Sample records for quadrature laser interferometer

  1. Measurement of the Ti X ion density in a theta-pinch plasma by a laser heterodyne quadrature interferometer

    SciTech Connect

    Datla, R.U.

    1985-04-01

    The increase in the radial line integral of the electron density in the National Bureau of Standards theta-pinch plasma due to the ionization of the titanium impurity has been measured with the use of a He-Ne laser heterodyne quadrature interferometer. Titanium is injected as an impurity into the base gas of hydrogen with the use of a coaxial gun discharge between titanium electrodes. The Ti X ion density at its peak abundance in the plasma is deduced in each discharge from the measured increase in electron density by knowing the temporal charge-state distribution of Ti ions with the use of spectroscopy and assuming charge neutrality.

  2. Quadrature density interferometer with optical fiber

    NASA Astrophysics Data System (ADS)

    Kim, M.-S.; Bellan, P. M.

    2000-10-01

    A He-Ne interferometer is being constructed and will be used to measure the plasma density in the Caltech solar prominence simulation experiment. The design is based on the Buchenauer-Jacobson [1] quadrature concept but uses retroreflectors to have a double-pass optical path and also an optical fiber in order to have flexibility in the optical path. A 632.8 nm polarized He-Ne laser beam is split and travels along two separate paths (reference and scene beams). The scene beam is guided by a one meter single-mode phase-maintaining fiber before entering the vacuum chamber. The beam will pass through the plasma, be reflected from a retroreflector mounted inside the vacuum chamber and then travel back to re-enter the fiber. The flexibility of the fiber permits translations or rotations of the signal path so that different portions of the plasma can be measured. We have successfully demonstrated the operation of the fiber-coupled quadrature interferometer on the benchtop and will be installing it shortly on the solar prominence equipment. [1]: C.J. Buchenauer and A.R. Jacobson, Rev. Sci. Instrum. 48, 769 (1997).

  3. Quadrature density interferometer with optical fiber

    NASA Astrophysics Data System (ADS)

    Remy, Jerome; Bellan, Paul

    1999-11-01

    A He-Ne interferometer is being constructed and will be used to measure the plasma density in the Caltech solar prominence simulation experiment. The design is based on the Buchenauer-Jacobson [1] quadrature concept but uses retroreflectors to have a double-pass optical path and also an optical fiber in order to have flexibility in the optical path. A 632.8 nm polarized He-Ne laser beam is split and travels along two separate paths (reference and scene beams). The scene beam is guided by a one meter single-mode phase-maintaining fiber before entering the vacuum chamber. The beam will pass through the plasma, reflect from a retroreflector mounted inside the vacuum chamber and then travel back to re-enter the fiber. The flexibility of the fiber permits translations or rotations of the signal path so that different portions of the plasma can be measured. We have successfully managed to send light into the fiber and make it travel back. The next step will be to combine this light with the reference beam. [1]: C. J. Buchenauer and A. R. Jacobson, Rev. Sci. Instrum. 48, 769 (1977).

  4. Quadrature phase interferometer for high resolution force spectroscopy

    SciTech Connect

    Paolino, Pierdomenico; Aguilar Sandoval, Felipe A.; Bellon, Ludovic [Laboratoire de physique, Université de Lyon, ENS Lyon, CNRS, Lyon 69364 (France)] [Laboratoire de physique, Université de Lyon, ENS Lyon, CNRS, Lyon 69364 (France)

    2013-09-15

    In this article, we present a deflection measurement setup for Atomic Force Microscopy (AFM). It is based on a quadrature phase differential interferometer: we measure the optical path difference between a laser beam reflecting above the cantilever tip and a reference beam reflecting on the static base of the sensor. A design with very low environmental susceptibility and another allowing calibrated measurements on a wide spectral range are described. Both enable a very high resolution (down to 2.5×10{sup ?15}?m/?(Hz)), illustrated by thermal noise measurements on AFM cantilevers. They present an excellent long-term stability and a constant sensitivity independent of the optical phase of the interferometer. A quick review shows that our precision is equaling or out-performing the best results reported in the literature, but for a much larger deflection range, up to a few ?m.

  5. Quadrature phase interferometer for high resolution force spectroscopy.

    PubMed

    Paolino, Pierdomenico; Aguilar Sandoval, Felipe A; Bellon, Ludovic

    2013-09-01

    In this article, we present a deflection measurement setup for Atomic Force Microscopy (AFM). It is based on a quadrature phase differential interferometer: we measure the optical path difference between a laser beam reflecting above the cantilever tip and a reference beam reflecting on the static base of the sensor. A design with very low environmental susceptibility and another allowing calibrated measurements on a wide spectral range are described. Both enable a very high resolution (down to 2.5×10(-15) m/?Hz), illustrated by thermal noise measurements on AFM cantilevers. They present an excellent long-term stability and a constant sensitivity independent of the optical phase of the interferometer. A quick review shows that our precision is equaling or out-performing the best results reported in the literature, but for a much larger deflection range, up to a few ?m. PMID:24089852

  6. Spheromak Plasma Density Measurement Using a Quadrature Phase Interferometer

    NASA Astrophysics Data System (ADS)

    Kumar, Deepak; Bellan, Paul

    2004-11-01

    A quadrature phase interferometer as described in [1] is being developed in a double-pass Michelson geometry, to measure the density of plasma produced by a planar spheromak gun. The design is specially suited for large vacuum chambers ( 1.5m in diameter) and for experiments with time scales ( 10 ? s) much less than the time scale of acoustic vibrations. The design utilizes a 1mW linearly polarized HeNe laser. The beam path lengths are approximately 3m. Ultra low noise detectors (noise power 20nW) are used to maximize the SNR. An optical isolator is also employed to ensure laser stability against back reflection. While working on the prototype, a novel optic alignment scheme was used to maximize the signal amplitude and to reduce the jitter/drift despite the long path lengths. The phase lag can be unambiguously measured from quadrature information generated by the interference of the linearly polarized scene beam (passing through the plasma) and a circularly polarized reference beam. ^1C. J. Buchenauer, A. R. Jacobson Rev. Sci. Instrum. 48, 769(1977) Supported by U.S. Department Of Energy.

  7. Microwave interferometer with a differential quadrature phase detection

    Microsoft Academic Search

    S. Vergamota; L. Cupido; M. E. Manso; F. Eusébio; A. Silva; P. Varela; J. A. C. Cabral; F. Serra; C. A. F. Varandas

    1995-01-01

    A single channel microwave interferometer has been developed for a tokamak with an improved detection that uses an heterodyne configuration and is based on a differential quadrature phase concept. With the new detection very sensitive and accurate direct phase measurements are obtained due to the elimination of the spurious variations of the detected signals resulting from the nonideal behavior of

  8. VISAR: Interferometer quadrature signal recording by electronic streak camera

    NASA Astrophysics Data System (ADS)

    Hemsing, W. F.

    This short paper describes a demonstration to record the four quadrature signals from a push-pull VISAR velocity interferometer using an electronic streak camera. Optical fibers were used to transmit the interferometer outputs to the camera photocathode. Brightness variations of these signals were recorded on film during the experiment. Velocity information was later recovered from this record to give a continuous velocity history. Anticipated advantages over previous methods are increased time resolution, the ability to record multiple velocities simultaneously and greater dynamic range.

  9. Compensation for the Variable Cyclic Error in Homodyne Laser Interferometers

    PubMed Central

    Hu, Pengcheng; Zhu, Jinghao; Guo, Xuanbiao; Tan, Jiubin

    2015-01-01

    This paper presents a real-time method to compensate for the variable cyclic error in a homodyne laser interferometer. The parameters describing the quadrature signals of the interferometer are estimated using simple peak value detectors. The cyclic error in the homodyne laser interferometer was then corrected through simple arithmetic calculations of the quadrature signals. A field programmable gate array was utilized for the real-time compensation of the cyclic error in a homodyne laser interferometer. The simulation and experimental results indicated that the proposed method could provide a cyclic error that was fixed without compensation down to a value under 0.6 nm in a homodyne laser interferometer. The proposed method could also reduce the time-varying cyclic error to a value under 0.6 nm in a homodyne laser interferometer, in contrast to the equivalent value of 13.3 nm for a conventional elliptical fitting method. PMID:25647739

  10. Instrument reflections and scene amplitude modulation in a polychromatic microwave quadrature interferometer

    Microsoft Academic Search

    Chris C. Dobson; Jonathan E. Jones; D. Gregory Chavers

    2004-01-01

    A polychromatic microwave quadrature interferometer has been characterized using several laboratory plasmas. Reflections between the transmitter and the receiver have been observed, and the effects of including reflection terms in the data reduction equation have been examined. An error analysis which includes the reflections, modulation of the scene beam amplitude by the plasma, and simultaneous measurements at two frequencies has

  11. Quantum noise in laser-interferometer gravitational-wave detectors with a heterodyne readout scheme

    Microsoft Academic Search

    Alessandra Buonanno; Yanbei Chen; Nergis Mavalvala

    2003-01-01

    We analyze and discuss the quantum noise in signal-recycled laser interferometer gravitational-wave detectors, such as Advanced LIGO, using a heterodyne readout scheme and taking into account the optomechanical dynamics. Contrary to homodyne detection, a heterodyne readout scheme can simultaneously measure more than one quadrature of the output field, providing an additional way of optimizing the interferometer sensitivity, but at the

  12. The laser interferometer: Application to plasma diagnostics

    Microsoft Academic Search

    J. B. Gerardo; J. T. Verdeyen

    1964-01-01

    A laser interferometer employing a reference arm with a spherical mirror is discussed. This interferometer is extremely promising in many fields of scientific endeavor, for instance, in plasma physics, due to its simplicity and high sensitivity. Its sensitivity is greater than that of a similar interferometer with planar mirrors because the closely spaced normal modes with nonzero transverse indexes can

  13. Detection of Interference Phase by Digital Computation of Quadrature Signals in Homodyne Laser Interferometry

    PubMed Central

    Rerucha, Simon; Buchta, Zdenek; Sarbort, Martin; Lazar, Josef; Cip, Ondrej

    2012-01-01

    We have proposed an approach to the interference phase extraction in the homodyne laser interferometry. The method employs a series of computational steps to reconstruct the signals for quadrature detection from an interference signal from a non-polarising interferometer sampled by a simple photodetector. The complexity trade-off is the use of laser beam with frequency modulation capability. It is analytically derived and its validity and performance is experimentally verified. The method has proven to be a feasible alternative for the traditional homodyne detection since it performs with comparable accuracy, especially where the optical setup complexity is principal issue and the modulation of laser beam is not a heavy burden (e.g., in multi-axis sensor or laser diode based systems). PMID:23202038

  14. Instrument Reflections and Scene Amplitude Modulation in a Polychromatic Microwave Quadrature Interferometer

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Jones, Jonathan E.; Chavers, Greg

    2003-01-01

    A polychromatic microwave quadrature interferometer has been characterized using several laboratory plasmas. Reflections between the transmitter and the receiver have been observed, and the effects of including reflection terms in the data reduction equation have been examined. An error analysis which includes the reflections, modulation of the scene beam amplitude by the plasma, and simultaneous measurements at two frequencies has been applied to the empirical database, and the results are summarized. For reflection amplitudes around 1096, the reflection terms were found to reduce the calculated error bars for electron density measurements by about a factor of 2. The impact of amplitude modulation is also quantified. In the complete analysis, the mean error bar for high- density measurements is 7.596, and the mean phase shift error for low-density measurements is 1.2". .

  15. Quantum noise limits to simultaneous quadrature amplitude and phase stabilization of solid-state lasers

    NASA Astrophysics Data System (ADS)

    Huntington, E. H.; Harb, C. C.; Heurs, M.; Ralph, T. C.

    2007-01-01

    A quantum mechanical model is formulated to describe the coupling between pump intensity noise and laser frequency noise in a solid-state laser. The model allows us to investigate the limiting effects of closed-loop stabilization schemes that utilize this coupling. Two schemes are considered: active control of the quadrature phase noise of the laser and active control of the amplitude noise of the laser. We show that the noise of the laser in the actively stabilized quadrature is ultimately limited by the vacuum noise introduced by the feedback beamsplitter in both schemes. In the case of active control of the quadrature phase noise, the noise is also limited by the intensity noise floor of the detection scheme. We also show that some sources of noise in the passively stabilized quadrature can be suppressed and that it is possible to achieve simultaneous quadrature amplitude and phase stabilization of a solid-state laser. However, the quantum mechanically driven noise in the passively stabilized quadrature cannot be suppressed. While this poses the ultimate limit to the noise in the passively stabilized quadrature, we show that it is experimentally feasible to observe squeezing directly generated by a solid-state laser using this technique.

  16. Adaptive elements in a precision laser interferometer

    NASA Astrophysics Data System (ADS)

    Simonova, Galina V.; Polovtsev, Igor G.; Tartakovsky, Valery A.

    2004-02-01

    The accuracy of a high-precision interferometric experiment depends on both instrument errors and errors connected with processing the interferograms. Both types of errors can be minimized by an optimum adjustment of the functions of the basic unit of the system. The paper addresses the issue of error optimization using different adaptive systems within a laser interferometer design.

  17. Laser-Ranging Long Baseline Differential Atom Interferometers for Space

    E-print Network

    Chiow, Sheng-wey; Yu, Nan

    2015-01-01

    High sensitivity differential atom interferometers are promising for precision measurements in science frontiers in space, including gravity field mapping for Earth science studies and gravitational wave detection. We propose a new configuration of twin atom interferometers connected by a laser ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and a means to phase-lock the two independent interferometer lasers over long distances, thereby further enhancing the feasibility of long baseline differential atom interferometers. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential atom interferometer measurement system. LRI-AI isolates the laser requirements for atom interferometers and for optical phase readout between distant locations, thus enabling optimized allocation of available laser power within a limited physical size and resource budget. A unique aspect of LRI-AI also enables...

  18. Measurement of the Ti X ion density in a theta pinch plasma utilizing a laser interferometer

    SciTech Connect

    Datla, R.U.

    1985-05-01

    The increase in the radial line integral of the electron density in the NBS theta pinch plasma due to the ionization of titanium impurity has been measured with the use of a He-Ne laser heterodyne quadrature interferometer. Titanium is injected as an impurity into the base gas of hydrogen with the use of a coaxial gun discharge with titanium electrodes. The abundance of the Ti X ion density in the plasma is deduced in each discharge from the measured increase in electron density by knowing the temporal charge state distribution of Ti ions obtained by spectroscopic methods.

  19. 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-

  20. Compact in-line laser radial shear interferometer

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Moghbel, M.; Venkateswarlu, P.

    1992-01-01

    A compact in-line radial shearing interferometer using laser as a light source is presented. The interferometer is made out of a cube-type beam splitter so that the two opposite surfaces are generated with different curvatures while the normal to the entrance and exit surfaces are in the same line. The interferometer is simple to make and easy to align. Aberration analysis of the interferometer is also presented. Some applications of the interferometer for testing lenses and infrared optical systems and for accessing the quality of an emerging wave front from the exit slit of a monochromator are suggested.

  1. Mission analysis for the Laser Interferometer Space Antenna (LISA) mission

    Microsoft Academic Search

    F. Hechler; W. M. Folkner

    2003-01-01

    The interplanetary orbits of three pairs of spacecraft, forming three laser interferometers, are designed such that their separations, i.e. the lengths of the interferometer arms, remain nearly constant. Each spacecraft pair is located near the vertex of a rotating equilateral triangle formed by the individual orbits of the spacecraft about the Sun. Feasible spacecraft masses are computed for a scenario

  2. Gravitational wave detection with single-laser atom interferometers

    E-print Network

    Nan Yu; Massimo Tinto

    2010-03-22

    We present a new general design approach of a broad-band detector of gravitational radiation that relies on two atom interferometers separated by a distance L. In this scheme, only one arm and one laser will be used for operating the two atom interferometers. We consider atoms in the atom interferometers not only as perfect inertial reference sensors, but also as highly stable clocks. Atomic coherence is intrinsically stable and can be many orders of magnitude more stable than a laser. The unique one-laser configuration allows us to then apply time-delay interferometry to the responses of the two atom interferometers, thereby canceling the laser phase fluctuations while preserving the gravitational wave signal in the resulting data set. Our approach appears very promising. We plan to investigate further its practicality and detailed sensitivity analysis.

  3. Gravitational wave detectors based on matter wave interferometers (MIGO) are no better than laser interferometers (LIGO)

    E-print Network

    Albert Roura; Dieter R. Brill; B. L. Hu; Charles W. Misner; William D. Phillips

    2004-12-17

    We show that a recent claim that matter wave interferometers have a much higher sensitivity than laser interferometers for a comparable physical setup is unfounded. We point out where the mistake in the earlier analysis is made. We also disprove the claim that only a description based on the geodesic deviation equation can produce the correct physical result. The equations for the quantum dynamics of non-relativistic massive particles in a linearly perturbed spacetime derived here are useful for treating a wider class of related physical problems. A general discussion on the use of atom interferometers for the detection of gravitational waves is also provided.

  4. Low-coherence interferometer using a pulsation laser diode

    NASA Astrophysics Data System (ADS)

    Suzuki, Takamasa; Ueno, Yusuke; Choi, Samuel; Sasaki, Osami

    2014-05-01

    A self-pulsation laser diode interferometer based on spectral-domain optical coherence tomography is proposed. A visible multimode laser diode allows easy optical alignment and an economical, configurable system. A cylindrical lens and acousto-optic deflector used in our system enable rapid and stable scanning. Experimental results confirm that full-field measurement is possible without mechanical scanning devices.

  5. Mission analysis for the Laser Interferometer Space Antenna (LISA) mission

    NASA Astrophysics Data System (ADS)

    Hechler, F.; Folkner, W. M.

    2003-10-01

    The interplanetary orbits of three pairs of spacecraft, forming three laser interferometers, are designed such that their separations, i.e. the lengths of the interferometer arms, remain nearly constant. Each spacecraft pair is located near the vertex of a rotating equilateral triangle formed by the individual orbits of the spacecraft about the Sun. Feasible spacecraft masses are computed for a scenario with an Ariane 5 launch into a Geostationary Transfer Orbit (GTO) and a three-burn transfer from the GTO to the triangular configuration. The relative motion is perturbed by planetary gravity. However, the arm rate differences degrading the interferometer accuracy can be kept below certain limits by choosing optimum initial conditions and/or by controlling them by occasional orbit adjustment manoeuvres. The achievable orbit determination accuracy is given for systems processing two-way range and Doppler data collected on ground and/or laser interferometer measurements of the rate of change of distance between spacecraft.

  6. Optical resolution of phase measurements of laser Fizeau interferometer

    Microsoft Academic Search

    Erik Novak; Chiayu Ai; James C. Wyant

    1996-01-01

    Accurate interferometric measurement of large laser slabs requires spatial frequencies of 1 mm\\/cycle to 33 mm\\/cycle over a 100 mm field of view to be passed by the system with no more than 25% loss in modulation. To eliminate noise and artifacts due to strictly coherent imaging, many commercial interferometers employ a rotating diffuser on an intermediate image plane and

  7. LIGO - The Laser Interferometer Gravitational-Wave Observatory

    Microsoft Academic Search

    Alex Abramovici; William E. Althouse; Ronald W. P. Drever; Yekta Gursel; Seiji Kawamura; Frederick J. Raab; David Shoemaker; Lisa Sievers; Robert E. Spero; Kip S. Thorne; R. E. Vogt; R. Weiss; S. E. Whitcomb; M. E. Zucker

    1992-01-01

    The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics for gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses,

  8. Laser diode feedback interferometer for measurement of displacements without ambiguity

    Microsoft Academic Search

    S. Donati; G. Giuliani; S. Merlo

    1995-01-01

    We report what, to our knowledge, is the first example of laser feedback interferometer capable of measuring displacements of arbitrary form using a single interferometric channel. With a GaAlAs laser diode we can measure 1.2-m displacements, with interferometric resolution, simply by means of the backreflection from the surface (reflective or diffusive) under test. The operation is performed at moderate (i.e.,

  9. A lunar gravitational wave antenna using a laser interferometer

    SciTech Connect

    Stebbins, R.T.; Bender, P.L. (Joint Institute for Laboratory Astrophysics, University of Colorado, Boulder, CO (USA) National Institute of Standards and Technology, Boulder, CO (USA))

    1990-03-15

    A moon-based laser interferometer for detecting gravitational radiation could detect signals in the band 10{sup {minus}1} to 10{sup 4} Hz. A preliminary evaluation of the noise budget for an optimistic antenna design is reported here and compared to that for other planned gravitational wave interferometers. Over most of the frequency range, the sensitivity is controlled by the thermal noise in the test mass suspensions. From roughly 3 to a few hundred Hertz, it is about the same as the sensitivity expected in terrestrial antennas of the same construction, which will have been operating for at least a decade. Below 0.3 Hz, a proposed space-based interferometer, designed for operation down to 10{sup {minus}5} Hz, would have better sensitivity. As pointed out by others, the most important role of a lunar antenna would be the improved angular resolution made possible by the long baseline to terrestrial antennas.

  10. 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.

  11. Measurement of a Stochastic Gravitational Wave Background with a Single Laser Interferometer

    E-print Network

    Adrian C. Melissinos; William E. Butler

    2005-01-27

    Laser interferometer gravitational wave detectors can be operated at their free spectral range frequency. We show that in this case and when the interferometer is well understood one could detect a stochastic background using a single detector.

  12. Influence of laser frequency noise on scanning Fabry-Perot interferometer based laser Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Rodrigo, Peter John; Pedersen, Christian

    2014-03-01

    In this work, we study the performance of a scanning Fabry-Perot interferometer based laser Doppler velocimeter (sFPILDV) and compare two candidate 1.5 um single-frequency laser sources for the system - a fiber laser (FL) and a semiconductor laser (SL). We describe a straightforward calibration procedure for the sFPI-LDV and investigate the effect of different degrees of laser frequency noise between the FL and the SL on the velocimeter's performance.

  13. Multiwavelength fiber ring laser source based on a delayed interferometer

    Microsoft Academic Search

    H. Dong; G. Zhu; Q. Wang; H. Sun; N. K. Dutta; J. Jaques; A. B. Piccirilli

    2005-01-01

    A multiwavelength fiber laser source is demonstrated with a semiconductor optical amplifier as the gain medium. A delayed interferometer is incorporated in the ring cavity serving as a comb-like multichannel filter. A stable 75-wavelength simultaneous operation spaced at 40 GHz with the extinction ratio of 40 dB is achieved. By tuning the cavity loss, the center wavelength of the generated

  14. The GRACE Follow-On Laser Ranging Interferometer

    NASA Astrophysics Data System (ADS)

    Görth, Alexander

    2014-05-01

    In the year 2017 a follow-on mission to the joint German / NASA mission GRACE (Gravity Recovery And Climate Experiment) will be launched. While a microwave ranging instrument has been used for the ranging measurement in GRACE, an additional laser ranging interferometer (LRI) will be implemented into the architecture of the GRACE Follow-On satellites as a technology demonstrator. An overview of the current status of the development of the LRI will be presented.

  15. Novel phase measurement technique of the heterodyne laser interferometer

    SciTech Connect

    Choi, Hyunseung; Park, Kyihwan; La, Jongpil [Department of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Compressor Development Group, Samsung Gwangju Electronic Company, 1119 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    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.

  16. Antiresonant ring interferometer for laser cavity dumping, mode locking, and other applications

    NASA Technical Reports Server (NTRS)

    Siegman, A. E.

    1975-01-01

    Applications in lasers for antiresonant ring interferometer include coupled laser cavities, variable laser-output coupling, intercavity harmonic-output coupling, mode locking, cavity dumping, and pulse code modulation.

  17. Performance analysis of a swept-source optical coherence tomography system with a quadrature interferometer and optical amplification

    NASA Astrophysics Data System (ADS)

    Mao, Youxin; Flueraru, Costel; Chang, Shoude; Popescu, Dan P.; Sowa, Michael G.

    2011-05-01

    A performance analysis of signal to noise ratio for an optical coherence tomography system with quadrature detection and a semiconductor optical amplifier in the sample arm is discussed. The results are compared and discussed in relation to a conventional OCT system (without optical amplification). An increase of the signal to noise ratio up to 14 dB at a depth of 0.5 mm is obtained compared to the system without the optical amplifier. Overall, an improvement was demonstrated for signal coming from deeper regions within the samples. Arterial plaque from a myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbit is visualized and characterized using this system. Improvement of signal to noise ratio increases the penetration depth possible for OCT images, from 1 mm to 2 mm within the vessel wall of an artery. Preliminary results show that vulnerable plaque with fibrous cap, macrophage accumulations and calcification in the arterial tissue are measurable with this OCT system.

  18. Simple, real-time method for removing the cyclic error of a homodyne interferometer with a quadrature detector system

    SciTech Connect

    Keem, Taeho; Gonda, Satoshi; Misumi, Ichiko; Huang, Qianxiang; Kurosawa, Tomizo

    2005-06-10

    The cyclic error of a homodyne interferometer is caused mainly by phase mixing due to the imperfection of polarizing optical components such as polarizing beam splitters. In Appl. Opt. 43, 2443 (2004), we concentrated on the relationship between these imperfect optical characteristics and the cyclic error and found the preamplifier-gains condition for removing the cyclic error. Here we demonstrate the cyclic error correction method experimentally and show that the method can be applied in real time. We obtained 0.04-nm cyclic errors, with a standard deviation above 5 {mu}m.

  19. A Fiber Optic PD Sensor Using a Balanced Sagnac Interferometer and an EDFA-Based DOP Tunable Fiber Ring Laser

    PubMed Central

    Wang, Lutang; Fang, Nian; Wu, Chunxu; Qin, Haijuan; Huang, Zhaoming

    2014-01-01

    A novel fiber-optic acoustic sensor using an erbium-doped fiber amplifier (EDFA)-based fiber ring laser and a balanced Sagnac interferometer for acoustic sensing of the partial discharge (PD) in power transformers is proposed and demonstrated. As a technical background, an experimental investigation on how the variations of the fiber birefringence affect the sensor performances was carried out, and the results are discussed. The operation principles are described, and the relevant formulas are derived. The analytical results show that an EDFA-based fiber ring laser operating in chaotic mode can provide a degree of polarization (DOP) tunable light beam for effectively suppressing polarization fading noises. The balanced Sagnac interferometer can eliminate command intensity noises and enhance the signal-to-noise ratio (SNR). Furthermore, it inherently operates at the quadrature point of the response curve without any active stabilizations. Several experiments are conducted for evaluating the performances of the sensor system, as well as for investigating the ability of the detection of high-frequency acoustic emission signals. The experimental results demonstrate that the DOP of the laser beam can be continuously tuned from 0.2% to 100%, and the power fluctuation in the whole DOP tuning range is less than 0.05 dBm. A high-frequency response up to 300 kHz is reached, and the high sensing sensitivity for detections of weak corona discharges, as well as partial discharges also is verified. PMID:24824371

  20. Detection of volcanic infrasound with a ring laser interferometer

    NASA Astrophysics Data System (ADS)

    Dunn, Robert W.; Hosman, Ashley R.

    2014-11-01

    Over the last 15 years, large horizontally mounted ring lasers have been used to study numerous geophysical phenomena. This paper provides examples of the sensitivity of large active ring laser interferometers to far field infrasound emissions from explosive volcanic eruptions. Volcanic infrasound is reported from representative eruptions of volcanoes Kelut (Kelud), Klyuchevskaya (Kliuchevskoi), Puyehua, Santa Maria, Sakurajima, and Tungurahua. The detected infrasound frequencies are in basic agreement with the far field air wave frequencies from the 1980 eruption of Mount St. Helens and the 1991 eruption of Mount Pinatubo. Cavities of large horizontally mounted active ring lasers contain two counter-propagating waves that in the presence Earth's rotation become traveling waves of slightly different frequencies. The Sagnac or beat frequency due to the difference in the traveling wave frequencies is modulated by geophysical phenomena, in this case volcanic infrasound. Signatures of the infrasound are found in the frequency modulated side bands.

  1. Submillimeter laser interferometer-polarimeter for poloidal field measurements in the tokamak-15

    SciTech Connect

    Gorbunov, E.P.; Skosyrev, Yu.V.; Khilil, V.V. [Kurchatov Institute, Moscow (Russian Federation); Kuleshov, E.M.; Nesterov, P.N. [Institute of Radioelectronics, Khar`kov (Ukraine)

    1994-12-31

    In order to measure the current density distribution in the T-15 plasma, an interferometer-polarimeter with DCN-laser at {lambda} = 195 {mu}m is inserted into the existing multichannel interferometer with HCN-laser at {lambda} = 337 {mu}m. The device scheme and bench test results are described. High sensitivity of the developed polarimeter (0.1{degrees}) and interferometer (15{degrees}) is obtained. 5 refs., 2 figs.

  2. Measurement of the emission linewidth of a single-frequency semiconductor laser with a ring fibre interferometer

    SciTech Connect

    Trikshev, A I; Kurkov, Andrei S; Tsvetkov, V B; Pyrkov, Yu N; Paramonov, V N

    2011-07-31

    A simple scanning interferometer is implemented for measuring the emission linewidth of single-frequency semiconductor lasers. The free dispersion region of the interferometer is 28 MHz, the spectral resolution being 470 kHz. (laser spectroscopy)

  3. Linear interpolation of periodic error in a heterodyne laser interferometer at subnanometer levels

    SciTech Connect

    Tanaka, M.; Nakyama, K. (Nanometrology Group, Quantum Section, National Research Lab. of Metrology, Umezono, Tsukuba (JP)); Yamagami, T. (Hoya Corp., 3-3-1 Musashino, Akishima, Tokyo (JP))

    1989-04-01

    Heterodyne laser interferometry and its accuracy at subnanometer levels are discussed. The simplest optical nonpolarization heterodyne interferometer is tested experimentally in order to understand and reduce fringe distortion. An accuracy of 0.1 mm for the 633-nm He-Ne laser interferometer is achieved.

  4. Analytic and interferometric techniques for the Laser Interferometer Space Antenna

    NASA Astrophysics Data System (ADS)

    Pollack, Scott E.

    The Laser Interferometer Space Antenna (LISA) is being designed to detect and study in detail gravitational waves from sources throughout the Universe such as massive black holes. The conceptual formulation of the LISA space-borne gravitational wave detector is now well developed. The interferometric measurements between the sciencecraft remain one of the most important technological and scientific design areas for the mission. Our work has concentrated on developing the interferometric technologies to create a LISA-like optical signal and to measure the phase of that signal using commercially available instruments. One of the most important goals of this research is to demonstrate the LISA phase timing and phase reconstruction for a LISA-like fringe signal, in the case of a high fringe rate and a low signal level. To this end we have constructed a table-top interferometer which produces LISA-like fringe signals. Over the past few years questions have been raised concerning the use of laser communications links between sciencecraft to transmit phase information crucial to the reduction of laser frequency noise in the LISA science measurement. The concern is that applying medium frequency phase modulations to the laser carrier could compromise the phase stability of the LISA fringe signal. We have modified our table-top interferometer by applying a phase modulation to the laser beam in order to evaluate the effects of such modulations on the LISA science fringe signal. We have demonstrated that the phase resolution of the science signal is not degraded by the presence of medium frequency phase modulations. Each spacecraft in LISA houses a proof mass which follows a geodesic through space. Disturbances that change the proof mass position, momentum, and acceleration will appear in the LISA data stream as additive quadratic functions. These data disturbances inhibit signal extraction and must be removed. Much of our analytical work has been focused on discussing the identification and fitting of monochromatic signals in the data set in the presence of data disturbances. We also present a preliminary analysis of the extent of science result limitations with respect to the frequency of data disturbances.

  5. GRACE-Follow On Laser Ranging Interferometer: German contribution

    NASA Astrophysics Data System (ADS)

    Abich, Klaus; Bogan, Christina; Braxmaier, Claus; Danzmann, Karsten; Dehne, Marina; Gohlke, Martin; Görth, Alexander; Heinzel, Gerhard; Herding, Mark; Mahrdt, Christoph; Müller, Vitali; Nicklaus, Kolja; Sanjuan, Josep; Schütze, Daniel; Sheard, Benjamin; Stede, Gunnar; Voss, Kai

    2015-05-01

    The Gravity Recovery and Climate Experiment (GRACE) is a joint US/German mission that has been mapping the Earth's gravity field since 2002 by measuring the distance variations between two spacecraft using a micro-wave link. GRACE is reaching the end of its lifetime. For this reason and in order to minimize data gaps, an almost identical mission will be launched in 2017. This mission is called GRACE-Follow On (GRACE-FO) and it will include an additional instrument as a technological demonstrator to monitor distance changes between the spacecraft. This instrument is the Laser Ranging Interferometer (LRI), which is based on heterodyne laser interferometry at 1064 nm and takes advantage of many technologies developed for LISA. In this paper a short overview of the current status of the German contribution is presented.

  6. Selection of linear-cavity fibre laser radiation using a reflection interferometer

    SciTech Connect

    Terentyev, V S; Simonov, V A [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2013-08-31

    We consider the use of a two-mirror multibeam reflection interferometer as a selector of linear-cavity single-mode fibre laser radiation and present experimental data on continuous wavelength tuning of an erbium-doped fibre laser. Conditions are found for single-longitudinal-mode operation of the fibre laser cavity using a reflection interferometer, with the possibility of broadband wavelength tuning. (control of laser pulse parameters)

  7. file: /home/coyne/Presentations/IEEE/P950017_02_IEEE_paper.fm LASER INTERFEROMETER GRAVITATIONAL WAVE OBSERVATORY

    E-print Network

    Frey, Raymond E.

    to the cosmic microwave background). The Laser Interferometer Gravitational Wave Observa- tory (LIGOfile: /home/coyne/Presentations/IEEE/P950017_02_IEEE_paper.fm LASER INTERFEROMETER GRAVITATIONAL The Laser Interferometer Gravitational- Wave Observatory (LIGO) Project Document Type LIGO-P950017-02 E- 6

  8. Two-wavelength scanning spot interferometer using single-frequency diode lasers.

    PubMed

    Boef, A J

    1988-01-15

    A two-wavelength interferometer is described that can be used to measure distances to rough surfaces with micrometer resolution. The measuring range can be made as large as several centimeters. Owing to the small numerical aperture of the object beam, the interferometer is particularly suitable in applications where a long working distance is required. The interferometer uses two single-frequency diode lasers to create a virtual two-wavelength laser. The equivalent wavelength of this laser can be easily tuned by changing the temperature of the laser diodes in opposite directions. PMID:20523591

  9. LIGO - The Laser Interferometer Gravitational-Wave Observatory

    NASA Technical Reports Server (NTRS)

    Abramovici, Alex; Althouse, William E.; Drever, Ronald W. P.; Gursel, Yekta; Kawamura, Seiji; Raab, Frederick J.; Shoemaker, David; Sievers, Lisa; Spero, Robert E.; Thorne, Kip S.

    1992-01-01

    The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics for gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998.

  10. LIGO: The Laser Interferometer Gravitational-Wave Observatory

    E-print Network

    The LIGO Scientific Collaboration; B. Abbott

    2009-05-19

    The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves of astrophysical origin. Direct detection of gravitational waves holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black hole and neutron stars, and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech-MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction, and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than 1 part in 1E21. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on gravitational waves from a variety of potential astrophysical sources.

  11. Microkelvin thermal control system for the laser interferometer space antenna mission and beyond

    Microsoft Academic Search

    Sei Higuchi

    2009-01-01

    The Laser Interferometer Space Antenna (LISA) mission aims to detect directly gravitational waves from massive black holes and galactic binaries. Through detecting gravitational waves, we can study blackholes and the origin of the universe, which is inaccessible from the electromagnetic wave spectrum. It will open a new window to the universe. LISA is essentially a Michelson interferometer placed in space

  12. Differential interferometer for measurement of displacement of laser resonator mirrors

    NASA Astrophysics Data System (ADS)

    Macúchová, Karolina; N?mcová, Šárka; Hošek, Jan

    2015-01-01

    This paper covers a description and a technique of a possible optical method of mode locking within a laser resonator. The measurement system is a part of instrumentation of laser-based experiment OSQAR at CERN. The OSQAR experiment aims at search of axions, axion-like particles and measuring of ultra-fine vacuum magnetic birefringence. It uses a laser resonator to enhance the coupling constant of hypothetical photon-to-axion conversion. The developed locking-in technique is based on differential interferometry. Signal obtained from the measurement provide crucial information for adaptive control of the locking-in of the resonator in real time. In this paper we propose several optical setups used for measurement and analysis of mutual position of the resonator mirrors. We have set up a differential interferometer under our laboratory conditions. We have done measurements with hemi-spherical cavity resonator detuned with piezo crystals. The measurement was set up in a single plane. Laser light was directed through half-wave retarder to a polarizing beam splitter and then converted to circular polarization by lambda/4 plates. After reflection at the mirrors, the beam is recombined in a beam splitter, sent to analyser and non-polarizing beam splitter and then inspected by two detectors with mutually perpendicular polarizers. The 90 degrees phase shift between the two arms allows precise analysis of a mutual distance change of the mirrors. Because our setup was sufficiently stable, we were able to measure the piezo constant and piezo hysteresis. The final goal is to adapt the first prototype to 23 m resonator and measure the displacement in two planes.

  13. The Implications of the Microwave Background Anisotropies for Laser-Interferometer-Tested Gravitational Waves

    E-print Network

    L. P. Grishchuk

    1997-03-06

    The observed microwave background anisotropies in combination with the theory of quantum mechanically generated cosmological perturbations predict a well measurable amount of relic gravitational waves in the frequency intervals tested by LISA and ground-based laser interferometers.

  14. Ultra-stable performance of an underground-based laser interferometer observatory for gravitational waves

    E-print Network

    S. Sato; S. Miyoki; S. Telada; D. Tatsumi; A. Araya; M. Ohashi; Y. Totsuka; M. Fukushima; M. -K. Fujimoto

    2004-03-18

    In order to detect the rare astrophysical events that generate gravitational wave (GW) radiation, sufficient stability is required for GW antennas to allow long-term observation. In practice, seismic excitation is one of the most common disturbances effecting stable operation of suspended-mirror laser interferometers. A straightforward means to allow more stable operation is therefore to locate the antenna, the ``observatory'', at a ``quiet'' site. A laser interferometer gravitational wave antenna with a baseline length of 20m (LISM) was developed at a site 1000m underground, near Kamioka, Japan. This project was a unique demonstration of a prototype laser interferometer for gravitational wave observation located underground. The extremely stable environment is the prime motivation for going underground. In this paper, the demonstrated ultra-stable operation of the interferometer and a well-maintained antenna sensitivity are reported.

  15. An extreme ultraviolet Michelson interferometer for experiments at free-electron lasers

    SciTech Connect

    Hilbert, Vinzenz; Fuchs, Silvio; Paulus, Gerhard G.; Zastrau, Ulf [Institute of Optics and Quantum Electronics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany)] [Institute of Optics and Quantum Electronics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Blinne, Alexander [Institute for Theoretical Physics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany)] [Institute for Theoretical Physics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Feigl, Torsten [Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Straße 7, 07745 Jena (Germany)] [Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Straße 7, 07745 Jena (Germany); Kämpfer, Tino; Rödel, Christian; Uschmann, Ingo; Wünsche, Martin; Förster, Eckhart [Institute of Optics and Quantum Electronics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany) [Institute of Optics and Quantum Electronics, Friedrich-Schiller University Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Helmholtz Institute, Fröbelstieg 3, 07743 Jena (Germany)

    2013-09-15

    We present a Michelson interferometer for 13.5 nm soft x-ray radiation. It is characterized in a proof-of-principle experiment using synchrotron radiation, where the temporal coherence is measured to be 13 fs. The curvature of the thin-film beam splitter membrane is derived from the observed fringe pattern. The applicability of this Michelson interferometer at intense free-electron lasers is investigated, particularly with respect to radiation damage. This study highlights the potential role of such Michelson interferometers in solid density plasma investigations using, for instance, extreme soft x-ray free-electron lasers. A setup using the Michelson interferometer for pseudo-Nomarski-interferometry is proposed.

  16. Phase-coherent mapping of gravitational-wave backgrounds using ground-based laser interferometers

    E-print Network

    Romano, Joseph D; Cornish, Neil J; Gair, Jonathan; Mingarelli, Chiara M F; van Haasteren, Rutger

    2015-01-01

    We extend the formalisms developed in Gair et al. and Cornish and van Haasteren to create maps of gravitational-wave backgrounds using a network of ground-based laser interferometers. We show that in contrast to pulsar timing arrays, which are insensitive to half of the gravitational-wave sky (the curl modes), a network of ground-based interferometers is sensitive to both the gradient and curl components of the background. The spatial separation of a network of interferometers, or of a single interferometer at different times during its rotational and orbital motion around the Sun, allows for recovery of both components. We derive expressions for the response functions of a laser interferometer in the small-antenna limit, and use these expressions to calculate the overlap reduction function for a pair of interferometers. We also construct maximum-likelihood estimates of the + and x-polarization modes of the gravitational-wave sky in terms of the response matrix for a network of ground-based interferometers, e...

  17. Phase-coherent mapping of gravitational-wave backgrounds using ground-based laser interferometers

    E-print Network

    Joseph D. Romano; Stephen R. Taylor; Neil J. Cornish; Jonathan Gair; Chiara M. F. Mingarelli; Rutger van Haasteren

    2015-05-27

    We extend the formalisms developed in Gair et al. and Cornish and van Haasteren to create maps of gravitational-wave backgrounds using a network of ground-based laser interferometers. We show that in contrast to pulsar timing arrays, which are insensitive to half of the gravitational-wave sky (the curl modes), a network of ground-based interferometers is sensitive to both the gradient and curl components of the background. The spatial separation of a network of interferometers, or of a single interferometer at different times during its rotational and orbital motion around the Sun, allows for recovery of both components. We derive expressions for the response functions of a laser interferometer in the small-antenna limit, and use these expressions to calculate the overlap reduction function for a pair of interferometers. We also construct maximum-likelihood estimates of the + and x-polarization modes of the gravitational-wave sky in terms of the response matrix for a network of ground-based interferometers, evaluated at discrete times during Earth's rotational and orbital motion around the Sun. We demonstrate the feasibility of this approach for some simple simulated backgrounds (a single point source and spatially-extended distributions having only grad or curl components), calculating maximum-likelihood sky maps and uncertainty maps based on the (pseudo)inverse of the response matrix. The distinction between this approach and standard methods for mapping gravitational-wave power is also discussed.

  18. Very small portable holographic interferometers and compact speckle interferometer with semiconductor laser sources well suited for industrial inspections

    NASA Astrophysics Data System (ADS)

    Petrov, Valery

    2001-10-01

    Current manufacturing processes require rapid, reliable methods and compact, user-friendly, elegant devices capable to work even in unpromising environment. Innovative user- friendly methods and techniques as well as small holographic and speckle interferometers are presented in this paper. The devices are very compact, easy to operate, incorporate semiconductor laser sources and do not require personnel skilled in optics. Miniature semiconductor laser sources were successfully used in holography and laser speckle metrology for the tasks of 3-dimensional data acquisition, storage and display. Semiconductor lasers enable compact recording and display devices which are easy in operation and well fitted to practical industrial environments. Novel inspection methods and compact devices incorporating miniature semiconductor laser sources can be applied for automated inspections and optical precision measurements in optomechatronic systems. They fit well for real time monitoring of local deformations. Presented devices and techniques meet modern industrial requirements and permit to work in unpromising environment, perform in situ checks of products and components. Vast experimental data are given and the possibilities of innovative devices and techniques are properly illustrated in multiple practical examples. Photographs from holograms and holographic interferograms recorded with semiconductor lasers and successive sets of snapshots during real time monitoring of thermal fields are presented.

  19. Quadrature frequency conversion

    NASA Astrophysics Data System (ADS)

    Eimerl, David

    1987-08-01

    A technique for frequency conversion of high-power lasers is described which uses two crystals for each conversion step rather than one. The two crystals are oriented so that the waves generated in them are orthogonally polarized. The conversion efficiency of these quadrature arrangements is much less sensitive to laser pulse nonuniformities than that in single-crystal methods. Consequently, very high conversion efficiency is possible for typically nonuniform laser pulses. Realization of the quadrature concept for all types of nonlinear optical processes is described. Data taken on second harmonic generation of Gaussian pulses shows that very high (internal) conversion efficiency is possible (greater than 95 percent) over a substantial range of input energy.

  20. Multiprobe scanning system comprising three laser interferometers and one autocollimator for measuring flat bar mirror profile with nanometer accuracy

    Microsoft Academic Search

    Ping Yang; Tomohiko Takamura; Satoru Takahashi; Kiyoshi Takamasu; Osamu Sato; Sonko Osawa; Toshiyuki Takatsuji

    2011-01-01

    This paper describes a multi-probe scanning system comprising three laser interferometers and one autocollimator to measure a flat bar mirror profile with nanometer accuracy. The laser interferometers probe the surface of the flat bar mirror that is fixed on top of a scanning stage, while the autocollimator simultaneously measures the yaw error of the scanning stage. The flat bar mirror

  1. A laser interferometer for measuring skin friction in three-dimensional flows

    NASA Technical Reports Server (NTRS)

    Monson, D. J.

    1983-01-01

    A new, nonintrusive method is described for measuring skin friction in three-dimensional flows with unknown direction. The method uses a laser interferometer to measure the changing slope of a thin oil film applied to a surface experiencing shear stress. The details of the method are described, and skin friction measurements taken in a swirling three-dimensional boundary-layer flow are presented. Comparisons between analytical results and experimental values from the laser interferometer method and from a bidirectional surface-fence gauge are made.

  2. A laser interferometer for combustion, aerodynamics and heat transfer studies

    Microsoft Academic Search

    S. S. Sandhu; F. J. Weinberg

    1972-01-01

    A large-area interferometer is described which is based on schlieren system and designed to be used subtractively by a double exposure method. The beam is split using front and rear surface reflections from a small-angle prism. On the double exposure interferogram both the fringe spacing and shear are variable. The aim is to subtract not only aberrations and windows, but

  3. Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry

    PubMed Central

    Šmíd, Radek; ?ížek, Martin; Mikel, B?etislav; ?íp, Ond?ej

    2015-01-01

    We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency. PMID:25587980

  4. Frequency noise suppression of a single mode laser with an unbalanced fiber interferometer for subnanometer interferometry.

    PubMed

    Šmíd, Radek; ?ížek, Martin; Mikel, B?etislav; ?íp, Ond?ej

    2015-01-01

    We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency. PMID:25587980

  5. A laser frequency and power control system in an atomic Talbot-Lau interferometer

    NASA Astrophysics Data System (ADS)

    Yang, Ting; Hu, Zhaohui; Qi, Lu

    2013-12-01

    The importance of atom interferometers that have high sensitivity and super precision is well recognized in the fields of rotation sensing, inertial and gravitational forces sensing, relativity tests, and other precision measures. So many researchers are absorbed in atom interferometers. An atom interferometer consists of many parts, among of which optical part plays a significant role because of the need of laser beams in every parts. Based on this situation and some specific quantitive requirements to laser beams, this article presents a laser frequency and power control system for atom interferometer which can realize the functions of frequency shift and scan, power stabilization and modulation, and highspeed switch. The system lies on acousto-optical modulators (AOM) and a phase-locked loop frequency synthesizer is designed in the system as a very important part which has wide capture range of frequency and well stability. The experimental results show that the designed system is available and the performances of laser through AOM are as good as expected and the phase noise of the output is restrained. In addition, the system also could be used in other instruments and devices, such as atomic clock, gravimeter, gradiometer, and gyroscope.

