiometry (LHR) to detect methane in the Martian atmosphere is investigated. The LHR technique allows high spectral resolution (greater than 0.001 cm-1) measurements over a narrow spectral range (~10 cm-1) when a distributed feedback quantum cascade laser (QCL) is used as local oscillator. The advantages of such an instrument, including its compact lightweight design, over current remote sensing spectral instruments are reviewed. The Laser Heterodyne Radiometer Laser heterodyne radiometers have been used extensively, and with much success, for atmospheric studies such as work on stratospheric ozone [4], mainly because the ultrahigh spectral resolution of the instrument allows fully resolved narrow molecular absorption line-shapes, which contain information on vertical concentration profiles. It has been shown that a carefully selected specific high resolution micro-window provides as much vertical profile information as a medium resolution radiometer covering a broad spectral range [5]. In addition to the high spectral resolution, the LHR is also extremely compact and robust and so has a significant advantage when targeting specific trace species over larger instruments such as high-resolution Fourier Transform spectrometers. Quantum Cascade Laser as Local Oscillator At the heart of the current generation infrared LHR is the use of a Quantum Cascade

  17. Fast, high-resolution surface potential measurements in air with heterodyne Kelvin probe force microscopy

    NASA Astrophysics Data System (ADS)

    Garrett, Joseph L.; Munday, Jeremy N.

    2016-06-01

    Kelvin probe force microscopy (KPFM) adapts an atomic force microscope to measure electric potential on surfaces at nanometer length scales. Here we demonstrate that Heterodyne-KPFM enables scan rates of several frames per minute in air, and concurrently maintains spatial resolution and voltage sensitivity comparable to frequency-modulation KPFM, the current spatial resolution standard. Two common classes of topography-coupled artifacts are shown to be avoidable with H-KPFM. A second implementation of H-KPFM is also introduced, in which the voltage signal is amplified by the first cantilever resonance for enhanced sensitivity. The enhanced temporal resolution of H-KPFM can enable the imaging of many dynamic processes, such as such as electrochromic switching, phase transitions, and device degredation (battery, solar, etc), which take place over seconds to minutes and involve changes in electric potential at nanometer lengths.

  18. Heterodyne Receiver Requirements for the Single Aperture Far-Infrared (SAFIR) Observatory

    NASA Technical Reports Server (NTRS)

    Benford, Dominic J.; Kooi, Jacob; Oegerle, William (Technical Monitor)

    2003-01-01

    In the next few years, work will commence in earnest on the development of technology for the next generation large cryogenic far-infrared telescope: the Single Aperture Far- Infrared (SAFIR) Observatory. SAFIR's science goals are driven by the fact that youngest stages of almost all phenomena in the universe are shrouded in absorption by cool dust, resulting in the energy being emitted primarily in the far-infrared. The earliest stages of star formation, when gas and dust clouds are collapsing and planets forming, can only be observed in the far-infrared. Spectral diagnostics in the far-infrared are typically quite narrow (approx. 1 km/s) and require high sensitivity to detect them. SAFIR is a 10 m-class telescope designed for cryogenic operation at L2, removing all sources of thermal emission from the telescope and atmosphere. Despite its limited collecting area and angular resolution as compared to the ALMA interferometer, its potential for covering the entire far-infrared band cannot be matched by any ground-based or airborne observatory. This places a new challenge on heterodyne receivers: broad frequency coverage. The ideal mixer would be able to detect frequencies over several octaves (e.g., 0.6 THz - 12 THz) with near quantum-limited performance at all frequencies. In contrast to ground-based observatories, it may not be necessary to strive for high instantaneous bandwidth, as direct detection spectroscopy is preferable for bandwidths of Delta v/ v greater than or equal to 10(exp -4) (e.g., 1 GHz at 10 THz). We consider likely directions for technology development for heterodyne receivers for SAFIR.

  19. Characteristics and performance of offset phase locked single frequency heterodyned laser systems

    NASA Astrophysics Data System (ADS)

    Tulchinsky, David A.; Hastings, Alexander S.; Williams, Keith J.

    2016-05-01

    We demonstrate and characterize the performance of two heterodyned optical phase locked loop (PLL) laser systems for use in characterizing photodetector RF frequency response and nonlinearities. Descriptions of PLL circuit parameters for Nd:YAG non-planar ring oscillator lasers at 1064 nm and 1319 nm, and Er ion fiber lasers from 1530 nm to 1565 nm are presented. Both laser systems have piezoelectric transducer wavelength control over the PLL voltage controlled oscillator circuit. Offset frequency phase locking from 1.5 kHz to 51+ GHz is demonstrated. Frequency stability at 10 MHz is measured to be ±50 μHz, limited by the stability of the Rb stabilized crystal oscillator. Phase noise of the phase-locked 1319 nm laser system is discussed where we find that the phase noise is dominated by the input source noise at frequency offsets below 100 Hz and by the laser's RIN noise at frequency offsets > 100 Hz. Comparing nonlinearity data from an InGaAs p-i-n photodiode using both 1319 nm and 1550 nm PLL nonlinearity measurement systems, we find two new separate photodetector nonlinearity mechanisms. Measurements of the harmonic components of a 11 MHz sinusoidal heterodyned optical beat note signal are found to be at or below 1 nW/mW for the second harmonic (at 22 MHz) and at or below 0.25 nW/mW for the 3rd harmonic (at 33 MHz), confirming the nearly pure sinusoidal nature of the optically generated microwave beat note.

  20. Characteristics and performance of offset phase locked single frequency heterodyned laser systems.

    PubMed

    Tulchinsky, David A; Hastings, Alexander S; Williams, Keith J

    2016-05-01

    We demonstrate and characterize the performance of two heterodyned optical phase locked loop (PLL) laser systems for use in characterizing photodetector RF frequency response and nonlinearities. Descriptions of PLL circuit parameters for Nd:YAG non-planar ring oscillator lasers at 1064 nm and 1319 nm, and Er ion fiber lasers from 1530 nm to 1565 nm are presented. Both laser systems have piezoelectric transducer wavelength control over the PLL voltage controlled oscillator circuit. Offset frequency phase locking from 1.5 kHz to 51+ GHz is demonstrated. Frequency stability at 10 MHz is measured to be ±50 μHz, limited by the stability of the Rb stabilized crystal oscillator. Phase noise of the phase-locked 1319 nm laser system is discussed where we find that the phase noise is dominated by the input source noise at frequency offsets below 100 Hz and by the laser's RIN noise at frequency offsets > 100 Hz. Comparing nonlinearity data from an InGaAs p-i-n photodiode using both 1319 nm and 1550 nm PLL nonlinearity measurement systems, we find two new separate photodetector nonlinearity mechanisms. Measurements of the harmonic components of a 11 MHz sinusoidal heterodyned optical beat note signal are found to be at or below 1 nW/mW for the second harmonic (at 22 MHz) and at or below 0.25 nW/mW for the 3rd harmonic (at 33 MHz), confirming the nearly pure sinusoidal nature of the optically generated microwave beat note.

  1. Initial Ground-based Thermospheric Wind Measurements Using Doppler Asymmetric Spatial Heterodyne Spectroscopy (DASH)

    NASA Astrophysics Data System (ADS)

    Englert, C. R.; Harlander, J.; Emmert, J. T.; Babcock, D. D.; Roesler, F. L.

    2010-12-01

    The Doppler Asymmetric Spatial Heterodyne (DASH) concept has recently been proposed to measure upper atmospheric winds. The DASH approach is identical to the concept of Spatial Heterodyne Spectroscopy (SHS) except that one interferometer arm exhibits an additional optical path offset, similar to the phase stepping Michelson technique which was used for the WINDII (Wind Imaging Interferometer) experiment. DASH therefore can be viewed as an optical remote sensing concept that is a hybrid of these two interferometric techniques. Its advantages include no moving parts, high sensitivity, and the ability to simultaneously observe a known light source for real time calibration. Both SHS and phase stepping Michelson instruments have already flown successfully on Earth orbiting satellites (SHIMMER on STPSat-1, WINDII on UARS) and DASH has been demonstrated successfully in the laboratory, which provides significant heritage for DASH. To further mitigate the risk of a future DASH satellite instrument, we built a brassboard DASH instrument, that is capable of measuring thermospheric winds from the ground, using the atomic oxygen red line emission OI(3P-1D) at λ=630nm. Such ground based Doppler shift measurements are routinely performed at many ground stations across the globe, typically using Fabry-Perot interferometers. A ground based DASH instrument gives us the opportunity to demonstrate thermospheric wind measurements using an atmospheric emission feature that is also suitable for space borne measurements. We will present the design of the Redline DASH Demonstration Instrument (REDDI) and the results of the initial ground based thermospheric wind observations. These successful ground based observations further increase the maturity of the DASH technique.

  2. First calibration and visible band observations of Khayyam, a Tunable Spatial Heterodyne Spectroscopy (SHS)

    NASA Astrophysics Data System (ADS)

    Hosseini, S.; Harris, W.; Corliss, J.