  6. Errors caused by nearly parallel optical elements in a laser Fizeau interferometer utilizing strictly coherent imaging

    Microsoft Academic Search

    Erik Novak; Chiayu Ai; James C. Wyant

    1997-01-01

    Most commercial laser Fizeau interferometers employ a rotating diffuser on an intermediate image plane. The image formed on this plane is relayed to the detector using incoherent imaging, eliminating potential interference effects from elements after the diffuser. Systems requiring high spatial frequency resolution cannot employ the diffuser or incoherent relay system to the degradation they cause to the system transfer

  7. Two-dimensional interferogram of an exploding selenium foil using a soft X-ray laser interferometer

    Microsoft Academic Search

    L. B. Da Silva; R. Cauble; P. Celliers; D. Ciarlo; S. Libby; R. A. London; D. Matthews; S. Mrowka; J. C. Moreno; D. Ress; J. E. Trebes; A. S. Wan; F. Weber

    1996-01-01

    We have developed a soft X-ray interferometer capable of probing large high-density plasmas with micron spatial resolutions. A neon-like yttrium X-ray laser operating at 155 Å was combined with the Mach-Zehnder interferometer to obtain electron density profiles of a laser-produced exploding selenium foil plasma. The plasma was produced with one Nova laser beam using a 120-?m line focus, the same

  8. Development Towards a Space Qualified Laser Stabilization System in Support of Space-Based Optical Interferometers

    NASA Technical Reports Server (NTRS)

    Seidel, David J.; Dubovitsky, Serge

    2000-01-01

    We report on the development, functional performance and space-qualification status of a laser stabilization system supporting a space-based metrology source used to measure changes in optical path lengths in space-based stellar interferometers. The Space Interferometry Mission (SIM) and Deep Space 3 (DS-3) are two missions currently funded by the National Aeronautics and Space Administration (NASA) that are space-based optical interferometers. In order to properly recombine the starlight received at each telescope of the interferometer it is necessary to perform high resolution laser metrology to stabilize the interferometer. A potentially significant error source in performing high resolution metrology length measurements is the potential for fluctuations in the laser gauge itself. If the laser frequency or wavelength is changing over time it will be misinterpreted as a length change in one of the legs of the interferometer. An analysis of the frequency stability requirement for SIM resulted in a fractional frequency stability requirement of square root (S(sub y)(f)) = <2 x 10(exp -12)/square root(Hz) at Fourier frequencies between 10 Hz and 1000 Hz. The DS-3 mission stability requirement is further increased to square root (S(sub y)(f)) = <5 x 10(exp -14)/Square root(Hz) at Fourier frequencies between 0.2 Hz and 10 kHz with a goal of extending the low frequency range to 0.05 Hz. The free running performance of the Lightwave Electronics NPRO lasers, which are the baseline laser for both SIM and DS-3 vary in stability and we have measured them to perform as follows (9 x l0(exp -11)/ f(Hz))(Hz)/square root(Hz)) = <( square root (S(sub y)(f)) = <(1.3 x l0(exp -8)/ f(Hz))/Square root(Hz). In order to improve the frequency stability of the laser we stabilize the laser to a high finesse optical cavity by locking the optical frequency of the laser to one of the transmission modes of the cavity. At JPL we have built a prototype space-qualifiable system meeting the stability requirements of SIM, which has been delivered to one of the SIM testbeds. We have also started on the development of a system to meet the stability needs of DS-3.

  9. Experimental Demonstration of Time-Delay Interferometry for the Laser Interferometer Space Antenna

    E-print Network

    Glenn de Vine; Brent Ware; Kirk McKenzie; Robert E. Spero; William M. Klipstein; Daniel A. Shaddock

    2010-05-12

    We report on the first demonstration of time-delay interferometry (TDI) for LISA, the Laser Interferometer Space Antenna. TDI was implemented in a laboratory experiment designed to mimic the noise couplings that will occur in LISA. TDI suppressed laser frequency noise by approximately 10^9 and clock phase noise by 6x10^4, recovering the intrinsic displacement noise floor of our laboratory test bed. This removal of laser frequency noise and clock phase noise in post-processing marks the first experimental validation of the LISA measurement scheme.

  10. Pulse shortening of gain switched single mode semiconductor lasers using a variable delay interferometer.

    PubMed

    Consoli, Antonio; Esquivias, Ignacio

    2012-09-24

    We propose a pulse shaping and shortening technique for pulses generated from gain switched single mode semiconductor lasers, based on a Mach Zehnder interferometer with variable delay. The spectral and temporal characteristics of the pulses obtained with the proposed technique are investigated with numerical simulations. Experiments are performed with a Distributed Feedback laser and a Vertical Cavity Surface Emitting Laser, emitting at 1.5 µm, obtaining pulse duration reduction of 25-30%. The main asset of the proposed technique is that it can be applied to different devices and pulses, taking advantage of the flexibility of the gain switching technique. PMID:23037397

  11. Active laser frequency stabilization and resolution enhancement of interferometers for the measurement of gravitational waves in space

    E-print Network

    Markus Herz

    2005-08-23

    Laser frequency stabilization is notably one of the major challenges on the way to a space-borne gravitational wave observatory. The proposed Laser Interferometer Space Antenna (LISA) is presently under development in an ESA, NASA collaboration. We present a novel method for active laser stabilization and phase noise suppression in such a gravitational wave detector. The proposed approach is a further evolution of the "arm locking" method, which in essence consists of using an interferometer arm as an optical cavity, exploiting the extreme long-run stability of the cavity size in the frequency band of interest. We extend this method by using the natural interferometer arm length differences and existing interferometer signals as additional information sources for the reconstruction and active suppression of the quasi-periodic laser frequency noise, enhancing the resolution power of space-borne gravitational wave detectors.

  12. Measurements of laser-induced thermoelastic deformation using all-fiber heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Park, Seong Jun; Eom, Jong Hyun; Lee, Chang Su; Lee, Byeong Ha

    2014-05-01

    We report an all-fiber heterodyne interferometer for the measurements of laser-induced thermoelastic deformation to estimate the Gruneisen coefficient and the optical attenuation depth of a sample. The system comprises a Q-switched Nd-YAG laser providing a nanosecond excitation pulse and an all-fiber heterodyne interferometer that measures the induced displacement of the sample surface. To evaluate the system, phantom experiments were carried out with various gelatin-based models. The results show that the attenuation depth and Gruneisen coefficient of the phantoms were about 4.256 mm and 0.568, respectively. In addition, increase of the weight fraction of gelatin led increase in the Gruneisen coefficient.

  13. Mirror thermal noise in laser interferometer gravitational wave detectors operating at room and cryogenic temperature

    E-print Network

    Janyce Franc; Nazario Morgado; Raffaele Flaminio; Ronny Nawrodt; Iain Martin; Liam Cunningham; Alan Cumming; Sheila Rowan; James Hough

    2009-12-01

    Mirror thermal noise is and will remain one of the main limitations to the sensitivity of gravitational wave detectors based on laser interferometers. We report about projected mirror thermal noise due to losses in the mirror coatings and substrates. The evaluation includes all kind of thermal noises presently known. Several of the envisaged substrate and coating materials are considered. The results for mirrors operated at room temperature and at cryogenic temperature are reported.

  14. Observation of the laser-induced surface dynamics by the single-shot x-ray laser interferometer

    NASA Astrophysics Data System (ADS)

    Hasegawa, Noboru; Ochi, Yoshihiro; Kawachi, Tetsuya; Nishikino, Masaharu; Ishino, Masahiko; Imazono, Takashi; Kaihori, Takeshi; Sasaki, Akira; Terakawa, Kota; Minami, Yasuo; Tomita, Takuro; Yamamoto, Minoru; Umeda, Yoshifumi; Yamagiwa, Mitsuru; Suemoto, Tohru

    2011-09-01

    We have developed a soft x-ray laser (SXRL) interferometer capable of the single-shot imaging of nano-scaled structure dynamics. The interferometer consisted of the reflection optics including double Lloyd's mirrors and focusing optics, and the interference fringes are produced on the detector surface. The depth and lateral resolutions of the interferometer were about 1 nm and 1.8 ?m, respectively. By using this interferometer, the initial stage (~50 ps) of the ablation process of the Pt surface pumped by a 70 fs Ti:Sapphire laser pulse was observed. The expansion speed of the surface estimated from the result (34 nm/50 ps) indicated that the nano-bubble structures were formed in the initial stage of the ablation. In order to observe the detailed dynamics, the temporal synchronization between the pump and probe pulses was improved to be 3 ps by adopting a portion of the SXRL and pump beams as the time fiducials, to which the pump and probe timing was adjusted by using the x-ray streak camera.

  15. Two-dimensional interferogram of an exploding selenium foil using a soft X-ray laser interferometer

    SciTech Connect

    Da Silva, L.B.; Cauble, R.; Barbee, T.W. [Lawrence Livermore National Lab., CA (United States)] [Lawrence Livermore National Lab., CA (United States)

    1996-02-01

    The authors have developed a soft X-ray interferometer capable of probing large high-density plasmas with micron spatial resolutions. A neon-like yttrium X-ray laser operating at 155 {angstrom} was combined with the Mach-Zehnder interferometer to obtain electron density profiles of a laser-produced exploding selenium foil plasma. The plasma was produced with one Nova laser beam using a 120-{micro}m line focus, the same conditions used to create a selenium X-ray laser. The interferogram of the selenium plasma was obtained from an end-on perspective.

  16. Soft-x-ray interferometer for single-shot laser linewidth measurements

    NASA Astrophysics Data System (ADS)

    Chilla, Juan L. A.; Rocca, Jorge J.; Martinez, Oscar E.; Marconi, Mario C.

    1996-07-01

    A soft-x-ray Mach-Zehnder interferometer configuration that makes use of the time delay introduced by diffraction gratings to conduct single-shot measurements of the linewidth of soft-x-ray laser amplifiers is proposed and analyzed. The scheme was experimentally demonstrated in the near-IR region of the spectrum by measurement of the mode separation of a semiconductor laser. A symmetric configuration with compensated time delays that can be implemented for plasma diagnostics and for evaluating soft-x-ray optics is also discussed.

  17. Measuring preheat in laser-drive aluminum using velocity interferometer system for any reflector: Experiment

    NASA Astrophysics Data System (ADS)

    Shu, Hua; Fu, Sizu; Huang, Xiuguang; Wu, Jiang; Xie, Zhiyong; Zhang, Fan; Ye, Junjian; Jia, Guo; Zhou, Huazhen

    2014-08-01

    In this paper, we systematically study preheating in laser-direct-drive shocks by using a velocity interferometer system for any reflector (VISAR). Using the VISAR, we measured free surface velocity histories of Al samples over time, 10-70 ?m thick, driven directly by a laser at different frequencies (2?, 3?). Analyzing our experimental results, we concluded that the dominant preheating source was X-ray radiation. We also discussed how preheating affected the material initial density and the measurement of Hugoniot data for high-Z materials (such as Au) using impedance matching. To reduce preheating, we proposed and tested three kinds of targets.

  18. Measuring preheat in laser-drive aluminum using velocity interferometer system for any reflector: Experiment

    SciTech Connect

    Shu, Hua; Fu, Sizu; Huang, Xiuguang; Wu, Jiang; Xie, Zhiyong; Zhang, Fan; Ye, Junjian; Jia, Guo; Zhou, Huazhen [Shanghai Institute of Laser Plasma, P.O. BOX 800-229, Shanghai 201800 (China)

    2014-08-15

    In this paper, we systematically study preheating in laser-direct-drive shocks by using a velocity interferometer system for any reflector (VISAR). Using the VISAR, we measured free surface velocity histories of Al samples over time, 10–70??m thick, driven directly by a laser at different frequencies (2?, 3?). Analyzing our experimental results, we concluded that the dominant preheating source was X-ray radiation. We also discussed how preheating affected the material initial density and the measurement of Hugoniot data for high-Z materials (such as Au) using impedance matching. To reduce preheating, we proposed and tested three kinds of targets.

  19. Status of advanced ground-based laser interferometers for gravitational-wave detection

    NASA Astrophysics Data System (ADS)

    Dooley, K. L.; Akutsu, T.; Dwyer, S.; Puppo, P.

    2015-05-01

    Ground-based laser interferometers for gravitational-wave (GW) detection were first constructed starting 20 years ago and as of 2010 collection of several years’ worth of science data at initial design sensitivities was completed. Upgrades to the initial detectors together with construction of brand new detectors are ongoing and feature advanced technologies to improve the sensitivity to GWs. This conference proceeding provides an overview of the common design features of ground-based laser interferometric GW detectors and establishes the context for the status updates of each of the four gravitational-wave detectors around the world: Advanced LIGO, Advanced Virgo, GEO 600 and KAGRA.

  20. LCOS as a reference element in Twyman-Green laser interferometer

    NASA Astrophysics Data System (ADS)

    Kacperski, Jacek; Kujawinska, Malgorzata; Jozwik, Michal

    2006-04-01

    Micro-Electro-Mechanical Systems are nowadays frequently used in many fields of industry. The number of their applications increases and their functions become more responsible, therefore precise knowledge about their properties is necessary. Due to its fragility and small sizes non-contact and high sensitive measurement method is required. Two-beam laser interferometry is one of the most popular testing methods of microelements. Such method implemented in Twyman-Green interferometer allows for full-field shape determination and out-of-plane displacement measurement. However the elements under test may bring additional challenges: their surfaces may have complicated shape or large shape gradients which prohibit their testing by means of interferometer with a flat reference mirror. To overcome such problems we propose to use LCOS (Liquid Crystal On Silicon) - phase, reflective SLM as an active reference element. LCOS serves as an adaptive reference mirror and phase shifter. The use of such element allows increasing measurement range of the interferometer and simplifies out-of-plane displacement measurement through object wavefront compensation. The applicability of the modified Twyman-Green interferometer will be shown at the examples of active micromembranes testing.

  1. Performance of a wavelength-tunable erbium-doped fiber laser using a Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Sheu, Fang-Wen; Chiou, Chung-Yao; Yang, Shu-Chun

    2008-09-01

    We experimentally demonstrate a wavelength-tunable erbium-doped fiber laser that is composed of a ring cavity and a single-mode fiber Sagnac interferometer in a new and simple arrangement. We find that the fiber laser output wavelength is tunable by adjusting the filter effect of the Sagnac fiber loop through a fiber polarization controller set there. The quasi-single-wavelength continuously tunable laser outputs could be achieved within some wavelength range. The multi-wavelength laser outputs could also be observed under some appropriate settings of the polarization controller. A theoretical demonstration of the wavelength tunability about the transmission-type Sagnac loop filter has also been achieved using the Jones calculus theory.

  2. A nonintrusive laser interferometer method for measurement of skin friction

    NASA Technical Reports Server (NTRS)

    Monson, D. J.

    1983-01-01

    A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows, including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows. Previously announced in STAR as N83-12393

  3. A nonintrusive laser interferometer method for measurement of skin friction

    NASA Technical Reports Server (NTRS)

    Monson, D. J.

    1982-01-01

    A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows.

  4. SUNLITE program. Sub-Hertz relative frequency stabilization of two diode laser pumped Nd:YAG lasers locked to a Fabry-Perot interferometer

    NASA Technical Reports Server (NTRS)

    Byer, R. L.

    1990-01-01

    Two laser pumped Nd:YAG lasers were frequency stabilized to a commercial 6.327 GHz free spectral range Fabry-Perot interferometer yielding a best case beatnote linewidth of 330 MHz. In addition, a Fabry-Perot interferometer with a free spectral range of 680 MHz, a linewidth of 25 kHz, and a finesse of 27,500 was built, and when it was substituted in place of the commercial interferometer, it produced a robust and easily repeatable beatnote linewidth of 700 MHz.

  5. Thermal calcium atom interferometer with a phase resolution of a few milliradians based on a narrow-linewidth diode laser

    Microsoft Academic Search

    Tomoya Akatsuka; Yoshihiro Mori; Nobuhiko Sone; Yurie Ohtake; Mamoru Machiya; Atsuo Morinaga

    2011-01-01

    A symmetrical atom interferometer with a thermal calcium atom beam has been developed using a narrow linewidth diode laser stabilized to the resonance of a high-finesse cavity. The linewidth of the diode laser was estimated to be less than 1 Hz relative to the cavity resonance in noise measurement over the range of 100 Hz to 1 MHz, and the

  6. A LIRA Twin-Wave Laser Interferometer–Reflector for Plasma Diagnostics at Large-Scale Facilities

    Microsoft Academic Search

    G. I. Kozin; A. P. Kuznetsov; M. O. Lebedinskii; A. V. Savel'ev; A. P. Sokolov; A. S. Savelov

    2003-01-01

    A LIRA interferometric system (active laser interferometer–reflector) is designed for measuring the plasma density and controlling the degree of modification of the reflector surface under conditions of intense vibrations of a plasma facility. The operating principle of the system is based on the intralaser (autodyne) reception of the radiation reflected into the laser. An element of the structure of the

  7. Construction and performance of a Fabry-Perot-interferometer-based airborne autonomous wavemeter for laser tuning

    NASA Astrophysics Data System (ADS)

    Goad, Joseph H.

    1990-04-01

    This paper summarizes a continuing effort to develop, design, construct, and evaluate the performance of an airborne autonomous wavemeter for laser tuning. The wavemeter supports tunable solid-state lasers that are used for atmospheric remote sensing. This sensing approach is the Differential Absorption Lidar (DIAL) technique. One atmospheric species, water vapor is measured by tuning one laser to line center of a water vapor line and by tuning another laser off the line. The two sets of received backscattered radiation are ratioed and corrected to determine the vertical profiles of water vapor. On a spacecraft platform, an advanced system could monitor the global water vapor profiles. This would provide a technology improvement for meteorological forecasting. One experiment to make water vapor DIAL measurements from a down-looking airborne platform is the NASA-LASE (Lidar Atmos pheric Sensing Experiment) Project instrument1 to be flown on a NASA ER-2 aircraft. Breadboard results have been obtained that predict that a wavemeter can be built to survive the harsh air-borne environment of low temperatures and low pressures that exist in high altitude flight. Based on the breadboard results, the airborne wavemeter consist of three stages of Fabry-Perot interferometers. Stages #1 and #2 provide the necessary information to provide laser wavelength centroid measurements to the required accuracy of less than 0-.25 picometers. This provides the real-time information necessary for tuning the two tunable alexandrite lasers for the water vapor measurement. A high resolution stage #3 interferometer provides the laser spectral profile measurement with an instrumental profile less than 0.5 picometers full-width at half-maximum amplitude for the post-flight science data reduction. To maintain interferometric stability, the first two stages are thermally controlled and contained in a vacuum chamber. A two level control approach is used to stabilize the interferometers above the highest ambient temperature. Techniques have been developed to evaluate the accuracy of the wavelength centroid algorithms. By using a single wavelength stabilized He-Ne laser as a perfect source, the end-to-end random errors (short term stability) are determined in a period too short for any thermal/mechanical response. The end--to-end sys

  8. A fast scanning laser probe based on Sagnac interferometer for RF surface and bulk acoustic wave devices

    Microsoft Academic Search

    Ken-ya Hashimoto; Keisuke Kashiwa; Tatsuya Omori; Masatsune Yamaguchi; Osamu Takano; Sakae Meguro; Koichi Akahane

    2008-01-01

    This paper describes the development of a new laser probe for radio frequency (RF) surface and bulk acoustic wave (SAW\\/BAW) devices. The Sagnac interferometer was introduced for the selective detection of RF vertical motion associated with RF SAW\\/BAW propagation and vibration. A high-pass characteristic of the interferometer makes the measurement very insusceptible to the low-frequency vibration. Combining such a feature

  9. In-fiber modal interferometer based on dual-core photonic crystal fiber and its application in fiber laser

    Microsoft Academic Search

    Weiguo Chen; Shuqin Lou; Liwen Wang; Shuisheng Jian

    2010-01-01

    An in-fiber modal interferometer is proposed by splicing a section of homemade dual-core dual-core photonic crystal fiber and two segments of single-mode fibers with the air-holes collapsed in the splice regions. With the proposed interferometer as wavelength-selective filter, a room-temperature switchable multi-wavelength fiber laser is proposed and experimentally demonstrated.

  10. Interferometer for the measurement of plasma density

    DOEpatents

    Jacobson, Abram R. (Los Alamos, NM)

    1980-01-01

    An interferometer which combines the advantages of a coupled cavity interferometer requiring alignment of only one light beam, and a quadrature interferometer which has the ability to track multi-fringe phase excursions unambiguously. The device utilizes a Bragg cell for generating a signal which is electronically analyzed to unambiguously determine phase modulation which is proportional to the path integral of the plasma density.

  11. Experimental study of laser-induced air plasma using a Nomarski interferometer

    NASA Astrophysics Data System (ADS)

    Oh, Seong Y.; Lim, Changhwan; Ha, Sung Yong; Nam, Sungmo; Han, Jaemin

    2015-07-01

    The spatial and temporal evolution of plasma generated via laser-induced breakdown in air was investigated. The plasma was produced in air using a focused Nd:YAG Q-switched laser (? = 1064 nm; pulse duration ?5 ns; pulse energy ?60 mJ). The interference patterns of the resulting plasma were measured as a function of time using a Nomarski interferometer. The elapsed times were in the range 59–232 ns. A frequency-doubled Q-switched Nd:YAG laser (? = 532 nm; pulse duration ?10 ns; pulse energy ?10.5 mJ) was coupled with the Nomarski interferometer to form an interferometric probe beam. The electron density was inferred from Abel inversion and fast Fourier transformation analysis of the recorded interference patterns. The measured electron densities were on the order of ?1018 cm?3. Using the Saha equation, assuming that the plasma is in local thermodynamic equilibrium, and that the ionization reaction is (N ? N+ + e), the electron temperatures were estimated to be in the range 17600–15500 K.

  12. Demonstration of detuned dual recycling at the Garching 30m laser interferometer

    E-print Network

    A. Freise; G. Heinzel; K. A. Strain; J. Mizuno; K. D. Skeldon; H. Lueck; B. Willke; R. Schilling; A. Ruediger; W. Winkler; K. Danzmann

    2000-10-19

    Dual recycling is an advanced optical technique to enhance the signal-to-noise ratio of laser interferometric gravitational wave detectors in a limited bandwidth. To optimise the center of this band with respect to Fourier frequencies of expected gravitational wave signals detuned dual recycling has to be implemented. We demonstrated detuned dual recycling on a fully suspended 30m prototype interferometer. A control scheme that allows to tune the detector to different frequencies will be outlined. Good agreement between the experimental results and numerical simulations has been achieved.

  13. The laser interferometer skin-friction meter - A numerical and experimental study

    NASA Technical Reports Server (NTRS)

    Murphy, J. D.; Westphal, R. V.

    1986-01-01

    Limits to the applicability of thin-film lubrication theory are established. The following two problems are considered: (1) the response of the oil film to a time-varying skin friction such as is encountered in turbulent boundary layers, and (2) a 'surface-wave instability' encountered at high skin-friction levels. Results corresponding to the first problem reveal that the laser interferometer skin-friction meter may, in principle, be applied to the measurement of instantaneous skin friction. In addressing the second problem, it is shown that the observed surface waves are not the result of a hydrodynamic instability.

  14. Fiber inline Michelson interferometer fabricated by one-step femtosecond laser micromachining for sensing applications

    NASA Astrophysics Data System (ADS)

    Yuan, Lei; Wu, Hongbin; Wang, Cong; Yu, Yingyu; Wang, Sumei; Xiao, Hai

    2013-12-01

    A fiber inline Michelson interferometer fiber optic sensor was presented for sensing applications, including high temperature performance and refractive index change. The sensor was fabricated using one-step femtosecond (fs) laser micromachining technique. A step structure at the tip of a single mode optical fiber was formed during the micromachining process. The device had a loss of 16 dB and an interference visibility exceeding 18 dB. The capability of this device for temperature sensing up to 1000 °C and refractive index sensing application in various concentrations of ethanol solution were all demonstrated.

  15. Wavelength-insensitive laser Doppler velocimeter using beam position shift induced by Mach-Zehnder interferometers.

    PubMed

    Maru, Koichi; Fujii, Yusaku

    2009-09-28

    A novel wavelength-insensitive differential laser Doppler velocimeter (LDV) without a grating has been proposed. The proposed LDV utilizes a position shift of the beam at the input plane according to wavelength change induced by Mach-Zehnder interferometers (MZIs). The gradual shift in the incident angle of the beam to the object is brought about with the combination of MZIs, lenses and apertures. The characteristics of the proposed structure are simulated using paraxial approximation of a lens system with an aperture. The simulation results indicate that almost wavelength-insensitive operation can be obtained by using the proposed structure without any grating element. PMID:19907528

  16. Visibility oscillation in a multimode laser interferometer signal and its use in optimizing path lengths

    NASA Astrophysics Data System (ADS)

    Ruden, E. L.; Camacho, J. F.; Lynn, A. G.

    2013-10-01

    The interference signal visibility V (difference to sum ratio of intensities at maximum and minimum interference) of an interferometer that uses a multimode laser is here derived for a given laser gain profile and spectral mode separation as a function of the difference ZS between the probe and reference beam optical path lengths and the spectral separation kS between the center of the laser gain profile and the nearest laser mode of higher frequency. kS has a significant effect on V for a given ZS. This parameter, in lasers where it sweeps freely across the gain profile, and other effects, such as various misalignments and optical coupling inefficiencies, render V alone an unreliable parameter for quantifying ZS (for the purpose of reducing it, say). However, the difference to sum ratio of the maximum and minimum V due to variations in kS for a given ZS is an intrinsic property of the laser insensitive to configurational details. Parameter W so defined, therefore, proves very useful for balancing path lengths. This is of particular importance for systems where probe and/or reference beams are transmitted via long single mode optical fibers, so this application is detailed. Optical path lengths within such fibers often cannot be measured to sufficient accuracy by spatial path length measurements due to fiber nonuniformity resulting in variations in the mode's group velocity (needed to convert to optical path length). Two examples are provided using different makes and models of 0.633 ?m HeNe lasers with similar specifications. In the first case, the function W(ZS) is calculated directly from the laser's published gain profile and mode separation. In the second case, W is determined empirically for a range of ZS values for a laser with an unknown gain profile in a (heterodyned) interferometer whose interference signal oscillates between maximum and minimum intensity at 80 MHz due to the reference beam's optical frequency being acousto-optically upshifted by that amount, while kS spontaneously varies on an acoustic time scale. A single high-bandwidth waveform record for each ZS, therefore, provides all the information needed to determine W. Despite the second laser's gain profile apparently differing in detail, qualitative agreement is achieved between the two methods sufficient to validate the technique.

  17. Comparisons of multi-wavelength oscillations using Sagnac loop mirror and Mach-Zehnder interferometer for ytterbium doped fiber lasers

    Microsoft Academic Search

    M. R. A. Moghaddam; S. W. Harun; S. Shahi; K. S. Lim; H. Ahmad

    2010-01-01

    A multiwavelength Ytterbium-doped fiber ring laser operating at 1030 nm region is demonstrated using a Sagnac loop mirror\\u000a and a Mach-Zehnder interferometer. We report the Performance comparisons of multi-wavelength oscillations in Yb3+ doped fiber lasers (YDFL) with typical commercial ytterbium doped silica fibers. By adjusting the polarization controller\\u000a (PC), a widely tunable laser range of 22 nm from 1030 nm

  18. Comparisons of multi-wavelength oscillations using Sagnac loop mirror and Mach-Zehnder interferometer for ytterbium doped fiber lasers

    Microsoft Academic Search

    M. R. A. Moghaddam; S. W. Harun; S. Shahi; K. S. Lim; H. Ahmad

    2010-01-01

    A multiwavelength Ytterbium-doped fiber ring laser operating at 1030 nm region is demonstrated using a Sagnac loop mirror and a Mach-Zehnder interferometer. We report the Performance comparisons of multi-wavelength oscillations in Yb3+ doped fiber lasers (YDFL) with typical commercial ytterbium doped silica fibers. By adjusting the polarization controller (PC), a widely tunable laser range of 22 nm from 1030 nm

  19. Tunable dual-wavelength fiber laser based on an MMI filter in a cascaded Sagnac loop interferometer

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Kang, Zexin; Qi, Yanhui; Jian, Shuisheng

    2014-04-01

    A widely tunable dual-wavelength erbium-doped fiber laser based on a cascaded Sagnac loop interferometer incorporating a multimode interference filter is proposed and experimentally demonstrated in this paper. The mode selection is implemented by using the cascaded Sagnac loop interferometer with two segments of polarization maintaining fibers, and the wavelength tuning was achieved by using the refractive index characteristic of multimode interference effects. The tunable dual-wavelength fiber laser has a wavelength tuning of about 40 nm with a signal-to-noise ratio of more than 50 dB.

  20. Q-switching of a high-power solid-state laser by a fast scanning Fabry-Perot interferometer

    SciTech Connect

    Baburin, N V; Borozdov, Yu V; Danileiko, Yu K; Denker, B I; Ivanov, A D; Osiko, Vyacheslav V; Sverchkov, S E; Sidorin, A V; Chikov, V A [Laser Materials and Technology Research Center, A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Ifflander, R; Hack, R [Haas-Laser GmbH, Schramberg (Germany); Kertesz, I; Kroo, N [Research Institute for Solid State Physics, Budapest XII (Hungary)

    1998-07-31

    An investigation was made of the suitability of a Q-switch, based on a piezoelectrically scanned short-base Fabry-Perot interferometer, for an Nd{sup 3+}:YAG laser with an average output radiation power up to 2 kW. The proposed switch made it possible to generate of giant pulses of 60 - 300 ns duration at a repetition rate of 20 - 100 kHz. Throughout the investigated range of the pulse repetition rates the average power was at least equal to that obtained by cw lasing. Special requirements to be satisfied by the interferometer, essential for efficient Q-switching, were considered. (control of laser radiation parameters)

  1. LISA Mission Concept Study, Laser Interferometer Space Antenna for the Detection and Observation of Gravitational Waves

    NASA Technical Reports Server (NTRS)

    Folkner, W. M.; Bender, P. L.; Stebbins, R. T.

    1998-01-01

    This document presents the results of a design feasibility study for LISA (Laser Interferometer Space Antenna). The goal of LISA is to detect and study low-frequency astrophysical gravitational radiation from strongly relativistic regions. Astrophysical sources potentially visible to LISA include extra-galactic massive black hole binaries at cosmological distances, binary systems composed of a compact star and a massive black hole, galactic neutron star-black hole binaries, and background radiation from the Big Bang. The LISA mission will comprise three spacecraft located five million kilometers apart forming an equilateral triangle in an Earth-trailing orbit. Fluctuations in separation between shielded test masses located within each spacecraft will be determined by optical interferometry which determines the phase shift of laser light transmitted between the test masses.

  2. Fiber inline Michelson interferometer fabricated by CO2 laser irradiation for refractive index sensing

    NASA Astrophysics Data System (ADS)

    Wu, Hongbin; Yuan, Lei; Zhao, Longjiang; Cao, Zhitao; Wang, Peng

    2014-03-01

    A compact Michelson interferometer (MI) in a single-mode fiber (SMF) is successfully formed by CO2 laser irradiation to measure refractive index (RI) values. The fiber inline MI mainly consists of two parts: one is the waist region in fiber formed by CO2 laser irradiation and the other one is the fiber tip end facet with pure gold sputter coating. Based on the MI theory, the interference signal is generate between the core mode and the cladding mode excited by the core mode at the waist region. Reflective spectra at two different interference lengths of 5mm and 15mm are given and the calculated lengths based on theory are well verified. After the measurements of matching liquids with seven different refractive indices, the RI sensitivity of the MI sample is tested of -197.3+/-19.1nm/RIU (refractive index unit), which suggests well potential application in RI sensing.

  3. Application of a laser interferometer skin-friction meter in complex flows

    NASA Technical Reports Server (NTRS)

    Monson, D. J.; Driver, D. M.; Szodruch, J.

    1981-01-01

    The application of a nonintrusive laser-interferometer skin-friction meter, which measures skin friction with a remotely located laser interferometer that monitors the thickness change of a thin oil film, is extended both experimentally and theoretically to several complex wind-tunnel flows. These include two-dimensional seperated and reattached subsonic flows with large pressure and shear gradients, and two and three-dimensional supersonic flows at high Reynolds number, which include variable wall temperatures and cross-flows. In addition, it is found that the instrument can provide an accurate location of the mean reattachment length for separated flows. Results show that levels up to 120 N/sq m, or 40 times higher than previous tests, can be obtained, despite encountering some limits to the method for very high skin-friction levels. It is concluded that these results establish the utility of this instrument for measuring skin friction in a wide variety of flows of interest in aerodynamic testing.

  4. Turbulence measurements in high-speed flows using the Focusing Laser Differential Interferometer

    NASA Astrophysics Data System (ADS)

    Fulghum, Matthew; Settles, Gary

    2013-11-01

    The Focusing Laser Differential Interferometer (FLDI) was invented by Smeets at ISL in the 1970s, and was used recently by Parziale in the CalTech T5 shock tunnel. It is a relatively-simple, non-imaging common-path interferometer for measuring refractive signals from transition and turbulence, and it has a unique ability to look through facility windows, ignore sidewall boundary-layers and vibration, and concentrate only on the signal near a pair of sharp beam foci in the core flow. Benchtop experiments using a turbulent helium jet in air demonstrate focusing ability, frequency response, unwanted signal rejection, and ease of use. The FLDI is then used to measure freestream turbulence intensity and spectra in the PSU supersonic wind tunnel at Mach 3, with results compared to hot-wire-anemometer data. A special feature of the FLDI instrument used here is the replacement of traditional fixed Wollaston prisms with variable Sanderson prisms for laser-beam separation and recombination. Research sponsored by AEDC Hypervelocity Tunnel 9.

  5. Internal structure of laser supported detonation waves by two-wavelength Mach-Zehnder interferometer

    SciTech Connect

    Shimamura, Kohei; Kawamura, Koichi; Fukuda, Akio; Wang Bin; Yamaguchi, Toshikazu; Komurasaki, Kimiya [Department of Advanced Energy, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8561 (Japan); Hatai, Keigo; Fukui, Akihiro; Arakawa, Yoshihiro [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

    2011-04-15

    Characteristics of the internal structure of the laser supported detonation (LSD) waves, such as the electron density n{sub e} and the electron temperature T{sub e} profiles behind the shock wave were measured using a two-wavelength Mach-Zehnder interferometer along with emission spectroscopy. A TEA CO{sub 2} laser with energy of 10 J/pulse produced explosive laser heating in atmospheric air. Results show that the peak values of n{sub e} and T{sub e} were, respectively, about 2 x 10{sup 24} m{sup -3} and 30 000 K, during the LSD regime. The temporal variation of the laser absorption coefficient profile estimated from the measured properties reveals that the laser energy was absorbed perfectly in a thin layer behind the shock wave during the LSD regime, as predicted by Raizer's LSD model. However, the absorption layer was much thinner than a plasma layer, the situation of which was not considered in Raizer's model. The measured n{sub e} at the shock front was not zero while the LSD was supported, which implies that the precursor electrons exist ahead of the shock wave.

  6. Single-mode quantum cascade lasers with asymmetric Mach-Zehnder interferometer type Fabry-Perot cavity

    NASA Astrophysics Data System (ADS)

    Liu, Peter Q.; Wang, Xiaojun; Gmachl, Claire F.

    2013-03-01

    Quantum cascade (QC) lasers are compact and versatile light sources suitable for a broad range of absorption spectroscopy based molecular sensing applications. However, for most of such sensing applications, single-mode operation of QC lasers is a prerequisite. Conventional single-mode QC lasers, e.g., distributed feedback (DFB) [1] or external cavity QC lasers [2], have much higher cost than multi-mode simple ridge QC lasers, mainly due to their complicated and demanding device fabrication or time-consuming system integration and alignment processes. In order to achieve more cost-effective single-mode QC lasers, we demonstrate a novel type of laser cavity design which consists of an asymmetric Mach-Zehnder (AMZ) interferometer structure monolithically integrated in a conventional Fabry-Perot (FP) cavity with simple ridge waveguide and as-cleaved facets. Strong wavelength selectivity is introduced by the properly designed AMZ interferometer whose transmission spectrum comprises equidistantly spaced narrow peaks, which in turn selects a specific FP mode associated with the entire laser cavity near the optical gain spectrum peak, effectively facilitating single-mode operation of the laser. Continuously wavelength-tunable single-mode operation of QC lasers is achieved in pulsed mode from 80 K to room temperature and in continuous-wave (CW) mode with high side-mode suppression ratio (SMSR) up to ~35 dB. The observed spectral characteristics of the tested lasers are described with satisfying accuracy by our model developed for such cavity structures. The fabrication process for such AMZ interferometer type cavities is identical to that for simple ridge lasers, therefore providing a promising solution to achieving more cost-effective single-mode QC lasers.

  7. Reference Interferometer Using a Semiconductor Laser/LED Reference Source in a Cryogenic Fourier-Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Martino, Anthony J.; Cornwell, Donald M.

    1998-01-01

    A combination of a single mode AlGaAs laser diode and broadband LED was used in a Michelson interferometer to provide reference signals in a Fourier transform spectrometer, the Composite Infrared Spectrometer, on the Cassini mission to Saturn. The narrowband light from the laser produced continuous fringes throughout the travel of the interferometer, which were used to control the velocity of the scan mechanism and to trigger data sampling. The broadband light from the LED produced a burst of fringes at zero path difference, which was used as a fixed position reference. The system, including the sources, the interferometer, and the detectors, was designed to work both at room temperature and instrument operating temperature of 170 Kelvin. One major challenge that was overcome was preservation, from room temperature to 170 K, of alignment sufficient for high modulation of fringes from the broadband source. Another was the shift of the source spectra about 30 nm toward shorter wavelengths upon cooldown.

  8. Wavelength-Spacing Tunable Multi-wavelength Fiber Lasers Based on Hybrid Gain Medium and Mach-Zehnder Interferometer

    Microsoft Academic Search

    Daru Chen; Shan Qin; Ying Gao; Sailing He

    2007-01-01

    Wavelength-spacing continuously tunable multi-wavelength fiber lasers based on a Mach-Zehnder interferometer comb filter are achieved. Stable multi-wavelength lasing based on hybrid gains of Erbium-doped fiber amplification and fiber Raman amplification (semiconductor optical amplification) is demonstrated.

  9. Self-referencing Mach-Zehnder interferometer as a laser system diagnostic: Active and adaptive optical systems

    Microsoft Academic Search

    M. Feldman; D. J. Mockler; R. E. Jr. English; J. L. Byrd; J. T. Salmon

    1991-01-01

    We are incorporating a novel self-referencing Mach-Zehnder interferometer into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement. The instrument is capable of absolute wavefront measurements accurate to better than λ\\/10 pv over a wavelength range > 300 nm without readjustment of the optical components. This performance is achieved through the design of both

  10. Demonstration of a tunable hybrid laser diode using an electrostatically tunable silicon micromachined Fabry-Perot interferometer device

    Microsoft Academic Search

    Yakov Sidorin; Martti Blomberg; Pentti Karioja

    1999-01-01

    A previously reported silicon micromachined Fabry-Perot interferometer device is used for the first time with an edge-emitting single-quantum-well high-power laser diode in an extremely short external cavity configuration to realize a tunable laser diode. This hybrid configuration is advantageous in that it allows the use of “off-the-shelf” components, loose adjustment tolerances and potentially has low cost. In the current demonstration,

  11. CONTROL OF LASER RADIATION PARAMETERS: Stabilization of the emission frequency of a cw dye laser using an external Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Baraulya, Vladimir I.; Vasilenko, L. S.; Gol'dort, V. G.; Om, A. É.; Shishaev, A. V.

    1990-06-01

    The results are given of an experimental study of the stabilization of the emission frequency of a cw dye laser with the aid of the pass band of an external thermally stabilized Fabry-Perot interferometer. Two acoustooptic modulators were used to form a dispersive profile of the error signal and this profile had a linear region much wider than the slope of the pass band of the interferometer, which made it possible to achieve stable operation of the laser with a line width not exceeding 100 kHz and continuous tuning in the range ~ 3 GHz throughout the range of stimulated emission of the R101 dye (620-670 nm).

  12. Ground-based laser interferometers for GW detection: status and prospects for operations

    NASA Astrophysics Data System (ADS)

    Dooley, Katherine

    We are living in an exciting time for the maturing field of gravitational-wave (GW) physics. A world-wide network of advanced multi-kilometer long laser interferometers for GW detection is currently under construction in the United States, Europe, and Japan. Compared to the initial detectors which were in operation until 2011, the advanced detectors will be about 10 times more sensitive, resulting in a 1000-fold increase in observable volume. In only a couple years' time, we expect to make not only the first direct detection of GWs, but to start an era in which signals are routinely observed. We present a general overview of the advanced detectors and the status of their construction and commissioning.

  13. Deciphering Inflation with Gravitational Waves: Cosmic Microwave Background Polarization vs. Direct Detection with Laser Interferometers

    E-print Network

    Smith, T L; Cooray, A R; Smith, Tristan L.; Peiris, Hiranya V.; Cooray, Asantha

    2006-01-01

    A detection of the primordial gravitational wave background is considered to be the ``smoking-gun '' evidence for inflation. While super-horizon waves are probed with cosmic microwave background (CMB) polarization, the relic background will be studied with laser interferometers. The long lever arm spanned by the two techniques improves constraints on the inflationary potential and validation of consistency relations expected under inflation. If gravitational waves with a tensor-to-scalar amplitude ratio greater than 0.01 are detected by the CMB, then a direct detection experiment with a sensitivity consistent with current concept studies should be pursued vigorously. If no primordial tensors are detected by the CMB, a direct detection experiment to understand the simplest form of inflation must have a sensitivity improved by two to three orders of magnitude over current plans.

  14. Application of a Laser Interferometer Skin-Friction Meter in Complex Flows

    NASA Technical Reports Server (NTRS)

    Monson, D. J.; Driver, D. M.; Szodruch, J.

    1981-01-01

    A nonintrusive skin-friction meter has been found useful for a variety of complex wind-tunnel flows. This meter measures skin friction with a remotely located laser interferometer that monitors the thickness change of a thin oil film. Its accuracy has been proven in a low-speed flat-plate flow. The wind-tunnel flows described here include sub-sonic separated and reattached flow over a rearward-facing step, supersonic flow over a flat plate at high Reynolds numbers, and supersonic three - dimensional vortical flow over the lee of a delta wing at angle of attack. The data-reduction analysis was extended to apply to three-dimensional flows with unknown flow direction, large pressure and shear gradients, and large oil viscosity changes with time. The skin friction measurements were verified, where possible, with results from more conventional techniques and also from theoretical computations.

  15. Deciphering inflation with gravitational waves: Cosmic microwave background polarization vs direct detection with laser interferometers

    SciTech Connect

    Smith, Tristan L. [California Institute of Technology, Mail Code 130-33, Pasadena, California 91125 (United States); Peiris, Hiranya V. [Kavli Institute for Cosmological Physics and Enrico Fermi Institute, University of Chicago, Chicago Illinois 60637 (United States); Cooray, Asantha [Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

    2006-06-15

    A detection of the primordial gravitational wave background is considered to be the 'smoking-gun' evidence for inflation. While superhorizon waves are probed with cosmic microwave background (CMB) polarization, the relic background will be studied with laser interferometers. The long lever arm spanned by the two techniques improves constraints on the inflationary potential and validation of consistency relations expected under inflation. If gravitational waves with a tensor-to-scalar amplitude ratio greater than 0.01 are detected by the CMB, then a direct-detection experiment with a sensitivity consistent with current concept studies should be pursued vigorously. If no primordial tensors are detected by the CMB, a direct-detection experiment to understand the simplest form of inflation must have a sensitivity improved by two to 3 orders of magnitude over current plans.

  16. Monitoring Rotational Components of Seismic Waves with a Ring Laser Interferometer

    NASA Astrophysics Data System (ADS)

    Gakundi, Jackson; Dunn, Robert

    2015-04-01

    It has been known for decades that seismic waves can introduce rotation in the surface of the Earth. There are historic records of tombstones in Japan being rotated after large earthquakes. Until fairly recently, the primary way to detect ground rotation from earthquakes was with an array of several seismographs. The development of large ring laser interferometers has provided a way for a single instrument to make extremely sensitive measurements of ground motion. In this poster, a diagram of a large ring laser will be presented. For comparison, seismograms recorded with a ring laser and a collocated standard seismograph will be presented. A major thrust of this research is the detection and analysis of seismic responses from directional drilling sites in Arkansas and Oklahoma. There are suggestions that the injection of pressurized water used to fracture gas bearing shale may cause small earthquakes. The Arkansas Oil and Gas Commission ordered the closing of certain waste water disposal wells in North Central Arkansas. Apparently, these wells injected waste water into a previously unknown fault causing it to slip. An attempt is being made to determine if the seismic wave patterns from earthquakes generated near directional drilling sites differ from those generated miles away.

  17. Monostatic coaxial 1.5 ?m laser Doppler velocimeter using a scanning Fabry-Perot interferometer.

    PubMed

    Rodrigo, Peter John; Pedersen, Christian

    2013-09-01

    We present a laser Doppler velocimeter (LDV) in monostatic coaxial arrangement consisting of off-the-shelf telecom-grade components: a single frequency laser (wavelength ? = 1.5 ?m) and a high-finesse scanning Fabry-Perot interferometer (sFPI). In contrast to previous 1.5 ?m LDV systems based on heterodyne detection, our sFPI-LDV has the advantages of having large remote sensing range not limited by laser coherence, high velocity dynamic range not limited by detector bandwidth and inherent sign discrimination of Doppler shift. The more optically efficient coaxial arrangement where transmitter and receiver optics share a common axis reduces the number of components and greatly simplifies the optical alignment. However, the sensitivity to unwanted backreflections is increased. To circumvent this problem, we employ a custom optical circulator design which compared to commercial fiber-optic circulator achieves ~40 dB reduction in strength of unwanted reflections (i.e. leakage) while maintaining high optical efficiency. Experiments with a solid target demonstrate the performance of the sFPI-LDV system with high sensitivity down to pW level at present update rates up to 10 Hz. PMID:24103985

  18. Tunable double-clad ytterbium-doped fiber laser based on a double-pass Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Meng, Yichang; Zhang, Shumin; Wang, Xinzhan; Du, Juan; Li, Hongfei; Hao, Yanping; Li, Xingliang

    2012-03-01

    We have demonstrated an adjustable double-clad Yb 3+-doped fiber laser using a double-pass Mach-Zehnder interferometer. The laser is adjustable over a range of 40 nm from 1064 nm to 1104 nm. By adjusting the state of the polarization controller, which is placed in the double-pass Mach-Zehnder interferometer, we obtained central lasing wavelengths that can be accurately tuned with controllable spacing between different tunable wavelengths. The laser has a side mode suppression ratio of 42 dB, the 3 dB spectral width is less than 0.2 nm, and the slope efficiencies at 1068 nm, 1082 nm and 1098 nm are 23%, 32% and 26%, respectively. In addition, we have experimentally observed tunable multi-wavelengths lasing output.

  19. Hohlraum glint and laser pre-pulse detector for NIF experiments using velocity interferometer system for any reflector.

    PubMed

    Moody, J D; Clancy, T J; Frieders, G; Celliers, P M; Ralph, J; Turnbull, D P

    2014-11-01

    Laser pre-pulse and early-time laser reflection from the hohlraum wall onto the capsule (termed "glint") can cause capsule imprint and unwanted early-time shocks on indirect drive implosion experiments. In a minor modification to the existing velocity interferometer system for any reflector diagnostic on NIF a fast-response vacuum photodiode was added to detect this light. The measurements show evidence of laser pre-pulse and possible light reflection off the hohlraum wall and onto the capsule. PMID:25430354

  20. Imaging velocity interferometer system for any reflector based on Shen Guang-III prototype laser facility

    NASA Astrophysics Data System (ADS)

    Feng, Wang; Xiaoshi, Peng; Rui, Zhang

    2013-06-01

    The imaging velocity interferometer system for any reflector (VISAR) has been introduced in this report for shock-timing experiment in inertia confined fusion (ICF). Some important technique has been provided, including the probe laser with single mode and shaped capability, imaging technique with high resolution and calibration character. The new target design can be used widely after analyzing the interaction of laser and target. Then the blanking effect on the signal can be avoided. Without the quartz window effect, the new target concept with the reflected design can be provided to do the Deuterium-tritium (DT) material experiment. After using this concept, the fourth shock can be diagnosis easily in shock-timing experiment. Since the one dimension Fourier transform method (FTM) may occur the data loss, the new unwrap algorithm should be developed. The new flood algorithm with high confidence has been programmed. Although the fringe contrast of VISAR is very low, the unwrapping phase map can be satisfied. The space resolution of imaging VISAR is 5 ?m, and the time resolution is 10 ps ~ 30 ps. The uncertainty is less than 2%, which has reached the international level.

  1. Skin Friction Measurements by a Dual-Laser-Beam Interferometer Technique

    NASA Technical Reports Server (NTRS)

    Monson, D. J.; Higuchi, H.

    1981-01-01

    A portable dual-laser-beam interferometer that nonintrusively measures skin friction by monitoring the thickness change of an oil film subject to shear stress is described. The method is an advance over past versions in that the troublesome and error-introducing need to measure the distance to the oil leading edge and the starting time for the oil flow has been eliminated. The validity of the method was verified by measuring oil viscosity in the laboratory, and then using those results to measure skin friction beneath the turbulent boundary layer in a low speed wind tunnel. The dual-laser-beam skin friction measurements are compared with Preston tube measurements, with mean velocity profile data in a "law-of-the-well" coordinate system, and with computations based on turbulent boundary-layer theory. Excellent agreement is found in all cases. (This validation and the aforementioned improvements appear to make the present form of the instrument usable to measure skin friction reliably and nonintrusively in a wide range of flow situations in which previous methods are not practical.)

  2. Study of a defect detection accuracy of a granite nondestructive resonance technique based on a laser interferometer

    NASA Astrophysics Data System (ADS)

    Pod?orny, Tomasz; Budzy?, Grzegorz; Rzepka, Janusz; Tkaczyk, Jakub

    2014-05-01

    A nondestructive testing technique based on a resonance approach and a laser interferometer device is introduced in the presented paper. It utilizes a not synchronized with an acquisition device and low power excitation source. Induced vibrations are acquired using high resolution laser interferometer in a configuration of a vibrometer. As a result, the test equipment is significantly simplified and tailored to the industry requirements. Sample evaluation process is based on a processing that fits lowest order resonance frequencies to p-wave and s-wave frequencies. Obtained velocities are used to fit higher order resonance frequencies present in the response with positions and lengths of resonators formed by cracks or flaws. Presented research focuses on an assessment of accuracy and sensitivity of the introduced method. Performed measurements revealed that it is possible to obtain decent parameters for industry applications.

  3. Observation of a critically refracted converted SP wave using laser Doppler interferometer

    NASA Astrophysics Data System (ADS)

    Gurevich, Boris; Lebedev, Maxim; Madadi, Mahyar; Bona, Andrej; Pevzner, Roman

    2015-04-01

    Laboratory measurements of elastic properties of rocks are important for calibration of seismic data and for corroboration of theoretical models of rocks. The most common way of determining the elastic properties of rock samples in laboratory settings is to estimate the velocities of ultrasonic waves propagating in different directions. The wave velocities are usually obtained from the travel times of waves generated and recorded by ultrasonic piezoelectric transducers. This approach has a large uncertainty associated with shear-wave travel time estimation and separation of differently polarised shear waves, as well as uncertainty as to whether phase or group velocity is measured. The problems are caused by the relatively large size and small number of transducers. One way to address some of these issues is by using laser Doppler interferometer, which records a particle like movement that can serve to separate the waves and to pick the travel times from which the ray velocities cab be estimated reliably, and with a huge data redundancy. In this paper, laser Doppler interferometer is used to record wave propagation in an anisotropic rock sample by measuring three orthogonal components of particle velocity on the sample surface. These measurements allow a clear separation of different wave types. The travel time of these waves are used for estimation of anisotropy parameters of the sample. A key observation is the very strong wave which at small offsets has traveltimes equal to those of the S-wave, but at large offsets travels with a velocity close to that of the P-wave. We interpret this wave as a converted SP wave critically refracted at the free surface. The nature and characteristics of this wave are confirmed by numerical simulations in both isotropic and anisotropic media. These simulations show the same traveltimes as measured in the experiment, but the amplitude of the converted SP wave is much stronger in the measured data. Analysis of this inconsistency is part of the future research, but perhaps one possible explanation is a complex radiation pattern of the source. Such a non-trivial radiation pattern is probably also the reason for the different frequency content in the SH and P-waves compared to the SV and the critically refracted SP wave. Knowledge of the radiation pattern of the source will allow it to be deconvolved from the observed data. Based on our preliminary results, such a deconvolution would also allow us to use semblance as a fitting algorithm, which would eliminate the need to pick the travel times and make the fitting more robust.

  4. MIRI: A multichannel far-infrared laser interferometer for electron density measurements on TFTR (Tokamak Fusion Test Reactor)

    SciTech Connect

    Mansfield, D.K.; Park, H.K.; Johnson, L.C.; Anderson, H.M.; Chouinard, R.; Foote, V.S.; Ma, C.H.; Clifton, B.J.

    1987-07-01

    A ten-channel far-infrared laser interferometer which is routinely used to measure the spatial and temporal behavior of the electron density profile on the TFTR tokamak is described and representative results are presented. This system has been designed for remote operation in the very hostile environment of a fusion reactor. The possible expansion of the system to include polarimetric measurements is briefly outlined. 13 refs., 8 figs.

  5. C- and L-band tunable fiber ring laser using a two-taper Mach-Zehnder interferometer filter.

    PubMed

    Wang, Xiaozhen; Li, Yi; Bao, Xiaoyi

    2010-10-15

    A stable C- and L-band tunable fiber ring laser, using a two-taper Mach-Zehnder interferometer (MZI) as a filter, is proposed and demonstrated experimentally. One of the two taper waists is mechanically bent to tune the laser wavelength. Being amplified by an L-band erbium-doped fiber amplifier and an erbium-doped fiber, respectively, the fiber ring laser has a full L-band (1564-1605nm) and C-band (1550-1565nm) tuning range with a side-mode suppression ratio as high as 50dB. The laser linewidth and the minimum tuning step are related to the MZI's cavity length. It was also found that thermal annealing relieved the internal stresses of the tapers and greatly improved the laser performance. PMID:20967064

  6. Detection of laser-generated ultrasound based on phase demodulation technique using a fibre Fabry Perot interferometer

    NASA Astrophysics Data System (ADS)

    Park, Hee Su; Thursby, Graham; Culshaw, Brian

    2005-06-01

    This paper describes a novel non-contact laser-ultrasound system which is compact and has a high level of immunity to ambient vibration, based on the use of an optical fibre Fabry-Perot interferometer as an acoustic detector. The new optical acoustic detector was employed for measuring a high-frequency acoustic wave of small amplitude generated by a relatively low output power source using an erbium-doped fibre amplifier. Together with the characteristics of the proposed detector, the preliminary results of 80 MHz laser-ultrasound experiments on an aluminium film are described.

  7. Laser interferometer skin-friction measurements of crossing-shock-wave/turbulent-boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Garrison, T. J.; Settles, G. S.; Narayanswami, N.; Knight, D. D.

    1994-01-01

    Wall shear stress measurements beneath crossing-shock-wave/turbulent boundary-layer interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 deg at Mach 3 and 15 deg at Mach 3.85. The measurements were made using a laser interferometer skin-friction meter, a device that determines the wall shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin-friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction center line. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k-epsilon model, are compared with the experimental results for the Mach 3.85, 15-deg interaction case. Although the k-epsilon model did a reasonable job of predicting the overall trend in portions of the skin-friction distribution, neither computation fully captured the physics of the near-surface flow in this complex interaction.

  8. Extreme phase and rotated quadrature measurements

    E-print Network

    Juha-Pekka Pellonpää

    2009-11-03

    We determine the extreme points of the convex set of covariant phase observables. Such extremals describe the best phase parameter measurements of laser light - the best in the sense that they are free from classical randomness due to fluctuations in the measuring procedure. We also characterize extreme fuzzy rotated quadratures.

  9. Correlated quadratures of resonance fluorescence and the generalized uncertainty relation

    NASA Technical Reports Server (NTRS)

    Arnoldus, Henk F.; George, Thomas F.; Gross, Rolf W. F.

    1994-01-01

    Resonance fluorescence from a two-state atom has been predicted to exhibit quadrature squeezing below the Heisenberg uncertainty limit, provided that the optical parameters (Rabi frequency, detuning, laser linewidth, etc.) are chosen carefully. When the correlation between two quadratures of the radiation field does not vanish, however, the Heisenberg limit for quantum fluctuations might be an unrealistic lower bound. A generalized uncertainty relation, due to Schroedinger, takes into account the possible correlation between the quadrature components of the radiation, and it suggests a modified definition of squeezing. We show that the coherence between the two levels of a laser-driven atom is responsible for the correlation between the quadrature components of the emitted fluorescence, and that the Schrodinger uncertainty limit increases monotonically with the coherence. On the other hand, the fluctuations in the quadrature field diminish with an increasing coherence, and can disappear completely when the coherence reaches 1/2, provided that certain phase relations hold.

  10. Second generation instruments for the Laser Interferometer Gravitational Wave Observatory (LIGO)

    Microsoft Academic Search

    Peter Fritschel

    2003-01-01

    The interferometers being planned for second generation LIGO promise an order of magnitude increase in broadband strain sensitivity-with the corresponding cubic increase in detection volume-and an extension of the observation band to lower frequencies. In addition, one of the interferometers may be designed for narrowband performance, giving further improved sensitivity over roughly an octave band above a few hundred Hertz.

  11. Microkelvin thermal control system for the laser interferometer space antenna mission and beyond

    NASA Astrophysics Data System (ADS)

    Higuchi, Sei

    2009-10-01

    The Laser Interferometer Space Antenna (LISA) mission aims to detect directly gravitational waves from massive black holes and galactic binaries. Through detecting gravitational waves, we can study blackholes and the origin of the universe, which is inaccessible from the electromagnetic wave spectrum. It will open a new window to the universe. LISA is essentially a Michelson interferometer placed in space with a third spacecraft added. Gravitational waves are time-varying strain in space-time, which is detectable as a fractional change in a proper distance. LISA will monitor fractional changes in the interferometer arms of a nominally 5 million km. The fractional change in the arm length can be as small as 1 x 10-21 m/(m · Hz ) even for powerful sources. LISA makes use of the gravitational reference sensors (GRS) for drag-free control and will achieve the required sensitivity through management of specific acceleration noise. The total acceleration disturbance to each proof mass, which floats at the center of each GRS, is required to be below 3 x 10-15 m/(s2 · Hz ). Thermal variations due to, for example, solar irradiation, or temperature gradients across the proof mass housing, are expected to be significant disturbance source to the LISA sensitivity requirements. Even a small temperature gradient can produce distortions in the housing structure, which results in a mass attraction force. In this thesis, I focus on developing a thermal control system that aims to achieve the temperature stability of 10 muK / Hz over 0.1 mHz to 1 Hz. We have chosen glass-bead thermistors as the temperature sensor for feedback temperature control of the GRS. First, we created a temperature sensor design program in MATLAB that provides an optimal values of resistances in the thermistor bridge circuit for the given application. The spectral stability of the sensor achieves as low as 20 muK/ Hz at 1 mHz with a DC excitation source. The LISA thermal requirement is met by employing AC excitation and phase sensitive demodulation. Second, a passive thermal isolation system with a specially designed multilayer thermal chamber has been developed. For ground testing, the thermal specification can be met fairly readily with a massive amount of thermal mass. However, for spacecraft the thermal mass is limited, which calls for active compensation particularly in the low frequency range. In order for our test facility to simulate in-flight conditions and to compensate for solar radiation and other thermal disturbance sources we have designed it be analogous to the spacecraft structure. The temperature requirement is met to a frequency as low as 10 mHz through passive thermal isolation. Finally, to overcome the limited bandwidth of passive designs to reduce the temperature variations below 10 mHz, a model predictive control (MPC) algorithm is developed for active disturbance temperature cancellation. The system attenuates low frequency variations as low as 2 mK/ Hz at 0.1 mHz.

  12. Self-referencing Mach-Zehnder interferometer as a laser system diagnostic: Active and adaptive optical systems

    SciTech Connect

    Feldman, M.; Mockler, D.J.; English, R.E. Jr.; Byrd, J.L.; Salmon, J.T.

    1991-02-01

    We are incorporating a novel self-referencing Mach-Zehnder interferometer into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement. The instrument is capable of absolute wavefront measurements accurate to better than {lambda}/10 pv over a wavelength range > 300 nm without readjustment of the optical components. This performance is achieved through the design of both refractive optics and catadioptric collimator to achromatize the Mach-Zehnder reference arm. Other features include polarization insensitivity through the use of low angles of incidence on all beamsplitters as well as an equal path length configuration that allows measurement of either broad-band or closely spaced laser-line sources. Instrument accuracy is periodically monitored in place by means of a thermally and mechanically stable wavefront reference source that is calibrated off-line with a phase conjugate interferometer. Video interferograms are analyzed using Fourier transform techniques on a computer that includes dedicated array processor. Computer and video networks maintain distributed interferometers under the control of a single analysis computer with multiple user access. 7 refs., 11 figs.

  13. Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

    DOEpatents

    Buchenauer, C.J.

    1981-09-23

    The quadrature phase angle phi (t) of a pair of quadrature signals S/sub 1/(t) and S/sub 2/(t) is digitally encoded on a real time basis by a quadrature digitizer for fractional phi (t) rotational excursions and by a quadrature up/down counter for full phi (t) rotations. The pair of quadrature signals are of the form S/sub 1/(t) = k(t) sin phi (t) and S/sub 2/(t) = k(t) cos phi (t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle phi (t).

  14. Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

    SciTech Connect

    Buchenauer, C.J.

    1984-01-17

    The quadrature phase angle /phi/(t) of a pair of quadrature signals s/sub 1/(t) and s/sub 2/(t) is digitally encoded on a real time basis by a quadrature digitizer for fractional /phi/(t) rotational excursions and by a quadrature up/down counter for full /phi/(t) rotations. The pair of quadrature signals are of the form S/sub 1/=k(t) sin /phi/(t) and S/sub 2/(t)=k(t) cos /phi/(t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle /phi/(t).

  15. Analog quadrature signal to phase angle data conversion by a quadrature digitizer and quadrature counter

    SciTech Connect

    Buchenauer, C. Jerald (Los Alamos, NM)

    1984-01-01

    The quadrature phase angle .phi.(t) of a pair of quadrature signals S.sub.1 (t) and S.sub.2 (t) is digitally encoded on a real time basis by a quadrature digitizer for fractional .phi.(t) rotational excursions and by a quadrature up/down counter for full .phi.(t) rotations. The pair of quadrature signals are of the form S.sub.1 (t)=k(t) sin .phi.(t) and S.sub.2 (t)=k(t) cos .phi.(t) where k(t) is a signal common to both. The quadrature digitizer and the quadrature up/down counter may be used together or singularly as desired or required. Optionally, a digital-to-analog converter may follow the outputs of the quadrature digitizer and the quadrature up/down counter to provide an analog signal output of the quadrature phase angle .phi.(t).

  16. Two-wave multichannel laser submillimeter interferometer (TMLSI) for horizontal probing of the plasma in the T-15

    SciTech Connect

    Vereszinskii, Z.; Gerasimov, V.G.; Gorbunov, E.P.; Kasperchuk, A.; Lesnewski, M.; Molchanov, A.Yu.; Padukh, M.; Paprotski, K.

    1992-02-01

    A multichannel interferometer for horizontal probing of the T-15 using heterodyne laser systems with optical pumping has been developed. In order to measure the plasma density under conditions when vibrational noise is present two waves are used at the same time, at 184.6 and 118.8 {mu}m. In the calculations of the optical system expressions for Gaussian beams are used. Separation plates of a precise thickness have been fabricated from crystalline quartz. In order to detect the signals low-temperature InSb detectors in a nonuniform magnetic field have been used. It is planned to mount the complete interferometer in T-15 in 1991. 3 refs., 3 figs.

  17. What can be expected from the GRACE-FO Laser Ranging Interferometer for Earth Science applications?

    NASA Astrophysics Data System (ADS)

    Flechtner, Frank; Neumayer, Karl-Hans; Dahle, Christoph; Dobslaw, Henryk; Güntner, Andreas; Raimondo, Jean-Claude; Fagiolini, Elisa

    2015-04-01

    The primary objective of the Gravity Recovery and Climate Experiment Follow-on (GRACE-FO) satellite mission is to continue the GRACE time series of global monthly gravity field models. For this, evolved versions of the GRACE microwave instrument (MWI), GPS-receiver, and accelerometer will be used. A secondary objective is to demonstrate the effectiveness of a laser ranging interferometer (LRI) in improving the low-low satellite-to-satellite tracking measurement performance. In order to investigate the expected benefit of the LRI for Earth science applications, we performed a full-scale simulation in terms of spherical harmonics over the nominal mission lifetime of five years using a realistic orbit scenario and error assumptions for orbit, instrument and background model errors. We will present results in the spectral and spatial domain showing moderate improvements when using LRI instead of MWI observations for global quality indicators. As these global indicators are not meaningful for Earth system applications which show a clear mass variation signal in regionally defined areas such as water mass changes in hydrological basins or melting of glaciers we have also additionally investigated how simulated seasonal, sub-seasonal, secular and instantaneous (Earthquake) signals are recovered when using GRACE-FO MWI or LRI data. Related results will be presented at the conference. Analysis of the different individual error contributions to the overall monthly gravity model error has shown that dominant errors are still due to accelerometer noise and imperfect modeling of tidal and non-tidal mass variations. Consequently, these errors have to be further reduced when using LRI observations on Next Generation Gravity Missions.

  18. A variable coefficient microwave photonic filter based on multi-wavelength fiber laser and Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Cao, Ye; Liu, Ce; Tong, Zheng-rong

    2014-11-01

    A microwave photonic filter (MPF) with variable coefficient is proposed and demonstrated, which is constructed by a multi-wavelength fiber laser and Mach-Zehnder interferometer (MZI). Through changing the slope characteristics of Mach-Zehnder interference spectrum adjusted by optical variable delay line (OVDL), the conversion from phase modulation (PM) to intensity modulation (IM) is realized. The multi-wavelength fiber laser with Lyot-Sagnac optical filter has variable wavelength spacing. So the designed filter has a variable number of taps and tap weights. As a result, the tunable range of passband center frequency is 2.6 GHz. The reconfigurability of MPF can be also realized by adjusting the output of fiber laser.

  19. Atom Interferometers

    E-print Network

    Alexander D. Cronin; Joerg Schmiedmayer; David E. Pritchard

    2007-12-21

    Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review we first describe the basic tools for coherent atom optics including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on AtomChips. Then we review scientific advances in a broad range of fields that have resulted from the application of atom interferometers. These are grouped in three categories: (1) fundamental quantum science, (2) precision metrology and (3) atomic and molecular physics. Although some experiments with Bose Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e. phenomena where each single atom interferes with itself.

  20. Iodine-stabilized Nd:YAG laser applied to a long-baseline interferometer for wideband earth strain observations

    NASA Astrophysics Data System (ADS)

    Araya, Akito; Kunugi, Takashi; Fukao, Yoshio; Yamada, Isao; Suda, Naoki; Maruyama, Sumitaka; Mio, Norikatsu; Moriwaki, Shigenori

    2002-06-01

    We stabilized a frequency-doubled Nd:YAG laser (?=532 nm) with reference to an iodine absorption line, and applied it to a long-baseline interferometer for earth strain observations. To obtain unmodulated light, saturated absorption signals of an external iodine cell were detected by the modulation transfer technique using an acousto-optic modulator working as both amplitude and frequency modulators. Two feedback loops, which could control the laser frequency by a piezo-electric actuator and a thermal actuator, realized fast and wide-range frequency stabilization, and ensured long-term stable operation. From a beat-note measurement between two identical systems, we obtained a frequency stability (in Allan variance) of ?2×10-13 for time intervals of 10 to 1000 s. By applying the stabilized Nd:YAG laser to a light source of a 10 m interferometer, we successfully observed earth tides and earthquakes in strain variations. Other geophysical signals, detectable by this strainmeter, are also discussed.

  1. Thermal calcium atom interferometer with a phase resolution of a few milliradians based on a narrow-linewidth diode laser

    SciTech Connect

    Akatsuka, Tomoya; Mori, Yoshihiro; Sone, Nobuhiko; Ohtake, Yurie; Machiya, Mamoru; Morinaga, Atsuo [Faculty of Science and Technology, Tokyo University of Science, Noda-shi, Chiba 278-8510 (Japan)

    2011-08-15

    A symmetrical atom interferometer with a thermal calcium atom beam has been developed using a narrow linewidth diode laser stabilized to the resonance of a high-finesse cavity. The linewidth of the diode laser was estimated to be less than 1 Hz relative to the cavity resonance in noise measurement over the range of 100 Hz to 1 MHz, and the phase instability of the interference fringes obtained from the Allan deviation was improved to 2 mrad at an integration time of 300 s. Using this atom interferometer, the ac Stark phase shift between the {sup 1}S{sub 0} and {sup 3}P{sub 1} states of a Ca atom was measured as a function of a laser power near the resonance of the {sup 1}S{sub 0}-{sup 1} P{sub 1} transition at a wavelength of 423 nm. The decay rate of the {sup 1}P{sub 1} state was determined to be {gamma}=1.91(33)x10{sup 8} s{sup -1}.

  2. CO2 laser-based dispersion interferometer utilizing orientation-patterned gallium arsenide for plasma density measurements.

    PubMed

    Bamford, D J; Cummings, E A; Panasenko, D; Fenner, D B; Hensley, J M; Boivin, R L; Carlstrom, T N; Van Zeeland, M A

    2013-09-01

    A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma. A simple phase-extraction technique based on combining measurements from two successive pulses of the plasma has been used. The noise-equivalent line density was measured to be 1.7 × 10(17) m(-2) in a detection bandwidth of 950 kHz. One of the orientation-patterned crystals produced 13 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 13 W of peak power. Two crystals arranged sequentially produced 58 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 37 W of peak power. PMID:24089824

  3. CO{sub 2} laser-based dispersion interferometer utilizing orientation-patterned gallium arsenide for plasma density measurements

    SciTech Connect

    Bamford, D. J.; Cummings, E. A.; Panasenko, D. [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States)] [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States); Fenner, D. B.; Hensley, J. M. [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States)] [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States); Boivin, R. L.; Carlstrom, T. N.; Van Zeeland, M. A. [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)] [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)

    2013-09-15

    A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma. A simple phase-extraction technique based on combining measurements from two successive pulses of the plasma has been used. The noise-equivalent line density was measured to be 1.7 × 10{sup 17} m{sup ?2} in a detection bandwidth of 950 kHz. One of the orientation-patterned crystals produced 13 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 13 W of peak power. Two crystals arranged sequentially produced 58 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 37 W of peak power.

  4. Laser-based ultrasonics for QNDE applications

    NASA Astrophysics Data System (ADS)

    Fomitchov, Pavel A.; Wang, Lewis S.; Steckenrider, J. Scott; Krishnaswamy, Sridhar; Achenbach, Jan D.

    1997-03-01

    Surface and plate acoustic waves are commonly used to nondestructively investigate the near-surface region of a solid component for cracks and other defects. An attractive method of generation and detection of ultrasonic signals is laser based ultrasonics (LBU). Because it is non-contact, LBU can be implemented for inspection of limited access components using optical fibers, requiring only a small cross-sectional area for access. The work presented here employs optical fibers to remotely generate and detect ultrasound with energy focused into a selected narrow frequency band. The generation system uses a binary diffraction grating to separate the single laser beam into 10 equal but spatially separated laser beams which are focused into 10 individual fibers, thereby maximizing optical throughput to the component surface. In addition, a low noise fiberized Sagnac interferometer for ultrasonic signal measurement is discussed. The main advantage of this interferometer is improved signal-to-noise ratio, which has been achieved using an optical frequency shifting technique for biasing to quadrature and for elimination of parasitic interference between sampling beams and other unwanted beams in the interferometer. The Sagnac interferometer is truly path-matched, and as such is insensitive to low frequency thermal fluctuations and vibration noise. An acousto-optic modulator is included in the Sagnac loop, and serves a two-fold purpose: frequency shifting and quadrature biasing. Experimental results are presented for both the fiber-optic ultrasound generating array and the Sagnac interferometer.

  5. Tunable dual-wavelength fiber laser based on a single fiber Bragg grating in a Sagnac loop interferometer

    NASA Astrophysics Data System (ADS)

    Moon, Dae Seung; Sun, Guoyong; Lin, Aoxiang; Liu, Xueming; Chung, Youngjoo

    2008-05-01

    We propose a simple dual-wavelength Er-doped fiber laser configuration based on a dual-wavelength fiber Bragg grating written on the splice joint between two different fibers for wavelength-selective filter in the Sagnac loop interferometer. The wavelength separation between the adjacent lasing wavelengths is 1.12 nm and the side-mode suppression ratio (SMSR) is over 55 dB. The output power variation is less than 0.8 dB over a two-minute period. Moreover, the lasing wavelength can be effectively tuned using the thermal heating method.

  6. Narrow-spectral-linewidth silicon photonic wavelength-tunable laser with highly asymmetric Mach-Zehnder interferometer.

    PubMed

    Tang, Rui; Kita, Tomohiro; Yamada, Hirohito

    2015-04-01

    We propose a narrow-spectral-linewidth silicon photonic wavelength-tunable laser with a novel external wavelength-tunable filter, which consists of two silicon ring resonators with different circumferences and a highly asymmetric Mach-Zehnder interferometer (MZI), the two optical paths of which have significantly different lengths. Calculations and experimental results indicated that the gain difference between longitudinal modes was increased by the highly asymmetric MZI. Consequently, a narrow spectral linewidth of 12 kHz and a stable single-mode oscillation were obtained. PMID:25831370

  7. Spatio-temporal coherence of free-electron laser radiation in the extreme ultraviolet determined by a Michelson interferometer

    SciTech Connect

    Hilbert, V.; Rödel, C.; Zastrau, U., E-mail: ulf.zastrau@uni-jena.de [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena (Germany); Brenner, G.; Düsterer, S.; Dziarzhytski, S.; Harmand, M.; Przystawik, A.; Redlin, H.; Toleikis, S. [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg (Germany); Döppner, T.; Ma, T. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Fletcher, L. [Department of Physics, University of California, Berkeley, California 94720 (United States); Förster, E. [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena (Germany); Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena (Germany); Glenzer, S. H.; Lee, H. J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Hartley, N. J. [Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Kazak, L.; Komar, D.; Skruszewicz, S. [Institut für Physik, Universität Rostock, 18051 Rostock (Germany); and others

    2014-09-08

    A key feature of extreme ultraviolet (XUV) radiation from free-electron lasers (FELs) is its spatial and temporal coherence. We measured the spatio-temporal coherence properties of monochromatized FEL pulses at 13.5?nm using a Michelson interferometer. A temporal coherence time of (59±8) fs has been determined, which is in good agreement with the spectral bandwidth given by the monochromator. Moreover, the spatial coherence in vertical direction amounts to about 15% of the beam diameter and about 12% in horizontal direction. The feasibility of measuring spatio-temporal coherence properties of XUV FEL radiation using interferometric techniques advances machine operation and experimental studies significantly.

  8. VISAR (Velocity Interferometer System for Any Reflector): Line-imaging interferometer

    SciTech Connect

    Hemsing, W.F.; Mathews, A.R.; Warnes, R.H.; Whittemore, G.R.

    1990-01-01

    This paper describes a Velocity Interferometer System for Any Reflector (VISAR) technique that extends velocity measurements from single points to a line. Single-frequency argon laser light was focused through a cylindrical lens to illuminate a line on a surface. The initially stationary, flat surface was accelerated unevenly during the experiment. Motion produced a Doppler-shift of light reflected from the surface that was proportional to the velocity at each point. The Doppler-shifted image of the illuminated line was focused from the surface through a push-pull VISAR interferometer where the light was split into four quadrature-coded images. When the surface accelerated, the Doppler-shift caused the interference for each point on each line image to oscillate sinusoidally. Coherent fiber optic bundles transmitted images from the interferometer to an electronic streak camera for sweeping in time and recording on film. Data reduction combined the images to yield a continuous velocity and displacement history for all points on the surface that reflected sufficient light. The technique was demonstrated in an experiment where most of the surface was rapidly driven to a saddle shape by an exploding foil. Computer graphics were used to display the measured velocity history and to aid visualization of the surface motion. 6 refs., 8 figs.

  9. Quadrature, Interpolation and Observability

    NASA Technical Reports Server (NTRS)

    Hodges, Lucille McDaniel

    1997-01-01

    Methods of interpolation and quadrature have been used for over 300 years. Improvements in the techniques have been made by many, most notably by Gauss, whose technique applied to polynomials is referred to as Gaussian Quadrature. Stieltjes extended Gauss's method to certain non-polynomial functions as early as 1884. Conditions that guarantee the existence of quadrature formulas for certain collections of functions were studied by Tchebycheff, and his work was extended by others. Today, a class of functions which satisfies these conditions is called a Tchebycheff System. This thesis contains the definition of a Tchebycheff System, along with the theorems, proofs, and definitions necessary to guarantee the existence of quadrature formulas for such systems. Solutions of discretely observable linear control systems are of particular interest, and observability with respect to a given output function is defined. The output function is written as a linear combination of a collection of orthonormal functions. Orthonormal functions are defined, and their properties are discussed. The technique for evaluating the coefficients in the output function involves evaluating the definite integral of functions which can be shown to form a Tchebycheff system. Therefore, quadrature formulas for these integrals exist, and in many cases are known. The technique given is useful in cases where the method of direct calculation is unstable. The condition number of a matrix is defined and shown to be an indication of the the degree to which perturbations in data affect the accuracy of the solution. In special cases, the number of data points required for direct calculation is the same as the number required by the method presented in this thesis. But the method is shown to require more data points in other cases. A lower bound for the number of data points required is given.

  10. Wavelength-switchable erbium-doped fiber ring laser employing chirped Moiré fiber grating and tunable Sagnac loop interferometer filter

    NASA Astrophysics Data System (ADS)

    Lu, Shaohua; Feng, Suchun; Zheng, Jingjing

    2010-10-01

    A simple, cost-effective and switchable five-wavelength fiber ring laser based on a chirped moiré fiber grating (CMFG) and a wavelength-tunable Sagnac loop interferometer (FSI) filter is proposed and experimentally demonstrated. To serve as wavelength selective element, the CMFG possesses excellent comb-like filtering characteristics including stable wavelength interval and ultra-narrow passband, and its fabrication method is easy and flexible. The usage of the FSI filter helps remove the high-cost optical circulator and improve the output performance of optical signal-to-noise ratio from 50dB to 70dB. With this laser configuration, the output power fluctuation of each wavelength is less than 0.5 dB within a one-hour period, and the output power of different channels is almost identical (difference less than 1dB) within the tunable range.

  11. Linear cavity all-fiber dual wavelength actively Q-switched fiber laser with a Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Durán-Sánchez, M.; Álvarez-Tamayo, R. I.; Pottiez, O.; Ibarra-Escamilla, B.; Kuzin, E. A.; Barcelata-Pinzón, A.

    2015-03-01

    We report an all-fiber dual-wavelength actively Q-switched pulsed laser. The linear cavity is limited by two fiber Bragg gratings with central wavelengths of 1538.3 nm and 1548 nm respectively in one side and Sagnac interferometer (SI) in the other side. The pump power is coupled into the doped fiber through a beam combiner. The SI used to equalize generated laser lines competition by cavity losses adjustment is formed by high birefringence (Hi-Bi) fiber in the loop. The SI spectrum wavelength displacement adjustment is performed by temperature variations applied on the Hi-Bi fiber loop with a temperature controller. The Q-switch operation is achieved at pulse repetition rate of 120 kHz with average pulsed output power of 404 mW and pulse duration of 470 ns.

  12. Multi-chord fiber-coupled interferometer with a long coherence length laser for the Plasma Liner Experiment

    E-print Network

    Merritt, Elizabeth C; Gilmore, Mark A; Hsu, Scott C

    2011-01-01

    This paper describes a 561 nm laser heterodyne interferometer that provides time-resolved measurements of line-integrated plasma electron density within the range of 10^15-10^18 cm^(-2). Such plasmas are produced by railguns on the Plasma Liner Experiment (PLX), which aims to produce $\\mu$s-, cm-, and Mbar-scale plasmas through the merging of thirty plasma jets in a spherically convergent geometry. A long coherence length, 320 mW laser allows for a strong, sub-fringe phase-shift signal without the need for closely-matched probe and reference path lengths. Thus only one reference path is required for all eight probe paths, and an individual probe chord can be altered without altering the reference or other probe path lengths. Fiber-optic decoupling of the probe chord optics on the vacuum chamber from the rest of the system allows the probe paths to be easily altered to focus on different spatial regions of the plasma. We demonstrate that sub-fringe resolution capability allows the interferometer to operate dow...

  13. Diagonalization of the length sensing matrix of a dual recycled laser interferometer gravitational wave antenna

    SciTech Connect

    Sato, Shuichi; Kawamura, Seiji; Kokeyama, Keiko; Kawazoe, Fumiko; Somiya, Kentaro [TAMA project, National Astronomical Observatory of Japan, 2-21-1, Mitaka, Osawa, Tokyo 181-8588 (Japan); The Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo 112-8610 (Japan); Max-Planck-Institut fuer Gravitationsphysik, Am Muehlenberg 1, 14476 Potsdam (Germany)

    2007-04-15

    Next generation gravitational wave antennas employ resonant sideband extraction (RSE) interferometers with Fabry-Perot cavities in the arms as an optical configuration. In order to realize stable, robust control of the detector system, it is a key issue to extract appropriate control signals for longitudinal degrees of freedom of the complex coupled-cavity system. In this paper, a novel length sensing and control scheme is proposed for the tuned RSE interferometer that is both simple and efficient. The sensing matrix can be well diagonalized, owing to a simple allocation of two rf modulations and to a macroscopic displacement of the cavity mirrors, which cause a detuning of the rf modulation sidebands.

  14. Displacement measuring technique for satellite-to-satellite laser interferometer to determine Earth's gravity field

    Microsoft Academic Search

    Shigeo Nagano; Taizoh Yoshino; Hiroo Kunimori; Mizuhiko Hosokawa; Seiji Kawamura; Takashi Sato; Masashi Ohkawa

    2004-01-01

    We present a new displacement measuring technique with simplicity, robustness, high sensitivity and wide measurement range. A set of a frequency shifter and a voltage-frequency converter is used to lock a homodyne interferometer on the half-bright fringe by eliminating the Doppler fringe resulting from mirror motion. The mirror displacement is directly retrieved from the feedback signal of a fringe control

  15. Fiber-optic gas pressure sensing with a laser-heated silicon-based Fabry-Perot interferometer.

    PubMed

    Liu, Guigen; Han, Ming

    2015-06-01

    We report a novel fiber-optic sensor for measurement of static gas pressure based on the natural convection of a heated silicon pillar attached to a fiber tip functioning as a Fabry-Perot interferometer (FPI). A visible laser beam is guided by the fiber to efficiently heat the silicon pillar, while an infrared whitelight source, also guided by the fiber, is used to measure the temperature of the FPI, which is influenced both by the laser power and the pressure through natural convection. We theoretically and experimentally show that, by monitoring the fringe shift caused by the laser heating, air pressure sensing with little temperature cross-sensitivity can be achieved. The pressure sensitivity can be easily tuned by adjusting the heating laser power. In our experiment, the sensor performance within the temperature range from 20°C to 50°C and the pressure range from 0 to 1400 psi has been characterized, showing an average sensitivity of -0.52??pm/psi. Compared to the passive version of the sensor, the pressure sensitivity was ?15 times larger, and the temperature cross-sensitivity was ?100 times smaller. PMID:26030532

  16. Uncertainty propagation: Quadrature

    NSDL National Science Digital Library

    David Liao

    The quadrature formula relates the fluctuations of a function to fluctuations in the variables on which the function depends. In this derivation, we approximate a multivariable function using a Taylor expansion, and we assume that fluctuations in the underlying variables are statistically independent, which allows us to apply an identity previously derived in the unit on statistics. Namely, "variances of sums are sums of variances" for variables that fluctuate independently.

  17. Microwave interferometer techniques for detonation study

    SciTech Connect

    Stanton, P.L.; Venturini, E.L.; Dietzel, R.W.

    1985-01-01

    Techniques have been developed to improve resolution in microwave interferometry of detonating explosives. Unwanted reflections in the measurement arm of the interferometer result in phase distortion of the recorded signal. By using tuning techniques, unwanted reflections can be virtually eliminated, and phase distortion is minimized, for some experimental conditions. The use of a quadrature detector and an intensity monitor also improve the resolution of the interferometer. Data obtained in several detonation experiments are presented and interpreted. 13 refs., 7 figs.

  18. 2-?m switchable dual-wavelength fiber laser with cascaded filter structure based on dual-channel Mach-Zehnder interferometer and spatial mode beating effect

    NASA Astrophysics Data System (ADS)

    Wang, Shun; Lu, Ping; Zhao, Shui; Liu, Deming; Yang, Wei; Zhang, Jiangshan

    2014-06-01

    We demonstrated a 2-?m switchable dual-wavelength fiber laser with cascaded filter structure based on dual-channel Mach-Zehnder interferometer and spatial mode beating effect. Few-mode fiber-embedded Sagnac ring configuration and a Mach-Zehnder interferometer are cascaded to form a multiwavelength filter for our previous 2-?m fiber laser. By adopting suitable fiber length and adjusting the polarization controller, we obtained a 2-?m dual-wavelength fiber laser with switchable wavelength interval. Experimental results revealed that the proposed laser shows higher quality and better stability compared with our previous work and it has potential applications in the fields of atmospheric propagation and microwave photonics.

  19. Self-Q-switched Er–Yb double clad fiber laser with dual wavelength or tunable single wavelength operation by a Sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Álvarez-Tamayo, R. I.; Durán-Sánchez, M.; Pottiez, O.; Ibarra-Escamilla, B.; Bello-Jiménez, M.; Kuzin, E. A.

    2015-07-01

    We report a self-Q-switched Erbium-Ytterbium-doped double cladding fiber ring laser with dual wavelength or tunable single wavelength operations. A Sagnac interferometer with a high birefringence fiber in the loop was used for the wavelength tuning of the single line operation and cavity loss adjustment for dual wavelength laser operation. Single wavelength laser operation for a pump power of 421?mW tunable in a range of 1561.4?nm to 1569.8?nm and dual wavelength laser operation at 1561.1?nm and 1571.4?nm with equal output powers are presented.

  20. Large Scale Laser Interferometer On Suspended Mirrors As New Geophysical Instrument.

    NASA Astrophysics Data System (ADS)

    Bradaschia, C.; Giazotto, A.; Rudenko, V. N.

    We discuss an application of the interferometric gravitational antenna on free masses for different geophysical measurements. Such large scale (3-4 km) optical interferometer on suspended mirrors might be considered as a combined geophysical instrument: three dimensional strain and tilt meter as well as gravity gradio-meter in a wide band frequency range from 10-5 Hz up to 103 Hz. Mechanical tilts and shifts of test mass-mirrors on pendulum suspension at the low frequency zone are compensated by feedback circuits keeping the interferometer operational position. The error signal bears a useful information on gravity gradient variations and surface deformations both longitudinal and vertical ones. Specifics of the interferometer construction allows to separate gravitational and strain perturbations. The instrumental sensitivity of this new tool potentially might be higher the corresponding sensitivity of conventional geophysical devices due to extremely low intrinsic noises of gravitational antennae. A list of fundamental geophysical phenomena which could be monitored by the setup includes traditional tidal crust deformations, free Earth oscillations, earthquakes echo, acoustical emission effects etc. The problem of filtering of these effects on the environmental noise background is discussed.

  1. A high-quality Mach-Zehnder interferometer fiber sensor by femtosecond laser one-step processing.

    PubMed

    Zhao, Longjiang; Jiang, Lan; Wang, Sumei; Xiao, Hai; Lu, Yongfeng; Tsai, Hai-Lung

    2011-01-01

    During new fiber sensor development experiments, an easy-to-fabricate simple sensing structure with a trench and partially ablated fiber core is fabricated by using an 800 nm 35 fs 1 kHz laser. It is demonstrated that the structure forms a Mach-Zehnder interferometer (MZI) with the interference between the laser light passing through the air in the trench cavity and that in the remained fiber core. The fringe visibilities are all more than 25 dB. The transmission spectra vary with the femtosecond (fs) laser ablation scanning cycle. The free spectral range (FSR) decreases as the trench length increases. The MZI structure is of very high fabrication and sensing repeatability. The sensing mechanism is theoretically discussed, which is in agreement with experiments. The test sensitivity for acetone vapor is about 10(4) nm/RIU, and the temperature sensitivity is 51.5 pm/°C at 200 ? 875 °C with a step of 25 °C. PMID:22346567

  2. Dual surface interferometer

    DOEpatents

    Pardue, Robert M. (Knoxville, TN); Williams, Richard R. (Oak Ridge, TN)

    1982-01-01

    A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarter-wave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

  3. Dual surface interferometer

    DOEpatents

    Pardue, R.M.; Williams, R.R.

    1980-09-12

    A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarterwave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

  4. Microwave interferometer techniques for detonation study

    Microsoft Academic Search

    P. L. Stanton; E. L. Venturini; R. W. Dietzel

    1985-01-01

    Techniques have been developed to improve resolution in microwave interferometry of detonating explosives. Unwanted reflections in the measurement arm of the interferometer result in phase distortion of the recorded signal. By using tuning techniques, unwanted reflections can be virtually eliminated, and phase distortion is minimized, for some experimental conditions. The use of a quadrature detector and an intensity monitor also

  5. Development of a High-Speed Laser Interferometer Using an Acousto-Optic Deflector

    Microsoft Academic Search

    Tetsuo Fukuchi; Takuya Nayuki; Koshichi Nemoto; Kiichiro Uchino

    2003-01-01

    An acousto-optic laser deflector was used as a shutter for high-speed imaging of laser interference fringes using an ordinary CCD camera. The exposure duration was set by the pulse width of the high frequency signal applied to the acousto-optic deflector. Changes in laser interference fringes due to an impulse discharge in air were obtained at an exposure duration of 4mus.

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

    SciTech Connect

    Choi, Hyunseung; La, Jongpil; Park, Kyihwan [Intelligent Manufacturing Group, LG Production Engineering Research Institute, 19-1 Cheongho-Ri, Jinwuy-myun, Pyungtaik, Kyunggi-Do 451-713 (Korea, Republic of); Compressor Development Group, Samsung Gwangju Electronic Company, 1119 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Department of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    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.

  7. Digital quadrature phase detection

    DOEpatents

    Smith, James A. (Idaho Falls, ID); Johnson, John A. (Idaho Falls, ID)

    1992-01-01

    A system for detecting the phase of a frequency of phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2.pi. when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2.pi. when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention.

  8. Digital quadrature phase detection

    DOEpatents

    Smith, J.A.; Johnson, J.A.

    1992-05-26

    A system for detecting the phase of a frequency or phase modulated signal that includes digital quadrature sampling of the frequency or phase modulated signal at two times that are one quarter of a cycle of a reference signal apart, determination of the arctangent of the ratio of a first sampling of the frequency or phase modulated signal to the second sampling of the frequency or phase modulated signal, and a determination of quadrant in which the phase determination is increased by 2[pi] when the quadrant changes from the first quadrant to the fourth quadrant and decreased by 2[pi] when the quadrant changes from the fourth quadrant to the first quadrant whereby the absolute phase of the frequency or phase modulated signal can be determined using an arbitrary reference convention. 6 figs.

  9. Optimized quadrature surface coil designs

    PubMed Central

    Kumar, Ananda; Bottomley, Paul A.

    2008-01-01

    Background Quadrature surface MRI/MRS detectors comprised of circular loop and figure-8 or butterfly-shaped coils offer improved signal-to-noise-ratios (SNR) compared to single surface coils, and reduced power and specific absorption rates (SAR) when used for MRI excitation. While the radius of the optimum loop coil for performing MRI at depth d in a sample is known, the optimum geometry for figure-8 and butterfly coils is not. Materials and methods The geometries of figure-8 and square butterfly detector coils that deliver the optimum SNR are determined numerically by the electromagnetic method of moments. Figure-8 and loop detectors are then combined to create SNR-optimized quadrature detectors whose theoretical and experimental SNR performance are compared with a novel quadrature detector comprised of a strip and a loop, and with two overlapped loops optimized for the same depth at 3 T. The quadrature detection efficiency and local SAR during transmission for the three quadrature configurations are analyzed and compared. Results The SNR-optimized figure-8 detector has loop radius r8 ? 0.6d, so r8/r0 ? 1.3 in an optimized quadrature detector at 3 T. The optimized butterfly coil has side length ? d and crossover angle of ? 150° at the center. Conclusions These new design rules for figure-8 and butterfly coils optimize their performance as linear and quadrature detectors. PMID:18057975

  10. Ultimate linewidth reduction of a semiconductor laser frequency-stabilized to a Fabry-Pérot interferometer.

    PubMed

    Bahoura, Messaoud; Clairon, André

    2003-11-01

    We report a theoretical dynamical analysis on effect of semiconductor laser phase noise on the achievable linewidth when locked to a Fabry-Pérot cavity fringe using a modulation-demodulation frequency stabilization technique such as the commonly used Pound-Drever-Hall frequency locking scheme. We show that, in the optical domain, the modulation-demodulation operation produces, in the presence of semiconductor laser phase noise, two kinds of excess noise, which could be much above the shot noise limit, namely, conversion noise (PM-to-AM) and intermodulation noise. We show that, in typical stabilization conditions, the ultimate semiconductor laser linewidth reduction can be severely limited by the intermodulation excess noise. The modulation-demodulation operation produces the undesirable nonlinear intermodulation effect through which the phase noise spectral components of the semiconductor laser, in the vicinity of even multiples of the modulation frequency, are downconverted into the bandpass of the frequency control loop. This adds a spurious signal, at the modulation frequency, to the error signal and limits the performance of the locked semiconductor laser. This effect, reported initially in the microwave domain using the quasistatic approximation, can be considerably reduced by a convenient choice of the modulation frequency. PMID:14682624

  11. Effect of injection current and temperature on signal strength in a laser diode optical feedback interferometer.

    PubMed

    Al Roumy, Jalal; Perchoux, Julien; Lim, Yah Leng; Taimre, Thomas; Raki?, Aleksandar D; Bosch, Thierry

    2015-01-10

    We present a simple analytical model that describes the injection current and temperature dependence of optical feedback interferometry signal strength for a single-mode laser diode. The model is derived from the Lang and Kobayashi rate equations, and is developed both for signals acquired from the monitoring photodiode (proportional to the variations in optical power) and for those obtained by amplification of the corresponding variations in laser voltage. The model shows that both the photodiode and the voltage signal strengths are dependent on the laser slope efficiency, which itself is a function of the injection current and the temperature. Moreover, the model predicts that the photodiode and voltage signal strengths depend differently on injection current and temperature. This important model prediction was proven experimentally for a near-infrared distributed feedback laser by measuring both types of signals over a wide range of injection currents and temperatures. Therefore, this simple model provides important insight into the radically different biasing strategies required to achieve optimal sensor sensitivity for both interferometric signal acquisition schemes. PMID:25967631

  12. Switchable multi-wavelength erbium-doped fiber ring laser based on cascaded polarization maintaining fiber Bragg gratings in a Sagnac loop interferometer

    NASA Astrophysics Data System (ADS)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Ning, Tigang; Jian, Shuisheng

    2008-12-01

    A switchable multi-wavelength erbium-doped fiber (EDF) ring laser based on cascaded polarization maintaining fiber Bragg gratings (PMFBGs) in a Sagnac loop interferometer as the wavelength-selective filter at room temperature is proposed. Due to the polarization hole burning (PHB) enhanced by the PMFBGs, stable single-, dual-, three- and four-wavelength lasing operations can be obtained. The laser can be switched among the stable single-, dual-, three- and four-wavelength lasing operations by adjusting the polarization controllers (PCs). The optical signal-to-noise ratio (OSNR) is over 50 dB.

  13. Dual-wavelength erbium-doped fiber ring laser based on one polarization maintaining fiber Bragg grating in a Sagnac loop interferometer

    NASA Astrophysics Data System (ADS)

    Feng, Suchun; Li, Honglei; Xu, Ou; Lu, Shaohua; Mao, Xiangqiao; Ning, Tigang; Jian, Shuisheng

    2008-11-01

    Dual-wavelength with orthogonal polarizations erbium-doped fiber ring laser at room temperature is proposed. One polarization-maintaining fiber Bragg grating (PMFBG) in a Sagnac loop interferometer is used as the wavelength-selective filter. Due to the polarization hole burning (PHB) enhanced by the PMFBG, the laser can operate in stable dual-wavelength operation with wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The optical signal-to-noise ratio (OSNR) is over 52 dB. The amplitude variation in nearly one and half an hour is less than 0.6 dB for both wavelengths.

  14. Wide single-mode tuning in quantum cascade lasers with asymmetric Mach-Zehnder interferometer type cavities with separately biased arms

    SciTech Connect

    Zheng, Mei C., E-mail: meizheng@princeton.edu; Gmachl, Claire F. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)] [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Liu, Peter Q. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States) [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Institute of Quantum Electronics, ETH Zürich, 8093 Zürich (Switzerland); Wang, Xiaojun; Fan, Jen-Yu; Troccoli, Mariano [AdTech Optics, Inc., City of Industry, California 91748 (United States)] [AdTech Optics, Inc., City of Industry, California 91748 (United States)

    2013-11-18

    We report on the experimental demonstration of a widely tunable single mode quantum cascade laser with Asymmetric Mach-Zehnder (AMZ) interferometer type cavities with separately biased arms. Current and, consequently, temperature tuning of the two arms of the AMZ type cavity resulted in a single mode tuning range of 20?cm{sup ?1} at 80?K in continuous-wave mode operation, a ten-fold improvement from the lasers under a single bias current. In addition, we also observed a five fold increase in the tuning rate as compared to the AMZ cavities controlled by one bias current.

  15. Laser Interferometer Skin-Friction measurements of crossing-shock wave/turbulent boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Garrison, T. J.; Settles, G. S.

    1993-01-01

    Wall shear stress measurements beneath crossingshock wave/turbulent boundary-layer interactions have been made for three interactions of different strengths. The interactions are generated by two sharp fins at symmetric angles of attack mounted on a flat plate. The shear stress measurements were made for fin angles of 7 and 11 degrees at Mach 3 and 15 degrees at Mach 4. The measurements were made using a Laser Interferometer Skin Friction (LISF) meter; a device which determines the wail shear by optically measuring the time rate of thinning of an oil film placed on the test model surface. Results of the measurements reveal high skin friction coefficients in the vicinity of the fin/plate junction and the presence of quasi-two-dimensional flow separation on the interaction centerline. Additionally, two Navier-Stokes computations, one using a Baldwin-Lomax turbulence model and one using a k- model, are compared to the experimental results for the Mach 4, 15 degree interaction case. While the k- model did a reasonable job of predicting the overall trend in portions of the skin friction distribution, neither computation fully captured the physics of the near surface flow in this complex interaction.