    2013-12-01

    We present initial results from observations of wide-field targets using new instrumentation based on an all-reflective spatial heterodyne spectrometer (SHS). SHS instruments are quasi common path two-beam Fourier transform spectrometers that produce 2-D spatial interference patterns without the requirement for moving parts. The utility of SHS comes from its combination of a wide input acceptance angle (0.5-1°), high resolving power (of order ~10^5), compact format, high dynamic range, and relaxed optical tolerances compared with other interferometer designs. This combination makes them extremely useful for velocity resolved for observations of wide field targets from both small and large telescopes. We have constructed both narrow band pass and broadly tunable designs at fixed focal plane facilities on Mt Hamilton and Kitt Peak. This report focuses on the tunable instrument at Mt Hamilton, which is at the focus of the Coudé Auxiliary Telescope (CAT). The CAT provides a test case for on-axis use of SHS, and the impact of the resulting field non-uniformity caused by the spider pattern will be discussed. Observations of several targets will be presented that demonstrate the capabilities of SHS, including comet C/2012 S1 (ISON), Jupiter, and both the day sky and night glow. Raw interferometric data and transformed power spectra will be shown and evaluated in terms of instrumental stability. Khayyam, The Tunable all-reflective Special Heterodyne Spectrometer (SHS) that has being characterized at the Coudé Auxiliary Telescope (CAT) on Mt. Hamilton.

  3. Vertical profiling of methane and carbon dioxide using high resolution near-infrared heterodyne spectroscopic observations

    NASA Astrophysics Data System (ADS)

    Rodin, Alexander; Klimchuk, Artem; Churbanov, Dmitry; Pereslavtseva, Anastasia; Spiridonov, Maxim; Nadezhdinskyi, Alexander

    2014-05-01

    We present new method of monitoring greenhouse gases using spectroscopic observations of solar radiation passed through the atmosphere with spectral resolution ΛvδΛ up to 108. Such a high resolution is achieved by heterodyne technique and allows to retrieve full information about spectral line shape which, in turn, is used to distinguish contribution of different atmospheric layers to the resulting absorption. Weak absorption line at 6056.5 cm-1 was selected for CO2 measurements and a quartet of lines centered at 6057 cm-1for CH4. The instrument setup includes Sun tracker with a microtelescope and chopper, diode DFB laser used as a local oscillator, a bundle of single mode optical fibers that provides medium for radiation transfer and beam coupling, reference cell with depressurized methane for LO frequency stabilization, and Fabry-Perot etalon for LO frequency calibration. A commercial p-i-n diode with squared detector replaces a mixer and IF spectrometer, providing measurement of heterodyne beating within a bandpass of few MHz, which determines the effective spectral resolution of the instrument. Spectral coverage within narrow range (about 1 cm-1) is provided by ramping the LO frequency based on feedback from the reference channel. Observations of Sun in the Moscow region have resulted for the first time in measurements of the atmospheric transmission near 1.65 μm with sub-Doppler spectral resolution. In order to retrieve vertical profiles of methane and carbon dioxide we developed the inversion algorithm implementing Tikhonov regularization approach. With measured transmission having S/N ratio of 100 or higher, the uncertainty of CH4 profile is about 10 ppb, with the uncertainty of CO2 profile at 1 ppm. This techniques is promising an affordable opportunity or widespread monitoring of greenhouse gases and may be implemented on existing ground-based stations. This work has been supported by the grant of Russian Ministry of education and science #11.G34.31.0074

  4. Laser photothermoacoustic heterodyned lock-in depth profilometry in turbid tissue phantoms.

    PubMed

    Fan, Ying; Mandelis, Andreas; Spirou, Gloria; Vitkin, I Alex; Whelan, William M

    2005-11-01

    Frequency-domain correlation and spectral analysis photothermoacoustic (FD-PTA) imaging is a promising new technique, which is being developed to detect tumor masses in turbid biological tissue. Unlike conventional biomedical photoacoustics which uses time-of-flight acoustic information induced by a pulsed laser to indicate the tumor size and location, in this research, a new FD-PTA instrument featuring frequency sweep (chirp) and heterodyne modulation and lock-in detection of a continuous-wave laser source at wavelength is constructed and tested for its depth profilometric capabilities with regard to turbid media imaging. Owing to the linear relationship between the depth of acoustic signal generation and the delay time of signal arrival to the transducer, information specific to a particular depth can be associated with a particular frequency in the chirp signal. Scanning laser-fluence modulation frequencies with a linear frequency sweep method preserves the depth-to-delay time linearity and recovers FD-PTA signals from a range of depths. Combining with the depth information carried by the back-propagated acoustic chirp signal at each scanning position, one could rapidly generate subsurface three-dimensional images of the scanning area at optimal signal-to-noise ratios and low laser fluences, a combination of tasks that is difficult or impossible by use of pulsed photoacoustic detection. In this paper, results of PTA scans performed on tissue mimicking control phantoms with various optical, acoustical, and geometrical properties are presented. A mathematical model is developed to study the laser-induced photothermoacoustic waves in turbid media. The model includes both the scattering and absorption properties of the turbid medium. A good agreement is obtained between the experimental and numerical results. It is concluded that frequency domain photothermoacoustics using a linear frequency sweep method and heterodyne lock-in detection has the potential to be a

  5. High spatial Resolution mapping of Venus Mesospheric Winds by infrared heterodyne Spectroscopy of CO2

    NASA Astrophysics Data System (ADS)

    Sonnabend, G.; Sornig, M.; Krötz, P.; Stupar, D.; Livengood, T.; Schieder, R.; Kostiuk, T.

    2007-08-01

    We present wind measurements in the Venusian upper mesosphere / lower thermosphere by means of infrared heterodyne spectroscopy of CO2 features at 959.3917 cm-1. Observations are carried out using the Cologne Tuneable Heterodyne Infrared Spectrometer (THIS) from May 25th to June 6th 2007 shortly before Venus superior conjunction at the McMath-Pierce solar telescope on Kitt Peak in Arizona. Providing high spectral resolution winds can be retrieved from Doppler-shifts of CO2 non-thermal emission from the upper mesosphere. The sub-solar to anti-solar flow (SS-AS flow) and the retrograde superrotating zonal circulation (RSZ) are targeted and observations are carried out systematically on the day-side of the planet which is illuminated appr. 50%. The mesospheric region is of special interest because it is the not very well understood transitions zone form the RSZ dominated troposphere and the SS-AS flow dominated thermosphere. Measurements are part of the coordinated ground-based observing campaign to support VenusExpress from May 25th to June 9th. Complementary ground based observing methods probing wind velocities at different altitudes in the atmosphere of Venus provide the possibility to get a vertical wind profile. E.g. Doppler shifts of CO2 lines at visible wavelength together with reflected solar Frauenhofer lines probe dynamics at the cloud tops and a few kilometer above while interferometric CO millimeter observations provide information about the lower mesosphere and sub-millimeter spectral line observations are pointing to a region between 95 and 105km. The presented mid- IR measurements probe an altitude of 100-120km.

  6. Automated reduction of sub-millimetre single-dish heterodyne data from the James Clerk Maxwell Telescope using ORAC-DR

    NASA Astrophysics Data System (ADS)

    Jenness, Tim; Currie, Malcolm J.; Tilanus, Remo P. J.; Cavanagh, Brad; Berry, David S.; Leech, Jamie; Rizzi, Luca

    2015-10-01

    With the advent of modern multidetector heterodyne instruments that can result in observations generating thousands of spectra per minute it is no longer feasible to reduce these data as individual spectra. We describe the automated data reduction procedure used to generate baselined data cubes from heterodyne data obtained at the James Clerk Maxwell Telescope (JCMT). The system can automatically detect baseline regions in spectra and automatically determine regridding parameters, all without input from a user. Additionally, it can detect and remove spectra suffering from transient interference effects or anomalous baselines. The pipeline is written as a set of recipes using the ORAC-DR pipeline environment with the algorithmic code using Starlink software packages and infrastructure. The algorithms presented here can be applied to other heterodyne array instruments and have been applied to data from historical JCMT heterodyne instrumentation.

  7. Balanced Matrices

    DTIC Science & Technology

    1994-04-01

    Kapoor M.R. Rao § Kristina Vu~kovic ¶ DTIC April 1994 ELECTE 1 SJjUN 01 1994uG - ,)ýK94-16267 "Dipartimento di Matematica Pura ed Applicata...introduce the connection with propositional logic and nonlinear 0, 1 optimization. In Section 3, we show how to sign a 0,1 matrix into a 0, ±1 balanced...polytope P(A) is irreducible. Then A is perfect if and only if all the monotone completions of A are perfect 0, 1 matrices. 2.4 Propositional Logic In

  8. Video image processing greatly enhances contrast, quality, and speed in polarization-based microscopy

    PubMed Central

    1981-01-01

    Video cameras with contrast and black level controls can yield polarized light and differential interference contrast microscope images with unprecedented image quality, resolution, and recording speed. The theoretical basis and practical aspects of video polarization and differential interference contrast microscopy are discussed and several applications in cell biology are illustrated. These include: birefringence of cortical structures and beating cilia in Stentor, birefringence of rotating flagella on a single bacterium, growth and morphogenesis of echinoderm skeletal spicules in culture, ciliary and electrical activity in a balancing organ of a nudibranch snail, and acrosomal reaction in activated sperm. PMID:6788777

  9. Elimination of depth degeneracy in optical frequency-domain imaging through polarization-based optical demodulation

    PubMed Central

    Vakoc, B. J.; Yun, S. H.; Tearney, G. J.; Bouma, B. E.

    2009-01-01

    A novel optical frequency-domain imaging system is demonstrated that employs a passive optical demodulation circuit and a chirped digital acquisition clock derived from a voltage-controlled oscillator. The demodulation circuit allows the separation of signals from positive and negative depths to better than 50 dB, thereby eliminating depth degeneracy and doubling the imaging depth range. Our system design is compatible with dual-balanced and polarization-diverse detection, important techniques in the practical biomedical application of optical frequency-domain imaging. PMID:16480209

  10. Keeping Your Balance

    MedlinePlus

    ... Exercise/Safe Movement › Keeping Your Balance Keeping Your Balance Balance is very important for people with osteoporosis. Your ... all play an important role in maintaining your balance and preventing broken bones. Medical conditions and medicines ...

  11. Balance Disorders (For Parents)

    MedlinePlus

    ... Habits for TV, Video Games, and the Internet Balance Disorders KidsHealth > For Parents > Balance Disorders Print A ... feel as happy and healthy as possible. How Balance Works To understand balance problems, it's important to ...

  12. Absolute distance measurement by multi-heterodyne interferometry using a frequency comb and a cavity-stabilized tunable laser.

    PubMed

    Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Balling, Petr; Qu, Xinghua

    2016-05-20

    In this paper, we develop a multi-heterodyne system capable of absolute distance measurement using a frequency comb and a tunable diode laser locked to a Fabry-Perot cavity. In a series of subsequent measurements, numerous beat components can be obtained by downconverting the optical frequency into the RF region with multi-heterodyne interferometry. The distances can be measured via the mode phases with a series of synthetic wavelengths. The comparison with the reference interferometer shows an agreement within 1.5 μm for the averages of five measurements and 2.5 μm for the single measurement, which is at the 10-8 relative precision level.

  13. Two-micrometer heterodyne differential absorption lidar measurements of the atmospheric CO2 mixing ratio in the boundary layer

    NASA Astrophysics Data System (ADS)

    Gibert, Fabien; Flamant, Pierre H.; Bruneau, Didier; Loth, Claude

    2006-06-01

    A 2 μm heterodyne differential absorption lidar (HDIAL) has been operated at the Instïtut Pierre Simon Laplace, Laboratoire de Météorologie Dynamique (Paris) to monitor the CO2 mixing ratio in absolute value at high accuracy in the atmospheric boundary layer. Horizontal measurements at increasing range are made to retrieve the optical depth. The experimental setup takes advantage of a heterodyne lidar developed for wind velocity measurements. A control unit based on a photoacoustic cell filled with CO2 is tested to correct afterward for ON-line frequency drift. The HDIAL results are validated using in situ routine measurements. The Doppler capability is used to follow the change in wind direction in the Paris suburbs.

  14. Atmospheric observations of multiple molecular species using ultra-high-resolution external cavity quantum cascade laser heterodyne radiometry.

    PubMed

    Weidmann, Damien; Tsai, Tracy; Macleod, Neil A; Wysocki, Gerard

    2011-06-01

    We demonstrate a widely tunable laser heterodyne radiometer operating in the thermal IR during an atmospheric observation campaign in the solar occultation viewing mode. An external cavity quantum cascade laser tunable within a range of 1120 to 1238 cm(-1) is used as the local oscillator (LO) of the instrument. Ultra-high-resolution (60 MHz or 0.002 cm(-1) transmission spectroscopy of several atmospheric species (water vapor, ozone, nitrous oxide, methane, and dichlorodifluoromethane) has been demonstrated within four precisely selected molecule-specific narrow spectral windows (∼1 cm(-1). Atmospheric transmission lines within each selected window were fully resolved through mode-hop-free continuous tuning of the LO frequency. Comparison measurements were made simultaneously with a high-resolution Fourier transform spectrometer to demonstrate the advantages of the laser heterodyne system for atmospheric sounding at high spectral and spatial resolutions. © 2011 Optical Society of America

  15. Two-micrometer heterodyne differential absorption lidar measurements of the atmospheric CO2 mixing ratio in the boundary layer.

    PubMed

    Gibert, Fabien; Flamant, Pierre H; Bruneau, Didier; Loth, Claude

    2006-06-20

    A 2 microm heterodyne differential absorption lidar (HDIAL) has been operated at the Instïtut Pierre Simon Laplace, Laboratoire de Météorologie Dynamique (Paris) to monitor the CO(2) mixing ratio in absolute value at high accuracy in the atmospheric boundary layer. Horizontal measurements at increasing range are made to retrieve the optical depth. The experimental setup takes advantage of a heterodyne lidar developed for wind velocity measurements. A control unit based on a photoacoustic cell filled with CO(2) is tested to correct afterward for ON-line frequency drift. The HDIAL results are validated using in situ routine measurements. The Doppler capability is used to follow the change in wind direction in the Paris suburbs.

  16. Nondestructive evaluation of as-implanted and annealed ultra shallow junctions by photothermal and photoluminescence heterodyne techniques

    NASA Astrophysics Data System (ADS)

    Geiler, H. D.; Karge, H.; Wagner, M.; Lerch, W.; Paul, S.

    2005-08-01

    The control of implantation dose, ion energy and the junction depth after annealing are key points of the on-line metrology for ultra shallow junction fabrication. Nondestructive and non-contact optical methods are examined with respect to their applicability for related tasks. High sensitive low noise photothermal heterodyne (PTH) and photoluminescence heterodyne (PLH) techniques are applied to control implant parameters of 0.5 keV B+ - implants both immediately after implantation and after spike annealing. The photothermal response shows that beside dose and energy dependencies monitored after implantation the spike annealing results in a layer with reduced carrier lifetime and mobility. By photoluminescence response the existence of an impurity band and the correlation with the p-n-junction depth is demonstrated by measuring the response of carrier dynamics.

  17. Modulated heterodyne light scattering set-up for measuring long relaxation time at small and wide angle

    NASA Astrophysics Data System (ADS)

    Leone, Nancy; Villari, Valentina; Micali, Norberto

    2012-08-01

    We present a simple, compact, and versatile experimental setup working in the heterodyne detection mode with modulation of the reference beam. The system is implemented with a collection optics based on a unimodal optical fiber coupler. This choice allows the heterodyne to be used in a wide range of scattering angles, even for very small ones, without losing the optical beating. The apparatus can be successfully used to study translational diffusive dynamics of dispersed particles at scattering angles smaller than 5° and it is suitable for exploring slow relaxation processes in sub-Hertz frequency domain, for example, in glass-forming systems. It is also possible to measure the electrophoretic mobility by applying an electric field into a charged particles solution.

  18. Shaft balancing

    DOEpatents

    Irwin, John A.

    1979-01-01

    A gas turbine engine has an internal drive shaft including one end connected to a driven load and an opposite end connected to a turbine wheel and wherein the shaft has an in situ adjustable balance system near the critical center of a bearing span for the shaft including two 360.degree. rings piloted on the outer diameter of the shaft at a point accessible through an internal engine panel; each of the rings has a small amount of material removed from its periphery whereby both of the rings are precisely unbalanced an equivalent amount; the rings are locked circumferentially together by radial serrations thereon; numbered tangs on the outside diameter of each ring identify the circumferential location of unbalance once the rings are locked together; an aft ring of the pair of rings has a spline on its inside diameter that mates with a like spline on the shaft to lock the entire assembly together.

  19. The Investigation of the Fundamental Limits of Heterodyne Holographic Interferometry with the Application of Imaging Laser Generated Lamb Waves

    DTIC Science & Technology

    1989-04-01

    study was conducted on the feasi- bility of using heterodyne holographic interferometry to detect and size surface breaking cracks in 718 inconel alloy...This information would include an accurate assessment of the integrity of the material along with the size and location of defects. However contact...example, from a manufacturing stand point, it would be advantageous to locate flaws and defects while a part was still at an elevated tem- perature

  20. NO2 heterodyne frequency measurements with a tunable diode laser, a CO laser transfer oscillator and CO2 laser standards

    NASA Technical Reports Server (NTRS)

    Zink, L. R.; Vanek, M.; Wells, J. S.

    1987-01-01

    Heterodyne frequency measurements have been made on selected groups of nitrogen dioxide rovibronic transitions between 1580.8 and 1650.7/cm. The groups are separated by 7 to 10/cm, and the intent is to provide a limited (and interim) calibration table for the region. In addition to a table of measured frequencies in the region, figures of spectra in the vicinity of the measured lines are included to provide a map for identifying the transitions measured.

  1. Ultrafast dynamics in complex fluids observed through the ultrafast optically-heterodyne-detected optical-Kerr-effect (OHD-OKE).

    PubMed

    Hunt, Neil T; Jaye, Andrew A; Meech, Stephen R

    2007-06-14

    The ultrafast molecular dynamics of complex fluids have been recorded using the optically-heterodyne-detected optical-Kerr-effect (OHD-OKE). The OHD-OKE method is reviewed and some recent refinements to the method are described. Applications to a range of complex fluids, including microemulsions, polymer melts and solutions, liquid crystal and ionic liquids are surveyed. The level of detail attainable with the OHD-OKE method in these complex fluids is discussed. The prospects for future experiments are discussed.