  16. Radial quadrature for multiexponential integrands.

    PubMed

    Gill, Peter M W; Chien, Siu-Hung

    2003-04-30

    We introduce a Gaussian quadrature, based on the polynomials that are orthogonal with respect to the weight function ln(2)x on the interval [0, 1], which is suitable for the evaluation of radial integrals. The quadrature is exact if the non-Jacobian part of the integrand is a linear combination of a geometric sequence of exponential functions. We find that the new scheme is a useful alternative to existing approaches, particularly for integrands that exhibit multiexponential behavior. PMID:12666165

  17. Fiber laser strain sensor based in the measurement of a Sagnac interferometer optical power spectrum

    NASA Astrophysics Data System (ADS)

    Durán Sánchez, M.; Álvarez Tamayo, R. I.; Pottiez, O.; Kuzin, E. A.; Ibarra-Escamilla, B.; Barcelata Pinzón, A.

    2014-06-01

    In this paper a linear cavity Erbium doped fiber (EDF) laser based in a fiber Bragg grating (FBG) and a fiber optical loop mirror with a high birefringence fiber in the loop (Hi-Bi FOLM) is used as a strain sensor. The Fabry-Perot cavity is formed by the FBG and the Hi-Bi FOLM, used as a measurement system of strain variations produced on the FBG, used as a strain sensor device. Usually, fiber laser sensor experimental setups determine the measured variable magnitude by using of an optical spectrum analyzer (OSA). Hi-Bi FOLM transmission spectrum wavelength displacement by fiber loop temperature variations measurement can be an attractive application exploiting the characteristics of FOLM transmission spectrum behavior due to Hi-Bi fiber loop temperature variations to determine the FBG strain applied through the maximal optical power monitoring by simple use of a photodetector and a temperature meter.

  18. Fiber-optic coupled heterodyne interferometer

    Microsoft Academic Search

    Liang Zhang

    2003-01-01

    A lightweight and electrically passive interferometer is demanded by a number of applications for precision metrology such as machine tool metrology and on-machine feedback. To satisfy these requirements, a fiber-optic coupled heterodyne displacement measuring Michelson interferometer is developed. In this interferometer, the laser light is coupled into the interferometer with a polarization-maintaining (PM) fiber to separate the application environment of

  19. Fiber Sagnac interferometers with ultralong and random distributed feedback Raman laser amplification

    NASA Astrophysics Data System (ADS)

    Nuño, J.; Ania-Castañón, J. D.

    2014-03-01

    We numerically study and compare the performance limitations imposed by accumulated noise and nonlinear phase difference in various configurations of amplified fiber optic gyroscopes in which amplification is provided by stimulated Raman scattering, with a focus on ultralong and random distributed feedback Raman fiber lasers. We show that, even in the presence of pump power and signal instabilities, some of the proposed configurations have the potential to allow the use of up to 5 times longer spool lengths, with a corresponding 5-fold increase in sensitivity. The results could have direct application to the improvement of the detection of seismic rotational events.

  20. Recording of Phase Transition in Tin in Shock and Release Waves Using Laser Interferometer

    NASA Astrophysics Data System (ADS)

    Finyushin, Stanislav; Fedorov, Alexey; Mikhailov, Anatoliy; Nazarov, Dmitriy; Chudakov, Evgeniy; Kalashnikov, Denis; Trunin, Ivan; Tereshkina, Irina

    2013-06-01

    In this paper the authors present results of experiments, concerning the recording of free surface velocity and particle velocity of tin/LiF window interface of tin sample at the dynamic pressure in the range 10 to 70 GPa, using laser interferometry methods Fabry-Perot and PDV. The features of recorded velocity histories interpreted the polymorphous transitions (the direct ? - ? phase transition, the reverse ? - ? phase transition) and some points on tin melting curve. The tin samples were loaded by impactor accelerated by explosion products of HE cartridge (the wave with the rectangular profile) or by direct detonation wave of HE layer (the wave with the decaying profile). With the help of PDV method, velocity of particles cloud was recorded with the free surface velocity at the moment when the shock wave front arrived to the tin free surface with the pressure amplitude of P >= 19 GPa. This could is corresponded to appearing of the liquid-solid phase at the release wave. The tin melting in the shock wave is recorded at the loading pressure of P >= 51 GPa. The pressure and temperature numerical simulations were performed for shock compression and the further releasing of tin.

  1. Design and Operation of a Two-Color Interferometer to Measure Plasma and Neutral Gas Densities in a Laser-Triggered Spark Gap Switch

    NASA Astrophysics Data System (ADS)

    Camacho, J. F.; Ruden, E. L.; Domonkos, M. T.; Schmitt-Sody, A.; Lucero, A.

    2014-10-01

    A Mach-Zehnder imaging interferometer, operating with 1064-nm and 532-nm wavelength beams from a short-pulse laser and a frequency-doubled branch, respectively, has been designed and built to simultaneously measure plasma free electron and neutral gas densities profiles within a laser-triggered spark gap switch with a 5-mm gap. The switch will be triggered by focusing a separate 532-nm or 1064-nm laser pulse along the gap's axis to trigger low-jitter breakdown. Illuminating the gap transverse to this axis, the diagnostic will generate interferograms for each wavelength, which will then be numerically converted to phase-shift maps. These will be used to calculate independent line-integrated free electron and neutral density profiles by exploiting their different frequency dispersion curves. The density profiles themselves, then, will be calculated by Abel inversion. Details of the interferometer's design will be presented along with density data obtained using a variety of fill gasses at various pressures. Other switch parameters will be varied as well in order to characterize more fully the performance of the switch.

  2. Laser anemometer using a Fabry-Perot interferometer for measuring mean velocity and turbulence intensity along the optical axis in turbomachinery

    NASA Technical Reports Server (NTRS)

    Seasholtz, R. G.; Goldman, L. J.

    1982-01-01

    A technique for measuring a small optical axis velocity component in a flow with a large transverse velocity component is presented. Experimental results are given for a subsonic free jet operating in a laboratory environment, and for a 0.508 meter diameter turbine stator cascade. Satisfactory operation of the instrument was demonstrated in the stator cascade facility with an ambient acoustic noise level during operation of about 105 dB. In addition, the turbulence intensity measured with the interferometer was consistent with previous measurements taken with a fringe type laser anemometer.

  3. Switchable dual-wavelength erbium-doped fiber-ring laser based on one polarization maintaining fiber Bragg grating in a Sagnac loop interferometer

    NASA Astrophysics Data System (ADS)

    Feng, Suchun; Xu, Ou; Lu, Shaohua; Mao, Xiangqiao; Ning, Tigang; Jian, Shuisheng

    2009-04-01

    A switchable erbium-doped fiber-ring laser providing dual-wavelength outputs with orthogonal polarizations when operating at room temperature is proposed. One polarization-maintaining fiber Bragg grating (PMFBG) in a Sagnac loop interferometer is used as the wavelength-selective filter. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The optical signal-to-noise ratio (OSNR) is over 42 dB. The amplitude variation over 90 min is less than 0.6 dB for both wavelengths.

  4. Development of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics for the free electron density of laser-generated plasma.

    PubMed

    Börner, M; Fils, J; Frank, A; Blaževi?, A; Hessling, T; Pelka, A; Schaumann, G; Schökel, A; Schumacher, D; Basko, M M; Maruhn, J; Tauschwitz, An; Roth, M

    2012-04-01

    This article reports on the development and set-up of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics of the free electron density in laser-generated plasma. The interferometer allows the recording of a series of 4 images within 6 ns of a single laser-plasma interaction. For the setup presented here, the minimal accessible free electron density is 5 × 10(18) cm(-3), the maximal one is 2 × 10(20) cm(-3). Furthermore, it provides a resolution of the electron density in space of 50 ?m and in time of 0.5 ns for one image with a customizable magnification in space for each of the 4 images. The electron density was evaluated from the interferograms using an Abel inversion algorithm. The functionality of the system was proven during first experiments and the experimental results are presented and discussed. A ray tracing procedure was realized to verify the interferometry pictures taken. In particular, the experimental results are compared to simulations and show excellent agreement, providing a conclusive picture of the evolution of the electron density distribution. PMID:22559530

  5. Development of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics for the free electron density of laser-generated plasma

    SciTech Connect

    Boerner, M.; Frank, A.; Pelka, A.; Schaumann, G.; Schoekel, A.; Schumacher, D.; Roth, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany); Fils, J.; Blazevic, A.; Hessling, T. [Helmholtzzentrum fuer Schwerionenforschung GSI, Planckstr. 1, 64291 Darmstadt (Germany); Basko, M. M. [ITEP, Moscow (Russian Federation); Maruhn, J.; Tauschwitz, An. [ITP, University of Frankfurt am Main (Germany)

    2012-04-15

    This article reports on the development and set-up of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics of the free electron density in laser-generated plasma. The interferometer allows the recording of a series of 4 images within 6 ns of a single laser-plasma interaction. For the setup presented here, the minimal accessible free electron density is 5 x 10{sup 18} cm{sup -3}, the maximal one is 2 x 10{sup 20} cm{sup -3}. Furthermore, it provides a resolution of the electron density in space of 50 {mu}m and in time of 0.5 ns for one image with a customizable magnification in space for each of the 4 images. The electron density was evaluated from the interferograms using an Abel inversion algorithm. The functionality of the system was proven during first experiments and the experimental results are presented and discussed. A ray tracing procedure was realized to verify the interferometry pictures taken. In particular, the experimental results are compared to simulations and show excellent agreement, providing a conclusive picture of the evolution of the electron density distribution.

  6. Multichord, near infrared interferometers for the CTX and ZT-40M experiments

    SciTech Connect

    Newman, E.W.; Buchenauer, C.J.; Hoida, H.W.

    1986-08-01

    A versatile, multichord CO/sub 2/ interferometer design with a wide dynamic range is adapted to several different experiments. The systems are double pass, Mach--Zehnder, heterodyne, interferometers (that employ a single germanium Bragg cell and 2/sup n-italic//sup +1/-1 (n-italic is an integer) 50% beamsplitters to produce 2/sup n-italic/ interferometer chords), and a single reference beam with matched optical path lengths. Heterodyne signals detected with room-temperature HgCdTe photoresistors are demodulated with digital phase detectors that can track several fringes per microsecond. The real-time electron density readouts provide a considerable savings in ADC channels and computation time when compared with quadrature phase detection schemes. High reliability is achieved with a temperature-controlled wave guide CO/sub 2/ laser operating on a single mode at intermittent duty. The CTX instrument has been operating with eight chords since March 1984. The ZT-40M instrument, which is under construction, employs a second wavelength to correct for room vibrations in the 0.01 fringe density range.

  7. High Resolution, Real-Time Interferometer for Coherent Beam Combination

    NASA Astrophysics Data System (ADS)

    Simion, Sandel; Blanaru, Constantin; Ursescu, Daniel

    2010-04-01

    Piston errors introduced during the pumping of high energy amplifiers in the laser chains are estimated to produce significant distortion and dramatically reduce the intensity of the combined beam resulted from the Coherent Beam Combination (CBC) of ultra intense short pulses. For monitoring the phase and optical path shift, we developed a high resolution real time interferometer. Based on the code counting method, the device is suitable for high speed/real time measurements and is immune to vibrations which might appear in the laser system. The device consists of an analog stage which generates the counting code, later processed by the microprocessor unit (CPU). The analog stage ensures 20 nm resolution, 2 m/s optical path variation speed measurements and has low sensitivity to variations of quadrature signals amplitude. The CPU is based on a complex programmable logic device (CPLD), with 8 ns processing time of the signals. The algorithm provides simultaneously measurements with increasing speed for lower resolution (20 nm at 2 m/s, 40 nm at 4 m/s and 80 nm at 8 m/s), making the system fault tolerant at high speed fluctuations of the optical path. The device contains also a digital-to-analog converter stage, making the instrument suitable for implementation of closed loop control.

  8. Multichannel microwave interferometer for the levitated dipole experiment

    SciTech Connect

    Boxer, Alexander C. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Garnier, Darren T.; Mauel, Michael E. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

    2009-04-15

    A four-channel microwave interferometer (center frequency: 60 GHz) has been constructed to measure plasma density profiles in the levitated dipole experiment (LDX). The LDX interferometer has a unique design owing to the unique geometry of LDX. The main design features of the interferometer are: (1) the transmitted beam traverses the plasma entirely in O-mode; (2) the interferometer is a heterodyne system employing two free-running oscillators; (3) four signals of data are received from just on transmitted beam; (4) phase shifts are detected in quadrature. Calibration tests demonstrate that the interferometer measures phase shifts with an uncertainty of approximately 5 deg. Plasma densities in LDX corresponding to phase shifts of up to 5{pi} are routinely and successfully measured.

  9. Multichannel microwave interferometer for the levitated dipole experiment.

    PubMed

    Boxer, Alexander C; Garnier, Darren T; Mauel, Michael E

    2009-04-01

    A four-channel microwave interferometer (center frequency: 60 GHz) has been constructed to measure plasma density profiles in the levitated dipole experiment (LDX). The LDX interferometer has a unique design owing to the unique geometry of LDX. The main design features of the interferometer are: (1) the transmitted beam traverses the plasma entirely in O-mode; (2) the interferometer is a heterodyne system employing two free-running oscillators; (3) four signals of data are received from just on transmitted beam; (4) phase shifts are detected in quadrature. Calibration tests demonstrate that the interferometer measures phase shifts with an uncertainty of approximately 5 degrees . Plasma densities in LDX corresponding to phase shifts of up to 5pi are routinely and successfully measured. PMID:19405655

  10. Measurements of line-averaged electron density of pulsed plasmas using a He-Ne laser interferometer in a magnetized coaxial plasma gun device

    NASA Astrophysics Data System (ADS)

    Iwamoto, D.; Sakuma, I.; Kitagawa, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    In next step of fusion devices such as ITER, lifetime of plasma-facing materials (PFMs) is strongly affected by transient heat and particle loads during type I edge localized modes (ELMs) and disruption. To clarify damage characteristics of the PFMs, transient heat and particle loads have been simulated by using a plasma gun device. We have performed simulation experiments by using a magnetized coaxial plasma gun (MCPG) device at University of Hyogo. The line-averaged electron density measured by a He-Ne interferometer is 2x10^21 m-3 in a drift tube. The plasma velocity measured by a time of flight technique and ion Doppler spectrometer was 70 km/s, corresponding to the ion energy of 100 eV for helium. Thus, the ion flux density is 1.4x10^26 m-2s-1. On the other hand, the MCPG is connected to a target chamber for material irradiation experiments. It is important to measure plasma parameters in front of target materials in the target chamber. In particular, a vapor cloud layer in front of the target material produced by the pulsed plasma irradiation has to be characterized in order to understand surface damage of PFMs under ELM-like plasma bombardment. In the conference, preliminary results of application of the He-Ne laser interferometer for the above experiment will be shown.

  11. Performance characteristics of the robust laser interferometer (RLI) with respect to health monitoring needs for civil, mechanical, and aerospace infrastructure elements

    NASA Astrophysics Data System (ADS)

    Zarroli, John M.; Karchnak, Martin; Goodenow, Theodore C.

    2004-07-01

    Correct sensing provides the availability of information for health monitoring interests, including those associated with unit health, stress, diagnostics and prognostics. Data is presented from measurement projects employing a 'highly linear,' wideband (0 to hundreds of kilohertz), large dynamic range (over 180 dB demonstrated in both displacement and acceleration), non-contact, vibration and Acoustic Emissions (AE) measurement capability. The measurement capability is currently embodied in an Epoch Engineering, Inc. Research and Development (R&D) Robust Laser Interferometer (RLI). Existing data from previous measurement projects is assessed in terms of its potential to provide meaningful information for health monitoring needs in situations involving civil, mechanical and aerospace infrastructure elements. In addition to performance considerations, implementation alternatives, integration benefits, cost considerations and remaining work that would need to be accomplished for commercializing the RLI capability is presented.

  12. Noise analysis of a suspended high power Michelson interferometer

    Microsoft Academic Search

    Partha Saha

    1997-01-01

    The Laser Interferometer Gravitational Wave Observatory (LIGO Project) will search for gravitational waves by observing shifts in the interference of a Michelson interferometer. To start detecting gravitational waves with any measure of confidence, current estimates require the interferometer to be sensitive to differences of at least 10-9 radians in the phase of light. Ground- based LIGO will offer this sensitivity

  13. Temperature compensated two-mode fiber interferometer 

    E-print Network

    Doma, Jagdish Ramchandra

    1993-01-01

    In this thesis we propose an innovative approach of designing and implementing a temperature compensated two-mode optical fiber interferometer in a control system of stabilizing the wavelength of a laser. We give the procedure for designing...

  14. Quadrature bandpass ?? modulation for digital radio

    Microsoft Academic Search

    Stephen A. Jantzi; Kenneth W. Martin; Adel S. Sedra

    1997-01-01

    A quadrature bandpass ?? modulator IC facilitates monolithic digital-radio-receiver design by allowing straightforward “complex A\\/D conversion” of an image reject mixer's I and Q, outputs. Quadrature bandpass ?? modulators provide superior performance over pairs of real bandpass ?? modulators in the conversion of complex input signals, using complex filtering embedded in ?? loops to efficiently realize asymmetric noise-shaped spectra. The

  15. Error Analysis of Quadrature Rules. Classroom Notes

    ERIC Educational Resources Information Center

    Glaister, P.

    2004-01-01

    Approaches to the determination of the error in numerical quadrature rules are discussed and compared. This article considers the problem of the determination of errors in numerical quadrature rules, taking Simpson's rule as the principal example. It suggests an approach based on truncation error analysis of numerical schemes for differential…

  16. Improved Skin Friction Interferometer

    NASA Technical Reports Server (NTRS)

    Westphal, R. V.; Bachalo, W. D.; Houser, M. H.

    1986-01-01

    An improved system for measuring aerodynamic skin friction which uses a dual-laser-beam oil-film interferometer was developed. Improvements in the optical hardware provided equal signal characteristics for each beam and reduced the cost and complexity of the system by replacing polarization rotation by a mirrored prism for separation of the two signals. An automated, objective, data-reduction procedure was implemented to eliminate tedious manual manipulation of the interferometry data records. The present system was intended for use in two-dimensional, incompressible flows over a smooth, level surface without pressure gradient, but the improvements discussed are not limited to this application.

  17. Modulator-free quadrature amplitude modulation signal synthesis

    NASA Astrophysics Data System (ADS)

    Liu, Zhixin; Kakande, Joseph; Kelly, Brian; O’Carroll, John; Phelan, Richard; Richardson, David J.; Slavík, Radan

    2014-12-01

    The ability to generate high-speed on–off-keyed telecommunication signals by directly modulating a semiconductor laser’s drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5?Gbit?s?1-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on–off-keyed 10?Gbit?s?1 systems and is absolutely prohibitive for today’s (>)100?Gbit?s?1 coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions.

  18. IR interferometers using modern cameras

    NASA Astrophysics Data System (ADS)

    Ai, Chiayu

    1997-11-01

    Laser interferometers have been used widely in the optics and disk drive industries. Often the surface of the sample is either too curved to resolve the fringes or too rough to reflect the incident beam back into the interferometer. Illuminating at a graze incident angle effectively increases the equivalent wavelength, and hence the reflectivity, but the image of a circular aperture becomes elliptical. Lasers with a long IR wavelength seem to be the solution. However,the spatial resolution of the vidicon cameras is usually poor, and the image lag is often too long. These limit the accuracy of an IR phase-shifting interferometer. Recently, we have designed tow types of interferometers for 3.39 micrometers and 10.6 micrometers using an InSb array and a micro- bolometer array, respectively. These modern cameras have a high resolution and hence greatly extend the range of measurable material from a blank to a finished optics. Because the refractive index of the optical material at the IR wavelength is usually very high, the anti-reflection coating of the optics at IR is more critical than that at a visible wavelength. The interferometer's design, the resolution, the dependence of the fringe contrast on the sample roughness, and the measurement results of various samples are presented.

  19. Digital holographic interferometer using simultaneously three lasers and a single monochrome sensor for 3D displacement measurements.

    PubMed

    Saucedo-A, Tonatiuh; De la Torre-Ibarra, M H; Santoyo, F Mendoza; Moreno, Ivan

    2010-09-13

    The use of digital holographic interferometry for 3D measurements using simultaneously three illumination directions was demonstrated by Saucedo et al. (Optics Express 14(4) 2006). The technique records two consecutive images where each one contains three holograms in it, e.g., one before the deformation and one after the deformation. A short coherence length laser must be used to obtain the simultaneous 3D information from the same laser source. In this manuscript we present an extension of this technique now illuminating simultaneously with three different lasers at 458, 532 and 633 nm, and using only one high resolution monochrome CMOS sensor. This new configuration gives the opportunity to use long coherence length lasers allowing the measurement of large object areas. A series of digital holographic interferograms are recorded and the information corresponding to each laser is isolated in the Fourier spectral domain where the corresponding phase difference is calculated. Experimental results render the orthogonal displacement components u, v and w during a simple load deformation. PMID:20940878

  20. Modulator-free quadrature amplitude modulation signal synthesis.

    PubMed

    Liu, Zhixin; Kakande, Joseph; Kelly, Brian; O'Carroll, John; Phelan, Richard; Richardson, David J; Slavík, Radan

    2014-01-01

    The ability to generate high-speed on-off-keyed telecommunication signals by directly modulating a semiconductor laser's drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5?Gbit?s(-1)-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on-off-keyed 10?Gbit?s(-1) systems and is absolutely prohibitive for today's (>)100?Gbit?s(-1) coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions. PMID:25523757

  1. Extending the frequency range of the National Physical Laboratory primary standard laser interferometer for hydrophone calibrations to 80 MHz.

    PubMed

    Esward, T J; Robinson, S P

    1999-01-01

    A method for the primary calibration of hydrophones in the frequency range up to 60 MHz is described. The current National Physical Laboratory (NPL) primary standard method of calibrating ultrasonic hydrophones from 500 kHz to 20 MHz is based on optical interferometry. The acoustic field produced by a transducer is detected by an acoustically transparent but optically reflecting pellicle. Optical interferometric measurements of pellicle displacement at discrete frequencies in tone-burst fields are converted to acoustic pressure, and the hydrophone for calibration is substituted at the same point, allowing sensitivity in volts per pascal to be obtained directly. For calibrations up to 60 MHz, the interferometer is capable of measuring the displacement of the pellicle as a function of frequency in a harmonically rich nonlinear field up to and including the 12th harmonic of the shocked field generated by a 5 MHz focusing transducer, allowing hydrophones to be calibrated by substitution in the same field. Sources of uncertainty in the new method have been investigated. Best combined random and systematic uncertainties at the 95% confidence level for the new method are 7% at 20 MHz, 11% at 40 MHz, and 16% at 60 MHz. PMID:18238474

  2. Quadrature flash digitizers and synchronous counters for conversion of analog quadrature signals to phase angle data

    SciTech Connect

    Buchenauer, C.J.

    1981-07-01

    The methodology and hardware used to deduce and digitally encode the phase angle Phi(t) from quadrature signals of the form S/sub 1/(t) = k(t) sin Phi(t) and S/sub 2/(t) = k(t) cos Phi(t) on an extremely fast time scale are described. Theory and experimental results are given for quadrature flash digitizers and quadrature synchronous counters. Designs for two-stage quadrature digitizers are described. Scaling formulas and design equations are given. These devices appear to be no more complex than conventional linear digitizers and synchronous counters.

  3. Herriott Cell Interferometer for Density Measurements in Small-Scale Length Plasmas

    Microsoft Academic Search

    Erik Antonsen; Rodney Burton; Scott Engelman; Greg Spanjers

    2000-01-01

    The introduction of a Herriott cell into a standard quadrature heterodyne interferometer is evaluated and demonstrated to increase the resolution of the system. Measurements of electron and neutral density during and after the current pulse are sought for modeling purposes for spacecraft contamination from Pulsed Plasma Thrusters. Testing is performed on the UIUC PPT-4, a coaxial electrothermal Pulsed Plasma Thruster

  4. Fiber-optic coupled heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Liang

    A lightweight and electrically passive interferometer is demanded by a number of applications for precision metrology such as machine tool metrology and on-machine feedback. To satisfy these requirements, a fiber-optic coupled heterodyne displacement measuring Michelson interferometer is developed. In this interferometer, the laser light is coupled into the interferometer with a polarization-maintaining (PM) fiber to separate the application environment of the interferometer from the laser head. The primary limitation of accuracy encountered with this fiber-optic coupled heterodyne interferometer is the optical mixing arising from the imperfection of fiber-optic coupling system. The optical mixing results in the nonlinearity (first order and second order errors) in the displacement measurement of the interferometer. Thermal translation is developed to measure the nonlinearity. A theoretical model using Jones calculus is developed and corresponding experiments are carried out with good agreement. A strategy of combined optical alignment and signal processing is determined to reduce nonlinearity below the level of 2 nm.

  5. A compact, robust and versatile moiré interferometer

    NASA Astrophysics Data System (ADS)

    Mollenhauer, D. H.; Ifju, P. G.; Han, B.

    A moiré interferometer was designed and constructed based on a general system design using a reflective crossed-line diffraction grating to produce the four beams of light necessary for moiré interferometry. The design concept, basic design and tuning procedures are discussed. The important features of the interferometer, i.e. compactness, versatility, polarization insensitivity, relaxed collimation requirements, low laser power and remote optics, are addressed. Several such interferometers have been constructed and successfully applied to engineering problems. These include examining the displacement fields surrounding drilled and preformed holes in composite laminates loaded in tension, and the evaluation of nonhomogeneous behavior in textile composites.

  6. Dual-beam skin friction interferometer

    NASA Technical Reports Server (NTRS)

    Monson, D. J. (inventor)

    1981-01-01

    A portable dual-laser beam interferometer is described that nonintrusively measures skin friction by monitoring the thickness change of an oil film at two locations while said oil film is subjected to shear stress. An interferometer flat is utilized to develop the two beams. Light detectors sense the beam reflections from the oil film and the surface thereunder. The signals from the detectors are recorded so that the number of interference fringes produced over a given time span may be counted.

  7. High efficiency second-harmonic generation in four-pass quadrature frequency conversion scheme

    Microsoft Academic Search

    Hiromitsu Kiriyama; Shinichi Matsuoka; Yoichiro Maruyama; Takashi Arisawa

    2000-01-01

    A four-pass quadrature frequency conversion scheme was developed to generate green output with high efficiency for pumping an ultrashort pulse laser system. With this scheme, an efficiency from fundamental energy into total second harmonic energy in excess of 80% was achieved for frequency doubling of 1064 nm in KTP with a low input fundamental laser intensity of 76 MW\\/cm2. A

  8. 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. PMID:26193022

  9. Handling accuracy in Bayesian automatic adaptive quadrature

    NASA Astrophysics Data System (ADS)

    Adam, Gh; Adam, S.

    2015-06-01

    New Bayesian inferences which significantly extend the coverage of the Bayesian automatic adaptive quadrature (BAAQ) approach to the solution of Riemann integrals are reported. The scrutiny of the possible floating-point machine number approximations of abscissa values inside an integration domain unveiled the occurrence of five classes of integration domains entering the quadrature problems: zero-length, open void, microscopic, mesoscopic, macroscopic. Correct approach to the class identifications and class adapted advancement to the solution are described. In the most complex, macroscopic case, the reversible addition of a new decision branch extends the BAAQ approach coverage to both difficult and easy integrals. The reliability of the code used for solving easy integrals was enhanced with four new analysis tools as compared to the standard automatic adaptive quadrature solution.

  10. Special relativity and interferometers

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1988-01-01

    A new generation of gravitational wave detectors is expected to be based on interferometers. Yurke et al. (1986) introduced a class of interferometers characterized by SU(1,1) which can in principle achieve a phase sensitivity approaching 1/N, where N is thte total number of photons entering the interferometer. It is shown here that the SU(1,1) interferometer can serve as an analog computer for Wigner's little group of the Poincare\\'| group.

  11. Robust spatiotemporal quadrature filter for multiphase stepping.

    PubMed

    Rivera, M; Marroquin, J L; Botello, S; Servín, M

    2000-01-10

    A robust algorithm for phase recovery from multi-phase-stepping images is presented. This algorithm is based on the minimization of an energy (cost) functional and is equivalent to the simultaneous application of a fixed temporal quadrature filter and a spatial adaptive quadrature filter to the phase-stepping pattern ensemble. The algorithm, believed to be new, is specially suited for those applications in which a large number of phase-stepping images may be obtained, e.g., profilometry with a computer-controlled fringe projector. We discuss the selection of parameter values and present examples of its performance in both synthetic and real image sequences. PMID:18337896

  12. Comparison of Atom Interferometers and Light Interferometers as Space-Based Gravitational Wave Detectors

    E-print Network

    John G. Baker; James Ira Thorpe

    2012-01-26

    We consider a class of proposed gravitational wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, non-inertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g. multiple arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe.

  13. Dispersion cancellation in a triple Laue interferometer

    NASA Astrophysics Data System (ADS)

    Lemmel, Hartmut

    2014-10-01

    The concept of dispersion cancellation has been established in light optics to improve the resolution of interferometric measurements on dispersive media. Odd order dispersion cancellation allows to measure phase shifts without defocusing the interferometer due to wave packet displacements, while even order dispersion cancellation allows to measure time lags without losing resolution due to wave packet spreading. We report that either type of dispersion cancellation can be realized very easily in a triple Laue interferometer. Such interferometers are Mach-Zehnder interferometers based on Bragg diffraction, and are commonly used for neutrons and x-rays. Although the first x-ray interferometer was built nearly five decades ago, the feature of dispersion cancellation hasn't been recognized so far because the concept was hardly known in the neutron and x-ray community. However, it explains right away the surprising decoupling of phase shift and spatial displacement that we have discovered recently in neutron interferometry (Lemmel and Wagh 2010 Phys. Rev. A 82 033626). Furthermore, this article might inspire the light optics community to consider whether a triple Laue interferometer for laser light would be useful and feasible. We explain how dispersion cancellation works in neutron interferometry, and we describe the setup rigorously by solving the Schrödinger equation and by calculating the path integral. We point out, that the latter has to be evaluated with special care since in our setup the beam trajectory moves with respect to the crystal lattice of the interferometer.

  14. Simulation of Fabry-Perot cavities in a Michelson interferometer

    Microsoft Academic Search

    Lina Aguilar-Lobo; Claudia Moreno; Guillermo Garcia-Torales

    2009-01-01

    The Laser Interferometer Gravitational-Wave Observatory (LIGO) has designed to detect Gravitational Waves (GW); its system of detection is based on the Michelson interferometer configuration. When a GW hit on it, the optical elements are disturbed inducing a change in the optical path difference (OPD). The arms length in the detector should be of hundreds of kilometers, due to the small

  15. Prospects for a Gradient Magnetometer Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Narducci, Frank A.; Davis, Jon P.

    2008-03-01

    Atom interferometers form the basis for state-of-the-art sensors, including gravimeters, gravity gradiometers, gyroscopes and atomic clocks. Notably absent from this list are magnetometers, which can have a wide range of applications ranging from military to medical applications. We propose a scheme to realize an atom interferometer gradient magnetometer. We begin by demonstrating a light-pulse magnetic beam-splitter. The analysis is based on a full multi-level 2-laser field Maxwell-Bloch model including state selection rules, polarization selectivity, laser detuning, and Doppler averaging. We then consider an ensemble of atoms subject to a ?/2-?-?/2 pulse sequence. The phase of the interference pattern depends on the phase of the action along the classical path and on the phase of the combined laser fields imprinted on the atoms during the pulse sequence. From this analysis, we conclude that, to first order, the phase of the interferometer output is insensitive to the field across the interferometer, but is sensitive to the gradient of the field. Using realizable numbers from existing interferometers, we show that a gradient magnetometer of this type has can have a greater gradient sensitivity than many current magnetic sensors. We discuss the status of our current experiments using ultra-cold atoms.

  16. Modulator-free quadrature amplitude modulation signal synthesis

    PubMed Central

    Liu, Zhixin; Kakande, Joseph; Kelly, Brian; O’Carroll, John; Phelan, Richard; Richardson, David J.; Slavík, Radan

    2014-01-01

    The ability to generate high-speed on–off-keyed telecommunication signals by directly modulating a semiconductor laser’s drive current was one of the most exciting prospective applications of the nascent field of laser technology throughout the 1960s. Three decades of progress led to the commercialization of 2.5?Gbit?s?1-per-channel submarine fibre optic systems that drove the growth of the internet as a global phenomenon. However, the detrimental frequency chirp associated with direct modulation forced industry to use external electro-optic modulators to deliver the next generation of on–off-keyed 10?Gbit?s?1 systems and is absolutely prohibitive for today’s (>)100?Gbit?s?1 coherent systems, which use complex modulation formats (for example, quadrature amplitude modulation). Here we use optical injection locking of directly modulated semiconductor lasers to generate complex modulation format signals showing distinct advantages over current and other currently researched solutions. PMID:25523757

  17. Analysis of spatial mode sensitivity of gravitational wave interferometer and targeted search for gravitational radiation from the Crab pulsar

    E-print Network

    Betzwieser, Joseph (Joseph Charles)

    2008-01-01

    Over the last several years the Laser Interferometer Gravitational Wave Observatory (LIGO) has been making steady progress in improving the sensitivities of its three interferometers, two in Hanford, Washington, and one ...

  18. Phase shifting interferometer

    DOEpatents

    Sommargren, Gary E. (Santa Cruz, CA)

    1999-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  19. Noise analysis of a simplified Michelson interferometer vibrometer hydrophone

    NASA Astrophysics Data System (ADS)

    Estes, Lee E.; Cray, Benjamin A.

    2001-05-01

    The use of a Michelson interferometer to sense acoustic vibrations imposed on a water/plate/air boundary is investigated. To focus on fundamentals, a simplified interferometer is considered rather than the usual heterodyne or dual track homodyne configurations. Based on analytical models, the sensitivity limits due to photoelectron shot noise, laser light amplitude and phase noise, atmospheric turbulence, thermal vibration, and amplifier noise are predicted. Techniques for mitigation of turbulence and laser noise will be discussed.

  20. Dispersion interferometer using modulation amplitudes on LHD (invited)

    SciTech Connect

    Akiyama, T., E-mail: takiyama@lhd.nifs.ac.jp; Yasuhara, R.; Kawahata, K. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu 509-5292 (Japan); Okajima, S.; Nakayama, K. [Chubu University, Matsumoto-cho, Kasugai-shi, Aichi 487-8501 (Japan)

    2014-11-15

    Since a dispersion interferometer is insensitive to mechanical vibrations, a vibration compensation system is not necessary. The CO{sub 2} laser dispersion interferometer with phase modulations on the Large Helical Device utilizes the new phase extraction method which uses modulation amplitudes and can improve a disadvantage of the original dispersion interferometer: measurement errors caused by variations of detected intensities. The phase variation within ±2 × 10{sup 17} m{sup ?3} is obtained without vibration compensation system. The measured line averaged electron density with the dispersion interferometer shows good agreement with that with the existing far infrared laser interferometer. Fringe jump errors in high density ranging up to 1.5 × 10{sup 20} m{sup ?3} can be overcome by a sufficient sampling rate of about 100 kHz.

  1. Interferometer for measuring displacement and distance

    Microsoft Academic Search

    Toshihiro Kubota; Makoto Nara; Toshihiko Yoshino

    1987-01-01

    A simple interferometer for measuring both relative displacement and absolute distance is fabricated that uses a laser diode. The sign of the displacementis detected by means of a lambda\\/8 plate, and the distance is measured by an FM radar technique of modulating the laser-diode frequency. Measurement accuracies of 0.02 micron for displacement and 100 microns for distance are obtained over

  2. Diffraction phases in atom interferometers

    E-print Network

    Caroline Champenois; Matthias Buchner; Remi Delhuille; Cecile Robilliard; Jacques Vigue; Alain Miffre

    2003-03-12

    Diffraction of atoms by laser is a very important tool for matter wave optics. Although this process is well understood, the phase shifts induced by this diffraction process are not well known. In this paper, we make analytic calculations of these phase shifts in some simple cases and we use these results to model the contrast interferometer recently built by the group of D. Pritchard at MIT. We thus show that the values of the diffraction phases are large and that they probably contribute to the phase noise observed in this experiment.

  3. Optical displacement measurement with GaAs\\/AlGaAs-based monolithically integrated Michelson interferometers

    Microsoft Academic Search

    Daniel Hofstetter; Hans P. Zappe; R. Dandliker

    1997-01-01

    Two monolithically integrated optical displacement sensors fabricated in the GaAs\\/AlGaAs material system are reported. These single-chip microsystems are configured as Michelson interferometers and comprise a distributed Bragg reflector (DBR) laser, photodetectors, phase shifters, and waveguide couplers. While the use of a single Michelson interferometer allows measurement of displacement magnitude only, a double Michelson interferometer with two interferometer signals in phase

  4. Multisite EPR oximetry from multiple quadrature harmonics.

    PubMed

    Ahmad, R; Som, S; Johnson, D H; Zweier, J L; Kuppusamy, P; Potter, L C

    2012-01-01

    Multisite continuous wave (CW) electron paramagnetic resonance (EPR) oximetry using multiple quadrature field modulation harmonics is presented. First, a recently developed digital receiver is used to extract multiple harmonics of field modulated projection data. Second, a forward model is presented that relates the projection data to unknown parameters, including linewidth at each site. Third, a maximum likelihood estimator of unknown parameters is reported using an iterative algorithm capable of jointly processing multiple quadrature harmonics. The data modeling and processing are applicable for parametric lineshapes under nonsaturating conditions. Joint processing of multiple harmonics leads to 2-3-fold acceleration of EPR data acquisition. For demonstration in two spatial dimensions, both simulations and phantom studies on an L-band system are reported. PMID:22154283

  5. Geometry of Lie integrability by quadratures

    NASA Astrophysics Data System (ADS)

    Cariñena, J. F.; Falceto, F.; Grabowski, J.; Rañada, M. F.

    2015-05-01

    In this paper, we extend the Lie theory of integration by quadratures of systems of ordinary differential equations in two different ways. First, we consider a finite-dimensional Lie algebra of vector fields and discuss the most general conditions under which the integral curves of one of the fields can be obtained by quadratures in a prescribed way. It turns out that the conditions can be expressed in a purely algebraic way. In the second step, we generalize the construction to the case in which we substitute the Lie algebra of vector fields by a module (generalized distribution). We obtain a much larger class of explicitly integrable systems, replacing standard concepts of solvable (or nilpotent) Lie algebra with distributional solvability (nilpotency).

  6. Superharmonic Injection Locked Quadrature LC VCO Using Current Recycling Architecture 

    E-print Network

    Kalusalingam, Shriram

    2011-02-22

    superharmonic coupling????..?.. 7 3.1 Conventional LC VCO?????..??????????.. 8 3.2 Proposed quadrature voltage controlled oscillator??..??? 9 3.3 Current recycling mechanism?????????..???? 11 3.4 Comparison of amplitude between proposed and conventional... QVCO????????????????????..?? 13 3.5 Modeling of QVCO for mathematical analysis?????...? 16 3.6 Quadrature catch up of proposed QVCO???????..?.. 18 3.7 Impedance plot of parallel RLC??????????..?? 23 3.8 Quadrature phase error vs coupling factor...

  7. 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. PMID:20441364

  8. Full-field Fabry-Perot interferometer

    SciTech Connect

    Mathews, A.R.; Boat, R.M.; Hemsing, W.F.; Warnes, R.H.; Whittemore, G.R.

    1991-01-01

    This paper describes the use of a Fabry-Perot interferometer for simultaneously measuring velocity at many points on the surface of a shock-loaded solid. The method is based upon work reported by S. Gidon and G. Behar in 1986, but the data analysis has been improved by the application of image-processing techniques. Light from a pulsed single-frequency laser is focused onto a moving target and the returned Doppler-shifted image passed through a Fabry-Perot interferometer. Output of the interferometer is a set of fringes that are formed for specific combinations of wavelength and light angle. These fringes are recorded on film for subsequent analysis. Fringe position determines the velocity for each point on the target that forms a fringe. A method for determining the velocity as a function of both position and time will also be discussed. 5 refs., 6 figs.

  9. Heterodyne interferometer with angstrom-level periodic nonlinearity

    DOEpatents

    Schmitz, Tony L. (Gainesville, FL); Beckwith, John F. (Indialantic, FL)

    2005-01-25

    Displacement measuring interferometer systems and methods are disclosed. One or more acousto-optic modulators for receiving a laser light beam from a laser light source can be utilized to split the laser light beam into two or more laser light beams, while spatially separating frequencies thereof. One or more reflective mechanisms can be utilized to reflect one or more of the laser light beams back to the acousto-optic modulator. Interference of two or more of the laser light beams generally at the acousto-optic modulator can provide an interfered laser light beam thereof. A detector for receiving the interfered laser light beam can be utilized to provide interferometer measurement data.

  10. Sub-Aperture Interferometers

    NASA Technical Reports Server (NTRS)

    Zhao, Feng

    2010-01-01

    Sub-aperture interferometers -- also called wavefront-split interferometers -- have been developed for simultaneously measuring displacements of multiple targets. The terms "sub-aperture" and "wavefront-split" signify that the original measurement light beam in an interferometer is split into multiple sub-beams derived from non-overlapping portions of the original measurement-beam aperture. Each measurement sub-beam is aimed at a retroreflector mounted on one of the targets. The splitting of the measurement beam is accomplished by use of truncated mirrors and masks, as shown in the example below

  11. VISAR (Velocity Interferometer System for Any Reflector): Line-imaging interferometer

    Microsoft Academic Search

    W. F. Hemsing; A. R. Mathews; R. H. Warnes; G. R. Whittemore

    1990-01-01

    This paper describes a Velocity Interferometer System for Any Reflector (VISAR) technique that extends velocity measurements from single points to a line. Single-frequency argon laser light was focused through a cylindrical lens to illuminate a line on a surface. The initially stationary, flat surface was accelerated unevenly during the experiment. Motion produced a Doppler-shift of light reflected from the surface

  12. Hybrid photonic chip interferometer for embedded metrology

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Martin, H.; Maxwell, G.; Jiang, X.

    2014-03-01

    Embedded metrology is the provision of metrology on the manufacturing platform, enabling measurement without the removal of the work piece. Providing closer integration of metrology upon the manufacturing platform can lead to the better control and increased throughput. In this work we present the development of a high precision hybrid optical chip interferometer metrology device. The complete metrology sensor system is structured into two parts; optical chip and optical probe. The hybrid optical chip interferometer is based on a silica-on-silicon etched integrated-optic motherboard containing waveguide structures and evanescent couplers. Upon the motherboard, electro-optic components such as photodiodes and a semiconductor gain block are mounted and bonded to provide the required functionality. The key structure in the device is a tunable laser module based upon an external-cavity diode laser (ECDL). Within the cavity is a multi-layer thin film filter which is rotated to select the longitudinal mode at which the laser operates. An optical probe, which uses a blazed diffracting grating and collimating objective lens, focuses light of different wavelengths laterally over the measurand. Incident laser light is then tuned in wavelength time to effectively sweep an `optical stylus' over the surface. Wavelength scanning and rapid phase shifting can then retrieve the path length change and thus the surface height. We give an overview of the overall design of the final hybrid photonic chip interferometer, constituent components, device integration and packaging as well as experimental test results from the current version now under evaluation.

  13. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E. (Santa Cruz, CA)

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  14. Fizeau plasma interferometer

    SciTech Connect

    Frank, A.M.

    1980-01-01

    This paper describes a technique by which the sensitivity of plasma interferometers can be increased. Stabilization and fractional fringe measurement techniques have improved to the point where additional optical sensitivity could be useful. (MOW)

  15. X-ray crystal interferometers

    NASA Astrophysics Data System (ADS)

    Lider, V. V.

    2014-11-01

    Various configurations of the X-ray crystal interferometer are reviewed. The interferometer applications considered include metrology, the measurement of fundamental physical constants, the study of weakly absorbing phase objects, time-resolved diagnostics, the determination of hard X-ray beam parameters, and the characterization of structural defects in the context of developing an X-ray Michelson interferometer. The three-crystal Laue interferometer (LLL-interferometer), its design, and the experimental opportunities it offers are given particular attention.

  16. Compressive optical image encryption with two-step-only quadrature phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Hongbing; Li, Jiaosheng; Pan, Yangyang; Li, Rong

    2015-06-01

    An image encryption method which combines two-step-only quadrature phase-shifting digital holography with compressive sensing (CS) has been proposed in the fully optical domain. An object image is firstly encrypted to two on-axis quadrature-phase holograms using the two random phase masks in the Mach-Zehnder interferometer. Then, the two encrypted images are highly compressed to a one-dimensional signal using the single-pixel compressive holographic imaging in the optical domain. At the receiving terminal, the two compressive encrypted holograms are exactly reconstructed from much less than the Nyquist sampling number of observations by solving an optimization problem, and the original image can be decrypted with only two reconstructed holograms and the correct keys. This method largely decreases holograms data volume for the current optical image encryption system, and it is also suitable for some special optical imaging cases such as different wavelengths imaging and weak light imaging. Numerical simulation is performed to demonstrate the feasibility and validity of this novel image encryption method.

  17. Differential quadrature for buckling analysis of laminated plates

    Microsoft Academic Search

    Xinwei Wang

    1995-01-01

    Two new sets of grid points are proposed for applying differential quadrature (DQ) to the analysis of structural problems. The accuracy and convergence of differential quadrature for buckling analysis of laminated plates are discussed in this paper. A variety of buckling problems, including composite laminated plates with various boundary constrains under uniaxial, biaxial, and combined uniaxial and shear loadings, are

  18. State reconstruction formulas for the s-distributions and quadratures

    E-print Network

    Jukka Kiukas; Juha-Pekka Pellonpää; Jussi Schultz

    2009-09-18

    We consider the method of infinite matrix inversion in the context of quantum state reconstruction. Using this method we give rigorous proofs for reconstruction formulas for the Cahill-Glauber s-parametrized distributions and the rotated quadrature distributions. We also demonstrate how to construct the s-distributions from the quadrature data.

  19. Principles of calculating alignment signals in complex resonant optical interferometers

    Microsoft Academic Search

    Yaron Hefetz; Nergis Mavalvala; Daniel Sigg

    1997-01-01

    In the long baseline laser interferometers, presently under construction to measure gravitational waves (LIGO), the alignment of the optical components with respect to the incoming laser beam is crucial to maintain maximum phase sensitivity. We present a basic formalism to analytically calculate the effects of misalignment and beam distortions in an arbitrarily complex optical system, including coupled cavities and Michelson

  20. 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. PMID:26125376

  1. Application of differential quadrature (DQ) and harmonic differential quadrature (HDQ) for buckling analysis of thin isotropic plates and elastic columns

    Microsoft Academic Search

    Ömer Civalek

    2004-01-01

    The main purpose of this study is to compare the methods of differential quadrature (DQ) and harmonic differential quadrature (HDQ). For this purpose, DQ and HDQ methods are presented for buckling, bending, and free vibration analysis of thin isotropic plates and columns. Plates of different shapes such as rectangular, circular, square, skew, trapezoidal, annular, and sectorial plate subjected to different

  2. DIODE LASER FREQUENCY STANDARD FOR LASER INTERFEROMETRY

    Microsoft Academic Search

    Janusz Pienkowski

    Diode lasers are becoming increasingly important in length metrology. We demonstrate construction of a simple single-frequency diode laser 632,8 nm, used as a frequency standard in the laser interferometers. We present two different systems applied for frequency stabil ization of diode laser . For diode laser used as the secondar y standard, the system stabilizes diode temperature, the frequ ency

  3. Integrated source of broadband quadrature squeezed light.

    PubMed

    Hoff, Ulrich B; Nielsen, Bo M; Andersen, Ulrik L

    2015-05-01

    An integrated silicon nitride resonator is proposed as an ultra-compact source of bright single-mode quadrature squeezed light at 850 nm. Optical properties of the device are investigated and tailored through numerical simulations, with particular attention paid to loss associated with interfacing the device. An asymmetric double layer stack waveguide geometry with inverse vertical tapers is proposed for efficient and robust fibre-chip coupling, yielding a simulated total loss of -0.75 dB/facet. We assess the feasibility of the device through a full quantum noise analysis and derive the output squeezing spectrum for intra-cavity pump self-phase modulation. Subject to standard material loss and detection efficiencies, we find that the device holds promises for generating substantial quantum noise squeezing over a bandwidth exceeding 1 GHz. In the low-propagation loss regime, approximately -6 dB squeezing is predicted for a pump power of only 75 mW. PMID:25969291

  4. Measurement of the structure coefficient of refractive index fluctuations in a turbulent premixed butane-air flame by means of a laser-based interferometer technique

    NASA Astrophysics Data System (ADS)

    Ngo Nyobe, Elisabeth; Pemha, Elkana; Hona, Jacques; Bilong, Jean; Lamara, Maurice

    2014-08-01

    With a view to measuring the structure coefficient of refractive index fluctuations in a turbulent premixed butane-air flame, a thin laser beam is sent into the flame perpendicular to the flow direction. The laser beam generally undergoes fluctuations of direction, phase, and amplitude. Only the random deflections of the laser beam may be taken into account. After having traversed the flame, the perturbed laser beam enters into an interferometric system. Materials and experimental procedure are described. In the unperturbed interference pattern, the zones only sensitive to fluctuations of the angle-of-arrival of the laser beam are detected. From the random displacements of the central bright fringe, the structure coefficient of refractive index fluctuations in the flame is measured. To prove that the method of measurement is satisfactory, the result obtained is applied for computing the power spectral density of the angle-of-arrival of the laser beam from the formula of correlations of the laser beam deflection angles which we have demonstrated in previous works. This computed power spectral density is compared to that measured from the effective position of the detector. A good agreement is observed between the two results.