  2. Comparison between traditional and heterodyned optical Kerr gated imaging for CS2 and Te glass Kerr media

    NASA Astrophysics Data System (ADS)

    Zhan, Pingping; Tong, Junyi; Tan, Wenjiang; Xu, Shichao

    2016-11-01

    We demonstrated heterodyned optical Kerr gate (HOKG) ballistic imaging of an object hidden behind a turbid medium with two Kerr media. The experimental results showed that when compared with using HOKG of common Kerr medium CS2, a higher spatial resolution of the imaging system can be obtained by using HOKG of tellurite glass, which more effectively compensates for the high spatial-frequency components of the objects.

  3. High sensitivity transient infrared spectroscopy: a UV/Visible transient grating spectrometer with a heterodyne detected infrared probe.

    PubMed

    Donaldson, Paul M; Strzalka, Halina; Hamm, Peter

    2012-06-04

    We describe here a high sensitivity means of performing time resolved UV/Visible pump, infrared probe spectroscopy using optically Heterodyne Detected UV-IR Transient Gratings. The experiment design employed is simple, robust and includes a novel means of generating phase locked pulse pairs that relies on only mirrors and a beamsplitter. A signal to noise ratio increase of 24 compared with a conventional pump-probe arrangement is demonstrated.

  4. Heterodyne gas cell measurements at 2.9 THz using a quantum cascade laser as local oscillator

    NASA Astrophysics Data System (ADS)

    Ren, Y.; Gao, J. R.; Hovenier, J. N.; Higgins, R.; Zhang, W.; Bell, A.; Klein, B.; Klapwijk, T. M.; Shi, S. C.; Kao, T.-Y.; Kumar, S.; Hu, Q.; Reno, J. L.

    2010-07-01

    High-resolution heterodyne spectrometers operating at above 2 THz are crucial for detecting, e.g., the HD line at 2.7 THz and oxygen OI line at 4.7 THz in astronomy. The potential receiver technology is a combination of a hot electron bolometer (HEB) mixer and a THz quantum cascade laser (QCL) local oscillator (LO).Here we report the first highresolution heterodyne spectroscopy measurement of a gas cell using such a HEB-QCL receiver. The receiver employs a 2.9 THz free-running QCL as local oscillator and a NbN HEB as a mixer. By using methanol (CH3OH) gas as a signal source, we successfully recorded the methanol emission line at 2.92195 THz. Spectral lines at IF frequency at different pressures were measured using a FFTS and well fitted with a Lorentzian profile. Our gas cell measurement is a crucial demonstration of the QCL as LO for practical heterodyne instruments. Together with our other experimental demonstrations, such as using a QCL at 70 K to operate a HEB mixer and the phase locking of a QCL such a receiver is in principle ready for a next step, which is to build a real instrument for any balloon-, air-, and space-borne observatory.

  5. Heterodyne coherent detection of WDM PDM-QPSK signals with spectral efficiency of 4b/s/Hz.

    PubMed

    Li, Xinying; Dong, Ze; Yu, Jianjun; Yu, Jianguo; Chi, Nan

    2013-04-08

    We experimentally demonstrate heterodyne coherent detection of 8 × 112-Gb/s ultra-density wavelength-division-multiplexing (WDM) polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) signal after 1120-km single-mode fiber-28 (SMF-28) transmission. The spectral efficiency (SE) is 4b/s/Hz. It is the first time to realize WDM signal transmission with high SE by adopting heterodyne coherent detection. At the heterodyne coherent receiver, intermediate frequency (IF) down conversion is realized in digital frequency domain after analog-to-digital conversion. A digital post filter and 1-bit maximum likelihood sequence estimation (MLSE) adopted after carrier phase estimation (CPE) in the conventional digital-signal-processing (DSP) process is used to suppress the enhanced noise and crosstalk as well as overcome the filtering effects. The bit-error ratio (BER) for all channels is under the forward-error-correction (FEC) limit of 3.8 × 10(-3) after 1120-km SMF-28 transmission.

  6. Heterodyne detection and transmission of 60-Gbaud PDM-QPSK signal with SE of 4b/s/Hz.

    PubMed

    Li, Xinying; Xiao, Jiangnan; Yu, Jianjun

    2014-04-21

    We experimentally demonstrate 8 × 240-Gb/s super-Nyquist wavelength-division-multiplexing (WDM) polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) signal transmission on a 50-GHz grid with a net spectral efficiency (SE) of 4b/s/Hz adopting hardware-efficient simplified heterodyne detection. 9-ary quadrature-amplitude-modulation-like (9QAM-like) processing based on multi-modulus blind equalization (MMBE) is adopted to reduce analog-to-digital converter (ADC) bandwidth requirement and improve receiver sensitivity. The transmission distance at the soft-decision forward-error-correction (SD-FEC) threshold of 2 × 10(-2) is 2 × 420 km based on digital post filtering while largely extended to over 5 × 420 km based on 9QAM-like processing, which well illustrates 9QAM-like processing is more efficient for heterodyne coherent WDM system. Moreover, only two ADC channels are needed for simplified heterodyne detection of one 60-Gbaud PDM-QPSK WDM channel, and thus only one commercial oscilloscope (OSC) with two input ports can work well for each WDM channel.

  7. Periodic error characterization in commercial heterodyne interferometer using an external cavity diode laser based Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Zhu, Minhao; Wei, Haoyun; Li, Yan

    2014-07-01

    Periodic error is a main error source that limits the measurement accuracy in heterodyne laser interferometry. An external cavity diode laser (ECDL) based Fabry-Perot (F-P) interferometer referenced to an optical frequency comb (OFC) is proposed to characterize the periodic error in heterodyne interferometers. The Pound-Drever-Hall locking technique is employed to lock the tracking ECDL frequency to the resonance of a high finesse F-P cavity. The frequency of a reference ECDL is locked to a selected mode of an OFC to generate a stable single optical frequency. The frequency change of the tracking ECDL induced by the cavity displacement is measured by beating with the reference ECDL locked to the OFC. Experiments show that the F-P interferometer system has a displacement resolution of 1.96 pm. We compared the measurement results of our system with a commercial plane mirror heterodyne interferometer. The period if the periodic error is about half wavelength, with an error amplitude of 4.8 nm.

  8. Greenhouse Gas Concentration Data Recovery Algorithm for a Low Cost, Laser Heterodyne Radiometer

    NASA Technical Reports Server (NTRS)

    Miller, J. Houston; Melroy, Hilary R.; Ott, Lesley E.; Mclinden, Matthew L.; Holben, Brent; Wilson, Emily L.

    2012-01-01

    The goal of a coordinated effort between groups at GWU and NASA GSFC is the development of a low-cost, global, surface instrument network that continuously monitors three key carbon cycle gases in the atmospheric column: carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), as well as oxygen (O2) for atmospheric pressure profiles. The network will implement a low-cost, miniaturized, laser heterodyne radiometer (mini-LHR) that has recently been developed at NASA Goddard Space Flight Center. This mini-LHR is designed to operate in tandem with the passive aerosol sensor currently used in AERONET (a well established network of more than 450 ground aerosol monitoring instruments worldwide), and could be rapidly deployed into this established global network. Laser heterodyne radiometry is a well-established technique for detecting weak signals that was adapted from radio receiver technology. Here, a weak light signal, that has undergone absorption by atmospheric components, is mixed with light from a distributed feedback (DFB) telecommunications laser on a single-mode optical fiber. The RF component of the signal is detected on a fast photoreceiver. Scanning the laser through an absorption feature in the infrared, results in a scanned heterodyne signal io the RF. Deconvolution of this signal through the retrieval algorithm allows for the extraction of altitude contributions to the column signal. The retrieval algorithm is based on a spectral simulation program, SpecSyn, developed at GWU for high-resolution infrared spectroscopies. Variations io pressure, temperature, composition, and refractive index through the atmosphere; that are all functions of latitude, longitude, time of day, altitude, etc.; are modeled using algorithms developed in the MODTRAN program developed in part by the US Air Force Research Laboratory. In these calculations the atmosphere is modeled as a series of spherically symmetric shells with boundaries specified at defined altitudes. Temperature

  9. A Miniaturized Laser Heterodyne Radiometer for a Global Ground-Based Column Carbon Monitoring Network

    NASA Technical Reports Server (NTRS)

    Wilson, Emily L.; Melroy, Hilary R.; Miller, J. Houston; McLinden, Matthew L.; Ott, Lesley E.; Holben, Brent

    2012-01-01

    We present progress in the development of a passive, miniaturized Laser Heterodyne Radiometer (mini-LHR) that will measure key greenhouse gases (C02, CH4, CO) in the atmospheric column as well as their respective altitude profiles, and O2 for a measure of atmospheric pressure. Laser heterodyne radiometry is a spectroscopic method that borrows from radio receiver technology. In this technique, a weak incoming signal containing information of interest is mixed with a stronger signal (local oscillator) at a nearby frequency. In this case, the weak signal is sunlight that has undergone absorption by a trace gas of interest and the local oscillator is a distributive feedback (DFB) laser that is tuned to a wavelength near the absorption feature of the trace gas. Mixing the sunlight with the laser light, in a fast photoreceiver, results in a beat signal in the RF. The amplitude of the beat signal tracks the concentration of the trace gas in the atmospheric column. The mini-LHR operates in tandem with AERONET, a global network of more than 450 aerosol sensing instruments. This partnership simplifies the instrument design and provides an established global network into which the mini-LHR can rapidly expand. This network offers coverage in key arctic regions (not covered by OCO-2) where accelerated warming due to the release of CO2 and CH4 from thawing tundra and permafrost is a concern as well as an uninterrupted data record that will both bridge gaps in data sets and offer validation for key flight missions such as OCO-2, OCO-3, and ASCENDS. Currently, the only ground global network that routinely measures multiple greenhouse gases in the atmospheric column is TCCON (Total Column Carbon Observing Network) with 18 operational sites worldwide and two in the US. Cost and size of TCCON installations will limit the potential for expansion, We offer a low-cost $30Klunit) solution to supplement these measurements with the added benefit of an established aerosol optical depth

  10. Miniaturized Laser Heterodyne Radiometer (LHR) for Measurements of Greenhouse Gases in the Atmospheric Column

    NASA Technical Reports Server (NTRS)

    Steel, Emily; McLinden, Matthew

    2012-01-01

    This passive laser heterodyne radiometer (LHR) instrument simultaneously measures multiple trace gases in the atmospheric column including carbon dioxide (CO2) and methane (CH4), and resolves their concentrations at different altitudes. This instrument has been designed to operate in tandem with the passive aerosol sensor currently used in AERONET (an established network of more than 450 ground aerosol monitoring instruments worldwide). Because aerosols induce a radiative effect that influences terrestrial carbon exchange, simultaneous detection of aerosols with these key carbon cycle gases offers a uniquely comprehensive measurement approach. Laser heterodyne radiometry is a technique for detecting weak signals that was adapted from radio receiver technology. In a radio receiver, a weak input signal from a radio antenna is mixed with a stronger local oscillator signal. The mixed signal (beat note, or intermediate frequency) has a frequency equal to the difference between the input signal and the local oscillator. The intermediate frequency is amplified and sent to a detector that extracts the audio from the signal. In the LHR instrument described here, sunlight that has undergone absorption by the trace gas is mixed with laser light at a frequency matched to a trace gas absorption feature in the infrared (IR). Mixing results in a beat signal in the RF (radio frequency) region that can be related to the atmospheric concentration. For a one-second integration, the estimated column sensitivities are 0.1 ppmv for CO2, and <1 ppbv for CH4. In addition to producing a standalone ground measurement product, this instrument could be used to calibrate/validate four Earth observing missions: ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons), OCO-2 (Orbiting Carbon Observatory), OCO-3, and GOSAT (Greenhouse gases Observational SATellite). The only network that currently measures CO2 and CH4 in the atmospheric column is TCCON (Total Carbon Column

  11. Measurement of the modulation transfer function of x-ray scintillators via heterodyne speckles (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Manfredda, Michele; Giglio, Marzio

    2016-09-01

    The approach can be seen as the optical transposition of what is done in electronics, when a system is fed with a white noise (the input signal autocorrelation is a Diract-delta) and the autocorrelation of the the output signal is then taken, thus yielding the Point Spread Function (PSF) of the system (which is the Fourier Transform of the MTF). In the realm of optics, the tricky task consists in the generation and handling of such a suitable random noise, which must be produced via scattering. Ideally, pure 2D white noise (random superposition of sinusoidal intensity modulation at all spatial frequencies in all the diractions) would be produced by ideal point-like scatterers illuminated with completely coherent radiation: interference between scattered waves would generate high-frequency fringes, realizing the sought noise signal. Practically, limited scatterer size and limited coherence properties of radiation introduce a limitation in the spatial bandwidth of the illuminating field. Whereas information about particle-size effect can be promptly obtained from the form factor of the sample used, which is very well known in the case of spherical particles, the information about beam coherence, in general, is usally not known with adequate accuracy, especially at the x-ray wavelengths. In the particular configuration used, speckles are produced by interfering the scattered waves with the strong transmitted beam, (heterodyne speckles), contrarily to the very common case where speckles are produced by the mutual interference between scattered waves (without any transmitted beam acting as local oscillator) (homodyne speckles). In the end the use of an heterodyne speckle field, thanks to its self-referencing scheme, allows to gather, at a fixed distance, response curves spanning a wide range of wavevectors. By crossing the info from curves acquired at few distances (e.g. 2-3) , it is possible to experimentally separate the contribution of spurious effects (such as

  12. A 2 THz Heterodyne Array Receiver for SOFIA: Summary of Research

    NASA Technical Reports Server (NTRS)

    Walker, Christopher K.

    1998-01-01

    We proposed to perform a comprehensive design study of a 16-element heterodyne array receiver for SOFIA. The array was designed to utilize hot-electron bolometers in an efficient, low-cost waveguide mount to achieve low noise performance between approximately 1500 and 2400 GHz. Due to the prevailing physical conditions in the interstellar medium, this frequency range is one of the richest in the Far-Infra Red (FIR) portion of the spectrum. An array designed for this wavelength range will make excellent use of the telescope and the available atmospheric transmission, and will provide a new perspective on stellar, chemical, and galactic evolution in the present as well as past epochs. A few of the most important molecular and atomic species which the instrument will sample are CII, OI, CO, OH, NII, and CH. The system used the most sensitive detectors available in an efficient optical system. The local oscillator was a compact CO2 pumped far-infrared laser currently under development for SOFIA. The backend spectrometer was an array acousto-optic spectrometer (aAOS). The spectrometer utilizes proven hardware and technologies to provide broadband performance (> 1 GHz per AOS channel) and high spectral resolution (1 MHz) with the maximum sensitivity and minimum complexity and cost. The proposed instrument would be the fastest and most sensitive heterodyne receiver ever to operate in the 1.5 - 2.4 THz band. One of the key technologies developed for the proposed instrument is the laser micromachining of waveguide structures. These structures provide both the optical link between the instrument and the telescope (via an array of efficient feedhorns) and the impedance transformation between the detectors and free space. With the assistance of funds provided from this grant, we were able to fabricate and test the world's first laser micromachined feedhorns. The quality of the waveguide structure is far better than that obtainable using any other fabrication technique. The

  13. A Miniaturized Laser Heterodyne Radiometer for a Global Ground-Based Column Carbon Monitoring Network

    NASA Astrophysics Data System (ADS)

    Wilson, E. L.; Melroy, H.; Miller, J. H.; McLinden, M. L.; Ott, L.; Holben, B. N.

    2012-12-01

    We present progress in the development of a passive, miniaturized Laser Heterodyne Radiometer (mini-LHR) that will measure key greenhouse gases (CO2, CH4, CO) in the atmospheric column as well as their respective altitude profiles, and O2 for a measure of atmospheric pressure. Laser heterodyne radiometry is a spectroscopic method that borrows from radio receiver technology. In this technique, a weak incoming signal containing information of interest is mixed with a stronger signal (local oscillator) at a nearby frequency. In this case, the weak signal is sunlight that has undergone absorption by a trace gas of interest and the local oscillator is a distributive feedback (DFB) laser that is tuned to a wavelength near the absorption feature of the trace gas. Mixing the sunlight with the laser light, in a fast photo-receiver, results in a beat signal in the RF. The amplitude of the beat signal tracks the concentration of the trace gas in the atmospheric column. The mini-LHR operates in tandem with AERONET, a global network of more than 450 aerosol sensing instruments. This partnership simplifies the instrument design and provides an established global network into which the mini-LHR can rapidly expand. This network offers coverage in key arctic regions (not covered by OCO-2) where accelerated warming due to the release of CO2 and CH4 from thawing tundra and permafrost is a concern as well as an uninterrupted data record that will both bridge gaps in data sets and offer validation for key flight missions such as OCO-2, OCO-3, and ASCENDS. Currently, the only ground global network that routinely measures multiple greenhouse gases in the atmospheric column is TCCON (Total Column Carbon Observing Network) with 18 operational sites worldwide and two in the US. Cost and size of TCCON installations will limit the potential for expansion. We offer a low-cost (<$30K/unit) solution to supplement these measurements with the added benefit of an established aerosol optical depth

  14. Optical heterodyne-detected Raman-Induced Kerr Effect (OHD-RIKE) microscopy

    PubMed Central

    Freudiger, Christian W.; Roeffaers, Maarten B. J.; Zhang, Xu; Saar, Brian G.; Min, X., Wei; Xie, Sunney

    2012-01-01

    Label-free microscopy based on Raman scattering has been increasingly used in biomedical research to image samples that cannot be labeled or stained. Stimulated Raman scattering (SRS) microscopy, allows signal amplification of the weak Raman signal for fast imaging speeds without introducing the non-resonant background and coherent image artifacts that are present in coherent anti-Stokes Raman scattering (CARS) microscopy. Here we present the Raman-induced Kerr effect (RIKE) as a contrast for label-free microscopy. RIKE allows us to measure different elements of the non-linear susceptibility tensor, both the real and imaginary parts by optical heterodyne detection (OHD-RIKE). OHD-RIKE microscopy provides information similar to polarization CARS (P-CARS) and interferometric CARS (I-CARS) microscopy, with a simple modification of the two-beam SRS microscopy setup. We show that while OHD-RIKE micro-spectroscopy can be in principle more sensitive than SRS, it does not supersede SRS microscopy of heterogeneous biological samples, such as mouse skin tissue, because it is complicated by variations of linear birefringence across the sample. PMID:21504149

  15. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    DOE PAGES

    Tobias, B.; Domier, C. W.; Luhmann, Jr., N. C.; ...