  5. Using a Ground-Based SAR Interferometer and a Terrestrial Laser Scanner to Monitor a Snow-Covered Slope: Results From an Experimental Data Collection in Tyrol (Austria)

    Microsoft Academic Search

    Guido Luzi; Linhsia Noferini; Daniele Mecatti; Giovanni Macaluso; Massimiliano Pieraccini; Carlo Atzeni; Andreas Schaffhauser; Reinhard Fromm; Thomas Nagler

    2009-01-01

    In this paper, we report on an experimental activity aimed at investigating the potential of two terrestrial remote-sensing techniques, namely, ground-based SAR (GB SAR) interferometry and terrestrial laser scanning, in order to retrieve snow-depth (SD) measurements in mountainous regions. Terrestrial laser scanning is a more consolidated technique based on the measurement of the optical (near infrared) reflectivity, and it is

  6. PDX multichannel interferometer

    SciTech Connect

    Bitzer, R.; Ernst, W.; Cutsogeorge, G.

    1980-10-01

    A 10 channel, 140 GHz homodyne interferometer is described for use on PDX. One feature of this interferometer is the separation of the signal source and electronics from the power splitters, delay line, and receiving systems. The latter is situated near the upper and lower vacuum ports between the toroidal field magnets. A second feature is the signal stabilization of the EIO source by means of an AFC system. The complete interferometer is described including block diagrams, circuit diagrams, test data, and magnetic field test conducted on the preamplifiers, microwave diodes, isolators, etc., to determine the extent of magnetic shielding required. The description of the tracking filters and digital phase display circuit is referenced to accompanying reports.

  7. Laser interferometry for satellite gravimetry

    Microsoft Academic Search

    Benjamin Sheard; Gerhard Heinzel; Marina Dehne; Christoph Mahrdt; Oliver Gerberding; Karsten Danzmann

    2010-01-01

    Satellite gravimetry has been demonstrated to be a useful tool for measuring the Earth's global scale static and dynamic mass distribution. Laser interferometer metrology developed for the Laser Interferometer Space Antenna (LISA), a space-based gravitational wave detector and its technology demonstrator, LISA Pathfinder, is applicable to inter-satellite ranging, local proof mass metrology and laser gravity gradiometery. An overview of the

  8. Parametric oscillatory instability in a signal-recycled LIGO interferometer

    SciTech Connect

    Vyatchanin, S P; Strigin, S E [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)

    2007-12-31

    The undesirable effect of parametric oscillatory instability in a LIGO (Laser Interferometer Gravitational-Wave Observatory) laser gravitational-wave antenna with a signal-recirculation mirror is analysed in detail. The instability is manifested in excitation of the Stokes optical mode and elastic mechanical mode of the mirror. It is shown that, if the eigenfrequencies of Fabry-Perot resonators in the interferometer arms are different, the parametric instability is quite small due to a small passband band width. (fifth seminar in memory of d.n. klyshko)

  9. Nd:YAG holographic interferometer for aerodynamic research

    NASA Technical Reports Server (NTRS)

    Craig, J. E.; Lee, G.; Bachalo, W. D.

    1983-01-01

    A holographic interferometer system has been installed in the NASA Ames 2- by 2-Foot Transonic Wind Tunnel. The system incorporates a modern 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described, as well as the integration of the system into the existing schlieren system. A two-plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models, the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.

  10. Multispectral infrared imaging interferometer

    NASA Technical Reports Server (NTRS)

    Potter, A. E., Jr.

    1971-01-01

    Device permitting simultaneous viewing of infrared images at different wavelengths consists of imaging lens, Michelson interferometer, array of infrared detectors, data processing equipment for Fourier transformation of detector signal, and image display unit. Invention is useful in earth resources applications, nondestructive testing, and medical diagnoses.

  11. Ultrasonic Interferometers Revisited

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    I have been tinkering with ultrasonic transducers once more. In earlier notes I reported on optics-like experiments performed with ultrasonics, described a number of ultrasonic interferometers, and showed how ultrasonic transducers can be used for Fourier analysis. This time I became interested in trying the technique of using two detectors in…

  12. Quadrature Mismatch Shaping for Digital-to-Analog Converters

    Microsoft Academic Search

    Stijn Reekmans; J. De Maeyer; P. Rombouts; Ludo Weyten

    2006-01-01

    Quadrature sigma-delta analog-to-digital converters require a feedback path for both the I and the Q parts of the complex feedback signal. If two separate multibit feedback digital-to-analog converters (DACs) are used, mismatch among the unit DAC elements leads to additional mismatch noise in the output spectrum as well as an I\\/Q imbalance. This paper proposes new quadrature bandpass (QBP) mismatch

  13. A Current Reuse Quadrature GPS Receiver in 0.13 m CMOS

    Microsoft Academic Search

    Kuang-Wei Cheng; Karthik Natarajan; David J. Allstot

    2010-01-01

    A fully-integrated quadrature low-IF L1-band GPS receiver consumes only 6.4 mW in 0.13 ?m CMOS. The RF front-end features a gate-modulated quadrature VCO for low phase noise and accurate quadrature phase signal generation. It merges the LNA, quadrature mixer, and quadrature VCO in a single current-reuse stacked topology that provides a conversion gain 42.5 dB with a power consumption of

  14. Laser-interference methods in hydroacoustic systems

    NASA Astrophysics Data System (ADS)

    Dolgikh, G. I.; Plotnikov, A. A.

    2008-03-01

    In article the description of bottom station is resulted, basic measuring device is laser-interference hydrophone. Laser-interference hydrophone is created on a basis Michelson interferometer of equal-arm type. As a light source in interferometer the semi-conductor laser is used. A sensitive element of a laser hydrophone is the round membrane which is included in system <>.

  15. Two integrator loop quadrature oscillators: A review

    PubMed Central

    Soliman, Ahmed M.

    2012-01-01

    A review of the two integrator loop oscillator circuits providing two quadrature sinusoidal output voltages is given. All the circuits considered employ the minimum number of capacitors namely two except one circuit which uses three capacitors. The circuits considered are classified to four different classes. The first class includes floating capacitors and floating resistors and the active building blocks realizing these circuits are the Op Amp or the OTRA. The second class employs grounded capacitors and includes floating resistors and the active building blocks realizing these circuits are the DCVC or the unity gain cells or the CFOA. The third class employs grounded capacitors and grounded resistors and the active building blocks realizing these circuits are the CCII. The fourth class employs grounded capacitors and no resistors and the active building blocks realizing these circuits are the TA. Transformation methods showing the generation of different classes from each other is given in details and this is one of the main objectives of this paper. PMID:25685396

  16. Two integrator loop quadrature oscillators: A review.

    PubMed

    Soliman, Ahmed M

    2013-01-01

    A review of the two integrator loop oscillator circuits providing two quadrature sinusoidal output voltages is given. All the circuits considered employ the minimum number of capacitors namely two except one circuit which uses three capacitors. The circuits considered are classified to four different classes. The first class includes floating capacitors and floating resistors and the active building blocks realizing these circuits are the Op Amp or the OTRA. The second class employs grounded capacitors and includes floating resistors and the active building blocks realizing these circuits are the DCVC or the unity gain cells or the CFOA. The third class employs grounded capacitors and grounded resistors and the active building blocks realizing these circuits are the CCII. The fourth class employs grounded capacitors and no resistors and the active building blocks realizing these circuits are the TA. Transformation methods showing the generation of different classes from each other is given in details and this is one of the main objectives of this paper. PMID:25685396

  17. Switchable multiwavelength filter based on a hybrid sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Shim, Young Bo; Han, Young-Geun

    2012-04-01

    A switchable multichannel filter based on a hybrid Sagnac interferometer was proposed and experimentally demonstrated. The hybrid Sagnac interferometer was realized by inserting a sampled fiber Bragg grating (SFBG) into a fiber loop mirror by using a polarization-insensitive 3-dB coupler. By using a beam scanning technique, we fabricated a sampled fiber Bragg grating by exposing a photosensitive fiber to a frequency-doubled 244-nm Ar+ laser. The fabricated SFBG had multiple reflection peaks corresponding to the chirp ratio and the spacing of grating. The multiple peaks in the hybrid Sagnac interferometer could be controlled by changing the relative phase difference between two counter-propagating signals. The transmission characteristics of the proposed switchable multichannel filter were analyzed by using a Jones matrix method. Consequently, a switchable multichannel filter based on a sampled fiber Bragg grating incorporating a Sagnac interferometer could be achieved.

  18. Searching for Gravitational Waves with a Geostationary Interferometer

    E-print Network

    M. Tinto; J. C. N. de Araujo; O. D. Aguiar; M. E. S. Alves

    2013-08-16

    We analyze the sensitivities of a geostationary gravitational wave interferometer mission operating in the sub-Hertz band. Because of its smaller armlength, in the lower part of its accessible frequency band ($10^{-4} - 2 \\times 10^{-2}$ Hz) our proposed Earth-orbiting detector will be less sensitive, by a factor of about seventy, than the Laser Interferometer Space Antenna (LISA) mission. In the higher part of its band instead ($2 \\times 10^{-2} - 10$ Hz), our proposed interferometer will have the capability of observing super-massive black holes (SMBHs) with masses smaller than $\\sim 10^{6}$ M$_{\\odot}$. With good event rates for these systems, a geostationary interferometer will be able to accurately probe the astrophysical scenarios that account for their formation.

  19. Achromatic self-referencing interferometer

    DOEpatents

    Feldman, M.

    1994-04-19

    A self-referencing Mach-Zehnder interferometer is described for accurately measuring laser wavefronts over a broad wavelength range (for example, 600 nm to 900 nm). The apparatus directs a reference portion of an input beam to a reference arm and a measurement portion of the input beam to a measurement arm, recombines the output beams from the reference and measurement arms, and registers the resulting interference pattern ([open quotes]first[close quotes] interferogram) at a first detector. Optionally, subportions of the measurement portion are diverted to second and third detectors, which respectively register intensity and interferogram signals which can be processed to reduce the first interferogram's sensitivity to input noise. The reference arm includes a spatial filter producing a high quality spherical beam from the reference portion, a tilted wedge plate compensating for off-axis aberrations in the spatial filter output, and mirror collimating the radiation transmitted through the tilted wedge plate. The apparatus includes a thermally and mechanically stable baseplate which supports all reference arm optics, or at least the spatial filter, tilted wedge plate, and the collimator. The tilted wedge plate is mounted adjustably with respect to the spatial filter and collimator, so that it can be maintained in an orientation in which it does not introduce significant wave front errors into the beam propagating through the reference arm. The apparatus is polarization insensitive and has an equal path length configuration enabling measurement of radiation from broadband as well as closely spaced laser line sources. 3 figures.

  20. Eight-chord CO/sub 2/ interferometer for plasma-density measurements on ZT-40

    SciTech Connect

    Jacobson, A.R.; Jolin, L.J.

    1981-01-01

    We describe a CO/sub 2/ laser interferometer which measures the path-integrated density along eight different chords simultaneously in the ZT-40 reversed-field pinch, a toroidal magnetic confinement experiment at Los Alamos. The interferometer system combines several reliable, commercially available components in a package which provides exceptional measurement resolution as well as ease of operation and maintenance.

  1. Analysis of a free oscillation atom interferometer

    SciTech Connect

    Kafle, Rudra P.; Zozulya, Alex A. [Department of Physics, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609 (United States); Anderson, Dana Z. [Department of Physics and JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)

    2011-09-15

    We analyze a Bose-Einstein condensate (BEC)-based free oscillation atom Michelson interferometer in a weakly confining harmonic magnetic trap. A BEC at the center of the trap is split into two harmonics by a laser standing wave. The harmonics move in opposite directions with equal speeds and turn back under the influence of the trapping potential at their classical turning points. The harmonics are allowed to pass through each other and a recombination pulse is applied when they overlap at the end of a cycle after they return for the second time. We derive an expression for the contrast of the interferometric fringes and obtain the fundamental limit of performance of the interferometer in the parameter space.

  2. Thermal-noise-limited underground interferometer CLIO

    NASA Astrophysics Data System (ADS)

    Agatsuma, Kazuhiro; Arai, Koji; Fujimoto, Masa-Katsu; Kawamura, Seiji; Kuroda, Kazuaki; Miyakawa, Osamu; Miyoki, Shinji; Ohashi, Masatake; Suzuki, Toshikazu; Takahashi, Ryutaro; Tatsumi, Daisuke; Telada, Souichi; Uchiyama, Takashi; Yamamoto, Kazuhiro; collaborators, CLIO

    2010-04-01

    We report on the current status of CLIO (Cryogenic Laser Interferometer Observatory), which is a prototype interferometer for LCGT (large scale cryogenic gravitational-wave telescope). LCGT is a Japanese next-generation interferometric gravitational-wave detector featuring the use of cryogenic mirrors and a quiet underground site. The main purpose of CLIO is to demonstrate a reduction of the mirror thermal noise by cooling the sapphire mirrors. CLIO is located in an underground site of the Kamioka mine, 1000 m deep from the mountain top, to verify its advantages. After a few years of commissioning work, we have achieved a thermal-noise-limited sensitivity at room temperature. One of the main results of noise hunting was the elimination of thermal noise caused by a conductive coil holder coupled with a pendulum through magnets.

  3. Erbium-doped fiber laser tuning using two cascaded unbalanced Mach-Zehnder interferometers as intracavity filter: numerical analysis and experimental confirmation

    Microsoft Academic Search

    Stéphane Calvez; X. Rejeaunier; P. Mollier; J.-P. Goedgebuer; W. T. Rhodes

    2001-01-01

    We propose a new method for tuning an Er3+-doped continuous-wave fiber-ring laser. We present a novel numerical model and confirm the model with experimental results. The numerical model relies on the implementation of the analytical solution of signal propagation over small (elemental) segments of amplifier fiber rather than using the usual Runge-Kutta algorithm. The validity of the model is verified

  4. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  5. Visible nulling interferometer

    NASA Technical Reports Server (NTRS)

    Shao, M.; Serabyn, E.; Martin, B. M.; Mennesson, B.; Velusamy, T.

    2002-01-01

    The direct detection of Earthlike planets in the visible is a very challenging goal. This paper describes a new concept for visible direct detection of Earths using a nulling interferometer instrument behind a 4m telescope in space. The basic concept is described along with the key advantages of the nulling interferometer over more traditional approaches, an apodized aperture telescope or coronagraph. In the baseline design, a 4 beam nuller produces a very deep theta^4 null. With perfect optics, the stellar leakage is less than le-11 of the starlight at the location of the planet. With diffraction limited (lambda/20) telescope optics suppression of the starlight to -1e-10 would be possible.

  6. Correlation interferometer geolocation

    Microsoft Academic Search

    Keith Struckman; Nashua NH

    2006-01-01

    Geolocation solutions based on the correlation interferometer geolocation (CIGL) equation depend on searching over (xi,y i) space and identifying the transmitter location as the (x,y) value that maximizes the correlation value. Under cross-polarized incident field conditions this correlation depends on both the array manifold calibration polarization and the targets transmission polarization. Computation of the transmitted polarization is accomplished by maximizing

  7. Noise reduction in an optical interferometer for picometer measurements

    Microsoft Academic Search

    Hiroyuki Fujimoto; M. Tanaka; K. Nakayama

    1995-01-01

    Picometer interferometry of moving objects is demonstrated experimentally over the frequency range 0 to 160 Hz. Active feedback is adopted to reduce the lowest frequency noise component due to coupling between geometrical fluctuations of the laser beam incident on the interferometer optics and imperfections in its optical elements. Passive measures to reduce the noise due to thermally induced changes of

  8. Nonlinear microwave spin wave interferometer

    Microsoft Academic Search

    A. B. Ustinov; B. A. Kalinikos

    2001-01-01

    The characteristics of a nonlinear microwave spin wave interferometer were experimentally studied for the first time. The\\u000a interferometer was implemented according to a bridge scheme with a nonlinear spin wave phase shifter based on an yttrium-iron\\u000a garnet film. The maximum sensitivity of the nonlinear interferometer with respect to the input signal level was reached with\\u000a a phase shifter operating on

  9. Optical analysis and alignment applications using the infrared Smartt interferometer

    SciTech Connect

    Viswanathan, V.K.; Bolen, P.D.; Liberman, I.; Seery, B.D.

    1981-01-01

    The possibility of using the infrared Smartt interferometer for optical analysis and alignment of infrared laser systems has been discussed previously. In this paper, optical analysis of the Gigawatt Test Facility at Los Alamos, as well as a deformable mirror manufactured by Rocketdyne, are discussed as examples of the technique. The possibility of optically characterizing, as well as aligning, pulsed high energy laser systems like Helios and Antares is discussed in some detail.

  10. Discrete Ordinate Quadrature Selection for Reactor-based Eigenvalue Problems

    SciTech Connect

    Jarrell, Joshua J [ORNL; Evans, Thomas M [ORNL; Davidson, Gregory G [ORNL

    2013-01-01

    In this paper we analyze the effect of various quadrature sets on the eigenvalues of several reactor-based problems, including a two-dimensional (2D) fuel pin, a 2D lattice of fuel pins, and a three-dimensional (3D) reactor core problem. While many quadrature sets have been applied to neutral particle discrete ordinate transport calculations, the Level Symmetric (LS) and the Gauss-Chebyshev product (GC) sets are the most widely used in production-level reactor simulations. Other quadrature sets, such as Quadruple Range (QR) sets, have been shown to be more accurate in shielding applications. In this paper, we compare the LS, GC, QR, and the recently developed linear-discontinuous finite element (LDFE) sets, as well as give a brief overview of other proposed quadrature sets. We show that, for a given number of angles, the QR sets are more accurate than the LS and GC in all types of reactor problems analyzed (2D and 3D). We also show that the LDFE sets are more accurate than the LS and GC sets for these problems. We conclude that, for problems where tens to hundreds of quadrature points (directions) per octant are appropriate, QR sets should regularly be used because they have similar integration properties as the LS and GC sets, have no noticeable impact on the speed of convergence of the solution when compared with other quadrature sets, and yield more accurate results. We note that, for very high-order scattering problems, the QR sets exactly integrate fewer angular flux moments over the unit sphere than the GC sets. The effects of those inexact integrations have yet to be analyzed. We also note that the LDFE sets only exactly integrate the zeroth and first angular flux moments. Pin power comparisons and analyses are not included in this paper and are left for future work.

  11. Discrete ordinate quadrature selection for reactor-based Eigenvalue problems

    SciTech Connect

    Jarrell, J. J.; Evans, T. M.; Davidson, G. G. [Oak Ridge National Laboratory, One Bethel Valley Rd., Oak Ridge, TN 37831 (United States)

    2013-07-01

    In this paper we analyze the effect of various quadrature sets on the eigenvalues of several reactor-based problems, including a two-dimensional (2D) fuel pin, a 2D lattice of fuel pins, and a three-dimensional (3D) reactor core problem. While many quadrature sets have been applied to neutral particle discrete ordinate transport calculations, the Level Symmetric (LS) and the Gauss-Chebyshev product (GC) sets are the most widely used in production-level reactor simulations. Other quadrature sets, such as Quadruple Range (QR) sets, have been shown to be more accurate in shielding applications. In this paper, we compare the LS, GC, QR, and the recently developed linear-discontinuous finite element (LDFE) sets, as well as give a brief overview of other proposed quadrature sets. We show that, for a given number of angles, the QR sets are more accurate than the LS and GC in all types of reactor problems analyzed (2D and 3D). We also show that the LDFE sets are more accurate than the LS and GC sets for these problems. We conclude that, for problems where tens to hundreds of quadrature points (directions) per octant are appropriate, QR sets should regularly be used because they have similar integration properties as the LS and GC sets, have no noticeable impact on the speed of convergence of the solution when compared with other quadrature sets, and yield more accurate results. We note that, for very high-order scattering problems, the QR sets exactly integrate fewer angular flux moments over the unit sphere than the GC sets. The effects of those inexact integrations have yet to be analyzed. We also note that the LDFE sets only exactly integrate the zeroth and first angular flux moments. Pin power comparisons and analyses are not included in this paper and are left for future work. (authors)

  12. The development of accurate and efficient methods of numerical quadrature

    NASA Technical Reports Server (NTRS)

    Feagin, T.

    1973-01-01

    Some new methods for performing numerical quadrature of an integrable function over a finite interval are described. Each method provides a sequence of approximations of increasing order to the value of the integral. Each approximation makes use of all previously computed values of the integrand. The points at which new values of the integrand are computed are selected in such a way that the order of the approximation is maximized. The methods are compared with the quadrature methods of Clenshaw and Curtis, Gauss, Patterson, and Romberg using several examples.

  13. Imaging Electron Interferometer

    NASA Astrophysics Data System (ADS)

    Leroy, B. J.; Bleszynski, A. C.; Aidala, K. E.; Westervelt, R. M.; Kalben, A.; Heller, E. J.; Shaw, S. E.; Maranowski, K. D.; Gossard, A. C.

    2005-04-01

    An imaging interferometer was created in a two-dimensional electron gas by reflecting electron waves emitted from a quantum point contact with a circular mirror. Images of electron flow obtained with a scanning probe microscope at liquid He temperatures show interference fringes when the mirror is energized. A quantum phase shifter was created by moving the mirror via its gate voltage, and an interferometric spectrometer can be formed by sweeping the tip over many wavelengths. Experiments and theory demonstrate that the interference signal is robust against thermal averaging.

  14. a Simple Heterodyne Temporal Speckle-Pattern Interferometer

    NASA Astrophysics Data System (ADS)

    Wong, W. O.; Gao, Z.; Lu, J.

    2010-05-01

    A common light path design of heterodyne speckle pattern interferometer based on temporal speckle pattern interferometry is proposed for non-contact, full-field and real-time continuous displacement measurement. Double frequency laser is produced by rotating a half wave plate. An experiment was carried out to measure the dynamic displacement of a cantilever plate for testing the proposed common path heterodyne speckle pattern interferometer. The accuracy of displacement measurement was checked by measuring the motion at the mid-point of the plate with a point displacement sensor.

  15. Noncontact photoacoustic imaging based on all-fiber heterodyne interferometer.

    PubMed

    Park, Seong Jun; Eom, Jonghyun; Kim, Yong Ho; Lee, Chang Su; Lee, Byeong Ha

    2014-08-15

    We report on a noncontact photoacoustic imaging system utilizing an all-fiber-optic heterodyne interferometer as an acoustic wave detector. The acoustic wave generated by a short laser pulse via the photoacoustic effect and arriving at the sample surface could be detected with the fiber-optic heterodyne interferometer without physical contact or using an impedance matching medium. A phantom experiment was conducted to evaluate the proposed system, and the initial acoustic pressure distribution was calculated using a Fourier-based reconstruction algorithm. It is expected that the all-fiber-optic configuration of the proposed system can be applied as a minimally invasive diagnostic tool. PMID:25121904

  16. Single-shot interferometer: Development and Testing

    E-print Network

    ;Interferometer Results · HeNe ­ Alignment ­ Visually observed interference pattern · Co2 ­ Golay cell ­ Interferometer ­ Detector Array ­ Reconstruction Algorithm · Hurdles ­ THz Optics ­ Alignment ­ THz transmission

  17. Discrete ordinates quadrature schemes for multidimensional radiative transfer

    Microsoft Academic Search

    R. Koch; W. Krebs; S. Wittig; R. Viskanta

    1995-01-01

    The fundamental problem of applying the method of discrete ordinates to radiative transfer predictions is the selection of the discrete directions and their associated weights. Both the accuracy of the solution and the computational effort depend on the angular discretization. This paper provides a sound mathematical methodology for the derivation of angular quadratures. By applying the collocation principle, the errors

  18. Thermodynamics of Quadrature Trajectories in Open Quantum Systems

    E-print Network

    James M. Hickey; Sam Genway; Igor Lesanovsky; Juan P. Garrahan

    2012-06-25

    We apply a large-deviation method to study the diffusive trajectories of the quadrature operators of light within a reservoir connected to dissipative quantum systems. We formulate the study of quadrature trajectories in terms of characteristic operators and show that in the long time limit the statistics of such trajectories obey a large-deviation principle. We take our motivation from homodyne detection schemes which allow the statistics of quadrature operator of the light field to be measured. We illustrate our approach with four examples of increasing complexity: a driven two-level system, a `blinking' three-level system, a pair of weakly-coupled two-level driven systems, and the micromaser. We discuss how quadrature operators can serve as alternative order parameters for the classification of dynamical phases, which is particularly useful in cases where the statistics of quantum jumps cannot distinguish between such phases. The formalism we introduce also allows us to analyse the properties of the light emitted by quantum jump trajectories which fluctuate far from the typical dynamics.

  19. An analytical formula for the design of quadrature mirror filters

    Microsoft Academic Search

    GIANCARLO PIRANI; VALERIO ZINGARELLI

    1984-01-01

    Quadrature mirror filters have an outstanding relevance in the implementation of filter banks for dividing the speech signal into frequency bands and for reconstructing it from these subbands. An analytical formula is given, which allows one to optimize the design of the basic low-pass FIR filter by means of a straight nonlinear minimization procedure.

  20. Digital computer simulation of satellite quadrature data communication systems

    Microsoft Academic Search

    M. C. Jeruchim

    1975-01-01

    This paper describes a Monte-Carlo simulation developed to predict the bit error rate (BER) for digital satellite communication links using quadrature signaling (QPSK or QAM). Primary emphasis is placed on modeling considerations. The model contains two nonlinear amplifiers and thermal noise, phase noise, and bit timing jitter. Provision is made to either insert arbitrary transfer functions or to specify the

  1. Archimedes Quadrature of the Parabola: A Mechanical View

    ERIC Educational Resources Information Center

    Oster, Thomas J.

    2006-01-01

    In his famous quadrature of the parabola, Archimedes found the area of the region bounded by a parabola and a chord. His method was to fill the region with infinitely many triangles each of whose area he could calculate. In his solution, he stated, without proof, three preliminary propositions about parabolas that were known in his time, but are…

  2. the bergman kernel and quadrature domains in the plane

    E-print Network

    1910-40-33

    will be that the Bergman kernel is a rational function of z and one other explicit ... to convert it to a quadrature domain. ... representative coordinates in a new and very interesting light. .... The power two in b + z2 is the only power larger than one that .... the form of a quotient of linear combinations of the Bergman kernel.

  3. QUADRATURE ON SIMPLICES OF ARBITRARY DIMENSION NOEL J. WALKINGTON y

    E-print Network

    on a simplex Sd #26; R d , and conjecture a general form for quadrature rules exact on polynomials of speci#12 in arbitrary dimension. When the parent element is a cube or simplex in R d it is relatively easy to generate dimensional simplex there appears to be a dearth of rules; for example, the most accurate scheme we found

  4. The discrete-time quadrature subsample estimation of delay

    Microsoft Academic Search

    Douglas L. Maskell; Graham S. Woods

    2002-01-01

    A high-resolution discrete-time delay estimator for determining the delay between two periodic signals is described. The technique is based upon the principles of analog quadrature detection and is relatively simple to implement digitally. Simulations in the presence of system noise show that the delay estimator does not exhibit any significant bias and outperforms other estimators in medium to high SNR

  5. Investigating the frequency-dependent amplification of a tapered amplifier in atom interferometers.

    PubMed

    Zhan, Su; Duan, Xiao-Chun; Zhou, Min-Kang; Yao, Hui-Bin; Xu, Wen-Jie; Hu, Zhong-Kun

    2015-01-01

    We present the investigation on the frequency-dependent amplification (FDA) of a tapered amplifier (TA) and the corresponding influence on Raman-type atom interferometers. In our interferometer, the output of two phase-locked diode lasers is injected into a TA to generate Raman beams. The frequency of one laser is chirped during the interfering process, which induces a variance of the Raman lasers power as a result of the FDA of the TA. The corresponding power ratio variation of the Raman lasers is measured by beat note method, which shows a linear dependence with a slope of -0.087(4)/GHz when the laser frequency changes over 2 GHz at 780 nm. The corresponding error related to AC Stark effect due to this frequency-dependent variation is estimated for our atom interferometer. The investigation presented here may provide hints for other experiments involving TAs. PMID:25531600

  6. Interferometer Studies Of Grain Burning Behavior In HMX Explosive

    NASA Astrophysics Data System (ADS)

    Benson, D. A.; Baer, M. R.

    1984-01-01

    A laser interferometer is used in experiments which probe the thermal initiation and burning of explosives on a microsecond time scale prior to detonation. In this work, small charges of HMX are confined by a piston in a steel chamber bore and thermally initiated with a foil on one surface of the chamber which is suddenly heated by a capacitor discharge. The burn process is observed through the motion of a piston which is driven by the gaseous combustion products. An air-delay leg VISAR velocity interferometer system is used to monitor the piston motion. This velocity data is directly processed to determine the chamber gas pressure as a function of volume during the piston expansion. High-pressure burn rates during deflagration can be deduced from these tests. Parasitic effects in small charge experiments due to thermal conduction from the walls, piston leakage, friction, as well as the interferometer resolution itself are discussed.

  7. Coherent detection of frequency-hopped quadrature modulations in the presence of jamming. II - QPR Class I modulation. [Quadrature Partial Response

    NASA Technical Reports Server (NTRS)

    Simon, M. K.

    1981-01-01

    This paper considers the performance of quadrature partial response (QPR) in the presence of jamming. Although a QPR system employs a single sample detector in its receiver, while quadrature amplitude shift keying (or quadrature phase shift keying) requires a matched-filter type of receiver, it is shown that the coherent detection performances of the two in the presence of the intentional jammer have definite similarities.

  8. Imaging Electron Interferometer

    NASA Astrophysics Data System (ADS)

    Bleszynski, A. C.; Aidala, K. E.; LeRoy, B. J.; Westervelt, R. M.; Heller, E. J.; Maranowski, K. D.; Gossard, A. C.

    2005-06-01

    An imaging electron interferometer was created in a two-dimensional electron gas (2DEG) using a liquid-He cooled scanning probe microscope (SPM). Electron waves emitted from a quantum point contact (QPC) return to the QPC along two paths: reflection from a concave mirror formed by a gate, and backscattering from the depleted disc underneath the charged SPM tip. Interference of these waves when they return to the QPC produces strong interference fringes in images of electron flow. A quantum phase shifter is formed by moving the mirror via its gate voltage — the fringes move a corresponding amount. The coherent fringes are robust to thermal averaging when the lengths of the two paths are within lT = ?vF/?kBT of each other.

  9. The Fizeau Interferometer Testbed

    NASA Technical Reports Server (NTRS)

    Zhang, Xiaolei; Carpenter, Kenneth G.; Lyon, Richard G,; Huet, Hubert; Marzouk, Joe; Solyar, Gregory

    2003-01-01

    The Fizeau Interferometer Testbed (FIT) is a collaborative effort between NASA's Goddard Space Flight Center, the Naval Research Laboratory, Sigma Space Corporation, and the University of Maryland. The testbed will be used to explore the principles of and the requirements for the full, as well as the pathfinder, Stellar Imager mission concept. It has a long term goal of demonstrating closed-loop control of a sparse array of numerous articulated mirrors to keep optical beams in phase and optimize interferometric synthesis imaging. In this paper we present the optical and data acquisition system design of the testbed, and discuss the wavefront sensing and control algorithms to be used. Currently we have completed the initial design and hardware procurement for the FIT. The assembly and testing of the Testbed will be underway at Goddard's Instrument Development Lab in the coming months.

  10. White light velocity interferometer

    DOEpatents

    Erskine, David J. (Oakland, CA)

    1997-01-01

    The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s.

  11. White light velocity interferometer

    DOEpatents

    Erskine, David J. (Oakland, CA)

    1999-01-01

    The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s.

  12. White light velocity interferometer

    DOEpatents

    Erskine, D.J.

    1997-06-24

    The invention is a technique that allows the use of broadband and incoherent illumination. Although denoted white light velocimetry, this principle can be applied to any wave phenomenon. For the first time, powerful, compact or inexpensive sources can be used for remote target velocimetry. These include flash and arc lamps, light from detonations, pulsed lasers, chirped frequency lasers, and lasers operating simultaneously in several wavelengths. The technique is demonstrated with white light from an incandescent source to measure a target moving at 16 m/s. 41 figs.

  13. Entanglement measurement of the quadrature components without homodyne detection in the bright, spatially multimode far field

    SciTech Connect

    Golubeva, T.; Golubev, Yu.; Samburskaya, K.; Fabre, C.; Treps, N.; Kolobov, M. [V. A. Fock Physics Institute, St. Petersburg State University, RU-198504 Stary Petershof, St. Petersburg (Russian Federation); Laboratoire Kastler Brossel, Universite Pierre et Marie Curie-Paris6, Place Jussieu, CC74, F-75252 Paris Cedex 05 (France); Laboratoire PhLAM, Universite de Lille 1, F-59655 Villeneuve d'Ascq Cedex (France)

    2010-01-15

    We present a procedure for the measurement of quadrature components of an electromagnetic field in the far field as an alternative to the traditional approach based on the homodyne detection (HD) technique. For that we suggest to use coherent sources such as phase-locked lasers or optical parametric oscillators operating above threshold. Then we show how to arrange the detection procedure in the far field that is exactly or partly equivalent to the HD. Our scheme can be applied for both the classical and nonclassical fields. The potential of the procedure is illustrated by an example which utilizes the pixellized sources of the nonclassical light. As an integral part of our investigation we develop a theory of the pixellized source of the spatiotemporally squeezed light.

  14. Interferometer-Controlled Optical Tweezers Constructed for Nanotechnology and Biotechnology

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2002-01-01

    A new method to control microparticles was developed in-house at the NASA Glenn Research Center in support of the nanotechnology project under NASA's Aerospace Propulsion and Power Base Research Program. A prototype interferometer-controlled optical tweezers was constructed to manipulate scanning probe microscope (SPM) tips. A laser beam passed through a Mach-Zehnder interferometer, and a microscope objective then produced an optical trap from the coaxial beams. The trap levitated and generated the coarse motion of a 10-mm polystyrene sphere used to simulate a SPM tip. The interference between the beams provided fine control of the forces and moments on the sphere. The interferometer included a piezoelectric-scanned mirror to modulate the interference pattern. The 10-mm sphere was observed to oscillate about 1 mm as the mirror and fringe pattern oscillated. The prototype tweezers proved the feasibility of constructing a more sophisticated interferometer tweezers to hold and manipulate SPM tips. The SPM tips are intended to interrogate and manipulate nanostructures. A more powerful laser will be used to generate multiple traps to hold nanostructures and SPM tips. The vibrating mirror in the interferometer will be replaced with a spatial light modulator. The modulator will allow the optical phase distribution in one leg of the interferometer to be programmed independently at 640 by 480 points for detailed control of the forces and moments. The interference patterns will be monitored to measure the motion of the SPM tips. Neuralnetwork technology will provide fast analysis of the interference patterns for diagnostic purposes and for local or remote feedback control of the tips. This effort also requires theoretical and modeling support in the form of scattering calculations for twin coherent beams from nonspherical particles.

  15. Dual interferometer system for measuring index of refraction

    NASA Astrophysics Data System (ADS)

    Goodwin, Eric Peter

    The optical power of a lens is determined by the surface curvature and the refractive index, n. Knowledge of the index is required for accurate lens design models and for examining material variations from sample to sample. The refractive index of glass can be accurately measured using a prism spectrometer, but measuring the index of soft contact lens materials presents many challenges. These materials are non-rigid, thin, and must remain hydrated in a saline solution during testing. Clearly an alternative to a prism spectrometer must be used to accurately measure index. A Dual Interferometer System has been designed, built and characterized as a novel method for measuring the refractive index of transparent optical materials, including soft contact lens materials. The first interferometer is a Low Coherence Interferometer in a Twyman-Green configuration with a scanning reference mirror. The contact lens material sample is placed in a measurement cuvette, where it remains hydrated. By measuring the locations of the multiple optical interfaces, the physical thickness t of the material is measured. A new algorithm has been developed for processing the low coherence signals obtained from the reflection at each optical interface. The second interferometer is a Mach-Zehnder interferometer with a tunable HeNe laser light source. This interferometer measures the optical path length (OPL) of the test sample in the cuvette in transmission as a function of five wavelengths in the visible spectrum. This is done using phase-shifting interferometry. Multiple thickness regions are used to solve 2pi phase ambiguities in the OPL. The outputs of the two interferometers are combined to determine the refractive index as a function of wavelength: n(lambda) = OPL(lambda)/t. Since both t and OPL are measured using a detector array, n is measured at hundreds of thousands of data points. A measurement accuracy of 0.0001 in refractive index is achieved with this new instrument, which is verified using custom glass calibration samples.

  16. Three-Dimensional Interferometer System

    NASA Astrophysics Data System (ADS)

    Pfeifer, T.; Waltar, Johann

    1990-04-01

    A new arrangement of interferometers allows to measure the movement of a retroreflector in space with high precision. Applications are the testing of the position accuracy of three dimensional coordinate machines, industrial mbots, tooling machines etc. This system uses four Michelson interferometers with deflector units, controlled by a servo system. For the position of the retro-reflector and the position of the deflector units are unknown at start-up, a at least ten point calibration cycle is necessary. A mathematical algorithm, using the signals of the four Michelson interferometers, allows to determine the position of the retroreflector and the deflector units in a given coordinate system.

  17. A synthetic heterodyne interferometer for small amplitude of vibration measurement.

    PubMed

    Kang, Seonggu; La, Jongpil; Yoon, Heesun; Park, Kyihwan

    2008-05-01

    The homodyne interferometer has the advantages of simple optical configuration and low cost. However, it requires a caution in using an electronic filter such as high pass filter (HPF) to get rid of low frequency electronic noises and the dc offset associated with the optical intensity in the photodiode electronic circuitry. When the vibration amplitude is smaller than at least 12 of the wavelength of He-Ne laser, a problem of incorrect velocity or distorted velocity measurement can be caused since a dc value of the interference signal is eliminated by using the HPF. To solve this problem of using the HPF in the homodyne interferometer, a synthetic interferometer using a mechanical modulation method is proposed in this work by exciting a reference mirror with the displacement larger than 12 of the wavelength. In this work, the analytical work is presented to show how the synthetic interferometer solves the problem of incorrect velocity measurement by using the Fourier-Bessel function description of the interference signals. Simulation and experimental works are also presented to validate the synthetic heterodyne interferometer proposed in this work. PMID:18513060

  18. Quantum Enhancement of the Zero-Area Sagnac Interferometer Topology for Gravitational Wave Detection

    NASA Astrophysics Data System (ADS)

    Eberle, Tobias; Steinlechner, Sebastian; Bauchrowitz, Jöran; Händchen, Vitus; Vahlbruch, Henning; Mehmet, Moritz; Müller-Ebhardt, Helge; Schnabel, Roman

    2010-06-01

    Only a few years ago, it was realized that the zero-area Sagnac interferometer topology is able to perform quantum nondemolition measurements of position changes of a mechanical oscillator. Here, we experimentally show that such an interferometer can also be efficiently enhanced by squeezed light. We achieved a nonclassical sensitivity improvement of up to 8.2 dB, limited by optical loss inside our interferometer. Measurements performed directly on our squeezed-light laser output revealed squeezing of 12.7 dB. We show that the sensitivity of a squeezed-light enhanced Sagnac interferometer can surpass the standard quantum limit for a broad spectrum of signal frequencies without the need for filter cavities as required for Michelson interferometers. The Sagnac topology is therefore a powerful option for future gravitational-wave detectors, such as the Einstein Telescope, whose design is currently being studied.

  19. Quantum enhancement of the zero-area Sagnac interferometer topology for gravitational wave detection.

    PubMed

    Eberle, Tobias; Steinlechner, Sebastian; Bauchrowitz, Jöran; Händchen, Vitus; Vahlbruch, Henning; Mehmet, Moritz; Müller-Ebhardt, Helge; Schnabel, Roman

    2010-06-25

    Only a few years ago, it was realized that the zero-area Sagnac interferometer topology is able to perform quantum nondemolition measurements of position changes of a mechanical oscillator. Here, we experimentally show that such an interferometer can also be efficiently enhanced by squeezed light. We achieved a nonclassical sensitivity improvement of up to 8.2 dB, limited by optical loss inside our interferometer. Measurements performed directly on our squeezed-light laser output revealed squeezing of 12.7 dB. We show that the sensitivity of a squeezed-light enhanced Sagnac interferometer can surpass the standard quantum limit for a broad spectrum of signal frequencies without the need for filter cavities as required for Michelson interferometers. The Sagnac topology is therefore a powerful option for future gravitational-wave detectors, such as the Einstein Telescope, whose design is currently being studied. PMID:20867358

  20. Proposed studies of a 30 meter imaging interferometer concept. [spaceborne astronomy

    NASA Technical Reports Server (NTRS)

    Stebbins, R. T.; Bender, P. L.; Faller, J. E.

    1987-01-01

    An imaging interferometer in space based on the use of 15 m sections of graphite-epoxy truss structure to form the basic mechanical support system is suggested. One simple design is a Y-shaped array of 3 coplanar arms, each 15 m long and 1.5 m in diameter, together with a perpendicualr mast of similar length. Roughly 15 observing telescopes of 0.5 m diameter would be used, with laser interferometers controlling the optical pathlengths. The total mass of the imaging interferometer is 3000 kg. With this design, the entire interferometer can be carried to orbit with a single STS launch and then deployed. The interferometer could be operated either in a fully illuminated Sun-synchronous orbit at 1400 km altitude or loosely attached to the Space Station.

  1. The aerospace imaging interferometer ALISEO: further improvements of calibration methods and assessment of interferometer response

    NASA Astrophysics Data System (ADS)

    Barducci, A.; Castagnoli, F.; Guzzi, D.; Marcoionni, P.; Pippi, I.

    2007-10-01

    ALISEO (Aerospace Leap-frog Imaging Stationary Interferometer for Earth Observation) belongs to the stationary interferometers representing a promising architecture for future Earth Observation (EO) sensors due to their simple optical layout. ALISEO has been selected by the Italian Space Agency as the principal payload for a new optical mission based on a micro-satellite (MIOsat). Payloads planned for MIOsat are an extensible telescope, a high-resolution panchromatic camera, a Mach-Zehnder MEMS interferometer, and ALISEO. MIOsat is expected to provide a platform with pointing capability for those advanced sensors. ALISEO operates in the common-path Sagnac configuration, and it does not employ any moving part to generate phase delay between the two rays. The sensor acquires the target images modulated by a pattern of autocorrelation functions: a fringe pattern that is fixed with respect to the instrument's field of view. The complete interferogram of each target location is retrieved introducing relative source-observer motion, which allows any image pixels to be observed under different phase delays. Recent laboratory measurements performed with ALISEO are described and discussed in this paper. In order to calibrate the optical path difference (OPD) of raw interferograms, a set of measurements have been carried out using a double planar diffuser system and several coloured He-Ne lasers. Standard reflectance tiles together doped with Holmium and Rare Earths have been used for validating the wavelength calibration of the instrument and proving the reliability of the reflectance retrieving procedure.

  2. Extraction of quadrature phase information from multiple pulse NMR signals

    NASA Technical Reports Server (NTRS)

    Rhim, W.-K.; Burum, D. P.; Vaughan, R. W.

    1976-01-01

    A multiple pulse sequence (8-pulse sequence) used for high-resolution solid state NMR is analyzed with regard to the information available from each of the four wide sampling windows. It is demonstrated that full quadrature phase information can be obtained using only a single phase detector and that, for the commonly encountered situation where the spectral width is much less than the folding frequency, the signals from the various windows can be combined easily using standard complex Fourier transform software. An improvement in the signal-to-noise ratio equal to the square root of 3 is obtained over either standard single or quadrature phase detection schemes. Procedures for correcting spectral distortions are presented.

  3. A novel image rejection architecture for quadrature radio receivers

    Microsoft Academic Search

    Mikko Valkama; Markku Renfors

    2004-01-01

    In radio communications, a bandpass-to-lowpass transformation is needed to demodulate the received signal down to baseband. One crucial question in this context is how to effectively attenuate the image band signal. For this purpose, inphase\\/quadrature (I\\/Q) signal processing is widely utilized in today's radio receivers. In this paper, a novel structure for obtaining an image-free baseband observation of the received

  4. A Chebyshev polynomial based quadrature for hypersingular integrals

    NASA Astrophysics Data System (ADS)

    Obaiys, Suzan J.; Eskhuvatov, Z. K.; Long, N. M. A. Nik

    2012-05-01

    This paper proposes an automatic quadrature scheme (AQS) for evaluating the hypersingular integrals with weight function w(t)=1 on the interval [0,1]. The density function f(x) is approximated by the shifted Chebyshev polynomials P*N(t) of the first kind of degree N. AQS for Cauchy principle value integrals on the interval [0,1] is also considered. Numerical examples are demonstrated in order to show that our developed approach can provide effective and reliable results.

  5. Gaussian quadrature rule for arbitrary weight function and interval

    NASA Astrophysics Data System (ADS)

    Fukuda, H.; Katuya, M.; Alt, E. O.; Matveenko, A. V.

    2005-04-01

    A program for calculating abscissas and weights of Gaussian quadrature rules for arbitrary weight functions and intervals is reported. The program is written in Mathematica. The only requirement is that the moments of the weight function can be evaluated analytically in Mathematica. The result is a FORTRAN subroutine ready to be utilized for quadrature. Program summaryTitle of program: AWGQ Catalogue identifier:ADVB Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVB Program obtained from: CPC Program Library, Queens University, Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: Computers: Pentium IV 1.7 GHz processor Installations: 512 MB RAM Operating systems or monitors under which the program has been tested: Windows XP Programming language used: Mathematica 4.0 No. of processors used: 1 Has the code been vectorized or parallelized?: No No. of lines in distributed program, including test data, etc.:1076 No. of bytes in distributed program, including test data, etc.: 32 681 Operating systems under which program has been tested: FORTRAN Distribution format: tar.gz Nature of physical problem: Integration of functions. Method of solution: The recurrence relations defining the orthogonal polynomials for arbitrary weight function and integration interval are written in matrix form. The abscissas and weights for the corresponding Gaussian quadrature are found from the solution of the eigenvalue equation for the tridiagonal symmetric Jacobi matrix. Restrictions on the complexity of the problem: The program is applicable if the moments of the weight function can be evaluated analytically in Mathematica. For our test example the degree of the Gaussian quadrature cannot not be larger than 96. Typical running time: The running time of the test run is about 1 [s] with a Pentium IV 1.7 GHz processor.

  6. Lasers

    Microsoft Academic Search

    Peter W. Milonni; Joseph H. Eberly

    1988-01-01

    Lasers A comprehensive introduction to the operating principles and applications of lasers. Explains basic principles, including the necessary elements of classical and quantum physics. Provides concise discussions of various laser types including gas, solid state, semiconductor, and free electron lasers, as well as of laser resonators, diffraction, optical coherence, and many applications including holography, phase conjugation, wave mixing, and nonlinear

  7. Differential heterodyne interferometer for measuring thickness of glass panels

    SciTech Connect

    Protopopov, Vladimir; Cho, Sunghoon; Kim, Kwangso; Lee, Sukwon; Kim, Hyuk [Samsung Electronics, Mechatronics Center, 416 Maetan-3Dong, Yeongtong-Gu, Suwon-City, Gyeonggi-Do 442-600 (Korea, Republic of)

    2007-07-15

    Differential heterodyne interferometer is applied for measuring spatial thickness variations across glass panels of liquid-crystal displays. This system uses the Zeeman laser as a source of two-frequency shifted orthogonally linearly polarized probe waves, passing through the glass in two spatially separated points. These waves are then recombined in a single beam to produce the intermediate frequency signal with the phase proportional to the thickness gradient of a glass sample. The phase of the intermediate signal is measured against the laser reference by means of a lock-in amplifier, and finally real-time integration provides the thickness variation. Since spatial separation of the probe beams is only 1.35 mm good approximation for the thickness gradient is achieved. Detailed design of the interferometer and experimental results on real samples are presented.