    2016-07-25

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads tomore » 10x improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). As a result, implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.« less

  16. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    SciTech Connect

    Tobias, B.; Domier, C. W.; Luhmann, Jr., N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A. -V.; Wang, Y.

    2016-07-25

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10x improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). As a result, implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  17. Optical dispersion spectroscopy using optical frequency comb applied to dual-heterodyne mixing

    NASA Astrophysics Data System (ADS)

    Kasuga, Kaishu; Miyamoto, Takayuki; Shioda, Tatsutoshi

    2016-03-01

    The optical dispersion can be obtained from the adjacent relative phase between neighbor peaks in the optical frequency comb. Thus, the dispersion measurement becomes possible by measuring the relative phase spectrum. Our group has experimentally confirmed the operation principle by parallel capturing of the dispersion spectrum using an arrayed waveguide grating. We have proposed a dual-heterodyne mixing that obtained relative phases (ΔΦ) by fitting data of beat intensity versus optical path length difference. The path difference was applied by a delay line. In this study, we removed the delay line to realize a fast measurement by measuring simultaneous three relative phases with path length differences corresponding to π⁄2 or π, with which we have measured the dispersion in millisecond speed (250 sec. in previous ). In general, it is effective to measured chromatic dispersion using high-speed signal transmission in the fundamental scientific research, such as the analysis of material properties and telecommunications. It is, however, that limit of cutoff frequency using measurement is the restriction on increasing of the speed. Our proposed method to observe it on a frequency domain is effective for the high-speed signal processing.

  18. An Extremely Wide Bandwidth, Low Noise SIS Heterodyne Receiver Design for Millimeter and Submillimeter Observations

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, J.

    2004-01-01

    Our group has designed a heterodyne submillimeter receiver that offers a very wide IF bandwidth of 12 GHz, while still maintaining a low noise temperature. The 180-300 GHz double-sideband design uses a single SI5 device excited by a full bandwidth, fixed-tuned waveguide probe on a silicon substrate. The IF output frequency (limited by the MMIC low noise IF preamplifier) is 6-18 GHz. providing an instantaneous RF bandwidth of 24 GHz (double-sideband). Intensive simulations predict that the junction will achieve a conversion loss better than 1-2 dB and a mixer noise temperature of less than 20 K across the band (twice the quantum limit). The single sideband receiver noise temperature goal is 70 K. The wide instantaneous bandwidth and low noise will result in an instrument capable of a variety of important astrophysical and environmental observations beyond the capabilities of current instruments. Lab testing of the receiver will begin this summer, and first light on the CSO should be in the Spring of 2003. At the CSO, we plan to use receiver with WASP2, a wideband spectrometer, to search for spectral lines from SCUBA sources. This approach should allow us to rapidly develop a catalog of redshifts for these objects.

  19. Improved Acousto-Optic Modulators For CO2 Heterodyne Laser Systems

    NASA Astrophysics Data System (ADS)

    Hulme, K. F.; Pinson, J. T.

    1983-12-01

    The features of the RSRE chirp-modulated CW CO2 laser rangefinder/velocimeter based on a purpose-built acousto-optic modulator are briefly restated. The significance of acoustic reflections inside the acousto-optic modulator is described, particularly their increased importance when the transition to a single transmit/receive aperture is attempted; the need then arises to provide effective 60 MHz acoustic damping in the modulator block. Experiments with tungsten-loaded epoxy, with chill-cast Wood's metal layers and with electroplated indium layers are described. Acoustic damping effects are assessed quantitatively on acoustical and optical test benches. It is found that indium layers provide practical effective damping and open the way for single-aperture heterodyne CO2 systems of the modulated-CW type. Optical measurements on modulator blocks shaped to reduce acoustic reflections show that indium damping reduces the first unwanted modulated pulse emerging from the modulator due to acoustic reflections down to -55 db in power relative to the initial wanted pulse, compared with -38 db for uncoated block; unwanted pulses emerging later are reduced even more powerfully and long-delayed pulses become unobservably small.

  20. First Measurements of Simulated Upper Atmospheric Winds Using a Monolithic Doppler Asymmetric Spatial Heterodyne (DASH) Interferometer

    NASA Astrophysics Data System (ADS)

    Babcock, D. D.; Harlander, J.; Englert, C. R.; Roesler, F. L.; Pedersen, T. R.; Feldman, R.

    2010-12-01

    Results of the first calibrated Doppler measurements taken with a Doppler Asymmetric Spatial Heterodyne (DASH) instrument optimized for measuring simulated upper atmospheric winds using the O(1D) red line at 630nm will be presented. A space flight prototype DASH instrument has been designed, built, and is currently operational through funding from the Air Force Research Laboratory (AFRL) and in-kind support from the Naval Research Laboratory (NRL). The DASH instrument named ARROW (Atmospheric Redline inteRferometer for dOppler Winds) includes an internal emission line source for simultaneous calibration of the Doppler shift measurements, measured a laboratory emission line source which was Doppler shifted by known velocities. The comparison between the Doppler shifts that were retrieved from the DASH data and the shifts that were imposed on the laboratory emission line source demonstrate the accuracy of the measurements. This laboratory validation contributes significantly to our efforts to rapidly increase the technical readiness level of the DASH optical interferometric technique.

  1. Design of an Fiber-Coupled Laser Heterodyne Interferometer for the FLARE

    NASA Astrophysics Data System (ADS)

    Frank, Samuel; Yoo, Jongsoo; Ji, Hantao; Jara-Almonte, Jon

    2016-10-01

    The FLARE (Facility for Laboratory Reconnection Experiments), which is currently under construction at PPPL, requires a complete set of laboratory plasma diagnostics. The Langmuir probes that will be used in the device to gather local density data require a reliable interferometer system to serve as baseline for density measurement calibration. A fully fiber-coupled infrared laser heterodyne interferometer has been designed in order to serve as the primary line-integrated electron density diagnostic. Thanks to advances in the communications industry many fiber optic devices and phase detection methods have advanced significantly becoming increasingly reliable and inexpensive. Fully fiber coupling a plasma interferometer greatly simplifies alignment procedures needed since the only free space laser path needing alignment is through the plasma itself. Fiber-coupling also provides significant resistance to vibrational noise, a common problem in plasma interferometry systems. This device also uses a greatly simplified phase detection scheme in which chips, originally developed for the communications industry, capable of directly detecting the phase shift of a signal with high time resolution. The design and initial performance of the system will be discussed.

  2. THz Instrumentation for the Herschel Space Observatory's Heterodyne Instrument for Far Infrared

    NASA Technical Reports Server (NTRS)

    Pearson, J. C.; Mehdi, I.; Ward, J. S.; Maiwald, F.; Ferber, R. R.; Leduc, H. G.; Schlecht, E. T.; Gill, J. J.; Hatch, W. A.; Kawamura, J. H.; Stern, J. A.; Gaier, T. C.; Samoska, L. A.; Weinreb, S.; Bumble, B.; Pukala, D. M.; Javadi, H. H.; Finamore, B. P.; Lin, R. H.; Dengler, R. J.; Velebir, J. R.; Luong, E. M.; Tsang, R.; Peralta, A .; Wells, M.

    2004-01-01

    The Heterodyne Instrument for Far Infrared (HIFI) on ESA's Herschel Space Observatory utilizes a variety of novel RF components in its five SIS receiver channels covering 480-1250 GHz and two HEB receiver channels covering 1410-1910 GHz. The local oscillator unit will be passively cooled while the focal plane unit is cooled by superfluid helium and cold helium vapors. HIFI employs W-band GaAs amplifiers, InP HEMT low noise IF amplifiers, fixed tuned broadband planar diode multipliers, high power W-bapd Isolators, and novel material systems in the SIS mixers. The National Aeronautics and Space Administration through the Jet Propulsion Laboratory is managing the development of the highest frequency (1119-1250 GHz) SIS mixers, the local oscillators oscillators for the three highest frequency receivers as well as W-band power amplifiers, high power W-band isolators, varactor diode devices for all high frequency multipliers and InP HEMT components for all the receiver channels intermediate frequency amplifiers. The NASA developed components represent a significant advancement in the available performance. This paper presents an update of the performance and the current state of development.

  3. Noncontact photoacoustic tomography of in vivo chicken chorioallantoic membrane based on all-fiber heterodyne interferometry

    NASA Astrophysics Data System (ADS)

    Eom, Jonghyun; Park, Seong Jun; Lee, Byeong Ha

    2015-10-01

    We present three-dimensional (3-D) in vivo photoacoustic (PA) images of the blood vasculature of a chicken chorioallantoic membrane (CAM) obtained by using a fiber-based noncontact PA tomography system. With a fiber-optic heterodyne interferometer, the system measures the surface displacement of a sample, induced by the PA wave, which overcomes the disadvantage of physical-contact of ultrasonic transducer in a conventional system. The performance of an implemented system is analyzed and its capability of in vivo 3-D bioimaging is presented. At a depth of 2.5 mm in a phantom experiment, the lateral and axial resolutions were measured as 100 and 30 μm, respectively. The lateral resolution became doubled at a depth of 7.0 mm however, interestingly, the axial resolution was not noticeably deteriorated with the depth. With the CAM experiment, performed under the American National Standards Institute laser safety standard condition, blood vessel structures placed as deep as 3.5 mm were clearly recognized.