  8. Fast evaluation of quadrature formulae on the sphere

    NASA Astrophysics Data System (ADS)

    Keiner, Jens; Potts, Daniel

    2008-03-01

    Recently, a fast approximate algorithm for the evaluation of expansions in terms of standard mathrm{L}^2left(mathbb{S}^2right) -orthonormal spherical harmonics at arbitrary nodes on the sphere mathbb{S}^2 has been proposed in [S. Kunis and D. Potts. Fast spherical Fourier algorithms. JE Comput. Appl. Math., 161:75-98, 2003]. The aim of this paper is to develop a new fast algorithm for the adjoint problem which can be used to compute expansion coefficients from sampled data by means of quadrature rules. We give a formulation in matrix-vector notation and an explicit factorisation of the spherical Fourier matrix based on the former algorithm. Starting from this, we obtain the corresponding factorisation of the adjoint spherical Fourier matrix and are able to describe the associated algorithm for the adjoint transformation which can be employed to evaluate quadrature rules for arbitrary weights and nodes on the sphere. We provide results of numerical tests showing the stability of the obtained algorithm using as examples classical Gauss-Legendre and Clenshaw-Curtis quadrature rules as well as the HEALPix pixelation scheme and an equidistribution.

  9. Thin-plate spline quadrature of geodetic integrals

    NASA Technical Reports Server (NTRS)

    Vangysen, Herman

    1989-01-01

    Thin-plate spline functions (known for their flexibility and fidelity in representing experimental data) are especially well-suited for the numerical integration of geodetic integrals in the area where the integration is most sensitive to the data, i.e., in the immediate vicinity of the evaluation point. Spline quadrature rules are derived for the contribution of a circular innermost zone to Stoke's formula, to the formulae of Vening Meinesz, and to the recursively evaluated operator L(n) in the analytical continuation solution of Molodensky's problem. These rules are exact for interpolating thin-plate splines. In cases where the integration data are distributed irregularly, a system of linear equations needs to be solved for the quadrature coefficients. Formulae are given for the terms appearing in these equations. In case the data are regularly distributed, the coefficients may be determined once-and-for-all. Examples are given of some fixed-point rules. With such rules successive evaluation, within a circular disk, of the terms in Molodensky's series becomes relatively easy. The spline quadrature technique presented complements other techniques such as ring integration for intermediate integration zones.

  10. Vibration diagnosis and remediation design for an x-ray optics stitching interferometer system

    NASA Astrophysics Data System (ADS)

    Preissner, Curt A.; Assoufid, Lahsen; Shu, Deming

    2004-10-01

    The Advanced Photon Source (APS) x-ray optics Metrology Laboratory currently operates a small-aperture Wyko laser interferometer in a stitching configuration. While the stitching configuration allows for easier surface characterization of long x-ray substrates and mirrors, the addition of mechanical components for optic element translation can compromise the ultimate measurement performance of the interferometer. A program of experimental vibration measurements, quantifying the laboratory vibration environment and identifying interferometer support-system behavior, has been conducted. Insight gained from the ambient vibration assessment and modal analysis has guided the development of a remediation technique. Discussion of the problem diagnosis and possible solutions are presented in this paper.

  11. A twelve-channel multiple-interferometer fabry-perot spectrometer.

    PubMed

    Daehler, M

    1970-11-01

    A specialized spectrometer has been built to meet the time and spectral resolution requirements of a difficult plasma diagnosticexperiment. Two or three Fabry-Perot interferometers are arranged in series to provide the required spectral resolution and contrast.Twelve-channel output is produced by an annular mirror image dissector in the focal plane of the Fabry-Perot fringes. The spectralregion may be shifted by a change of gas pressure in the interferometer chambers. Measurements of the passband profiles with two interferometers are presented. Sample data from an experiment measuring the spectrum of ruby laser light after being scattered anddoppler broadened by a theta-pinch plasma are given. PMID:20094300

  12. Long-Term Stability of an Area-Reversible Atom-Interferometer Sagnac Gyroscope

    E-print Network

    D. S. Durfee; Y. K. Shaham; M. A. Kasevich

    2005-10-27

    We report on a study of the long-term stability and absolute accuracy of an atom interferometer gyroscope. This study included the implementation of an electro-optical technique to reverse the vector area of the interferometer for reduced systematics and a careful study of systematic phase shifts. Our data strongly suggests that drifts less than 96 $\\mu$deg/hr are possible after empirically removing shifts due to measured changes in temperature, laser intensity, and several other experimental parameters.

  13. 678 OPTICS LETTERS / Vol. 18, No. 9 / May 1, 1993 Spatially coherent white-light interferometer based on

    E-print Network

    source. Ultrashort-pulse lasers are thus natural candidates for this purpose. Optical correlation of femtosecond dye lasers, and the stability is much better. A schematic diagram ofthe interferometer is shown in Fig. 1. The light source is a 50-gm Rhodamine 590 dye jet pumped by a 4-W multiline argon-ion laser

  14. The Einstein polarization interferometer for cosmology (EPIC) and the millimeter-wave bolometric interferometer (MBI)

    E-print Network

    Timbie, Peter

    The Einstein polarization interferometer for cosmology (EPIC) and the millimeter-wave bolometric). Our study investigates the advantages and tradeoffs of using an interferometer (EPIC) for the mission

  15. Phase-modulation interferometer for ICF-target characterization

    SciTech Connect

    Cooper, D.E.

    1981-01-01

    Characterization requirements for high gain laser fusion targets are severe. We are required to detect defects on the surfaces of opaque and transparent shells with an amplitude resolution of +- 5 nm and a spatial resolution of 1 to 10 ..mu..m. To achieve this we have developed a laser-illuminated phase-modulation interferometer. This instrument is based on a photoelastic polarization modulation technique which allows one to convert phase information into an intensity modulation which can be easily and sensitively measured using ac signal processing techniques. This interferometer has detected path length changes as small as 1 nm and the required spatial resolution is assured by using a microscope objective to focus the probe laser beam down to a small (approx. 1 ..mu..m) spot on the surface of a microballoon. The interferometer will soon be coupled to an LSI-11 controlled 4..pi.. sphere manipulator which will allow us to automatically inspect the entire surface area of a target sphere.

  16. Improving the performances of current optical interferometers & future designs

    NASA Astrophysics Data System (ADS)

    Arnold, L.; Le Coroller, H.; Surdej, J.

    2014-04-01

    The number of astrophysical studies making use of interferometers has steadily increased during the past 15 years. Nevertheless, the performances of interferometers are still limited: their sensitivity does not exceed magnitude V=12, and their imaging capability could yet be improved by increasing the number of telescopes/sub-apertures. In the context of the ELTs, it is not certain how future interferometry projects will be financed. However, interferometry remains the only way to observe compact astrophysical objects at very high angular resolution (< milli-arcsecond), like gravitational micro-lensing events, central engines of AGNs, proto-planetary disks, exoplanets, etc. The aim of this workshop was to review and discuss the development of technologies that could improve the performances of current and future interferometers: new optical designs; techniques to improve the accuracy of measurements (visibility, closure-phase, etc.); progress on delay-line performances; solutions without delay-lines; technologies for larger apertures at lower cost (ex: lightweight replica mirrors); optimized beam combiners (integrated optic, pupil densifier, etc.); fringe tracking systems; laser telemetry applied to interferometry; heterodyne interferometry; progress in heterodyne detection using new technologies (laser comb, time propagation technologies, etc.); progress in image reconstruction techniques; progress in nulling interferometry; and important science cases that could benefit from progress in interferometry (report of observations at the limit of current interferometers). Nearly 50 oral presentations have been delivered, followed by very lively discussions which eventually emerged with the proposition to organize the "Planet Formation Interferometer/Imager" (PFI) project. The present proceedings reflect most of the highlights of this international colloquium.

  17. High-sensitivity laser plasma interferometry

    Microsoft Academic Search

    R. A. Akhmedzhanov; I. N. Polushkin; Y. V. Rostovtsev; A. I. Shcherbakov

    1986-01-01

    A new approach to interferometric measurements is proposed. Wide-band tunable lasers with organic-dye solutions as active media and with a Michelson interferometer are used. The plasma being studied is in one arm of the Michelson interferometer. The installation of a selective element in the laser resonator makes it possible to translate the spectral shifts of the interference fringes into changes

  18. Frequency stabilized 633 nm diode laser

    Microsoft Academic Search

    Janusz Pienkowski; Andrzej Grobelny

    2007-01-01

    Construction of a simple single-frequency diode laser 632.8 nm, used as a frequency standard in the laser interferometers is demonstrated. Two different systems applied for frequency stabilization of diode laser were used . For diode laser used as the secondary standard, the system stabilizes diode temperature, the frequency stability of the laser reaches value 1 part in 106. For diode

  19. Two-wavelength quadrature multipoint detection of partial discharge in power transformers using fiber Fabry-Perot acoustic sensors

    NASA Astrophysics Data System (ADS)

    Dong, Bo; Han, Ming; Wang, Anbo

    2012-06-01

    A reliable and low-cost two-wavelength quadrature interrogating method has been developed to demodulate optical signals from diaphragm-based Fabry-Perot interferometric fiber optic sensors for multipoint partial discharge detection in power transformers. Commercial available fused-silica parts (a wafer, a fiber ferrule, and a mating sleeve) and a cleaved optical single mode fiber were bonded together to form an extrinsic Fabry-Perot acoustic sensor. Two lasers with center wavelengths separated by a quarter of the period of sensor interference fringes were used to probe acousticwave- induced diaphragm vibration. A coarse wavelength-division multiplexing (CWDM) add/drop multiplexer was used to separate the reflected two wavelengths before two photo detectors. Optical couplers were used to distribute mixed laser light to each sensor-detector module for multiplexing purpose. Sensor structure, detection system design and experiment results are presented.

  20. Electronically Tunable Quadrature Oscillator Using Grounded Components with Current and Voltage Outputs

    PubMed Central

    2014-01-01

    The electronically tunable quadrature oscillator using a single multiple-output current controlled current differencing transconductance amplifier (MO-CCCDTA) and grounded passive components is presented. The proposed configuration uses a single MO-CCCDTA, two grounded capacitors and one grounded resistor. Two high-output impedance quadrature current signals and two quadrature voltage signals with 90° phase difference. The oscillation condition and oscillation frequency of the proposed quadrature oscillator are independently controllable. The use of only grounded passive components makes the proposed circuit ideal for integrated circuit implementation. PMID:25121124

  1. Automatic Alignment of Displacement-Measuring Interferometer

    NASA Technical Reports Server (NTRS)

    Halverson, Peter; Regehr, Martin; Spero, Robert; Alvarez-Salazar, Oscar; Loya, Frank; Logan, Jennifer

    2006-01-01

    A control system strives to maintain the correct alignment of a laser beam in an interferometer dedicated to measuring the displacement or distance between two fiducial corner-cube reflectors. The correct alignment of the laser beam is parallel to the line between the corner points of the corner-cube reflectors: Any deviation from parallelism changes the length of the optical path between the reflectors, thereby introducing a displacement or distance measurement error. On the basis of the geometrical optics of corner-cube reflectors, the length of the optical path can be shown to be L = L(sub 0)cos theta, where L(sub 0) is the distance between the corner points and theta is the misalignment angle. Therefore, the measurement error is given by DeltaL = L(sub 0)(cos theta - 1). In the usual case in which the misalignment is small, this error can be approximated as DeltaL approximately equal to -L(sub 0)theta sup 2/2. The control system (see figure) is implemented partly in hardware and partly in software. The control system includes three piezoelectric actuators for rapid, fine adjustment of the direction of the laser beam. The voltages applied to the piezoelectric actuators include components designed to scan the beam in a circular pattern so that the beam traces out a narrow cone (60 microradians wide in the initial application) about the direction in which it is nominally aimed. This scan is performed at a frequency (2.5 Hz in the initial application) well below the resonance frequency of any vibration of the interferometer. The laser beam makes a round trip to both corner-cube reflectors and then interferes with the launched beam. The interference is detected on a photodiode. The length of the optical path is measured by a heterodyne technique: A 100- kHz frequency shift between the launched beam and a reference beam imposes, on the detected signal, an interferometric phase shift proportional to the length of the optical path. A phase meter comprising analog filters and specialized digital circuitry converts the phase shift to an indication of displacement, generating a digital signal proportional to the path length.

  2. Sensitivity and noise analysis of 4 km laser interferometric gravitational wave antennae

    E-print Network

    Adhikari, Rana, 1974-

    2004-01-01

    Around the world, efforts are underway to commission several kilometer-scale laser interferometers to detect gravitational radiation. In the United States, there are two collocated interferometers in Hanford, Washington ...

  3. Parametric generation of quadrature squeezing of mirrors in cavity optomechanics

    SciTech Connect

    Liao, Jie-Qiao; Law, C. K. [Department of Physics and Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region (Hong Kong)

    2011-03-15

    We propose a method to generate quadrature-squeezed states of a moving mirror in a Fabry-Perot cavity. This is achieved by exploiting the fact that when the cavity is driven by an external field with a large detuning, the moving mirror behaves as a parametric oscillator. We show that parametric resonance can be reached approximately by modulating the driving field amplitude at a frequency matching the frequency shift of the mirror. The parametric resonance leads to an efficient generation of squeezing, which is limited by the thermal noise of the environment.

  4. Generating quadrature squeezed light with dissipative optomechanical coupling

    NASA Astrophysics Data System (ADS)

    Qu, Kenan; Agarwal, G. S.

    2015-06-01

    The recent demonstration of cooling of a macroscopic silicon nitride membrane based on dissipative coupling makes dissipatively coupled optomechanical systems promising candidates for squeezing. We theoretically show that such a system in a cavity on resonance can yield good squeezing, which is comparable to that produced by dispersive coupling. We also report the squeezing resulting from the combined effects of dispersive and dissipative couplings; thus the device can be operated in one regime or the other. We derive the maximal frequency and quadrature angles needed to observe squeezing for given optomechanical coupling strengths. We also discuss the effects of temperature on squeezing.

  5. Quadrature-dependent Bogoliubov transformations and multiphoton squeezed states

    Microsoft Academic Search

    Silvio De Siena; Antonio Di Lisi; Fabrizio Illuminati

    2001-01-01

    We introduce a linear, canonical transformation of the fundamental\\u000asingle--mode field operators $a$ and $a^{\\\\dagger}$ that generalizes the linear\\u000aBogoliubov transformation familiar in the construction of the harmonic\\u000aoscillator squeezed states. This generalization is obtained by adding to the\\u000alinear transformation a nonlinear function of any of the fundamental quadrature\\u000aoperators $X_{1}$ and $X_{2}$, making the original Bogoliubov transformation\\u000aquadrature--dependent.

  6. Noise-cancelling quadrature magnetic position, speed and direction sensor

    DOEpatents

    Preston, Mark A. (Niskayuna, NY); King, Robert D. (Schenectady, NY)

    1996-01-01

    An array of three magnetic sensors in a single package is employed with a single bias magnet for sensing shaft position, speed and direction of a motor in a high magnetic noise environment. Two of the three magnetic sensors are situated in an anti-phase relationship (i.e., 180.degree. out-of-phase) with respect to the relationship between the other of the two sensors and magnetically salient target, and the third magnetic sensor is situated between the anti-phase sensors. The result is quadrature sensing with noise immunity for accurate relative position, speed and direction measurements.

  7. Design of a dual species atom interferometer for space

    NASA Astrophysics Data System (ADS)

    Schuldt, Thilo; Schubert, Christian; Krutzik, Markus; Bote, Lluis Gesa; Gaaloul, Naceur; Hartwig, Jonas; Ahlers, Holger; Herr, Waldemar; Posso-Trujillo, Katerine; Rudolph, Jan; Seidel, Stephan; Wendrich, Thijs; Ertmer, Wolfgang; Herrmann, Sven; Kubelka-Lange, André; Milke, Alexander; Rievers, Benny; Rocco, Emanuele; Hinton, Andrew; Bongs, Kai; Oswald, Markus; Franz, Matthias; Hauth, Matthias; Peters, Achim; Bawamia, Ahmad; Wicht, Andreas; Battelier, Baptiste; Bertoldi, Andrea; Bouyer, Philippe; Landragin, Arnaud; Massonnet, Didier; Lévèque, Thomas; Wenzlawski, Andre; Hellmig, Ortwin; Windpassinger, Patrick; Sengstock, Klaus; von Klitzing, Wolf; Chaloner, Chris; Summers, David; Ireland, Philip; Mateos, Ignacio; Sopuerta, Carlos F.; Sorrentino, Fiodor; Tino, Guglielmo M.; Williams, Michael; Trenkel, Christian; Gerardi, Domenico; Chwalla, Michael; Burkhardt, Johannes; Johann, Ulrich; Heske, Astrid; Wille, Eric; Gehler, Martin; Cacciapuoti, Luigi; Gürlebeck, Norman; Braxmaier, Claus; Rasel, Ernst

    2015-06-01

    Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species 85Rb/87Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for 10-11 mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (814 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.

  8. Design of a dual species atom interferometer for space

    NASA Astrophysics Data System (ADS)

    Schuldt, Thilo; Schubert, Christian; Krutzik, Markus; Bote, Lluis Gesa; Gaaloul, Naceur; Hartwig, Jonas; Ahlers, Holger; Herr, Waldemar; Posso-Trujillo, Katerine; Rudolph, Jan; Seidel, Stephan; Wendrich, Thijs; Ertmer, Wolfgang; Herrmann, Sven; Kubelka-Lange, André; Milke, Alexander; Rievers, Benny; Rocco, Emanuele; Hinton, Andrew; Bongs, Kai; Oswald, Markus; Franz, Matthias; Hauth, Matthias; Peters, Achim; Bawamia, Ahmad; Wicht, Andreas; Battelier, Baptiste; Bertoldi, Andrea; Bouyer, Philippe; Landragin, Arnaud; Massonnet, Didier; Lévèque, Thomas; Wenzlawski, Andre; Hellmig, Ortwin; Windpassinger, Patrick; Sengstock, Klaus; von Klitzing, Wolf; Chaloner, Chris; Summers, David; Ireland, Philip; Mateos, Ignacio; Sopuerta, Carlos F.; Sorrentino, Fiodor; Tino, Guglielmo M.; Williams, Michael; Trenkel, Christian; Gerardi, Domenico; Chwalla, Michael; Burkhardt, Johannes; Johann, Ulrich; Heske, Astrid; Wille, Eric; Gehler, Martin; Cacciapuoti, Luigi; Gürlebeck, Norman; Braxmaier, Claus; Rasel, Ernst

    2015-03-01

    Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species 85Rb/87Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for 10-11 mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (814 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.

  9. Design of a dual species atom interferometer for space

    E-print Network

    Thilo Schuldt; Christian Schubert; Markus Krutzik; Lluis Gesa Bote; Naceur Gaaloul; Jonas Hartwig; Holger Ahlers; Waldemar Herr; Katerine Posso-Trujillo; Jan Rudolph; Stephan Seidel; Thijs Wendrich; Wolfgang Ertmer; Sven Herrmann; André Kubelka-Lange; Alexander Milke; Benny Rievers; Emanuele Rocco; Andrew Hinton; Kai Bongs; Markus Oswald; Matthias Franz; Matthias Hauth; Achim Peters; Ahmad Bawamia; Andreas Wicht; Baptiste Battelier; Andrea Bertoldi; Philippe Bouyer; Arnaud Landragin; Didier Massonnet; Thomas Lévèque; Andre Wenzlawski; Ortwin Hellmig; Patrick Windpassinger; Klaus Sengstock; Wolf von Klitzing; Chris Chaloner; David Summers; Philip Ireland; Ignacio Mateos; Carlos F. Sopuerta; Fiodor Sorrentino; Guglielmo M. Tino; Michael Williams; Christian Trenkel; Domenico Gerardi; Michael Chwalla; Johannes Burkhardt; Ulrich Johann; Astrid Heske; Eric Wille; Martin Gehler; Luigi Cacciapuoti; Norman Gürlebeck; Claus Braxmaier; Ernst Rasel

    2014-12-08

    Atom interferometers have a multitude of proposed applications in space including precise measurements of the Earth's gravitational field, in navigation & ranging, and in fundamental physics such as tests of the weak equivalence principle (WEP) and gravitational wave detection. While atom interferometers are realized routinely in ground-based laboratories, current efforts aim at the development of a space compatible design optimized with respect to dimensions, weight, power consumption, mechanical robustness and radiation hardness. In this paper, we present a design of a high-sensitivity differential dual species $^{85}$Rb/$^{87}$Rb atom interferometer for space, including physics package, laser system, electronics and software. The physics package comprises the atom source consisting of dispensers and a 2D magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein condensate (BEC) creation and interferometry, the detection unit, the vacuum system for $10^{-11}$ mbar ultra-high vacuum generation, and the high-suppression factor magnetic shielding as well as the thermal control system. The laser system is based on a hybrid approach using fiber-based telecom components and high-power laser diode technology and includes all laser sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and switching of the laser beams is carried out on an optical bench using Zerodur bonding technology. The instrument consists of 9 units with an overall mass of 221 kg, an average power consumption of 608 W (819 W peak), and a volume of 470 liters which would well fit on a satellite to be launched with a Soyuz rocket, as system studies have shown.

  10. Microwave interferometer controls cutting depth of plastics

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.

    1969-01-01

    Microwave interferometer system controls the cutting of plastic materials to a prescribed depth. The interferometer is mounted on a carriage with a spindle and cutting tool. A cross slide, mounted on the carriage, allows the interferometer and cutter to move toward or away from the plastic workpiece.

  11. Slow wave atom interferometers for rotation sensing

    Microsoft Academic Search

    Meriç Özcan

    2007-01-01

    A gyroscope based on Sagnac interferometer measures the rotation rate relative to an inertial frame of reference. Sagnac effect originally has been derived and experimentally demonstrated with optical waves. Later, matter wave based Sagnac interferometers were developed due to inherent sensitivity over a photon based system. However in any interferometer whether it is photon or matter wave based the resultant

  12. Tunable semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

    2006-01-01

    Tunable semiconductor lasers are disclosed requiring minimized coupling regions. Multiple laser embodiments employ ring resonators or ring resonator pairs using only a single coupling region with the gain medium are detailed. Tuning can be performed by changing the phase of the coupling coefficient between the gain medium and a ring resonator of the laser. Another embodiment provides a tunable laser including two Mach-Zehnder interferometers in series and a reflector coupled to a gain medium.

  13. An interferometer tracking radar system

    NASA Technical Reports Server (NTRS)

    Broderick, R. F.

    1969-01-01

    Fine tuning acquisition and tracking interferometer radar system uses a first antenna array of at least three receiving antennas. Array includes a reference antenna, a coarse tuning antenna, and a fine tuning antenna aligned on a receiving axis. Short range rendezvous system provides increased position accuracy.

  14. Holographic Twyman-Green interferometer

    NASA Technical Reports Server (NTRS)

    Chen, C. W.; Breckinridge, J. B.

    1982-01-01

    A dichromated gelatin off-axis Fresnel zone plate was designed, fabricated, and used in a new type of interferometer for optical metrology. This single hologram optical element combines the functions of a beam splitter, beam diverger, and aberrated null lens. Data presented show the successful application for an interferometric test of an f/6, 200-mm diam parabolic mirror.

  15. Lasers

    SciTech Connect

    Eberly, J.H.; Milonni, P.W.

    1988-01-01

    This book explains the operating principles and applications of lasers, including central background material. It incorporates many intuitive explanations and practical examples. Introduces basic principles, including the necessary classical and quantum physics, and provides discussions of specific lasers, laser resonators, and applications, including nonlinear optics.

  16. Electromechanical analysis of electrostatic nano-actuators using the differential quadrature method

    Microsoft Academic Search

    Ming-Hung Hsu

    2007-01-01

    SUMMARY The nonlinear analysis of nanoelectromechanical systems using the differential quadrature model is investigated. The differential quadrature method is applied to overcome the difficulty of determining the nonlinear equation of motion. The characteristics of various combinations of curved electrodes and cantilever beams are considered to optimize the design. Various nano-actuators, such as the cantilever beam actuator, are derived and simulated

  17. Application of real zero concept to coherent detector for quadrature amplitude modulation

    Microsoft Academic Search

    Hiroki Ishibashi; Hiroshi Suzuki; Kazuhiko Fukawa; Satoshi Suyama

    2010-01-01

    This paper proposes a new coherent detector that exploits the real zero (RZ) concept for signal recovery. The detector recovers the complex envelope consisting of in-phase (I) and quadrature (Q) components of linear quadrature amplitude modulation (QAM). The received signal before amplification is processed by RZ conversion, after which the converted signal can be amplified by a severely distorted amplifier.

  18. The Nature of the Nodes, Weights and Degree of Precision in Gaussian Quadrature Rules

    ERIC Educational Resources Information Center

    Prentice, J. S. C.

    2011-01-01

    We present a comprehensive proof of the theorem that relates the weights and nodes of a Gaussian quadrature rule to its degree of precision. This level of detail is often absent in modern texts on numerical analysis. We show that the degree of precision is maximal, and that the approximation error in Gaussian quadrature is minimal, in a…

  19. Direct quadrature phase shift keying modulator using six-port technology

    E-print Network

    Frigon, Jean-François

    for microwave measurements [1] and direct conversion receivers of quadrature phase shift keying (QPSK) signals heterodyne architecture, which requires IF mixers, in-phase and quadrature carriers and an RF upconversion section. Compared with a heterodyne modulator, this direct QPSK modulator eliminates the need

  20. A 100 MHz MEMS SiBAR Phase Modulator for Quadrature Phase Shift Keying

    E-print Network

    Ayazi, Farrokh

    A 100 MHz MEMS SiBAR Phase Modulator for Quadrature Phase Shift Keying Logan Sorenson and Farrokh of a MEMS resonator to form the basic component of a switchless quadrature phase shift keying (QPSK) scheme. INTRODUCTION In recent years, microelectromechanical systems (MEMS)- based solutions have gained acceptance

  1. A Fiber Interferometer for the Magnetized Shock Experiment

    NASA Astrophysics Data System (ADS)

    Yoo, C. B.; Gao, K. W.; Weber, T. E.; Intrator, T. P.

    2012-10-01

    The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory requires remote diagnostics of plasma density. Laser interferometry can be used to determine the line-integrated density of the plasma. A multi-chord heterodyne fiber optic Mach-Zehnder interferometer is being assembled and integrated into the experiment. The advantage of the fiber coupling is that many different view chords can be easily obtained by simply moving transmit and receive fiber couplers. Several such fiber sets will be implemented to provide a time history of line-averaged density for several chords at once. The multiple chord data can then be Abel inverted to provide radially resolved spatial profiles of density. We describe the design and execution of this multiple fiber interferometer.

  2. A Fiber Interferometer for the Magnetized Shock Experiment

    SciTech Connect

    Yoo, Christian [Los Alamos National Laboratory

    2012-08-30

    The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory requires remote diagnostics of plasma density. Laser interferometry can be used to determine the line-integrated density of the plasma. A multi-chord heterodyne fiber optic Mach-Zehnder interferometer is being assembled and integrated into the experiment. The advantage of the fiber coupling is that many different view chords can be easily obtained by simply moving transmit and receive fiber couplers. Several such fiber sets will be implemented to provide a time history of line-averaged density for several chords at once. The multiple chord data can then be Abel inverted to provide radially resolved spatial profiles of density. We describe the design and execution of this multiple fiber interferometer.

  3. Standing waves in fiber-optic interferometers.

    PubMed

    de Haan, V; Santbergen, R; Tijssen, M; Zeman, M

    2011-10-10

    A study is presented giving the response of three types of fiber-optic interferometers by which a standing wave through an object is investigated. The three types are a Sagnac, Mach-Zehnder and Michelson-Morley interferometer. The response of the Mach-Zehnder interferometer is similar to the Sagnac interferometer. However, the Sagnac interferometer is much harder to study because of the fact that one input port and output port coincide. Further, the Mach-Zehnder interferometer has the advantage that the output ports are symmetric, reducing the systematic effects. Examples of standing wave light absorption in several simple objects are given. Attention is drawn to the influence of standing waves in fiber-optic interferometers with weak-absorbing layers incorporated. A method is described for how these can be theoretically analyzed and experimentally measured. Further experiments are needed for a thorough comparison between theory and experiment. PMID:22015361

  4. Tracking frequency laser distance gauge

    Microsoft Academic Search

    J. D. Phillips; R. D. Reasenberg

    2005-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require laser distance gauges of substantially improved performance. We describe a laser gauge, based on Pound–Drever–Hall locking, in which the optical frequency is adjusted to maintain an interferometer’s null condition. This technique has been demonstrated with pm performance. Automatic fringe hopping allows it to track arbitrary

  5. Astrophysical Adaptation of Points, the Precision Optical Interferometer in Space

    NASA Technical Reports Server (NTRS)

    Reasenberg, Robert D.; Babcock, Robert W.; Murison, Marc A.; Noecker, M. Charles; Phillips, James D.; Schumaker, Bonny L.; Ulvestad, James S.; McKinley, William; Zielinski, Robert J.; Lillie, Charles F.

    1996-01-01

    POINTS (Precision Optical INTerferometer in Space) would perform microarcsecond optical astrometric measurements from space, yielding submicroarcsecond astrometric results from the mission. It comprises a pair of independent Michelson stellar interferometers and a laser metrology system that measures both the critical starlight paths and the angle between the baselines. The instrument has two baselines of 2 m, each with two subapertures of 35 cm; by articulating the angle between the baselines, it observes targets separated by 87 to 93 deg. POINTS does global astrometry, i.e., it measures widely separated targets, which yields closure calibration, numerous bright reference stars, and absolute parallax. Simplicity, stability, and the mitigation of systematic error are the central design themes. The instrument has only three moving-part mechanisms, and only one of these must move with sub-milliradian precision; the other two can tolerate a precision of several tenths of a degree. Optical surfaces preceding the beamsplitter or its fold flat are interferometrically critical; on each side of the interferometer, there are only three such. Thus, light loss and wavefront distortion are minimized. POINTS represents a minimalistic design developed ab initio for space. Since it is intended for astrometry, and therefore does not require the u-v-plane coverage of an imaging, instrument, each interferometer need have only two subapertures. The design relies on articulation of the angle between the interferometers and body pointing to select targets; the observations are restricted to the 'instrument plane.' That plane, which is fixed in the pointed instrument, is defined by the sensitive direction for the two interferometers. Thus, there is no need for siderostats and moving delay lines, which would have added many precision mechanisms with rolling and sliding parts that would be required to function throughout the mission. Further, there is no need for a third interferometer, as is required when out-of-plane observations are made. An instrument for astrometry, unlike those for imaging, can be compact and yet scientifically productive. The POINTS instrument is compact and therefore requires no deployment of precision structures, has no low-frequency (i.e., under 100 Hz) vibration modes, and is relatively easy to control thermally. Because of its small size and mass, it is easily and quickly repointed between observations. Further, because of the low mass, it can be economically launched into high Earth orbit which, in conjunction with a solar shield, yields nearly unrestricted sky coverage and a stable thermal environment.

  6. The TEXT upgrade vertical interferometer

    SciTech Connect

    Hallock, G.A.; Gartman, M.L.; Li, W.; Chiang, K.; Shin, S.; Castles, R.L.; Chatterjee, R.; Rahman, A.S. (The University of Texas at Austin, Austin, Texas 78712 (United States))

    1992-10-01

    A far-infrared interferometer has been installed on TEXT upgrade to obtain electron density profiles. The primary system views the plasma vertically through a set of large (60-cm radial{times}7.62-cm toroidal) diagnostic ports. A 1-cm channel spacing (59 channels total) and fast electronic time response is used, to provide high resolution for radial profiles and perturbation experiments. Initial operation of the vertical system was obtained late in 1991, with six operating channels.

  7. Configurations of a new atomic interferometer for gravitational wave detection

    E-print Network

    Biao Tang; Baocheng Zhang; Lin Zhou; Jin Wang; Mingsheng Zhan

    2013-12-30

    Recently, the configuration using atomic interferometers (AIs) had been suggested for the detection of gravitational waves. A new AI with some additional laser pulses for implementing large momentum transfer was also put forward, in order to improve the influence of shot noise and laser frequency noise. In the paper, we use the sensitivity function to analyze all possible configurations of the new AI and to distinguish how many momenta are transferred in a specific configuration. With the analysis for the new configuration, we explore the detection scheme of gravitational wave further, in particular, for the amelioration of the laser frequency noise. We find that the amelioration is definite in such scheme, but novelly, in some cases the frequency noise can be canceled completely by using a proper data processing method.

  8. Configurations of a new atomic interferometer for gravitational wave detection

    E-print Network

    Tang, Biao; Zhou, Lin; Wang, Jin; Zhan, Mingsheng

    2013-01-01

    Recently, the configuration using atomic interferometers (AIs) had been suggested for the detection of gravitational waves. A new AI with some additional laser pulses for implementing large momentum transfer was also put forward, in order to improve the influence of shot noise and laser frequency noise. In the paper, we use the sensitivity function to analyze all possible configurations of the new AI and to distinguish how many momenta are transferred in a specific configuration. With the analysis for the new configuration, we explore the detection scheme of gravitational wave further, in particular, for the amelioration of the laser frequency noise. We find that the amelioration is definite in such scheme, but novelly, in some cases the frequency noise can be canceled completely by using a proper data processing method.

  9. An integrated source of broadband quadrature squeezed light

    E-print Network

    Hoff, Ulrich B; Andersen, Ulrik L

    2015-01-01

    An integrated silicon nitride resonator is proposed as an ultra-compact source of bright single-mode quadrature squeezed light at 850 nm. Optical properties of the device are investigated and tailored through numerical simulations, with particular attention paid to loss associated with interfacing the device. An asymmetric double layer stack waveguide geometry with inverse vertical tapers is proposed for efficient and robust fibre-chip coupling, yielding a simulated total loss of -0.75 dB/facet. We assess the feasibility of the device through a full quantum noise analysis and derive the output squeezing spectrum for intra-cavity pump self-phase modulation. Subject to standard material loss and detection efficiencies, we find that the device holds promises for generating substantial quantum noise squeezing over a bandwidth exceeding 1 GHz. In the low-propagation loss regime, approximately -7 dB squeezing is predicted for a pump power of only 50 mW.

  10. Quantum circuits for amplification of Kerr nonlinearity via quadrature squeezing

    E-print Network

    Monika Bartkowiak; Lian-Ao Wu; Adam Miranowicz

    2014-07-07

    Phase shifts induced by the Kerr effect are usually very small at the single-photon level. We propose two circuits for enhancing the cross-Kerr phase shift by applying one- and two-mode quadrature squeezing operators. Our results are based on the vector coherent state theory and can be implemented by physical operations satisfying the commutation relations for generators of the generalized special unitary group SU(1,1). While the proposed methods could be useful for the realization of quantum optical entangling gates based on Kerr nonlinear media at the single-photon level, they also indicate a general alternative approach to enhance higher-order nonlinearities by applying lower-order nonlinear effects.

  11. Residual Distribution Schemes for Conservation Laws Via Adaptive Quadrature

    NASA Technical Reports Server (NTRS)

    Barth, Timothy; Abgrall, Remi; Biegel, Bryan (Technical Monitor)

    2000-01-01

    This paper considers a family of nonconservative numerical discretizations for conservation laws which retains the correct weak solution behavior in the limit of mesh refinement whenever sufficient order numerical quadrature is used. Our analysis of 2-D discretizations in nonconservative form follows the 1-D analysis of Hou and Le Floch. For a specific family of nonconservative discretizations, it is shown under mild assumptions that the error arising from non-conservation is strictly smaller than the discretization error in the scheme. In the limit of mesh refinement under the same assumptions, solutions are shown to satisfy an entropy inequality. Using results from this analysis, a variant of the "N" (Narrow) residual distribution scheme of van der Weide and Deconinck is developed for first-order systems of conservation laws. The modified form of the N-scheme supplants the usual exact single-state mean-value linearization of flux divergence, typically used for the Euler equations of gasdynamics, by an equivalent integral form on simplex interiors. This integral form is then numerically approximated using an adaptive quadrature procedure. This renders the scheme nonconservative in the sense described earlier so that correct weak solutions are still obtained in the limit of mesh refinement. Consequently, we then show that the modified form of the N-scheme can be easily applied to general (non-simplicial) element shapes and general systems of first-order conservation laws equipped with an entropy inequality where exact mean-value linearization of the flux divergence is not readily obtained, e.g. magnetohydrodynamics, the Euler equations with certain forms of chemistry, etc. Numerical examples of subsonic, transonic and supersonic flows containing discontinuities together with multi-level mesh refinement are provided to verify the analysis.

  12. Integrating single-point vibrometer and full-field electronic speckle pattern interferometer to evaluate a micro-speaker

    Microsoft Academic Search

    Wen-Chi Chang; Yu-Chi Chen; Chih-Jen Chien; An-Bang Wang; Chih-Kung Lee

    2011-01-01

    A testing system contains an advanced vibrometer\\/interferometer device (AVID) and a high-speed electronic speckle pattern interferometer (ESPI) was developed. AVID is a laser Doppler vibrometer that can be used to detect single-point linear and angular velocity with DC to 20 MHz bandwidth and with nanometer resolution. In swept frequency mode, frequency response from mHz to MHz of the structure of

  13. Real-time and high-resolution absolute-distance measurement using a two-wavelength superheterodyne interferometer

    Microsoft Academic Search

    Shuko Yokoyama; Jun Ohnishi; Shigeo Iwasaki; Katuo Seta; Hirokazu Matsumoto; Norihito Suzuki

    1999-01-01

    We present here a new method for real-time absolute-distance measurement. It is based on a two-wavelength superheterodyne interferometer. It is performed by simultaneous measurement of its synthetic wavelength and one of two wavelengths. The phase of one of two wavelengths is electrically separated from the synthetic one, thus maintaining the resolution of a one-wavelength heterodyne interferometer. Two He-Ne lasers operating

  14. Optical zooming interferometer for subnanometer positioning using an optical frequency comb

    SciTech Connect

    Kajima, Mariko; Minoshima, Kaoru

    2010-10-20

    A high-precision positioning stage based on an optical zooming interferometer is proposed. Two external-cavity diode lasers, stabilized to a femtosecond optical frequency comb, are used as optical sources. The zooming principle is demonstrated, and the positioning resolution of 0.2 nm is achieved. The positioning accuracy was partly evaluated.

  15. Simple Ultra-Low-Cost Undergraduate Holography Using a Modified Michelson Interferometer.

    ERIC Educational Resources Information Center

    Rudmin, J. W.; And Others

    1980-01-01

    A technique is presented for producing holograms using equipment which is already in the possesion of the majority of college physics departments, which includes a slightly modified Michelson interferometer, a helium-neon laser, and a long focal-length lens. Production of high quality holograms has been achieved by inexperienced undergraduates…

  16. New configurations for the rotating shear-plate interferometer, a.k.a. shear madness

    Microsoft Academic Search

    William C. Sweatt; Richard N. Shagam

    1993-01-01

    We present two new devices that contain a lateral shear-plate interferometer, held in a mount that can be rotated about the centerline of the incident laser beam. This configuration ensures constant shear while allowing the shear orientation to be varied. One of these new systems relays the sheared image to a fixed video, 35 mm film, or other camera. With

  17. In-line interferometer for direction-sensitive displacement measurements by optical feedback detection

    Microsoft Academic Search

    Alvarado Tarun; Julius Jecong; Caesar Saloma

    2005-01-01

    We demonstrate a compact in-line interferometer for direction-sensitive displacement measurement by optical feedback detection with a semiconductor laser (SL) light source. Two reflected beams from a semitransparent reference mirror and a reflecting test object interfere in the SL medium, causing a variation in its output power. The reference mirror is located between the SL output facet and the test object.

  18. Nonlocal polarization interferometer for entanglement detection

    SciTech Connect

    Williams, Brian P [ORNL; Humble, Travis S [ORNL; Grice, Warren P [ORNL

    2014-01-01

    We report a nonlocal interferometer capable of detecting entanglement and identifying Bell states statistically. This is possible due to the interferometer's unique correlation dependence on the antidiagonal elements of the density matrix, which have distinct bounds for separable states and unique values for the four Bell states. The interferometer consists of two spatially separated balanced Mach-Zehnder or Sagnac interferometers that share a polarization-entangled source. Correlations between these interferometers exhibit nonlocal interference, while single-photon interference is suppressed. This interferometer also allows for a unique version of the Clauser-Horne-Shimony-Holt Bell test where the local reality is the photon polarization. We present the relevant theory and experimental results.

  19. Cryogenic Michelson interferometer on the space shuttle

    Microsoft Academic Search

    Stan Wellard; Jeff Blakeley; Steven Brown; Brent Bartschi; E. R. Huppi

    1993-01-01

    A helium-cooled interferometer was flown aboard shuttle flight STS-39. This interferometer, along with its sister radiometer, set new benchmarks for the quantity and quality of data collected. The interferometer generated approximately 150,000 interferograms during the course of the flight. Data was collected at tangent heights from the earth's surface to celestial targets. The interferograms encoded spectral data from aurora, earth

  20. Decoherence measure by gravitational wave interferometers

    E-print Network

    Yasushi Mino

    2008-08-14

    We consider the possibility to measure the quantum decoherence using gravitational wave interferometers. Gravitational wave interferometers create the superposition state of photons and measure the interference of the photon state. If the decoherence occurs, the interference of the photon state vanishes and it can be measured by the interferometers. As examples of decoherence mechanisms, we consider 1) decoherence by spontaneous localization, 2) gravitational decoherence and 3) decoherence by extra-dimensional gravity.

  1. A three-grating electron interferometer

    NASA Astrophysics Data System (ADS)

    Gronniger, G.; Barwick, B.; Batelaan, H.

    2006-10-01

    We report the observation of fringes from a three-grating electron interferometer. Interference fringes have been observed at low energies ranging from 6 to 10 keV. Contrasts of up to 25% are recorded and exceed the maximal contrast of the classical equivalent Moiré deflectometer. This type of interferometer could serve as a separate beam Mach Zehnder interferometer for low-energy electron interferometry experiments.

  2. Scanning, spherical-mirror Fabry-Perot interferometer: An upper-division optics laboratory experiment

    Microsoft Academic Search

    Paul Nachman; Aaron C. Bernstein

    1997-01-01

    Students in our upper-division\\/graduate physical optics laboratory course assemble a high-finesse Fabry-Perot interferometer (FPI) from components, mode-match it to a helium-neon (HeNe) laser, and examine some of the FPI system's properties and uses. Here, we specify the necessary equipment and describe experimental procedures. For example, the experiments use the FPI's high spectral resolution to monitor the laser's behavior as it

  3. Horizontal-view interferometer on TEXT-Upgrade

    SciTech Connect

    Jiang, Y.; Brower, D.L. (Electrical Engineering Department and Institute of Plasma and Fusion Research, University of California, Los Angeles, California 90024 (United States))

    1995-01-01

    The first experimental results from the horizontal-view, multichannel, heterodyne FIR interferometer system on TEXT-Upgrade are reported. The initial system employs parabolic beam-expansion optics and a 15 cm array with minimum channel spacing of 1.5 cm. Profiles of the plasma electron density will be presented. In addition, small-amplitude density perturbations resulting from sawteeth and tearing modes are examined. Due to the double pass of the laser beam through the plasma and the large distance of the detector array (2.5 m) from the plasma, refractive effects can be important. A ray tracing code is developed to correct the measured profiles.

  4. Programs for computing abscissas and weights for classical and nonclassical Gaussian quadrature formulas

    NASA Technical Reports Server (NTRS)

    Desmarais, R. N.

    1975-01-01

    Computer programs for computing Gaussian quadrature abscissas and weights are described. For the classical case the programs use Laguerre iteration to compute abscissas as zeros of orthogonal polynomials. The polynomials are evaluated from known recursion coefficients. The nonclassical case is handled similarly except that the recursion coefficients are computed by numerical integration. A sample problem, with input and output, is presented to illustrate the use of the programs. It computes the quadrature abscissas and weights associated with the weight function over the interval (0,1) for quadrature orders from 16 to 96 in increments of 8.

  5. Integrated Optical Interferometers with Micromachined Diaphragms for Pressure Sensing

    NASA Technical Reports Server (NTRS)

    DeBrabander, Gregory N.; Boyd, Joseph T.

    1996-01-01

    Optical pressure sensors have been fabricated which use an integrated optical channel waveguide that is part of an interferometer to measure the pressure-induced strain in a micromachined silicon diaphragm. A silicon substrate is etched from the back of the wafer leaving a rectangular diaphragm. On the opposite side of the wafer, ring resonator and Mach-Zehnder interferometers are formed with optical channel waveguides made from a low pressure chemical vapor deposited film of silicon oxynitride. The interferometer's phase is altered by pressure-induced stress in a channel segment positioned over the long edge of the diaphragm. The phase change in the ring resonator is monitored using a link-insensitive swept frequency laser diode, while in the Mach-Zehnder it is determined using a broad band super luminescent diode with subsequent wavelength separation. The ring resonator was found to be highly temperature sensitive, while the Mach-Zehnder, which had a smaller optical path length difference, was proportionally less so. The quasi-TM mode was more sensitive to pressure, in accord with calculations. Waveguide and sensor theory, sensitivity calculations, a fabrication sequence, and experimental results are presented.

  6. A study of relationship between laser intensity and scanning frequency in MEMS scanning system

    NASA Astrophysics Data System (ADS)

    Wang, Chunhui; Qu, Yang; Pang, Yajun; Ren, Xiaoyao

    2015-03-01

    The periodic variation of laser intensity in MEMS scanning interferometer system is one of the most important factors which influence the interferometer performance. In this paper, we analyzed the relationship between MEMS scanning device scanning frequency and the received laser intensity, by simulation and experiment, get the conclusion of that: in MEMS scanning interferometer system, the slow axis vibration frequency of MEMS scanning device determines the received laser intensity.

  7. Quantum Noise in Differential-type Gravitational-wave Interferometer and Signal Recycling

    E-print Network

    Atsushi Nishizawa; Seiji Kawamura; Masa-aki Sakagami

    2007-06-03

    There exists the standard quantum limit (SQL), derived from Heisenberg's uncertainty relation, in the sensitivity of laser interferometer gravitational-wave detectors. However, in the context of a full quantum-mechanical approach, SQL can be overcome using the correlation of shot noise and radiation-pressure noise. So far, signal recycling, which is one of the methods to overcome SQL, is considered only in a recombined-type interferometer such as Advanced-LIGO, LCGT, and GEO600. In this paper, we investigated quantum noise and the possibility of signal recycling in a differential-type interferometer. As a result, we found that signal recycling is possible and creates at most three dips in the sensitivity curve of the detector. Then, taking advantage of the third additional dip and comparing the sensitivity of a differential-type interferometer with that of a next-generation Japanese GW interferometer, LCGT, we found that SNR of inspiral binary is improved by a factor of 1.43 for neutron star binary, 2.28 for 50 M_sun black hole binary, and 2.94 for 100 M_sun black hole binary. We also found that power recycling to increase laser power is possible in our signal-recycling configuration of a detector.

  8. A Cross-Correlated Trellis-Coded Quadrature Modulation Representation of MIL-STD Shaped Offset Quadrature Phase-Shift Keying

    NASA Astrophysics Data System (ADS)

    Simon, M. K.; Li, L.

    2003-08-01

    We show that MIL-STD shaped offset quadrature phase-shift keying (SOQPSK), a highly bandwidth-efficient constant-envelope modulation, can be represented in the form of a cross-correlated trellis-coded quadrature modulation, a generic structure containing both memory and cross-correlation between the in-phase and quadrature-phase channels. Such a representation allows identification of the optimum form of receiver for MIL-STD SOQPSK and at the same time, through modification of the equivalent I and Q encoders to recursive types, allows for it to be embedded as the inner code of a serial or parallel (turbo-like) concatenated coding structure together with iterative decoding.

  9. Apparatus and method for laser velocity interferometry

    DOEpatents

    Stanton, Philip L. (Bernalillo County, NM); Sweatt, William C. (Albuquerque, NM); Crump, Jr., O. B. (Albuquerque, NM); Bonzon, Lloyd L. (Albuquerque, NM)

    1993-09-14

    An apparatus and method for laser velocity interferometry employing a fixed interferometer cavity and delay element. The invention permits rapid construction of interferometers that may be operated by those non-skilled in the art, that have high image quality with no drift or loss of contrast, and that have long-term stability even without shock isolation of the cavity.

  10. A quadrature-based technique for robust design with computer simulations

    E-print Network

    Lin, Yiben

    2007-01-01

    This thesis presents a method for estimating transmitted variance to enable robust parameter design in computer simulations. This method is based on the Hermite-Gaussian quadrature for a single input. It is extended to ...