  4. Noncontact photoacoustic tomography of in vivo chicken chorioallantoic membrane based on all-fiber heterodyne interferometry.

    PubMed

    Eom, Jonghyun; Park, Seong Jun; Lee, Byeong Ha

    2015-10-01

    We present three-dimensional (3-D) in vivo photoacoustic (PA) images of the blood vasculature of a chicken chorioallantoic membrane (CAM) obtained by using a fiber-based noncontact PA tomography system. With a fiber-optic heterodyne interferometer, the system measures the surface displacement of a sample, induced by the PA wave, which overcomes the disadvantage of physical-contact of ultrasonic transducer in a conventional system. The performance of an implemented system is analyzed and its capability of in vivo 3-D bioimaging is presented. At a depth of 2.5 mm in a phantom experiment, the lateral and axial resolutions were measured as 100 and 30  μm, respectively. The lateral resolution became doubled at a depth of 7.0 mm; however, interestingly, the axial resolution was not noticeably deteriorated with the depth. With the CAM experiment, performed under the American National Standards Institute laser safety standard condition, blood vessel structures placed as deep as 3.5 mm were clearly recognized.

  5. Heterodyne stabilization as a possible laser frequency stabilization technique for LISA

    NASA Astrophysics Data System (ADS)

    Eichholz, Johannes

    The Laser Interferometer Space Antenna is a joint NASA/ESA mission aimed at the detection of gravitational wave radiation in the frequency range from 30 uHz to 0.1 Hz. LISA uses a modified Michelson interferometer setup consisting of three identical spacecraft, arranged in an equilateral triangular constellation. It measures the differential length changes of the 5 · 109 m long interferometer arms between free-floating proof masses housed within each spacecraft. Laser pre-stabilization is required in conjunction with Time-Delay Interferometry data post-processing to monitor the armlength changes with picometer precision. A modulation/demodulation technique to stabilize the frequency of the lasers to an optical reference cavity has been proposed for a long time, but it requires several additional optical components and would need to be built as a separate system. Using a different sensing tech-nique, heterodyne interferometry, we propose a modified stabilization scheme, which similarly transfers the stability of an optical reference cavity to the laser frequency. It only uses com-ponents that are already available in the LISA assembly and can easily be integrated into the optical bench design. A similar stabilization scheme is going to be used in LISA Pathfinder. We will discuss this technique in detail and present initial experimental results, as well as predicted performances on the LISA bench.

  6. Heterodynes dominate precipitation isotopes in the East Asian monsoon region, reflecting interaction of multiple climate factors

    NASA Astrophysics Data System (ADS)

    Thomas, Elizabeth K.; Clemens, Steven C.; Sun, Youbin; Prell, Warren L.; Huang, Yongsong; Gao, Li; Loomis, Shannon; Chen, Guangshan; Liu, Zhengyu

    2016-12-01

    For the past decade, East Asian monsoon history has been interpreted in the context of an exceptionally well-dated, high-resolution composite record of speleothem oxygen isotopes (δ18Ocave) from the Yangtze River Valley. This record is characterized by a unique spectral response, with variance concentrated predominantly within the precession band and an enigmatic lack of variance at the eccentricity and obliquity bands. Here we examine the spectral characteristics of all existing >250-kyr-long terrestrial water isotope records in Asia, including a new water isotope record using leaf wax hydrogen isotope ratios from the Chinese Loess Plateau. There exist profound differences in spectral characteristics among all orbital-scale Asian water isotope records. We demonstrate that these differences result from latitudinal gradients in the influence of the winter and summer monsoons, both of which impact climate and water isotopes throughout East Asia. Water isotope records therefore do not reflect precipitation during a single season or from a single circulation system. Rather, water isotope records in East Asia reflect the complex interplay of oceanic and continental moisture sources, operating at multiple Earth-orbital periods. These non-linear interactions are reflected in water isotope spectra by the presence of heterodynes. Although complex, we submit that water isotope records, when paired with rapidly developing isotope-enabled model simulations, will have the potential to elucidate mechanisms causing seasonal precipitation variability and moisture source variability in East Asia.

  7. Uncertainty Analysis for the Miniaturized Laser Heterodyne Radiometer (mini-LHR)

    NASA Technical Reports Server (NTRS)

    Clarke, G. B.; Wilson E. L.; Miller, J. H.; Melroy, H. R.

    2014-01-01

    Presented here is a sensitivity analysis for the miniaturized laser heterodyne radiometer (mini-LHR). This passive, ground-based instrument measures carbon dioxide (CO2) in the atmospheric column and has been under development at NASA/GSFC since 2009. The goal of this development is to produce a low-cost, easily-deployable instrument that can extend current ground measurement networks in order to (1) validate column satellite observations, (2) provide coverage in regions of limited satellite observations, (3) target regions of interest such as thawing permafrost, and (4) support the continuity of a long-term climate record. In this paper an uncertainty analysis of the instrument performance is presented and compared with results from three sets of field measurements. The signal-to-noise ratio (SNR) and corresponding uncertainty for a single scan are calculated to be 329.4+/-1.3 by deploying error propagation through the equation governing the SNR. Reported is an absorbance noise of 0.0024 for 6 averaged scans of field data, for an instrument precision of approximately 0.2 ppmv for CO2.

  8. Improving a commercially available heterodyne laser interferometer to sub-nm uncertainty

    NASA Astrophysics Data System (ADS)

    Haitjema, Han; Cosijns, Suzanne J. A. G.; Roset, N. J. J.; Jansen, Maarten J.

    2003-11-01

    Laser interferometer systems are known for their high resolution, and especially for their high range/resolution ratio. In dimensional metrology laboratories, laser interferometers are popular workhorses for the calibration of displacements. The uncertainty is usually limited to about 10 nm due to polarization- and frequency mixing. For demanding applications however nanometer uncertainty is desired. We adapted a commercially available heterodyne laser interferometer by feeding the measurement signal into a fast lock-in amplifier and use the laser interferometer reference signal as a reference. By measuring both the in-phase and quadrature component an uncorrected phase can be directly measured. By recording both components while the phase changes between 0 and 2π a typical ellipse is recorded from which the first and second harmonics of periodic deviations can be derived. These can be corrected independent of their origin. Measurements show that this method can reduce severe non-linearities (40 nm top-bottom) to a standard deviation of about 0.02 nm. Also, optical set-ups can be analysed to predict the non-linearities when a non-compensated standard interferometer is used.

  9. Micro-vibration detection with heterodyne holography based on time-averaged method

    NASA Astrophysics Data System (ADS)

    Qin, XiaoDong; Pan, Feng; Chen, ZongHui; Hou, XueQin; Xiao, Wen

    2017-02-01

    We propose a micro-vibration detection method by introducing heterodyne interferometry to time-averaged holography. This method compensates for the deficiency of time-average holography in quantitative measurements and widens its range of application effectively. Acousto-optic modulators are used to modulate the frequencies of the reference beam and the object beam. Accurate detection of the maximum amplitude of each point in the vibration plane is performed by altering the frequency difference of both beams. The range of amplitude detection of plane vibration is extended. In the stable vibration mode, the distribution of the maximum amplitude of each point is measured and the fitted curves are plotted. Hence the plane vibration mode of the object is demonstrated intuitively and detected quantitatively. We analyzed the method in theory and built an experimental system with a sine signal as the excitation source and a typical piezoelectric ceramic plate as the target. The experimental results indicate that, within a certain error range, the detected vibration mode agrees with the intrinsic vibration characteristics of the object, thus proving the validity of this method.

  10. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    SciTech Connect

    Tobias, B.; Domier, C. W.; Luhmann, N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A.-V.; Wang, Y.

    2016-11-15

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50–150 GHz) to an intermediate frequency (IF) band (e.g. 0.1–18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  11. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    SciTech Connect

    Tobias, B.; Domier, C. W.; Luhmann, Jr., N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A. -V.; Wang, Y.

    2016-07-25

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10x improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). As a result, implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  12. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry

    NASA Astrophysics Data System (ADS)

    Tobias, B.; Domier, C. W.; Luhmann, N. C.; Luo, C.; Mamidanna, M.; Phan, T.; Pham, A.-V.; Wang, Y.

    2016-11-01

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  13. A laser-heterodyne bunch length monitor for the SLC interaction point

    SciTech Connect

    Kotseroglou, T.; Alley, R.; Jobe, K.

    1997-05-01

    Since 1996, the transverse beam sizes at the SLC interaction point (IP) can be determined with a `laser wire`, by detecting the rate of Compton-scattered photons as a function of the beam-laser separation in space. Nominal laser parameters are: 350 nm wavelength, 2 mJ energy per pulse, 40 Hz repetition rate, and 150 ps FWHM pulse length. The laser system is presently being modified to enable measurements of the longitudinal beam profile. For this purpose, two laser pulses of slightly different frequency are superimposed, which creates a travelling fringe pattern and, thereby, introduces a bunch-to-bunch variation of the Compton rate. The magnitude of this variation depends on the beat wavelength and on the Fourier transform of the longitudinal distribution. This laser heterodyne technique is implemented by adding a 1-km long optical fibre at the laser oscillator output, which produces a linearly chirped laser pulse with 4.5-A linewidth and 60-ps FWHM pulse length. Also, the pulse is amplified in a regenerative amplifier and tripled with two nonlinear crystals. Then a Michelson interferometer spatially overlaps two split chirped pulses, which are temporally shifted with respect to each other, generating a quasi-sinusoidal adjustable fringe pattern. This laser pulse is then transported to the Interaction Point.

  14. Rapid detection of urinary polyomavirus BK by heterodyne-based surface plasmon resonance biosensor

    NASA Astrophysics Data System (ADS)

    Su, Li-Chen; Tian, Ya-Chung; Chang, Ying-Feng; Chou, Chien; Lai, Chao-Sung

    2014-01-01

    In renal transplant patients, immunosuppressive therapy may result in the reactivation of polyomavirus BK (BKV), leading to polyomavirus-associated nephropathy (PVAN), which inevitably causes allograft failure. Since the treatment outcomes of PVAN remain unsatisfactory, early identification and continuous monitoring of BKV reactivation and reduction of immunosuppressants are essential to prevent PVAN development. The present study demonstrated that the developed dual-channel heterodyne-based surface plasmon resonance (SPR) biosensor is applicable for the rapid detection of urinary BKV. The use of a symmetrical reference channel integrated with the poly(ethylene glycol)-based low-fouling self-assembled monolayer to reduce the environmental variations and the nonspecific noise was proven to enhance the sensitivity in urinary BKV detection. Experimentally, the detection limit of the biosensor for BKV detection was estimated to be around 8500 copies/mL. In addition, urine samples from five renal transplant patients were tested to rapidly distinguish PVAN-positive and PVAN-negative renal transplant patients. By virtue of its simplicity, rapidity, and applicability, the SPR biosensor is a remarkable potential to be used for continuous clinical monitoring of BKV reactivation.

  15. Ultraviolet Stand-off Raman Measurements Using a Gated Spatial Heterodyne Raman Spectrometer.

    PubMed

    Lamsal, Nirmal; Sharma, Shiv K; Acosta, Tayro E; Angel, S Michael

    2016-04-01

    A spatial heterodyne Raman spectrometer (SHRS) is evaluated for stand-off Raman measurements in ambient light conditions using both ultraviolet (UV) and visible pulsed lasers with a gated ICCD detector. The wide acceptance angle of the SHRS simplifies optical coupling of the spectrometer to the telescope and does not require precise laser focusing or positioning of the laser on the sample. If the laser beam wanders or loses focus on the sample, as long as it is in the field of view of the SHRS, the Raman signal will still be collected. The SHRS is not overly susceptible to vibrations, and a vibration isolated optical table was not necessary for these measurements. The system performance was assessed by measuring stand-off UV and visible Raman spectra of a wide variety of materials at distances up to 18 m, using 266 nm and 532 nm pulsed lasers, with 12.4 in. and 3.8 in. aperture telescopes, respectively. © The Author(s) 2016.

  16. Miniature Spatial Heterodyne Raman Spectrometer with a Cell Phone Camera Detector.

    PubMed

    Barnett, Patrick D; Angel, S Michael

    2017-05-01

    A spatial heterodyne Raman spectrometer (SHRS) with millimeter-sized optics has been coupled with a standard cell phone camera as a detector for Raman measurements. The SHRS is a dispersive-based interferometer with no moving parts and the design is amenable to miniaturization while maintaining high resolution and large spectral range. In this paper, a SHRS with 2.5 mm diffraction gratings has been developed with 17.5 cm(-1) theoretical spectral resolution. The footprint of the SHRS is orders of magnitude smaller than the footprint of charge-coupled device (CCD) detectors typically employed in Raman spectrometers, thus smaller detectors are being explored to shrink the entire spectrometer package. This paper describes the performance of a SHRS with 2.5 mm wide diffraction gratings and a cell phone camera detector, using only the cell phone's built-in optics to couple the output of the SHRS to the sensor. Raman spectra of a variety of samples measured with the cell phone are compared to measurements made using the same miniature SHRS with high-quality imaging optics and a high-quality, scientific-grade, thermoelectrically cooled CCD.

  17. Low-noise heterodyne receiver for electron cyclotron emission imaging and microwave imaging reflectometry.

    PubMed

    Tobias, B; Domier, C W; Luhmann, N C; Luo, C; Mamidanna, M; Phan, T; Pham, A-V; Wang, Y

    2016-11-01

    The critical component enabling electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) to resolve 2D and 3D electron temperature and density perturbations is the heterodyne imaging array that collects and downconverts radiated emission and/or reflected signals (50-150 GHz) to an intermediate frequency (IF) band (e.g. 0.1-18 GHz) that can be transmitted by a shielded coaxial cable for further filtering and detection. New circuitry has been developed for this task, integrating gallium arsenide (GaAs) monolithic microwave integrated circuits (MMICs) mounted on a liquid crystal polymer (LCP) substrate. The improved topology significantly increases electromagnetic shielding from out-of-band interference, leads to 10× improvement in the signal-to-noise ratio, and dramatic cost savings through integration. The current design, optimized for reflectometry and edge radiometry on mid-sized tokamaks, has demonstrated >20 dB conversion gain in upper V-band (60-75 GHz). Implementation of the circuit in a multi-channel electron cyclotron emission imaging (ECEI) array will improve the diagnosis of edge-localized modes and fluctuations of the high-confinement, or H-mode, pedestal.

  18. Application of heterodyne velocimetry and pyrometry as diagnostics for explosive characterisation

    NASA Astrophysics Data System (ADS)

    Ferguson, J. W.; Taylor, P.

    2014-05-01

    The results of four cylinder tests performed on two batches of the HMX based explosive EDC37 using a new suite of diagnostics are described. Heterodyne laser velocimetry (het-v) and pyrometry were fielded for the first time on cylinder tests within AWE. Pyrometry gave a measurement of the temperature of the detonating HE of 2600-3485 K. Sixteen channels of het-v were fielded and provided high fidelity expansion data at distances of up to 30 mm. High speed framing camera images were obtained and show no signs of cylinder break up or spallation until distances greater then 35 mm. The het-v expansion data made it possible to resolve up to 8 shock reverberations in the wall as it expands. The expansion of the cylinder wall was recorded both before and after steady state detonation was reached and the results compared. Het-v probes were fielded at different angles to the expanding cylinder wall allowing both the vertical and horizontal expansion velocity to be determined. The extra information that these cylinder tests yielded will allow for more accurate code validation and determination of the equation of state of the explosive products.

  19. Heterodyne Phase-Sensitive Dispersion Spectroscopy in the Mid-Infrared with a Quantum Cascade Laser.

    PubMed

    Martín-Mateos, Pedro; Hayden, Jakob; Acedo, Pablo; Lendl, Bernhard

    2017-06-06

    Molecular dispersion spectroscopy encompasses a group of spectroscopic techniques for gas analysis that retrieve the characteristics of the sample from the measurement of the profile of its refractive index in the vicinity of molecular resonances. This approach, which is in clear contrast to traditional methods based on the detection of absorption, provides inherent immunity to power fluctuations, calibration-free operation, and an output that is linearly dependent on gas concentration. Heterodyne phase-sensitive dispersion spectroscopy (HPSDS) is a very recently proposed technique for molecular dispersion spectroscopy based on tunable lasers that is characterized by a very simple architecture in which data processing and concentration retrieval are straightforward. Different HPSDS implementations have been experimentally validated in the near-IR. Here, we present the first demonstration of HPSDS in the mid-IR using a directly modulated quantum cascade laser for the measurement of CO. The setup is put under test to characterize its response to changing concentrations, pressures, and levels of optical intensity on the detector, and the limit of detection is estimated. Besides this, an experimental comparison with wavelength modulation spectroscopy with second-harmonic detection (2f-WMS) is performed and discussed in detail in order to offer a clear view of the benefits and drawbacks that HPSDS can provide over what we could consider the reference method for gas analysis based on tunable laser spectroscopy.

  20. Heterodyne detection of the 752.033-GHz H2O rotational absorption line

    NASA Technical Reports Server (NTRS)

    Dionne, G. F.; Fitzgerald, J. F.; Chang, T. S.; Litvak, M. M.; Fetterman, H. R.

    1980-01-01

    A tunable high resolution two stage heterodyne radiometer was developed for the purpose of investigating the intensity and lineshape of the 752.033 GHz rotational transition of water vapor. Single-sideband system noise temperatures of approximately 45,000 K were obtained using a sensitive GaAs Schottky diode as the first stage mixer. First local oscillator power was supplied by a CO2 laser pumped formic acid laser (761.61 GHz), generating an X-band IF signal with theoretical line center at 9.5744 GHz. Second local oscillator power was provided by means of a 3 GHz waveguide cavity filter with only 9 dB insertion loss. In absorption measurements of the H2O taken from a laboratory simulation of a high altitude rocket plume, the center frequency of the 752 GHz line was determined to within 1 MHz of the reported value. A rotational temperature 75 K, a linewidth 5 MHz and a Doppler shift 3 MHz were measured with the line-of-sight intersecting the simulated-plume axis at a distance downstream of 30 nozzle diameters. These absorption data were obtained against continuum background radiation sources at temperatures of 1175 and 300 K.