  11. Increasing reliability of Gauss-Kronrod quadrature by Eratosthenes' sieve method

    NASA Astrophysics Data System (ADS)

    Adam, Gh.; Adam, S.

    2001-04-01

    The reliability of the local error estimates returned by the Gauss-Kronrod quadrature rules can be raised up to the theoretical 100% rate of success, under error estimate sharpening, provided a number of natural validating conditions are required. The self-validating scheme of the local error estimates, which is easy to implement and adds little supplementary computing effort, strengthens considerably the correctness of the decisions within the automatic adaptive quadrature.

  12. Determination of quasiprobability distributions in terms of probability distributions for the rotated quadrature phase

    Microsoft Academic Search

    K. Vogel; H. Risken

    1989-01-01

    It is shown that the probability distribution for the rotated quadrature phase [a°exp(itheta)+a exp(-itheta)]\\/2 can be expressed in terms of quasiprobability distributions such as P, Q, and Wigner functions and that also the reverse is true, i.e., if the probability distribution for the rotated quadrature phase is known for every theta in the interval 0<=theta

  13. Bending analysis of thin functionally graded plates using generalized differential quadrature method

    Microsoft Academic Search

    A. Fereidoon; M. Asghardokht seyedmahalle; A. Mohyeddin

    2011-01-01

    In this paper, the differential quadrature (DQ) method is presented for easy and effective analysis of isotropic functionally\\u000a graded (FG) and functionally graded coated (FGC) thin plates with constant Poisson’s ratio and varying Young’s modulus in\\u000a the thickness direction. The bending of FG and FGC plates under transverse loading has been studied using the polynomial differential\\u000a quadrature (PDQ) and the

  14. Direct modulation at L-band using a quadrature modulator with feedback

    NASA Technical Reports Server (NTRS)

    Datta, Ravi; Crozier, Stewart N.

    1995-01-01

    This paper describes how a high quality modulated signal can be generated directly at the frequency of transmission, using a standard quadrature modulator and other commercially-available, low-cost building blocks. The method uses a feedback technique for automatic correction of carrier leakage, differential gain and phase mismatch errors in the quadrature modulator, and other building blocks, by providing guidance to the digital baseband portion of the modulator. Experimental results are presented for direct modulation at 1.65 GHz.

  15. The DELTA Synchrotron Light Interferometer

    SciTech Connect

    Berges, U. [DELTA, University of Dortmund, Maria-Goeppert-Mayer Str. 2, 4421 Dortmund (Germany); Fachbereich Physik, University of Dortmund, Otto-Hahn-Str. 4, 44221 Dortmund (Germany)

    2004-05-12

    Synchrotron radiation sources like DELTA, the Dortmund Electron Accelerator, a third generation synchrotron light source, need an optical monitoring system to measure the beam size at different points of the ring with high resolution and accuracy. These measurements also allow an investigation of the emittance of the storage ring, an important working parameter for the efficiency of working beamlines with experiments using the synchrotron radiation. The resolution limits of the different types of optical synchrotron light monitors at DELTA are investigated. The minimum measurable beamsize with the normal synchrotron light monitor using visible light at DELTA is about 80 {mu}m. Due to this a synchrotron light interferometer was built up and tested at DELTA. The interferometer uses the same beamline in the visible range. The minimum measurable beamsize is with about 8 {mu}m one order of magnitude smaller. This resolution is sufficient for the expected small vertical beamsizes at DELTA. The electron beamsize and emittance were measured with both systems at different electron beam energies of the storage ring. The theoretical values of the present optics are smaller than the measured emittance. So possible reasons for beam movements are investigated.

  16. In-line Sagnac interferometer current sensor

    Microsoft Academic Search

    J. Blake; P. Tantaswadi; R. T. de Carvalho

    1996-01-01

    The authors demonstrate for the first time a near shot noise limited in-line Sagnac interferometer current sensor. It is shown to have a number of advantages over the optical current sensors based on polarimetric Faraday and Faraday\\/Sagnac loop interferometer topologies, including lower sensitivity to environmental disturbances, less demanding optical components, and easy installation.

  17. Mosaicking with Cosmic Microwave Background Interferometers

    Microsoft Academic Search

    Emory F. Bunn; Martin White

    2007-01-01

    Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, which is valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We extend the formalism for

  18. CIST....CORRTEX interferometer simulation test

    SciTech Connect

    Heinle, R.A.

    1994-12-01

    Testing was performed in order to validate and cross calibrate an RF interferometer and the crush threshold of cable. Nitromethane was exploded (inside of PVC pipe). The explosion was used to crush the interferometer sensor cables which had been placed inside and outside the pipe. Results are described.

  19. FLUOR fibered instrument at the IOTA interferometer

    Microsoft Academic Search

    Vincent Coudé du Foresto; Guy Perrin; Cyril Ruilier; Bertrand P. Mennesson; Wesley A. Traub; Marc G. Lacasse

    1998-01-01

    The FLUOR project started in 1991 with a prototype fiber recombination unit that transformed a pair of independent 80 cm telescopes into a stellar interferometer. An improved version of this unit is now used as part of the instrumentation at the IOTA interferometer on Mt. Hopkins. The system is based on fluoride glass single-mode waveguides for observations at IR wavelengths

  20. The FLUOR\\/IOTA fiber stellar interferometer

    Microsoft Academic Search

    Vincent Coudé du Foresto; Guy Perrin; Jean-Marie Mariotti; Marc Lacasse; Wes Traub

    1997-01-01

    The FLUOR project started in 1991 with a prototype fiber recombination unit that transformed a pair of independent 80cm telescopes into a stellar interferometer. An improved version of this unit is now used as part of the instrumentation at the IOTA interferometer on Mt Hopkins (Arizona). The system is based on fluoride glass single- mode waveguides (non polarization-preserving) for observations

  1. Study Of Space-Based Optical Interferometer

    NASA Technical Reports Server (NTRS)

    Redding, David C.; Laskin, Robert A.; Breckenridge, William G.; Shao, Michael

    1992-01-01

    Report discusses calibration and operation of conceptual Focus Mission Interferometer (FMI), consisting of component instruments mounted at widely separated locations on large truss structure in orbit 1,400 km above Earth. Includes six telescopes in linear array. Outputs combined in pairlike fashion so FMI operates as three distinct two-telescope interferometers. Accurate enough for submilliarcsecond astrometry.

  2. AN ATOM INTERFEROMETER GYROSCOPE JAMES GREENBERG

    E-print Network

    Cronin, Alex D.

    AN ATOM INTERFEROMETER GYROSCOPE By JAMES GREENBERG A Thesis Submitted to the Honors College gyroscope that is sensitive to the abso- lute rotation rate of the lab with respect to an inertial frame. We accelerations of ±0.005g and absolute rotation rates of ±0.5E. Sensitive atom interferometer gyroscopes

  3. Directional dual-tree complex wavelet packet transforms for processing quadrature signals.

    PubMed

    Serbes, Gorkem; Gulcur, Halil Ozcan; Aydin, Nizamettin

    2014-11-12

    Quadrature signals containing in-phase and quadrature-phase components are used in many signal processing applications in every field of science and engineering. Specifically, Doppler ultrasound systems used to evaluate cardiovascular disorders noninvasively also result in quadrature format signals. In order to obtain directional blood flow information, the quadrature outputs have to be preprocessed using methods such as asymmetrical and symmetrical phasing filter techniques. These resultant directional signals can be employed in order to detect asymptomatic embolic signals caused by small emboli, which are indicators of a possible future stroke, in the cerebral circulation. Various transform-based methods such as Fourier and wavelet were frequently used in processing embolic signals. However, most of the times, the Fourier and discrete wavelet transforms are not appropriate for the analysis of embolic signals due to their non-stationary time-frequency behavior. Alternatively, discrete wavelet packet transform can perform an adaptive decomposition of the time-frequency axis. In this study, directional discrete wavelet packet transforms, which have the ability to map directional information while processing quadrature signals and have less computational complexity than the existing wavelet packet-based methods, are introduced. The performances of proposed methods are examined in detail by using single-frequency, synthetic narrow-band, and embolic quadrature signals. PMID:25388779

  4. Efficient Implementations of the Quadrature-Free Discontinuous Galerkin Method

    NASA Technical Reports Server (NTRS)

    Lockard, David P.; Atkins, Harold L.

    1999-01-01

    The efficiency of the quadrature-free form of the dis- continuous Galerkin method in two dimensions, and briefly in three dimensions, is examined. Most of the work for constant-coefficient, linear problems involves the volume and edge integrations, and the transformation of information from the volume to the edges. These operations can be viewed as matrix-vector multiplications. Many of the matrices are sparse as a result of symmetry, and blocking and specialized multiplication routines are used to account for the sparsity. By optimizing these operations, a 35% reduction in total CPU time is achieved. For nonlinear problems, the calculation of the flux becomes dominant because of the cost associated with polynomial products and inversion. This component of the work can be reduced by up to 75% when the products are approximated by truncating terms. Because the cost is high for nonlinear problems on general elements, it is suggested that simplified physics and the most efficient element types be used over most of the domain.

  5. Radiation transport modeling using extended quadrature method of moments

    SciTech Connect

    Vikas, V., E-mail: vvikas@iastate.edu [Department of Aerospace Engineering, 2271 Howe Hall, Iowa State University, Ames, IA 50011 (United States); Hauck, C.D., E-mail: hauckc@ornl.gov [Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wang, Z.J., E-mail: zjw@ku.edu [Department of Aerospace Engineering, 2120 Learned Hall, University of Kansas, Lawrence, KS 66045 (United States); Fox, R.O., E-mail: rofox@iastate.edu [Department of Chemical and Biological Engineering, 2114 Sweeney Hall, Iowa State University, Ames, IA 50011 (United States)

    2013-08-01

    The radiative transfer equation describes the propagation of radiation through a material medium. While it provides a highly accurate description of the radiation field, the large phase space on which the equation is defined makes it numerically challenging. As a consequence, significant effort has gone into the development of accurate approximation methods. Recently, an extended quadrature method of moments (EQMOM) has been developed to solve univariate population balance equations, which also have a large phase space and thus face similar computational challenges. The distinct advantage of the EQMOM approach over other moment methods is that it generates moment equations that are consistent with a positive phase space density and has a moment inversion algorithm that is fast and efficient. The goal of the current paper is to present the EQMOM method in the context of radiation transport, to discuss advantages and disadvantages, and to demonstrate its performance on a set of standard one-dimensional benchmark problems that encompass optically thin, thick, and transition regimes. Special attention is given in the implementation to the issue of realizability—that is, consistency with a positive phase space density. Numerical results in one dimension are promising and lay the foundation for extending the same framework to multiple dimensions.

  6. Optimal interferometer designs for optical coherence tomography.

    PubMed

    Rollins, A M; Izatt, J A

    1999-11-01

    We introduce a family of power-conserving fiber-optic interferometer designs for low-coherence reflectometry that use optical circulators, unbalanced couplers, and (or) balanced heterodyne detection. Simple design equations for optimization of the signal-to-noise ratio of the interferometers are expressed in terms of relevant signal and noise sources and measurable system parameters. We use the equations to evaluate the expected performance of the new configurations compared with that of the standard Michelson interferometer that is commonly used in optical coherence tomography (OCT) systems. The analysis indicates that improved sensitivity is expected for all the new interferometer designs, compared with the sensitivity of the standard OCT interferometer, under high-speed imaging conditions. PMID:18079840

  7. Miniature interferometer for refractive index measurement in microfluidic chip

    NASA Astrophysics Data System (ADS)

    Chen, Minghui; Geiser, Martial; Truffer, Frederic; Song, Chengli

    2012-12-01

    The design and development of the miniaturized interferometer for measurement of the refractive index or concentration of sub-microliter volume aqueous solution in microfludic chip is presented. It is manifested by a successful measurement of the refractive index of sugar-water solution, by utilizing a laser diode for light source and the small robust instrumentation for practical implementation. Theoretically, the measurement principle and the feasibility of the system are analyzed. Experimental device is constructed with a diode laser, lens, two optical plate and a complementary metal oxide semiconductor (CMOS). Through measuring the positional changes of the interference fringes, the refractive index change are retrieved. A refractive index change of 10-4 is inferred from the measured image data. The entire system is approximately the size of half and a deck of cards and can operate on battery power for long time.

  8. Large-aperture phase-shifting interferometer for PSD measurements

    NASA Astrophysics Data System (ADS)

    Gu, Yuanyuan; Xu, Qiao; Cai, Lin

    2000-10-01

    In modern high power laser, reflected and transmitted wavefronts of optical components are being specified by the power spectral density function (PSD). In order to ensure accurate measurements of PSD of optical components, the test systems must be calibrated. This paper presents the results of the components wavefront measurements using large aperture laser Fizeau phase shifting interferometer. This paper also describes the testing results of optical components in size from approximately 100 mm X 100 mm to 240 mm X 480 mm, substrate including UBK7 glass, KDP crystal, Nd-glass. These measurements are performed after polishing, after coating and in Brewster. Using these data, we can qualify optical components and improve our fabrication processes under optics development program.

  9. Status and Progress on the Upgraded Infrared Spatial Interferometer

    NASA Technical Reports Server (NTRS)

    Danchi, W. C.; Townes, C. H.; Fitelson, W.; Hale, D.; Monnier, J.; Tevosian, S.; Weiner, J.; Oegerle, William (Technical Monitor)

    2002-01-01

    The U.C. Berkeley Infrared Spatial Interferometer is a two telescope stellar interferometer operating in the 9-12 micron atmospheric window, utilizing heterodyne detection with CO2 laser local oscillators. Science with the ISI has been focused on the measurements of the spatial distribution of dust and molecules around mass-losing late type stars, and more recently precision measurements of stellar diameters in the mid-infrared avoiding molecular lines. Also during the past few years, a NSF sponsored program of expansion from two to three telescopes has been underway. This expansion will allow the ISI to make visibility observations on three simultaneous baselines and a measure a closure phase. The third telescope was completed last year and shipped to Mt. Wilson, and more recently a Central Control Facility and Master Laser Oscillator Facility were also completed and recently shipped to Mt. Wilson. In this talk we report progress on this program and highlight some of the most recent astrophysical results.

  10. Real-time digital heterodyne interferometer for high resolution plasma density measurements at ISTTOK

    SciTech Connect

    Marques, T. G.; Gouveia, A.; Pereira, T.; Fortunato, J.; Carvalho, B. B.; Sousa, J.; Silva, C.; Fernandes, H. [Associacao Euratom/IST Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal)

    2008-10-15

    With the implementation of alternating discharges (ac) at the ISTTOK tokamak, the typical duration of the discharges increased from 35 to 250 ms. This time increase created the need for a real-time electron density measurement in order to control the plasma fueling. The diagnostic chosen for the real-time calculation was the microwave interferometer. The ISTTOK microwave interferometer is a heterodyne system with quadrature detection and a probing frequency of 100 GHz ({lambda}{sub 0}=3 mm). In this paper, a low-cost approach for real-time diagnostic using a digital signal programable intelligent computer embedded system is presented, which allows the measurement of the phase with a 1% fringe accuracy in less than 6 {mu}s. The system increases its accuracy by digitally correcting the offsets of the input signals and making use of a judicious lookup table optimized to improve the nonlinear behavior of the transfer curve. The electron density is determined at a rate of 82 kHz (limited by the analog to digital converter), and the data are transmitted for each millisecond although this last parameter could be much lower (around 12 {mu}s--each value calculated is transmitted). In the future, this same system is expected to control plasma actuators, such as the piezoelectric valve of the hydrogen injection system responsible for the plasma fueling.

  11. Solid optical ring interferometer for high-throughput feedback-free spectral analysis and filtering

    NASA Astrophysics Data System (ADS)

    Petrak, B.; Peiris, M.; Muller, A.

    2015-02-01

    We describe a simple and inexpensive optical ring interferometer for use in high-resolution spectral analysis and filtering. It consists of a solid cuboid, reflection-coated on two opposite sides, in which constructive interference occurs for waves in a rhombic trajectory. Due to its monolithic design, the interferometer's resonance frequencies are insensitive to environmental disturbances over time. Additional advantages are its simplicity of alignment, high-throughput, and feedback-free operation. If desired, it can be stabilized with a secondary laser without disturbance of the primary signal. We illustrate the use of the interferometer for the measurement of the spectral Mollow triplet from a quantum dot and characterize its long-term stability for filtering applications.

  12. Porous silicon integrated Mach-Zehnder interferometer waveguide for biological and chemical sensing.

    PubMed

    Kim, Kyowon; Murphy, Thomas E

    2013-08-26

    Optical waveguides comprised of nanoporous materials are uniquely suited for on-chip sensing applications, because they allow for a target chemical or analyte to directly infiltrate the optical material that comprises the core of the waveguide. We describe here the fabrication and characterization of nanoporous waveguides, and demonstrate their usefulness in measuring small changes in refractive index when exposed to a test analyte. We use a process of electrochemical etching and laser oxidation to produce channel waveguides and integrated on-chip Mach-Zehnder structures, and we compare the responsivity and interferometric stability of the integrated sensor to that of a fiber-based interferometer. We quantify the detection capability by selectively applying isopropanol to a 200 ?m length waveguide segment in one arm of the interferometer, which produces a phase shift of 9.7 ?. The integrated interferometer is shown to provide a more stable response in comparison to a comparable fiber-based implementation. PMID:24105496

  13. Implementation and applications of a Fizeau-based fiber tip interferometer

    NASA Astrophysics Data System (ADS)

    Baltazar-Lopez, Martin E.

    2005-02-01

    It is presented the results of experimental studies through the implementation of a Fizeau-based Fiber Tip Interferometer (FTI), as the realization of the open optics Fizeau Interferometer into Fiber-optics. The FTI was constructed with off-the shelf fiber optic components and can be compacted in a way of a "sensor head" for various purposes. The FTI can be used as a single probe device or as a multiple probes device for several simultaneous measurement points. The single probe FTI is integrated by a HeNe laser, a Fiber bi-conical tapered coupler and a fiber-coupled GRIN lens. A range of applications of such homodyne interferometer device for non-contact measurements, going from ultrasound detection to temperature measurements are presented.

  14. Portable, solid state, fiber optic coupled doppler interferometer system for detonation and shock diagnostics

    SciTech Connect

    Fleming, K.J.; Crump, O.B.

    1993-01-01

    VISAR (Velocity Interferometer System for Any Reflector) is a specialized Doppler interferometer system that is gaining world-wide acceptance as the standard for shock phenomena analysis. The VISAR's large power and cooling requirements, and the sensitive and complex nature of the interferometer cavity has restricted the traditional system to the laboratory. This paper describes the new portable VISAR, its peripheral sensors, and the role it played in optically measuring ground shock of an underground nuclear detonation (UGT). The Solid State VISAR uses a prototype diode pumped ND:YAG laser and solid state detectors that provide a suitcase-size system with low power requirements. A special window and sensor was developed for fiber optic coupling (1 kilometer long) to the VISAR. The system has proven itself as a reliable, easy-to-use instrument that is capable of field test use and rapid data reduction employing only a personal computer (PC).

  15. In-line interferometer for direction-sensitive displacement measurements by optical feedback detection

    SciTech Connect

    Tarun, Alvarado; Jecong, Julius; Saloma, Caesar

    2005-12-01

    We demonstrate a compact in-line interferometer for direction-sensitive displacement measurement by optical feedback detection with a semiconductor laser (SL) light source. Two reflected beams from a semitransparent reference mirror and a reflecting test object interfere in the SL medium, causing a variation in its output power. The reference mirror is located between the SL output facet and the test object. The performance of the interferometer is investigated numerically and experimentally to determine its optimal operating conditions. We have verified the operating conditions where the behavior of the SL output power profile could indicate accurately the displacement magnitude and direction of the moving test object. The profile behavior is robust against variations in optical feedback and scale of the interferometer configuration.

  16. X-ray shearing interferometer

    DOEpatents

    Koch, Jeffrey A. (Livermore, CA)

    2003-07-08

    An x-ray interferometer for analyzing high density plasmas and optically opaque materials includes a point-like x-ray source for providing a broadband x-ray source. The x-rays are directed through a target material and then are reflected by a high-quality ellipsoidally-bent imaging crystal to a diffraction grating disposed at 1.times. magnification. A spherically-bent imaging crystal is employed when the x-rays that are incident on the crystal surface are normal to that surface. The diffraction grating produces multiple beams which interfere with one another to produce an interference pattern which contains information about the target. A detector is disposed at the position of the image of the target produced by the interfering beams.

  17. Hubble Extra Solar Planet Interferometer

    NASA Technical Reports Server (NTRS)

    Shao, M.

    1991-01-01

    This paper describes a proposed third-generation Hubble instrument for extra-solar planet detection, the Hubble Extra-Solar Planet Interferometer (HESPI). This instrument would be able to achieve starlight cancellation at the 10 exp 6 to 10 exp 8 level, given a stellar wavefront with phase errors comparable to the present Hubble telescope wavefront. At 10 exp 6 starlight cancellation, HESPI would be able to detect a Jupiter-like planet next to a star at a distance of about 10 parsec, for which there are about 400 candidate stars. This paper describes a novel approach for starlight suppression, using a combination of active control and single-mode spatial filters, to achieve starlight suppression far below the classical limit set by scattering due to microsurface imperfections. In preliminary lab experiments, suppression by a factor of 40 below the classical scatter limit due to optical wavefront errors has been demonstrated.

  18. Tracking frequency laser distance gauge

    Microsoft Academic Search

    J. D. Phillips; R. D. Reasenberg

    2005-01-01

    Advanced astronomical missions with greatly enhanced resolution and physics missions of unprecedented accuracy will require laser distance gauges of substantially improved performance. We describe a laser gauge, based on Pound-Drever-Hall locking, in which the optical frequency is adjusted to maintain an interferometer's null condition. This technique has been demonstrated with pm performance. Automatic fringe hopping allows it to track arbitrary

  19. Prism-pair interferometer for precise measurement of the refractive index of optical glass by using a spectrum lamp.

    PubMed

    Hori, Yasuaki; Hirai, Akiko; Minoshima, Kaoru

    2014-05-01

    A prism-pair interferometer for a spectrum lamp was developed for precise measurement of the refractive index of a prism of optical glass. Previously we reported the prism-pair interferometer with a He-Ne laser light source, resulting in a measurement uncertainty of 1.1×10??. However, most of the refractive-index values managed by optical glass manufacturers are conventionally measured with spectrum lamps. We have optimized the prism-pair interferometer for spectrum lamps and implemented a signal-processing technique from Fourier-transform spectroscopy. When the refractive index is measured, the wavelength of the spectrum lamp is simultaneously calibrated by part of the interferometer, so that the resulting refractive index is traceable to a national standard of length. The combined standard uncertainty for a refractive index measured with the e-line (546 nm) of a Hg lamp is 6.9×10??. PMID:24921862

  20. Fiber optic acoustic hydrophone with double Mach-Zehnder interferometers for optical path length compensation

    NASA Astrophysics Data System (ADS)

    Lim, T. K.; Zhou, Y.; Lin, Y.; Yip, Y. M.; Lam, Y. L.

    1999-01-01

    We report on the development of a fiber optic acoustic hydrophone which consists of a sensing Mach-Zehnder (MZ) interferometer and a compensating MZ interferometer for optical path length compensation. This double-interferometer configuration has the following advantages: the hydrophone is a true heterodyne device; a laser source with a short coherence length can be used; the sensing interferometer is completely passive; the compensating interferometer can be located near the signal processing electronics, far away from the sensing interferometer; a conventional modulation analyzer can be used to demodulate the optical phase shift, which greatly simplifies the demodulation electronics. The performance of the hydrophone is evaluated experimentally by immersing the sensing interferometer in a water tank to detect underwater acoustic signals generated by an acoustic wave projector. Experimental results show that over the frequency range of 5 to 20 kHz, the hydrophone has an almost flat response with an average normalized phase sensitivity of -322.3 dB re 1/?Pa and an average pressure sensitivity of -153.7 dB re rad/?Pa. These performance figures are better than those obtained from a commercial piezoelectric hydrophone. Furthermore, we have also demonstrated that with improved signal processing techniques, the normalized phase sensitivity of the hydrophone increases to -313 dB re 1/?Pa, and the pressure sensitivity increases to -136.9 dB re rad/?Pa. These results indicate that the present design offers equal or better performance in terms of sensitivity over its counterparts employing conventional Mach-Zehner configurations.

  1. On the Potential of Large Ring Lasers

    E-print Network

    G. E. Stedman; R. B. Hurst; K. U. Schreiber

    2007-07-10

    We describe a new ring laser with area A = 833 m^2 and update performance statistics for several such machines. Anandan & Chaio 1982 judged ring lasers inferior to matter interferometers as possible detectors of gravitational waves. However, we note that geophysically interesting results have been obtained from large ring lasers and that there is still a lot of room for improvements.

  2. Slow wave atom interferometers for rotation sensing

    NASA Astrophysics Data System (ADS)

    Özcan, Meriç

    2007-02-01

    A gyroscope based on Sagnac interferometer measures the rotation rate relative to an inertial frame of reference. Sagnac effect originally has been derived and experimentally demonstrated with optical waves. Later, matter wave based Sagnac interferometers were developed due to inherent sensitivity over a photon based system. However in any interferometer whether it is photon or matter wave based the resultant phase shift due to counter-rotating waves is independent of the wave velocity. Here we show that one can have a larger phase shift with slower matter waves using Aharonov-Bohm effect: the phase difference of the counter propagating waves is proportional to the inverse square of the particle velocity.

  3. Active noise cancellation in a suspended interferometer

    E-print Network

    Jennifer C. Driggers; Matthew Evans; Keenan Pepper; Rana Adhikari

    2011-12-09

    We demonstrate feed-forward vibration isolation on a suspended Fabry-Perot interferometer using Wiener filtering and a variant of the common Least Mean Square (LMS) adaptive filter algorithm. We compare the experimental results with theoretical estimates of the cancellation efficiency. Using data from the recent LIGO Science Run, we also estimate the impact of this technique on full scale gravitational wave interferometers. In the future, we expect to use this technique to also remove acoustic, magnetic, and gravitational noise perturbations from the LIGO interferometers. This noise cancellation technique is simple enough to implement in standard laboratory environments and can be used to improve SNR for a variety of high precision experiments.

  4. X-ray Interferometer Using Prism Optics

    SciTech Connect

    Suzuki, Yoshio [JASRI/SPring-8 Mikazuki, Hyogo 6791-5198 (Japan)

    2004-05-12

    Two-beam X-ray interferometer using refractive optics has been developed. A prism made of acrylic resin is used as the beam deflector for hard X-ray wavefront dividing interferometer. This configuration is the same as that of the Fresnel's bi-prism interferometer or the Leith-Upatnieks type two-beam holography in visible light region. Therefore, quantitative analysis of the degree of transversal coherence can be performed by measuring the visibility of interference fringes. It is also possible to realize two-beam holographic imaging in hard X-ray regions.

  5. Design of a nonlinear, thin-film Mach-Zehnder interferometer

    NASA Technical Reports Server (NTRS)

    Pearson, Earl F.

    1996-01-01

    A Mach-Zehnder interferometer consists of a 3 db splitter to create the two separate beams, an optical path difference to control the interference between the two beams and another 3 db coupler to reconstruct the output signal. The performance of each of its components has been investigated. Since an optical path difference is required for its function, the performance of a Mach-Zehnder interferometer is not very sensitive to construction parameters. In designing an interferometer for this work, the following considerations must be observed: the interferometer is to be made of phthalocyanine or polydiacetylene thin films; in order to avoid thermal effects which are slower, the wavelength chosen must not be absorbed in either one or two photon processes; the wavelength chosen must be easily generated (laser line); the spacing between the interferometer arms must be large enough to allow attachment of external electrodes; the vapor deposition apparatus can accept disks no larger than 0.9 inches; and the design must allow multiple layer coating in order to determine the optimum film thickness or to change to another substance.

  6. The microwave interferometer on J-TEXT tokamak

    Microsoft Academic Search

    L. Gao; G. Zhuang; X. W. Hu; Z. J. Yang

    2008-01-01

    A 2 mm microwave interferometer is developed to measure plasma electron density for the J-TEXT tokamak. The interferometer views the plasma vertically through a set of large diagnostic ports and the system is configured as a frequency-modulated interferometer. The interferometer routinely provides real-time feedback control for the gas injection system.

  7. Overview of the control system for the Keck Interferometer

    Microsoft Academic Search

    Andrew J. Booth; Glenn Eychaner; Erik Hovland; Richard L. Johnson Jr.; William Lupton; Al Niessner; Dean L. Palmer; Leonard J. Reder; Andy C. Rudeen; Robert F. Smythe; Kevin Tsubota

    2002-01-01

    The Keck Interferometer links the two 10m Keck Telescopes located atop Mauna Kea in Hawaii. It is the first 10m class, fully AO equipped interferometer to enter operation. Further, it is the first large interferometer designed to be handed over from a design and implementation team to a separate operations team, and be used by astronomers who are not interferometer

  8. Simultaneous selective two-photon microscopy using MHz rate pulse shaping and quadrature detection of the time-multiplexed signal

    NASA Astrophysics Data System (ADS)

    Saytashev, Ilyas; Xu, Bingwei; Bremer, Marshall T.; Dantus, Marcos

    2014-02-01

    A broad-bandwidth oscillator and pulse shaper with a compensation phase mask applied produce sub-10 fs laser pulses is used to induce selective two-photon excitation in the 380 to 500 nm range. The output is split into two arms with different second order dispersion (SOD). The recombined beams create a train of pulses with phase-shape switching at a rate of 162 MHz. Each pulse induces selective TPEF on the sample at wavelengths determined by the amount of SOD in the beam, which tunes the selective TPEF wavelength. Fluorescence is detected by a single fast photomultiplier tube (PMT) detector; therefore, signal from the PMT detector contains fluorescence signals from two different selectivelyexcited fluorophores. The two separate signals are isolated by quadrature detection using a lock-in amplifier. Images are obtained from the two different fluorophores simultaneously at 81MHz. The wide tunability of the two-photon excitation wavelength, fast switching rate between the selective excitation, and low photodamage (due to low power of laser beam) enables potential application of this method for in vivo dynamic imaging in biological samples

  9. The 7-channel FIR HCN Interferometer on J-TEXT Tokamak

    E-print Network

    Wei Chen; L. Gao; J. Chen; Q. Li; Z. J. Wang; G. Zhuang

    2011-12-28

    A seven-channel far-infrared hydrogen cyanide (HCN) laser interferometer has been established aiming to provide the line integrated plasma density for the J-TEXT experimental scenarios. A continuous wave glow discharge HCN laser designed with a cavity length 3.4 m is used as the laser source with a wavelength of 337 {\\mu}m and an output power up to 100 mW. The system is configured as a Mach-Zehnder type interferometer. Phase modulation is achieved by a rotating grating, with a modulation frequency of 10 kHz which corresponds to the temporal resolution of 0.1 ms. The beat signal is detected by TGS detector. The phase shift induced by the plasma is derived by the comparator with a phase sensitivity of 0.06 fringe. The experimental results measured by the J-TEXT interferometer are presented in details. In addition, the inversed electron density profile done by a conventional approach is also given. The kinematic viscosity of dimethyl silicone and vibration control is key issues for the system performance. The laser power stability under different kinematic viscosity of silicone oil is presented. A visible improvement of measured result on vibration reduction is shown in the paper.

  10. Nonuniform sampling of hypercomplex multidimensional NMR experiments: Dimensionality, quadrature phase and randomization.

    PubMed

    Schuyler, Adam D; Maciejewski, Mark W; Stern, Alan S; Hoch, Jeffrey C

    2015-05-01

    Nonuniform sampling (NUS) in multidimensional NMR permits the exploration of higher dimensional experiments and longer evolution times than the Nyquist Theorem practically allows for uniformly sampled experiments. However, the spectra of NUS data include sampling-induced artifacts and may be subject to distortions imposed by sparse data reconstruction techniques, issues not encountered with the discrete Fourier transform (DFT) applied to uniformly sampled data. The characterization of these NUS-induced artifacts allows for more informed sample schedule design and improved spectral quality. The DFT-Convolution Theorem, via the point-spread function (PSF) for a given sampling scheme, provides a useful framework for exploring the nature of NUS sampling artifacts. In this work, we analyze the PSFs for a set of specially constructed NUS schemes to quantify the interplay between randomization and dimensionality for reducing artifacts relative to uniformly undersampled controls. In particular, we find a synergistic relationship between the indirect time dimensions and the "quadrature phase dimension" (i.e. the hypercomplex components collected for quadrature detection). The quadrature phase dimension provides additional degrees of freedom that enable partial-component NUS (collecting a subset of quadrature components) to further reduce sampling-induced aliases relative to traditional full-component NUS (collecting all quadrature components). The efficacy of artifact reduction is exponentially related to the dimensionality of the sample space. Our results quantify the utility of partial-component NUS as an additional means for introducing decoherence into sampling schemes and reducing sampling artifacts in high dimensional experiments. PMID:25899289

  11. Design and Application of Quadrature Compensation Patterns in Bulk Silicon Micro-Gyroscopes

    PubMed Central

    Ni, Yunfang; Li, Hongsheng; Huang, Libin

    2014-01-01

    This paper focuses on the detailed design issues of a peculiar quadrature reduction method named system stiffness matrix diagonalization, whose key technology is the design and application of quadrature compensation patterns. For bulk silicon micro-gyroscopes, a complete design and application case was presented. The compensation principle was described first. In the mechanical design, four types of basic structure units were presented to obtain the basic compensation function. A novel layout design was proposed to eliminate the additional disturbing static forces and torques. Parameter optimization was carried out to maximize the available compensation capability in a limited layout area. Two types of voltage loading methods were presented. Their influences on the sense mode dynamics were analyzed. The proposed design was applied on a dual-mass silicon micro-gyroscope developed in our laboratory. The theoretical compensation capability of a quadrature equivalent angular rate no more than 412 °/s was designed. In experiments, an actual quadrature equivalent angular rate of 357 °/s was compensated successfully. The actual compensation voltages were a little larger than the theoretical ones. The correctness of the design and the theoretical analyses was verified. They can be commonly used in planar linear vibratory silicon micro-gyroscopes for quadrature compensation purpose. PMID:25356646

  12. Design and application of quadrature compensation patterns in bulk silicon micro-gyroscopes.

    PubMed

    Ni, Yunfang; Li, Hongsheng; Huang, Libin

    2014-01-01

    This paper focuses on the detailed design issues of a peculiar quadrature reduction method named system stiffness matrix diagonalization, whose key technology is the design and application of quadrature compensation patterns. For bulk silicon micro-gyroscopes, a complete design and application case was presented. The compensation principle was described first. In the mechanical design, four types of basic structure units were presented to obtain the basic compensation function. A novel layout design was proposed to eliminate the additional disturbing static forces and torques. Parameter optimization was carried out to maximize the available compensation capability in a limited layout area. Two types of voltage loading methods were presented. Their influences on the sense mode dynamics were analyzed. The proposed design was applied on a dual-mass silicon micro-gyroscope developed in our laboratory. The theoretical compensation capability of a quadrature equivalent angular rate no more than 412 °/s was designed. In experiments, an actual quadrature equivalent angular rate of 357 °/s was compensated successfully. The actual compensation voltages were a little larger than the theoretical ones. The correctness of the design and the theoretical analyses was verified. They can be commonly used in planar linear vibratory silicon micro-gyroscopes for quadrature compensation purpose. PMID:25356646

  13. Fiber optics speckle interferometer for diffusivity measurements

    Microsoft Academic Search

    D. Paoletti; G. Schirripa Spagnolo

    1993-01-01

    A digital speckle pattern interferometer with optical fibers is proposed for the real time measurement of the diffusion coefficient of liquid binary mixtures. Some examples of application of the technique are reported.

  14. Atom Interferometers with Scalable Enclosed Area

    SciTech Connect

    Mueller, Holger; Chu, Steven [Department of Physics, 366 Le Conte Hall, University of California, Berkeley, California 94720-7300 (United States); Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720 (United States); Chiow, Sheng-wey; Herrmann, Sven [Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States)

    2009-06-19

    Bloch oscillations (i.e., coherent acceleration of matter waves by an optical lattice) and Bragg diffraction are integrated into light-pulse atom interferometers with large momentum splitting between the interferometer arms, and hence enhanced sensitivity. Simultaneous acceleration of both arms in the same internal states suppresses systematic effects, and simultaneously running a pair of interferometers suppresses the effect of vibrations. Ramsey-Borde interferometers using four such Bloch-Bragg-Bloch beam splitters exhibit 15% contrast at 24(Planck constant/2pi)k splitting, the largest so far ((Planck constant/2pi)k is the photon momentum); single beam splitters achieve 88(Planck constant/2pi)k. The prospects for reaching 100 s of (Planck constant/2pi)k and applications such as gravitational wave sensors are discussed.

  15. Polymeric slot waveguide interferometer for sensor applications.

    PubMed

    Hiltunen, Marianne; Hiltunen, Jussi; Stenberg, Petri; Aikio, Sanna; Kurki, Lauri; Vahimaa, Pasi; Karioja, Pentti

    2014-03-24

    A refractive index sensor based on slot waveguide Young interferometer was developed in this work. The interferometer was fabricated on a polymer platform and operates at a visible wavelength of 633 nm. The phase shift of the interference pattern was measured with various concentrations of glucose-water solutions, utilizing both TE and TM polarization states. The sensor was experimentally observed to detect a refractive index difference of 6.4 × 10(-6) RIU. Furthermore, the slot Young interferometer was found to compensate for temperature variations. The results of this work demonstrate that high performance sensing capability can be obtained with a polymeric slot Young interferometer, which can be fabricated by a simple molding process. PMID:24664071

  16. Direct reading fast microwave interferometer for EBT

    SciTech Connect

    Uckan, T.

    1984-10-01

    A simple and inexpensive 4-mm direct reading fast (rise time approx. 100 ..mu..s) microwave interferometer is described. The system is particularly useful for density measurements on the ELMO Bumpy Torus (EBT) during pulsed operation.

  17. Polarization phase shifting lateral shearing interferometer

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Zeng, Aijun; Zhu, Linglin; Song, Qiang; Huang, Huijie

    2013-08-01

    A polarization phase shifting lateral shearing interferometer based on a polarization beam splitting plate(PBSP) is proposed. The front surface of the PBSP is coated with polarization beam splitting film and its back surface is coated with total reflection film. The beam to be tested is split by the PBSP with an incidence angle of 45° and divided into two mutually perpendicular linearly polarization beams. Phase shifting can be introduced to the interferometer when the PBSP is combined with a polarzation temporal or spatial phase shifter. A polarizaiton temporal phase shifting lateral shearing interferometer system is built up both with the ASAP software and the experiments. The usefulness of the interferometer is verified.

  18. The effect of rotations on Michelson interferometers

    NASA Astrophysics Data System (ADS)

    Maraner, Paolo

    2014-11-01

    In the contest of the special theory of relativity, it is shown that uniform rotations induce a phase shift in Michelson interferometers. The effect is second order in the ratio of the interferometer's speed to the speed of light, further suppressed by the ratio of the interferometer's arms length to the radius of rotation and depends on the interferometer's position in the co-rotating frame. The magnitude of the phase shift is just beyond the sensitivity of turntable rotated optical resonators used in present tests of Lorentz invariance. It grows significantly large in Earth's rotated kilometer-scale Fabry-Perot enhanced interferometric gravitational-wave detectors where it appears as a constant bias. The effect can provide the means of sensing center and radius of rotations.

  19. Versatility of the vectorial shearing interferometer

    NASA Astrophysics Data System (ADS)

    Paez, Gonzalo; Strojnik, Marija

    2002-02-01

    Recently, we developed a new type of a shearing interferometer, based on the Mach-Zehnder configuration, except that a beam director is incorporated in one arm of the interferometer and a compensator in the other one. The wave-front displacement is accomplished upon the angle setting between two Risley prisms. With the control of this angle, wave-front displacements are effectuated such that large and small aberrations may be measured with the same instrument. The vectorial shearing interferometer allows the optimization of the measurement parameters tailored to the specific application and the possible absence of available references. We present several applications of the vectorial shearing interferometer to the optical testing and the alignment of the optical systems.

  20. The VLA Atmospheric Phase Interferometer

    NASA Astrophysics Data System (ADS)

    Morris, Keith

    2014-05-01

    The Atmospheric Phase Interferometer (API) is a two-element atmospheric seeing monitor located at the Very Large Array (VLA) site. The instrument measures turbulent refractive index variation through the atmosphere by examining phase differences in a satellite beacon signal detected at two (or more) antennas. With this measurement, the VLA scheduling software is able to consider atmospheric stability when determining which frequency observation to schedule next. We are in the process of extending this two-element interferometer to four elements, which will allow us to measure the turbulence in two dimensions and at multiple length scales. This thesis will look at some statistical properties of turbulence, the effects of atmospheric stability on radio interferometric observations, and discuss details of the instrument and the data that it collects. The thesis will also cover some techniques and principles of signal processing, and an analysis of some data from the instrument. The results demonstrate that other surface atmospheric variables (e.g. windspeed, water vapor pressure) show the same structure function exponent as the atmospheric phase fluctuations. In particular, the structure functions of water vapor partial pressure and wind speed show the same exponent as the phase. Though the agreement between meteorological variables and atmospheric phase is scientifically satisfying, these surface measurements are not nearly as sensitive as the API saturation phase measurement, and therefore cannot be used to schedule telescope time in its stead. What is informative about these results is that the similar structure functions for API and meteorological data are detecting reinforce the claim that both measurements represent turbulent transport, and not instrumental noise. Data from the instrument reveals that measurements are consistent with both Kolmogorov turbulence theory, and with prior observations. The API predominately measures three-dimensional isotropic turbulence, but is capable of seeing the transition to two-dimensional "thin screen" turbulence. There is evidence that water vapor scale height can be estimated from the API data. We can expect to be able measure and document variations in the water vapor scale height by looking at variation of structure function exponents. Once the reliability of the method is established, a series of altitude profiles could allow further validation of this method of scale height determination. We look at a method for statistical excision of instrumental noise from the data. The ability to discriminate noise from signal based on structure function exponent leads to a path to possible noise elimination techniques. With the redundant measurement baselines of the new API, experimental processing techniques such as this could be deployed on some baselines, but not others, leaving the production functions for VLA scheduling in a known state while allowing instrument improvement studies to proceed.

  1. In-Line Sagnac Interferometer Current Sensor

    Microsoft Academic Search

    Prinya Tantaswadi

    1995-01-01

    We demonstrate for the first time a near shot noise limited in-line Sagnac interferometer current sensor. It is shown to have a number of advantages over the optical current sensors based on polarimetric Faraday and Faraday\\/Sagnac loop interferometer topologies, including lower sensitivity to environmental disturbances, less demanding optical components, and easy installation. Our contributions to the field of fiber-optic current

  2. Nonlinear Michelson interferometer for improved quantum metrology

    E-print Network

    Alfredo Luis; Ángel Rivas

    2015-04-21

    We examine nonlinear quantum detection via a Michelson interferometer embedded in a gas with Kerr nonlinearity. The interferometer is illuminated by pulses of classical light. This strategy combines the robustness against practical imperfections of classical light with the improvement provided by nonlinear detection. Regarding ultimate quantum limits, we stress that, as a difference with linear schemes, the nonlinearity introduces pulse duration as a new variable into play along with the energy resources.

  3. Recent progress at the Keck Interferometer

    Microsoft Academic Search

    S. Ragland; R. Akeson; M. Colavita; R. Millan-Gabet; J. Woillez; P. Wizinowich; E. Appleby; B. Berkey; A. Cooper; C. Felizardo; J. Herstein; M. Hrynevych; D. Medeiros; D. Morrison; T. Panteleeva; J.-U. Pott; B. Smith; K. Summers; K. Tsubota; C. Tyau; E. Wetherell

    2010-01-01

    The Keck Interferometer (KI) combines the two 10m diameter Keck telescopes providing milliarcsecond angular resolution. KI has unique observing capabilities such as sensitive K-band V2, L-band V2 and N-band nulling operations. The instrument status of the Keck Interferometer since the last SPIE meeting in 2008 is summarized. We discuss the performance of new visibility observing capabilities including L-band and self-phase

  4. Development of displacement- and frequency-noise-free interferometer in 3-D configuration for gravitational wave detection

    E-print Network

    K. Kokeyama; S. Sato; A. Nishizawa; S. Kawamura; Y. Chen; A. Sugamoto

    2009-06-05

    The displacement- and frequency-noise-free interferometer (DFI) is a multiple laser interferometer array for gravitational wave detection free from both the displacement noise of optics and laser frequency noise. So far, partial experimental demonstrations of DFI have been done in 2-D table top experiments. In this paper, we report the complete demonstration of a 3-D DFI. The DFI consists of four Mach-Zehnder interferometers with four mirrors and two beamsplitters. The displacement noises both of mirrors and beamsplitters were suppressed by up to 40 dB. The non-vanishing DFI response to a gravitational wave was successfully confirmed using multiple electro-optic modulators and computing methods.

  5. Laser angle sensor

    NASA Technical Reports Server (NTRS)

    Pond, C. R.; Texeira, P. D.

    1985-01-01

    A laser angle measurement system was designed and fabricated for NASA Langley Research Center. The instrument is a fringe counting interferometer that monitors the pitch attitude of a model in a wind tunnel. A laser source and detector are mounted above the model. Interference fringes are generated by a small passive element on the model. The fringe count is accumulated and displayed by a processor in the wind tunnel control room. This report includes optical and electrical schematics, system maintenance and operation procedures.

  6. Laser angle sensor development

    NASA Technical Reports Server (NTRS)

    Pond, C. R.; Texeira, P. D.

    1980-01-01

    Electrical and optical parameters were developed for a two axis (pitch/roll) laser angle sensor. The laser source and detector were mounted in the plenum above the model. Two axis optical distortion measurements of flow characteristics in a 0.3 transonic cryogenic tunnel were made with a shearing interferometer. The measurement results provide a basis for estimating the optical parameters of the laser angle sensor. Experimental and analytical information was generated on model windows to cover the reflector. A two axis breadboard was assembled to evaluate different measurement concepts. The measurement results were used to develop a preliminary design of a laser angle sensor. Schematics and expected performance specifications are included.

  7. Linear scan control of tunable lasers using a scanning fabry-perot.

    PubMed

    Coulombe, M J; Pine, A S

    1979-05-15

    A simple technique is described for servo control of the scan rate and drift of tunable cw lasers based on peak position readout in a repetitively swept Fabry-Perot interferometer referenced to a stabilized laser. PMID:20212885

  8. Phase measurement device using inphase and quadrature components for phase estimation

    NASA Technical Reports Server (NTRS)

    Halverson, Peter G. (Inventor); Ware, Brent (Inventor); Shaddock, Daniel A. (Inventor); Spero, Robert E. (Inventor)

    2009-01-01

    A phasemeter for estimating the phase of a signal. For multi-tone signals, multiple phase estimates may be provided. An embodiment includes components operating in the digital domain, where a sampled input signal is multiplied by cosine and sine terms to provide estimates of the inphase and quadrature components. The quadrature component provides an error signal that is provided to a feedback loop, the feedback loop providing a model phase that tends to track the phase of a tone in the input signal. The cosine and sine terms are generated from the model phase. The inphase and quadrature components are used to form a residual phase, which is added to the model phase to provide an estimate of the phase of the input signal. Other embodiments are described and claimed.

  9. On the Spectrum of Field Quadratures for a Finite Number of Photons

    E-print Network

    Emilio Pisanty; Eduardo Nahmad-Achar

    2012-09-04

    The spectrum and eigenstates of any field quadrature operator restricted to a finite number $N$ of photons are studied, in terms of the Hermite polynomials. By (naturally) defining \\textit{approximate} eigenstates, which represent highly localized wavefunctions with up to $N$ photons, one can arrive at an appropriate notion of limit for the spectrum of the quadrature as $N$ goes to infinity, in the sense that the limit coincides with the spectrum of the infinite-dimensional quadrature operator. In particular, this notion allows the spectra of truncated phase operators to tend to the complete unit circle, as one would expect. A regular structure for the zeros of the Christoffel-Darboux kernel is also shown.

  10. A CONFOCAL LONGITUDINAL MODE SELECTOR FOR SINGLE-FREQUENCY OPERATION OF GAS LASERS

    Microsoft Academic Search

    Douglas C. Sinclair

    1968-01-01

    A new type of mode selector is described which uses a short confocal cavity illuminated off-axis. The mode selector is generally similar to a Fox-Smith interferometer, but is easier to use, because it does not need to be mode-matched to the laser. Experimental results obtained using the confocal interferometer with an argon-ion laser are described.

  11. Multichannel microwave interferometer with an antenna switching system for electron density measurement in a laboratory plasma experiment

    SciTech Connect

    Kawamori, Eiichirou; Lin, Yu-Hsiang [Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan (China)] [Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan (China); Mase, Atsushi [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga 816-8580 (Japan)] [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga 816-8580 (Japan); Nishida, Yasushi; Cheng, C. Z. [Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan (China) [Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan (China); Plasma and Space Science Center, National Cheng Kung University, Tainan 70101, Taiwan (China)

    2014-02-15

    This study presents a simple and powerful technique for multichannel measurements of the density profile in laboratory plasmas by microwave interferometry. This technique uses electromechanical microwave switches to temporally switch the connection between multiple receiver antennas and one phase-detection circuit. Using this method, the phase information detected at different positions is rearranged into a time series that can be acquired from a minimum number of data acquisition channels (e.g., two channels in the case of quadrature detection). Our successfully developed multichannel microwave interferometer that uses the antenna switching method was applied to measure the radial electron density profiles in a magnetized plasma experiment. The advantage of the proposed method is its compactness and scalability to multidimensional measurement systems at low cost.

  12. Multichannel microwave interferometer with an antenna switching system for electron density measurement in a laboratory plasma experiment.

    PubMed

    Kawamori, Eiichirou; Lin, Yu-Hsiang; Mase, Atsushi; Nishida, Yasushi; Cheng, C Z

    2014-02-01

    This study presents a simple and powerful technique for multichannel measurements of the density profile in laboratory plasmas by microwave interferometry. This technique uses electromechanical microwave switches to temporally switch the connection between multiple receiver antennas and one phase-detection circuit. Using this method, the phase information detected at different positions is rearranged into a time series that can be acquired from a minimum number of data acquisition channels (e.g., two channels in the case of quadrature detection). Our successfully developed multichannel microwave interferometer that uses the antenna switching method was applied to measure the radial electron density profiles in a magnetized plasma experiment. The advantage of the proposed method is its compactness and scalability to multidimensional measurement systems at low cost. PMID:24593361

  13. Discrete variable representation in electronic structure theory: Quadrature grids for least-squares tensor hypercontraction

    NASA Astrophysics Data System (ADS)

    Parrish, Robert M.; Hohenstein, Edward G.; Martínez, Todd J.; Sherrill, C. David

    2013-05-01

    We investigate the application of molecular quadratures obtained from either standard Becke-type grids or discrete variable representation (DVR) techniques to the recently developed least-squares tensor hypercontraction (LS-THC) representation of the electron repulsion integral (ERI) tensor. LS-THC uses least-squares fitting to renormalize a two-sided pseudospectral decomposition of the ERI, over a physical-space quadrature grid. While this procedure is technically applicable with any choice of grid, the best efficiency is obtained when the quadrature is tuned to accurately reproduce the overlap metric for quadratic products of the primary orbital basis. Properly selected Becke DFT grids can roughly attain this property. Additionally, we provide algorithms for adopting the DVR techniques of the dynamics community to produce two different classes of grids which approximately attain this property. The simplest algorithm is radial discrete variable representation (R-DVR), which diagonalizes the finite auxiliary-basis representation of the radial coordinate for each atom, and then combines Lebedev-Laikov spherical quadratures and Becke atomic partitioning to produce the full molecular quadrature grid. The other algorithm is full discrete variable representation (F-DVR), which uses approximate simultaneous diagonalization of the finite auxiliary-basis representation of the full position operator to produce non-direct-product quadrature grids. The qualitative features of all three grid classes are discussed, and then the relative efficiencies of these grids are compared in the context of LS-THC-DF-MP2. Coarse Becke grids are found to give essentially the same accuracy and efficiency as R-DVR grids; however, the latter are built from explicit knowledge of the basis set and may guide future development of atom-centered grids. F-DVR is found to provide reasonable accuracy with markedly fewer points than either Becke or R-DVR schemes.

  14. Practical heterodyne surface profiling interferometer with automatic focusing

    NASA Astrophysics Data System (ADS)

    Zhao, Hongzhi; Liang, Rong; Li, Dacheng; Cao, Mang

    2000-10-01

    In modern semiconductor and optics industries, there is a strong demand for a highly sensitive and non-contact surface profilometer. This paper describes an optical heterodyne surface profiling interferometer for on-line non-contact measurement with automatic focusing which has been developed recently. The essential feature of the profilometer is a newly designed common-path configuration to minimizes the effects caused by vibration, air turbulence and other environmental variations. A single-mode frequency-stabilized laser diode (780 nm) serves as the light source to make the whole system compact (total volume 250L x 200W x 100Dmm). A powerful signal processing scheme is also developed, which includes three parts: automatic voltage control, phase measurement and automatic focusing control. All these make the repeatability and stability of the profiling interferometer greatly improved. The system has vertical resolution of 0.39 nm and lateral resolution of 0.73 micrometer. During approximate an hour, the stability is within 1.95 nm (3?).

  15. Measurements of gravitational acceleration from an echo atom interferometer

    NASA Astrophysics Data System (ADS)

    Mok, C.; Carew, A.; Barrett, B.; Berthiaume, R.; Kumarakrishnan, A.

    2012-06-01

    We have developed two techniques involving a ground-state, time-domain echo atom interferometer (AI) to measure gravitational acceleration, g, from a sample of laser-cooled atoms. We compare and contrast measurements from a two-pulse and a three-pulse stimulated-echo AI described in PRA 84, 063623 (2011). The two-pulse AI involves excitation by standing wave pulses separated in time by T21, and detection at 2T21. In this case, the accumulation of the matter-wave fringes as a function of T21 is described by a frequency chirped signal analogous to the interference fringes recorded by a falling corner-cube Mach-Zehnder optical interferometer. In contrast, the three-pulse stimulated echo AI requires excitation by standing wave pulses separated by T21, T32 and detection at 2T21+T32. In this case, the signal from the AI as a function of T32 is modulated at a single frequency determined by T21. Since the three-pulse AI is less sensitive to mirror vibrations and magnetic gradients, the measurement timescale is appreciably increased. We also consider the implementation of a RF-optical feedback loop to actively stabilize both AIs from the effects of mirror vibrations.

  16. Measuring black-hole parameters and testing general relativity using gravitational-wave data from space-based interferometers

    Microsoft Academic Search

    Eric Poisson

    1996-01-01

    Among the expected sources of gravitational waves for the Laser Interferometer Space Antenna (LISA) is the capture of solar-mass compact stars by massive black holes residing in galactic centers. We construct a simple model for such a capture, in which the compact star moves freely on a circular orbit in the equatorial plane of the massive black hole. We consider

  17. A simple laser system for atom interferometry

    NASA Astrophysics Data System (ADS)

    Merlet, S.; Volodimer, L.; Lours, M.; Pereira Dos Santos, F.

    2014-07-01

    We present here a simple laser system for a laser-cooled atom interferometer, where all functions (laser cooling, interferometry and detection) are realized using only two extended cavity laser diodes, amplified by a common tapered amplifier. One laser is locked by frequency modulation transfer spectroscopy, the other being phase locked with an offset frequency determined by an field-programmable gate array-controlled direct digital synthesizer, which allows for efficient and versatile tuning of the laser frequency. Raman lasers are obtained with a double pass acoustooptic modulator. We demonstrate a gravimeter using this laser system, with performances close to the state of the art.

  18. Tools for detecting entanglement between different degrees of freedom in quadrature squeezed cylindrically polarized modes

    E-print Network

    Christian Gabriel; Andrea Aiello; Stefan Berg-Johansen; Christoph Marquardt; Gerd Leuchs

    2011-12-15

    Quadrature squeezed cylindrically polarized modes contain entanglement not only in the polarization and spatial electric field variables but also between these two degrees of freedom [1]. In this paper we present tools to generate and detect this entanglement. Experimentally we demonstrate the generation of quadrature squeezing in cylindrically polarized modes by mode transforming a squeezed Gaussian mode. Specifically, -1.2 dB of amplitude squeezing are achieved in the radially and azimuthally polarized mode. Furthermore, theoretically it is shown how the entanglement contained within these modes can be measured and how strong the quantum correlations, depending on the measurement scheme, are.

  19. Parallel multiplex laser feedback interferometry

    SciTech Connect

    Zhang, Song; Tan, Yidong; Zhang, Shulian, E-mail: zsl-dpi@mail.tsinghua.edu.cn [State Key Laboratory of Precision Measurements, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China)] [State Key Laboratory of Precision Measurements, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China)

    2013-12-15

    We present a parallel multiplex laser feedback interferometer based on spatial multiplexing which avoids the signal crosstalk in the former feedback interferometer. The interferometer outputs two close parallel laser beams, whose frequencies are shifted by two acousto-optic modulators by 2? simultaneously. A static reference mirror is inserted into one of the optical paths as the reference optical path. The other beam impinges on the target as the measurement optical path. Phase variations of the two feedback laser beams are simultaneously measured through heterodyne demodulation with two different detectors. Their subtraction accurately reflects the target displacement. Under typical room conditions, experimental results show a resolution of 1.6 nm and accuracy of 7.8 nm within the range of 100 ?m.

  20. Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

    PubMed

    Lee, Jin-Hyuk; Kim, Dae-Hyun

    2014-10-01

    A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions. PMID:25942819

  1. Bunch length measurement at the Fermilab A0 photoinjector using a Martin-Puplett interferometer

    SciTech Connect

    Thurman-Keup, Randy; Fliller, Raymond Patrick; Kazakevich, Grigory; /Fermilab

    2008-05-01

    We present preliminary measurements of the electron bunch lengths at the Fermilab A0 Photoinjector using a Martin-Puplett interferometer on loan from DESY. The photoinjector provides a relatively wide range of bunch lengths through laser pulse width adjustment and compression of the beam using a magnetic chicane. We present comparisons of data with simulations that account for diffraction distortions in the signal and discuss future plans for improving the measurement.

  2. Compact In-Fiber Interferometer Formed by Long-Period Gratings in Photonic Crystal Fiber

    Microsoft Academic Search

    Jian Ju; Wei Jin; Hoi Lut Ho

    2008-01-01

    We reported the design and implementation of an in-fiber Mach-Zehnder interferometer (MZI) based on a pair of long-period gratings (LPGs) written on a photonic crystal fiber (PCF). The LPG was fabricated by using a pulsed CO2 laser to carve grooves periodically along the PCF. The MZI relies on the interference between the fundamental core mode and a cladding mode of

  3. A common-path fast-scanning interferometer system for thin-film surface profiling

    Microsoft Academic Search

    M. S. Cheon; Y. U. Nam; Y. S. Hwang

    2002-01-01

    A common-path fast-scanning interferometer system has been developed to measure a thin-film surface profile. To get thin-film profiling with the resolution of approximately 10 nm, a He–Ne laser with the wavelength of 633 nm has been chosen as a beam source. To cancel out any path difference arising from the vibration of the target at such a short wavelength, a

  4. Plasma diagnostics using laser-excited coupled and transmission ring resonators

    Microsoft Academic Search

    Roger A. Haas

    1976-01-01

    In this paper a simple two-level laser model is used to investigate the frequency response of coupled-cavity laser interferometers. It is found that under certain circumstances, often satisfied by molecular gas lasers, the frequency response exhibits a resonant behavior. This behavior severely complicates the interpretation of coupled-cavity laser interferometer measurements of rapidly varying plasmas. To circumvent this limitation a new

  5. An interpolation?based local differential quadrature method to solve partial differential equations using irregularly distributed nodes

    Microsoft Academic Search

    Hang Ma

    2008-01-01

    SUMMARY To circumvent the constraint in application of the conventional differential quadrature (DQ) method that the solution domain has to be a regular region, an interpolation-based local differential quadrature (LDQ) method is proposed in this paper. Instead of using regular nodes placed on mesh lines in the DQ method (DQM), irregularly distributed nodes are employed in the LDQ method. That

  6. Laser interferometric experiments for the TJ-II stellarator electron-density measurements

    NASA Astrophysics Data System (ADS)

    Lamela, Horacio; Acedo, Pablo; Irby, James

    2001-01-01

    Laser two-color heterodyne interferometry is a proven method to measure electron density in fusion plasmas. Though only used in tokamaks with high electron densities, the idea of also using two-color laser interferometers for stellarators and small machines to replace far-infrared laser interferometers is being proposed. This will lead to low-cost, reliable, and easy to operate diagnostics for electron-density measurements. In this article, we present the interferometric experiments we have used for calibration of a two-color laser heterodyne system for electron-density measurements in the TJ-II stellarator. These experiments have been based on the use of a novel interferometric scheme: the heterodyne/homodyne interferometer. Finally, we describe the interferometer we have installed in the TJ-II stellarator and present the first results on mechanical-vibration subtraction and electron-density measurements with a two-color laser interferometer in a stellarator (TJ-II, Madrid, Spain).

  7. The 7-channel FIR HCN Interferometer on J-TEXT Tokamak

    E-print Network

    Chen, Wei; Chen, J; Li, Q; Wang, Z J; Zhuang, G

    2011-01-01

    A seven-channel far-infrared hydrogen cyanide (HCN) laser interferometer has been established aiming to provide the line integrated plasma density for the J-TEXT experimental scenarios. A continuous wave glow discharge HCN laser designed with a cavity length 3.4 m is used as the laser source with a wavelength of 337 {\\mu}m (cutoff density is 9.8*10^21/m^3) and an output power up to 100 mW. The system is configured as a Mach-Zehnder type interferometer. Phase modulation is achieved by a rotating grating, with a modulation frequency of 10 kHz which corresponds to the temporal resolution of 0.1 ms. The optic viewing chords travel through the plasma vertically, their radial positions are r=21cm, 14cm, 7cm, 0cm, -7cm, -14cm, -21cm, respectively. The beat signal is detected by TGS detector. The phase shift induced by the plasma is derived by the comparator with a phase sensitivity of 0.06 fringe. The experimental results measured by the J-TEXT interferometer are presented in details in this meeting. In addition, th...

  8. Sub-nanometer periodic nonlinearity error in absolute distance interferometers

    NASA Astrophysics Data System (ADS)

    Yang, Hongxing; Huang, Kaiqi; Hu, Pengcheng; Zhu, Pengfei; Tan, Jiubin; Fan, Zhigang

    2015-05-01

    Periodic nonlinearity which can result in error in nanometer scale has become a main problem limiting the absolute distance measurement accuracy. In order to eliminate this error, a new integrated interferometer with non-polarizing beam splitter is developed. This leads to disappearing of the frequency and/or polarization mixing. Furthermore, a strict requirement on the laser source polarization is highly reduced. By combining retro-reflector and angel prism, reference and measuring beams can be spatially separated, and therefore, their optical paths are not overlapped. So, the main cause of the periodic nonlinearity error, i.e., the frequency and/or polarization mixing and leakage of beam, is eliminated. Experimental results indicate that the periodic phase error is kept within 0.0018°.

  9. Optical image hiding with a modified Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Li, Jun; Li, Jiaosheng; Pan, Yangyang; Li, Rong

    2014-04-01

    A method for optical image hiding in a Fresnel domain is proposed. In our modified Mach-Zehnder interferometer (MZI) architecture, an object beam is inserted into the object image to be hidden; the reference beam is produced by laser illumination through the phase plates and the host image. Afterwards, the reference beam is not only restricted to providing phase shifts in the hologram-recording process, but it can also add host image to engage the image hiding function. After two images experience Fresnel diffraction, the diffraction waves are registered as interference patterns on a CCD plane, which resembles a Fresnel diffraction pattern of the host image. The object image is embedded in the host image inside the Fresnel domain. Here, we present a theoretical analysis and preliminary experimental results for this method. It can be widely applied to secure image transmissions at a high speed over the internet and for image watermarking.

  10. Fiberoptic Fabry-Perot engine pressure sensor system using a continuous wave laser source 

    E-print Network

    Choi, Han-Sun

    1994-01-01

    A fiber optic Fabry-Perot engine pressure sensor using a continuous wave laser source is implemented and tested. The operating point of the Fabrv-Perot sensor is locked to the quadrature point by electronic feedback control of laser temperature...

  11. Fiberoptic Fabry-Perot engine pressure sensor system using a continuous wave laser source

    E-print Network

    Choi, Han-Sun

    1994-01-01

    A fiber optic Fabry-Perot engine pressure sensor using a continuous wave laser source is implemented and tested. The operating point of the Fabrv-Perot sensor is locked to the quadrature point by electronic feedback control of laser temperature...

  12. Progress towards a first-of-its-kind ion interferometer

    NASA Astrophysics Data System (ADS)

    Archibald, James L.; Erickson, C. J.; Jackson, Jarom; Hermansen, Michael; Anderson, Dean; Cunningham, Mark; Durfee, Dallin S.

    2011-10-01

    We are building the first matter-wave ion interferometer that works by exploiting the internal structure of the ions. The completed apparatus will allow novel tests of electromagnetic theory and other fundamental physics. The apparatus consists of a low-velocity intense source (LVIS) for ^87Sr. Atoms emitted from the LVIS will be ionized using a two-photon transition to an auto-ionizing bound state. Interferometry will be achieved using stimulated Raman transitions between the hyperfine ground states of ^87Sr^+. The laser system that will stimulate these transitions consists of a grating-stabilized, 408 nm master laser which is arranged in a double-pass configuration through a 2.5 GHz frequency-shifter to generate two beams that are detuned from one another by 5 GHz (which corresponds to the hyperfine splitting). These beams are then used to injection lock two slave lasers. We will discuss the theory of operation, potential applications, experimental techniques and our preliminary results.

  13. Optical system design for a Lunar Optical Interferometer

    NASA Technical Reports Server (NTRS)

    Colavita, M. M.; Shao, M.; Hines, B. E.; Levine, B. M.; Gershman, R.

    1991-01-01

    The moon offers particular advantages for interferometry, including a vacuum environment, a large stable base on which to assemble multi-kilometer baselines, and a cold nighttime temperature to allow for passive cooling of optics for high IR sensitivity. A baseline design for a Lunar Optical Interferometer (LOI) which exploits these features is presented. The instrument operates in the visible to mid-IL region, and is designed for both astrometry and synthesis imaging. The design uses a Y-shaped array of 12 siderostats, with maximum arm lengths of about 1 km. The inner siderostats are monitored in three dimensions from a central laser metrology structure to allow for high precision astrometry. The outer siderostats, used primarily for synthesis imaging, exploit the availability of bright reference stars in order to determine the instrument geometry. The path delay function is partitioned into coarse and fine components, the former accomplished with switched banks of range mirrors monitored with an absolute laser metrology system, and the latter with a short cat's eye delay line. The back end of the instrument is modular, allowing for beam combiners for astrometry, visible and IR synthesis imaging, and direct planet detection. With 1 m apertures, the instrument will have a point-source imaging sensitivity of about 29 mag; with the laser metrology system, astrometry at the microarcsecond level will be possible.

  14. Adaptive optical phased array interferometer for acoustic wave detection

    NASA Astrophysics Data System (ADS)

    Murray, T. W.; Yi, Z.; Krishnaswamy, S.

    2001-04-01

    A multiplexed laser interferometer is presented which allows for the simultaneous detection of acoustic waves from a number of focussed points on the surface of a specimen. Phase gratings are used to create an array of laser beams that are directed to the specimen. The size of the receiver elements as well as the spacing between elements can be easily controlled using a lens system. The beams are collected and combined with a single reference beam in a photorefractive crystal, and imaged on separate photodetector elements. Detection of surface acoustic waves scattered from a defect in an aluminum specimen using a nine-element receiver is shown. The phased array system can be dynamically focussed by applying appropriate phase shifts between the detected signals. The wide bandwidth and non-contact nature of this receiver make it well suited for phased array detection and ultrasonic imaging applications. Furthermore, the acquisition of multiple signals simultaneously has the potential to reduce the scanning time required for laser ultrasonic inspection systems.

  15. ORIGINAL PAPER Flow Dynamics and Plasma Heating of Spheromaks in SSX

    E-print Network

    Brown, Michael R.

    surfaces are cleaned with helium glow discharge condi- tioning. Transient electron heating is inferred from averaged electron density is monitored with a quadrature HeNe laser interferometer [8]. We can scan density

  16. Photonic generation of a microwave signal by incorporating a delay interferometer and a saturable absorber.

    PubMed

    Chen, Guojie; Huang, Dexiu; Zhang, Xinliang; Cao, Hui

    2008-03-15

    A novel approach to generate microwave signals is presented by employing a dual-wavelength erbium-doped fiber ring laser. By using a delay interferometer as a comb filter cascaded with a tunable bandpass filter and a saturable absorber formed by an unpumped polarization-maintaining erbium-doped fiber, a stable wavelength-tunable dual-wavelength single longitudinal-mode laser is achieved. A microwave signal at 20.07 GHz with a linewidth of <25 kHz is demonstrated by beating the two wavelengths at a photodetector. PMID:18347707

  17. Regularized Quadrature Filters for Local Frequency Estimation: Application to Multimodal Volume Image Registration

    Microsoft Academic Search

    Jundong Liu

    2001-01-01

    Multimodal image registration is a fundamental problem in medical image analysis. In this paper, we propose a novel algorithm to compute the local frequency representations of the multimodal data sets to be registered. Local frequency representa- tion can detect edge and ridge information simul- taneously. In this algorithm, we develop regular- ized quadrature filters (RQFs) to compute local fre- quency

  18. Denoising performance of modified dual-tree complex wavelet transform for processing quadrature embolic Doppler signals.

    PubMed

    Serbes, Gorkem; Aydin, Nizamettin

    2014-01-01

    Quadrature signals are dual-channel signals obtained from the systems employing quadrature demodulation. Embolic Doppler ultrasound signals obtained from stroke-prone patients by using Doppler ultrasound systems are quadrature signals caused by emboli, which are particles bigger than red blood cells within circulatory system. Detection of emboli is an important step in diagnosing stroke. Most widely used parameter in detection of emboli is embolic signal-to-background signal ratio. Therefore, in order to increase this ratio, denoising techniques are employed in detection systems. Discrete wavelet transform has been used for denoising of embolic signals, but it lacks shift invariance property. Instead, dual-tree complex wavelet transform having near-shift invariance property can be used. However, it is computationally expensive as two wavelet trees are required. Recently proposed modified dual-tree complex wavelet transform, which reduces the computational complexity, can also be used. In this study, the denoising performance of this method is extensively evaluated and compared with the others by using simulated and real quadrature signals. The quantitative results demonstrated that the modified dual-tree-complex-wavelet-transform-based denoising outperforms the conventional discrete wavelet transform with the same level of computational complexity and exhibits almost equal performance to the dual-tree complex wavelet transform with almost half computational cost. PMID:24048958

  19. Increasing reliability of Gauss–Kronrod quadrature by Eratosthenes' sieve method

    Microsoft Academic Search

    Gh. Adam; S. Adam

    2001-01-01

    The reliability of the local error estimates returned by the Gauss–Kronrod quadrature rules can be raised up to the theoretical 100% rate of success, under error estimate sharpening, provided a number of natural validating conditions are required. The self-validating scheme of the local error estimates, which is easy to implement and adds little supplementary computing effort, strengthens considerably the correctness

  20. New methods for adaptation of quadrature modulators and demodulators in amplifier linearization circuits

    Microsoft Academic Search

    James K. Cavers

    1997-01-01

    Imperfections in analog quadrature modulators (QMs) and demodulators-gain and phase imbalance and DC offset-have a devastating effect on amplifier linearization circuits. Correction circuits have a simple structure, but their parameters must be adjusted adaptively. This paper introduces two new methods for such an adaptation. The first is based on a training sequence consisting of a tone at one or more

  1. A differential quadrature procedure for three-dimensional buckling analysis of rectangular plates

    Microsoft Academic Search

    T. M. Teo; K. M. Liew

    1999-01-01

    This paper presents an application of the differential quadrature (DQ) method for three-dimensional buckling analysis of rectangular plates. The governing equations of the plate model are first presented in terms of displacement, stress displacement relationship, and boundary conditions with three-dimensional flexibility. These equations are then normalised and discretised using the DQ procedure. Example problems pertaining to the buckling of rectangular

  2. Efficient Quadrature-Free 3D High-Order Spectral Volume Method on Unstructured Grids

    Microsoft Academic Search

    Michael Yang; Rob Harris; Z. J. Wang; Yen Liu

    The high-order spectral volume (SV) method has been extended for solving 3D hyperbolic conservation laws, and its implementation using an efficient quadrature-free approach has been performed to achieve high efficiency while maintaining accuracy. In the SV method, in order to perform a high-order polynomial reconstruction, each simplex cell - called a spectral volume (SV) - is partitioned into a \\

  3. A proof for the informational completeness of the rotated quadrature observables

    E-print Network

    J. Kiukas; P. Lahti; J. -P. Pellonpaa

    2007-12-03

    We give a new mathematically rigorous proof for the fact that, when $S$ is a dense subset of $[0,2\\pi)$, the rotated quadrature operators $Q_\\theta$, $\\theta\\in S$, of a single mode electromagnetic field constitute an informationally complete set of observables.

  4. Algorithm 655: IQPACK: FORTRAN subroutines for the weights of interpolatory quadratures

    Microsoft Academic Search

    Sylvan Elhay; Jaroslav Kautsky

    1987-01-01

    We present FORTRAN subroutines that implement the method described in [3] for the stable evaluation of the weights of interpolatory quadratures with prescribed simple or multiple knots. Given a set of knots and their multiplicities, the package generates the weights by using the zeroth moment ?0 of w, the weight function in the integrand, and the (symmetric tridiagonal) Jacobi matrix

  5. Supersonic combustion studies using a multivariate quadrature based method for combustion modeling

    E-print Network

    Raman, Venkat

    Supersonic combustion studies using a multivariate quadrature based method for combustion modeling function (PDF) of thermochemical variables can be used for accurately computing the combustion source term of predictive models for supersonic combustion is a critical step in design and development of scramjet engines

  6. Frequency and Scale Domain Analysis of Complex Quadrature Embolic Doppler UltrasoundSignals

    E-print Network

    Arslan, Tughrul

    Frequency and Scale Domain Analysis of Complex Quadrature Embolic Doppler Ultrasound blood cells [1][2]. Asymptomatic circulating emboli can be detected by transcranial Doppler ultrasound on the fast Fourier transform (FFT) processing, which is the standard processing used by Doppler ultrasound

  7. Vibration Analysis of Elastically Supported Turbomachinery Blades by the Modified Differential Quadrature Method

    Microsoft Academic Search

    S.-T. Choi; Y.-T. Chou

    2001-01-01

    The modified differential quadrature method (MDQM) is proposed for vibration analysis of elastically supported turbomachinery blades. A pre-twisted blade with varying cross-section is modelled as a Timoshenko beam. The blade is supported by two translational springs and three rotational springs at each end, and has a shroud that is modelled as a mass at the tip of the blade. The

  8. VIBRATION ANALYSIS OF ELASTICALLY SUPPORTED TURBOMACHINERY BLADES BY THE MODIFIED DIFFERENTIAL QUADRATURE METHOD

    Microsoft Academic Search

    S.-T. CHOI; Y.-T. CHOU

    2001-01-01

    The modified differential quadrature method (MDQM) is proposed for vibration analysis of elastically supported turbomachinery blades. A pre-twisted blade with varying cross-section is modelled as a Timoshenko beam. The blade is supported by two translational springs and three rotational springs at each end, and has a shroud that is modelled as a mass at the tip of the blade. The

  9. A multivariate quadrature based moment method for LES based modeling of supersonic combustion

    NASA Astrophysics Data System (ADS)

    Donde, Pratik; Koo, Heeseok; Raman, Venkat

    2012-07-01

    The transported probability density function (PDF) approach is a powerful technique for large eddy simulation (LES) based modeling of scramjet combustors. In this approach, a high-dimensional transport equation for the joint composition-enthalpy PDF needs to be solved. Quadrature based approaches provide deterministic Eulerian methods for solving the joint-PDF transport equation. In this work, it is first demonstrated that the numerical errors associated with LES require special care in the development of PDF solution algorithms. The direct quadrature method of moments (DQMOM) is one quadrature-based approach developed for supersonic combustion modeling. This approach is shown to generate inconsistent evolution of the scalar moments. Further, gradient-based source terms that appear in the DQMOM transport equations are severely underpredicted in LES leading to artificial mixing of fuel and oxidizer. To overcome these numerical issues, a semi-discrete quadrature method of moments (SeQMOM) is formulated. The performance of the new technique is compared with the DQMOM approach in canonical flow configurations as well as a three-dimensional supersonic cavity stabilized flame configuration. The SeQMOM approach is shown to predict subfilter statistics accurately compared to the DQMOM approach.

  10. A BOUNDARY ELEMENT FORMULATION TO SIMULATE LINEAR CRACKS IN POTENTIAL PROBLEMS WITH THE OPERATIONAL QUADRATURE METHOD

    Microsoft Academic Search

    Carlos Andrés Reyna Vera-Tudela; José Claudio de Faria Telles

    Over the last few years the Boundary Element Method (BEM) has been successfully applied to linear elastic fracture mechanics problems (LEFM), involving static and dynamic cases. An approach to solve LEFM problems is presented in this work. The Numerical Greens Function is used at the fundamental solution together with the Operational Quadrature Method. Proceeding this way, there is no need

  11. Utilization of Mechanical Quadrature in Silicon MEMS Vibratory Gyroscope to Increase and

    E-print Network

    Tang, William C

    Utilization of Mechanical Quadrature in Silicon MEMS Vibratory Gyroscope to Increase and Expand of the long term in-run bias stability of Coriolis vibratory gyroscopes. The approach is based on utilization of the mechanical quadra- ture error in gyroscopes to compensate for variation in system parameters. The proposed

  12. Solution of partial differential equations by a global radial basis function-based differential quadrature method

    Microsoft Academic Search

    C Shu; H Ding; K. S Yeo

    2004-01-01

    The conventional differential quadrature (DQ) method is limited in its application to regular regions by using functional values along a mesh line to approximate derivatives. In this work, we extend the idea of DQ method to a general case. In other words, any spatial derivative is approximated by a linear weighted sum of all the functional values in the whole

  13. Computing extinction maps of star nulling interferometers.

    PubMed

    Hénault, Francois

    2008-03-31

    Herein is discussed the performance of spaceborne nulling interferometers searching for extra-solar planets, in terms of their extinction maps projected on-sky. In particular, it is shown that the designs of Spatial Filtering (SF) and Achromatic Phase Shifter (APS) subsystems, both required to achieve planet detection and characterization, can sensibly affect the nulling maps produced by a simple Bracewell interferometer. Analytical relationships involving cross correlation products are provided and numerical simulations are performed, demonstrating marked differences in the aspect of extinction maps and the values of attained fringes contrasts. It is concluded that depending on their basic principles and designs, FS and APS will result in variable capacities for serendipitous discoveries of planets orbiting around their parent star. The mathematical relationships presented in this paper are assumed to be general, i.e. they should apply to other types of multi-apertures nulling interferometers. PMID:18542551

  14. Exact Integrations of Polynomials and Symmetric Quadrature Formulas over Arbitrary Polyhedral Grids

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel

    1997-01-01

    This paper is concerned with two important elements in the high-order accurate spatial discretization of finite volume equations over arbitrary grids. One element is the integration of basis functions over arbitrary domains, which is used in expressing various spatial integrals in terms of discrete unknowns. The other consists of quadrature approximations to those integrals. Only polynomial basis functions applied to polyhedral and polygonal grids are treated here. Non-triangular polygonal faces are subdivided into a union of planar triangular facets, and the resulting triangulated polyhedron is subdivided into a union of tetrahedra. The straight line segment, triangle, and tetrahedron are thus the fundamental shapes that are the building blocks for all integrations and quadrature approximations. Integrals of products up to the fifth order are derived in a unified manner for the three fundamental shapes in terms of the position vectors of vertices. Results are given both in terms of tensor products and products of Cartesian coordinates. The exact polynomial integrals are used to obtain symmetric quadrature approximations of any degree of precision up to five for arbitrary integrals over the three fundamental domains. Using a coordinate-free formulation, simple and rational procedures are developed to derive virtually all quadrature formulas, including some previously unpublished. Four symmetry groups of quadrature points are introduced to derive Gauss formulas, while their limiting forms are used to derive Lobatto formulas. Representative Gauss and Lobatto formulas are tabulated. The relative efficiency of their application to polyhedral and polygonal grids is detailed. The extension to higher degrees of precision is discussed.

  15. [Design of a compact structure interferometer].

    PubMed

    Shi, Lei; Li, Kai; Gao, Zhi-Fan; Zeng, Li-Bo; Wu, Qiong-Shui

    2013-08-01

    A novel interferometer system based on the combinations of cube-corner reflectors and fixed plane mirrors was designed, the moving mirror drive system was designed and analysed, and its governor PID algorithm was used to ensure that the movement of the moving mirror is collimated, uniform and smooth. The parameters of the optical system of the interferometer and the optical devices were described. Finally, after validation of the experiment, it was indicated that the wave number accuracy, resolution, signal to noise ratio and other key indicators can meet the needs of practical application. PMID:24159897

  16. Low-noise interferometer for microwave radiometry

    NASA Technical Reports Server (NTRS)

    Timbie, P. T.; Wilkinson, D. T.

    1988-01-01

    An interferometer for precision measurements in microwave radiometry is proposed which uses two low-noise heterodyne receivers based on SIS tunnel junction mixers in the 40-50-GHz band. The antenna interference pattern has lobes which lead to positive output signals and lobes which give negative output, and the radiometer measures the difference in the power from these lobes without beam switching or instrument motion. The present system cancels instrumental signals, has a very low 1/f noise in the output, and has a zero outpus signal when viewing a uniform source. It is noted that application of the interferometer may be limited to radiometry with relatively large beams.

  17. Sensitivity of an imaging space infrared interferometer.

    PubMed

    Nakajima, T; Matsuhara, H

    2001-02-01

    We study the sensitivities of space infrared interferometers. We formulate the signal-to-noise ratios of infrared images obtained by aperture synthesis in the presence of source shot noise, background shot noise, and detector read noise. We consider the case in which n beams are combined pairwise at n(n-1)/2 detectors and the case in which all the n beams are combined at a single detector. We apply the results to future missions, Terrestrial Planet Finder and Darwin. We also discuss the potential of a far-infrared interferometer for a deep galaxy survey. PMID:18357026

  18. One-beam interferometer by beam folding.

    PubMed

    Ferrari, José A; Frins, Erna M

    2002-09-01

    A novel one-beam interferometer based on beam folding is described. The device resembles a Mach-Zehnder interferometer in which the two arms are located together in one collimated beam. Different halves of the same beam interfere with the help of a mirror--with its reflecting surface along the axis of the optical system--placed near the focal plane of the imaging lens. Phase-delay control is achieved by application of an electrical potential to a Pockels cell, which permits the use of techniques of phase-stepping interferometry. PMID:12211558

  19. Modeling the imaging process in optical stellar interferometers

    Microsoft Academic Search

    M. Schöller; R. Wilhelm; B. Koehler

    2000-01-01

    Optical interferometers on the ground, like ESO's Very Large Telescope Interferometer (VLTI) and the Keck Interferometer, and in space, like the InfraRed Space Interferometer (IRSI\\/Darwin) and the Space Interferometry Mission (SIM), will bring a major breakthrough in optical and near-infrared high angular resolution astronomy at the beginning of the next millennium. These instruments are complex systems with an exceptionally interdisciplinary

  20. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging

    PubMed Central

    Pang, Yong; Yu, Baiying; Vigneron, Daniel B.

    2014-01-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than –35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla. PMID:24649430

  1. Quadrature transmit array design using single-feed circularly polarized patch antenna for parallel transmission in MR imaging.

    PubMed

    Pang, Yong; Yu, Baiying; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-02-01

    Quadrature coils are often desired in MR applications because they can improve MR sensitivity and also reduce excitation power. In this work, we propose, for the first time, a quadrature array design strategy for parallel transmission at 298 MHz using single-feed circularly polarized (CP) patch antenna technique. Each array element is a nearly square ring microstrip antenna and is fed at a point on the diagonal of the antenna to generate quadrature magnetic fields. Compared with conventional quadrature coils, the single-feed structure is much simple and compact, making the quadrature coil array design practical. Numerical simulations demonstrate that the decoupling between elements is better than -35 dB for all the elements and the RF fields are homogeneous with deep penetration and quadrature behavior in the area of interest. Bloch equation simulation is also performed to simulate the excitation procedure by using an 8-element quadrature planar patch array to demonstrate its feasibility in parallel transmission at the ultrahigh field of 7 Tesla. PMID:24649430

  2. Phase stabilization of laser beams in a cold atom accelerometer

    E-print Network

    Byrne, Nicole (Nicole Malenie)

    2014-01-01

    A cold atom accelerometer measures the displacement of a proof mass of laser cooled atoms with respect to an instrument reference frame. The cold atom interferometer's reference frame is defined by a pair of specially ...

  3. Ultraviolet-excimer laser-based incoherent Doppler lidar system

    NASA Technical Reports Server (NTRS)

    Mcdermid, I. Stuart; Laudenslager, James B.; Rees, David

    1985-01-01

    The topics covered include the following: principles of Doppler measurements, laser backscatter, eye safety, demonstration concepts, the wavelength-meter, the interferometer detector, return signal model, and comparison of incoherent and coherent lidars.

  4. Trade-off between quantum and thermal fluctuations in mirror coatings yields improved sensitivity of gravitational-wave interferometers

    E-print Network

    Voronchev, N V; Khalili, F Ya

    2012-01-01

    We propose a simple way to improve the laser gravitational-wave detectors sensitivity by means of reduction of the number of reflective coating layers of the core optics mirrors. This effects in the proportional decrease of the coating thermal noise, the most notorious among the interferometers technical noise sources. The price for this is the increased quantum noise, as well as high requirements for the pump laser power and power at the beamsplitter. However, as far as these processes depend differently on the coating thickness, we demonstrate that a certain trade-off is possible, yielding a 20-30% gain (for diverse gravitational wave signal types and interferometer configurations), providing that feasible values of laser power and power on the beamsplitter are assumed.

  5. Trade-off between quantum and thermal fluctuations in mirror coatings yields improved sensitivity of gravitational-wave interferometers

    E-print Network

    N. V. Voronchev; S. L. Danilishin; F. Ya. Khalili

    2012-02-29

    We propose a simple way to improve the laser gravitational-wave detectors sensitivity by means of reduction of the number of reflective coating layers of the core optics mirrors. This effects in the proportional decrease of the coating thermal noise, the most notorious among the interferometers technical noise sources. The price for this is the increased quantum noise, as well as high requirements for the pump laser power and power at the beamsplitter. However, as far as these processes depend differently on the coating thickness, we demonstrate that a certain trade-off is possible, yielding a 20-30% gain (for diverse gravitational wave signal types and interferometer configurations), providing that feasible values of laser power and power on the beamsplitter are assumed.

  6. An electron Talbot-Lau interferometer and magnetic field sensing

    SciTech Connect

    Bach, Roger; Batelaan, Herman [Department of Physics and Astronomy, University of Nebraska-Lincoln, Theodore P. Jorgensen Hall, Lincoln, Nebraska 68588 (United States)] [Department of Physics and Astronomy, University of Nebraska-Lincoln, Theodore P. Jorgensen Hall, Lincoln, Nebraska 68588 (United States); Gronniger, Glen [The National Secure Manufacturing Center (NSMC), National Nuclear Security Administration's Kansas City Plant, National Security Campus, 14520 Botts Road, Kansas City, Missouri 64147 (United States)] [The National Secure Manufacturing Center (NSMC), National Nuclear Security Administration's Kansas City Plant, National Security Campus, 14520 Botts Road, Kansas City, Missouri 64147 (United States)

    2013-12-16

    We present a demonstration of a three grating Talbot-Lau interferometer for electrons. As a proof of principle, the interferometer is used to measure magnetic fields. The device is similar to the classical Moiré deflectometer. The possibility to extend this work to build a scaled-up electron deflectometer or interferometer for sensitive magnetic field sensing is discussed.

  7. Phase conjugate Twyman-Green interferometer for testing conicoidal surfaces

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Dokhanian, Mostafa; Venkateswarlu, Putcha; George, M. C.

    1990-01-01

    An application of a phase conjugate Twyman-Green interferometer for testing a parabolic mirror is demonstrated. The interferometer is free from aberrations due to the self-focusing property of the phase conjugate mirror in one arm of the interferometer. It does not require a precision spherical mirror in the reference arm.

  8. A microwave interferometer radar for spacecraft rendezvous missions

    Microsoft Academic Search

    Werner Koppl; Rusty Smith

    1986-01-01

    A microwave interferometer docking radar is described. This system employs a pulse radar to measure the relative angles between two spacecraft at close ranges. A phase interferometer is implemented to provide accurate measurements of the angular location of the target spacecraft. A preliminary design of an interferometer radar is performed to illustrate the advantages of this approach.

  9. An electron Talbot-Lau interferometer and magnetic field sensing

    NASA Astrophysics Data System (ADS)

    Bach, Roger; Gronniger, Glen; Batelaan, Herman

    2013-12-01

    We present a demonstration of a three grating Talbot-Lau interferometer for electrons. As a proof of principle, the interferometer is used to measure magnetic fields. The device is similar to the classical Moiré deflectometer. The possibility to extend this work to build a scaled-up electron deflectometer or interferometer for sensitive magnetic field sensing is discussed.

  10. Control of Formation-Flying Multi-Element Space Interferometers with Direct Interferometer-Output Feedback

    NASA Technical Reports Server (NTRS)

    Lu, Hui-Ling; Cheng, Victor H. L.; Lyon, Richard G.; Carpenter, Kenneth G.

    2007-01-01

    The long-baseline space interferometer concept involving formation flying of multiple spacecrafts holds great promise as future space missions for high-resolution imagery. A major challenge of obtaining high-quality interferometric synthesized images from long-baseline space interferometers is to accurately control these spacecraft and their optics payloads in the specified configuration. Our research focuses on the determination of the optical errors to achieve fine control of long-baseline space interferometers without resorting to additional sensing equipment. We present a suite of estimation tools that can effectively extract from the raw interferometric image relative x/y, piston translational and tip/tilt deviations at the exit pupil aperture. The use of these error estimates in achieving control of the interferometer elements is demonstrated using simulated as well as laboratory-collected interferometric stellar images.

  11. Spatial phase-shifting lateral shearing interferometer

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoxian; Zeng, Aijun; Huang, Huijie

    2008-12-01

    The phase-shifting lateral shearing interferometer is widely adopted for wavefront measurement with high accuracy. For real-time wavefront measurement, a spatial phase-shifting lateral shearing interferometer is proposed. The interferometer includes a polarization lateral shearing module, a spatial phase-shifting module and an imaging module. The polarization lateral shearing module consists of a Savart polariscope. The spatial phase-shifting module is component of a non-polarization beam splitter, a polarization beam splitter, two rectangular prisms and a half wave-plate. The imaging module includes an imaging system and a CCD. The measured wavefront is sheared by the polarization lateral shearing module. The polarization directions of the two shearing beams are perpendicular to each other. The two shearing beams are split into four groups of beams by the spatial phase-shifting module to form four interferograms in a 2x2 matrix. The phase step of the four interferograms is 90 degrees. The four interferograms are captured in a single frame image by the imaging module. In experiments, a spherical wavefront with large radius of curvature was measured. Four spatial phase-shifting interferograms of the wavefront was obtained simultaneously. The usefulness of the interferometer is verified.

  12. A Novel Vector Microwave Phase Interferometer

    Microsoft Academic Search

    Jan Zela; Karel Hoffmannn; Premysl Hudec

    2006-01-01

    The paper describes a concept of a novel vector microwave phase interferometer based on a vector network analyzer system. The instrument is designed for fast vector measurements of a space distribution of an interference electromagnetic field using a matrix of antennas. It is supposed to be used in non-contact deformation and non-homogeneity measurements in civil engineering and other areas. Results

  13. Control system of the VLT Interferometer

    Microsoft Academic Search

    Massimo Verola

    1998-01-01

    During an interferometric observation the successful coordination of all the complex and heterogeneous devices of the VLT interferometer (VLTI) depends on the effectiveness and reliability of the control system, which carries out the ultimate system integration. The VLTI control system (VLTICS) is designed to satisfy both specific technical requirements and general operational constraints. It profits by the valuable experience gained

  14. Multipass holographic interferometer improves image resolution

    NASA Technical Reports Server (NTRS)

    Brooks, R. E.; Heflinger, L. O.

    1970-01-01

    Multipass holographic interferometer forms a hologram of high diffraction efficiency, and hence provides a bright and high contrast interferogram. It is used to study any effect which changes the index of refraction and to study surface deformations of a flat reflecting surface.

  15. Analysis of a Twophoton Interferometer Frank Rioux

    E-print Network

    Rioux, Frank

    , an atom simultaneously emits identical photons to the east and west. Two paths (long and short) are available to detectors A and B in the east and west arms of the interferometer. The short paths are the same on both sides, but the long paths can have different lengths causing phase differences for the east

  16. The VIRGO interferometer for gravitational wave detection

    Microsoft Academic Search

    V. Ferrari; E. Majorana; P. Puppo; P. Rapagnani; F. Ricci; F. Marion; L. Massonnet; C. Mehmel; R. Morand; B. Mours; V. Sannibale; M. Yvert; D. Babusci; S. Bellucci; S. Candusso; G. Giordano; G. Matone; J.-M. Mackowski; L. Pinard; F. Barone; E. Calloni; L. di Fiore; M. Flagiello; F. Garuti; A. Grado; M. Longo; M. Lops; S. Marano; L. Milano; S. Solimeno; V. Brisson; F. Cavalier; M. Davier; P. Hello; P. Heusse; P. Mann; Y. Acker; M. Barsuglia; B. Bhawal; F. Bondu; A. Brillet; H. Heitmann; J.-M. Innocent; L. Latrach; C. N. Man; M. Pham-Tu; E. Tournier; M. Taubmann; J.-Y. Vinet; C. Boccara; Ph. Gleyzes; V. Loriette; J.-P. Roger; G. Cagnoli; L. Gammaitoni; J. Kovalik; F. Marchesoni; M. Punturo; M. Beccaria; M. Bernardini; E. Bougleux; S. Braccini; C. Bradaschia; G. Cella; A. Ciampa; E. Cuoco; G. Curci; R. del Fabbro; R. de Salvo; A. di Virgilio; D. Enard; I. Ferrante; F. Fidecaro; A. Giassi; A. Giazotto; L. Holloway; P. La Penna; G. Losurdo; S. Mancini; M. Mazzoni; F. Palla; H.-B. Pan; D. Passuello; P. Pelfer; R. Poggiani; R. Stanga; A. Vicere; Z. Zhang

    1997-01-01

    The Virgo gravitational wave detector is an interferometer with 3 km long arms in construction near Pisa in Italy. The accessible sources at the design sensitivity and main noises are reviewed. Virgo has devoted a significant effort to extend sensitivity to low frequency reaching the strain level h~ = 10-21 Hz-1\\/2 at 10 Hz while at 200 Hzh~ = 3

  17. A stellar interferometer on the Moon

    Microsoft Academic Search

    Irene Porro

    1997-01-01

    The work I present in this document has been divided into two main parts, the first one related to the IOTA project and the second one related to the study on the lunar interferometer, and an introduction section. Each section can be read independently from the other, however they are presented following the logical order in which the research work

  18. Overview of the Palomar Testbed Interferometer

    NASA Astrophysics Data System (ADS)

    Colavita, M. M.

    1999-12-01

    The Palomar Testbed Interferometer (PTI) is a long baseline near-IR interferometer developed by JPL for NASA and installed at Palomar Observatory; first fringes were obtained in 1995. PTI serves as a testbed for other interferometer projects, especially the Keck Interferometer. PTI is capable of high accuracy fringe amplitude measurements at H and K using active fringe tracking over its 110-m baseline. Good visibilities are routinely obtained on sources as faint as 5.5 mK, with visibility calibration accuracies of 1.5-2% on brighter sources. The instrument is highly automated, and up to 100 130-sec scans per night are possible, allowing efficient pursuit of "amplitude" science on single and binary stars, and driving the development of automated planning, analysis, and archiving tools. PTI also incorporates a dual-star capability to enable high accuracy narrow-angle differential astrometry. From measurements of a bright visual binary, short-term precisions which correspond to a noise floor of less than 50 uas in an hour have been achieved, along with night-to-night positional repeatability of 100 uas over a 7-night run.

  19. A simple laser system for atom interferometry S. Merlet, L. Volodimer, M. Lours, F. Pereira Dos Santos

    E-print Network

    Boyer, Edmond

    A simple laser system for atom interferometry S. Merlet, L. Volodimer, M. Lours, F. Pereira Dos We present here a simple laser system for a laser cooled atom interferometer, where all functions (laser cooling, interferometry and detection) are realized using only two extended cavity laser diodes

  20. Space interferometry application of laser frequency stabilization with molecular iodine

    Microsoft Academic Search

    Volker Leonhardt; Jordan B. Camp

    2006-01-01

    A number of planned space interferometry missions, including the Laser Interferometer Space Antenna (LISA) gravitational wave detector, require a laser system with high-frequency stability over long time scales. A 1064 nm wavelength nonplanar ring oscillator (NPRO) laser stabilized to a resonant transition in molecular iodine is suitable for these missions, providing high-frequency stability at an absolute reference frequency. The iodine