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1

A precise and wide-dynamic-range displacement-measuring homodyne quadrature laser interferometer  

NASA Astrophysics Data System (ADS)

We present a fast, displacement-measuring, single-pass, two-detector homodyne quadrature laser interferometer and compare its performance with an arm-compensated, proportional, integral-derivative-controlled Michelson interferometer. Special attention is given to the extension of the dynamic range. The wide dynamic range is achieved by an accurate fringe subdivision based on an enhanced ellipse-specific fitting of the scattered Lissajous curve and by increasing the total displacement using the quadrature-detection technique. The common periodic deviations, i.e., the unequal AC amplitudes, the DC offsets, and the lack of quadrature are determined and reduced by data processing based on an ellipse-specific, least-squares fitting to obtain nanometric accuracy. The performance of the described interferometer is demonstrated through the measurement of high-amplitude and high-frequency laser-induced ultrasound.

Požar, T.; Gregor?i?, P.; Možina, J.

2011-11-01

2

Robust Laser-Ultrasonic Interferometer Based on Random Quadrature Demodulation  

NASA Astrophysics Data System (ADS)

The new interferometric scheme that was presented at last year QNDE conference for robust and sensitive detection of ultrasound in industrial environment has been further improved. The proposed architecture combines quadrature detection with detector arrays for multi-speckle processing. The quadrature is reached tanks to the random phase distribution of the speckle light and the parallel signal processing is simplified by using an approximated demodulation technique based on signal rectification. Results demonstrating this new principle of operation and its performances are presented.

Pouet, B.; Breugnot, S.; Clémenceau, P.

2006-03-01

3

A precise and wide-dynamic-range displacement-measuring homodyne quadrature laser interferometer  

Microsoft Academic Search

We present a fast, displacement-measuring, single-pass, two-detector homodyne quadrature laser interferometer and compare\\u000a its performance with an arm-compensated, proportional, integral-derivative-controlled Michelson interferometer. Special attention\\u000a is given to the extension of the dynamic range. The wide dynamic range is achieved by an accurate fringe subdivision based\\u000a on an enhanced ellipse-specific fitting of the scattered Lissajous curve and by increasing the total

T. Pozar; P. Gregorcic; J. Mozina

2011-01-01

4

Quadrature phase interferometer for high resolution force spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

5

Optimization of displacement-measuring quadrature interferometers considering the real properties of optical components  

SciTech Connect

We present the influence of alignment and the real properties of optical components on the performance of a two-detector homodyne displacement-measuring quadrature laser interferometer. An experimental method, based on the optimization of visibility and sensitivity, was established and theoretically described to assess the performance and stability of the interferometer. We show that the optimal performance of such interferometers is achieved with the iterative alignment procedure described.

Pozar, Tomaz; Gregorcic, Peter; Mozina, Janez

2011-03-20

6

Stable generation of quadrature entanglement using a ring interferometer  

SciTech Connect

We propose and demonstrate a scheme to stably generate quadrature-entangled optical pulses using a ring interferometer composed of an optical parametric amplifier and a dispersive media. The entangled light pulses at telecommunication wavelength are generated by combining two squeezed beams. In our scheme, the relative phase between the two beams is kept stable by the ring interferometer and is controllable using dispersive media. The amplitude and phase quadratures of the entangled beams are measured using two time-domain pulsed homodyne detectors. When the relative phase is fixed at {pi}/2, we verify the inseparability of the states by a sufficient criterion <{delta}{sup 2}[X{sub a}({phi}{sub 0})+X{sub b}({pi}-{phi}{sub 0})]>+<{delta}{sup 2}[X{sub a}({phi}{sub 0}{sup '})-X{sub b}(-{phi}{sub 0}{sup '})]>=0.64<1 where {phi}{sub 0}{sup '}-{phi}{sub 0}={pi}/2.

Eto, Yujiro; Nonaka, Akihiro; Hirano, Takuya [Department of Physics, Gakushuin University, Mejiro 1-5-1, Toshima-ku, Tokyo 171-8588 (Japan); CREST, Japan Science and Technology Agency, 1-9-9 Yaesu, Chuo-ku, Tokyo 103-0028 (Japan); Zhang Yun [Department of Electronic Engineering, The University of Electro-Communications, 1-5-1 Chofu-gaoka, Chofu-shi, Tokyo 182-8585 (Japan)

2009-05-15

7

Quadrature outputs from fiber interferometer with 4 x 4 coupler.  

PubMed

A broad stripe waveguide of width W and length L acts as a self-imaging 4 x 4 directional coupler if L = NW(2)/lambda, where N is the effective index. When the arms of a fiber-optic Mach-Zehnder interferometer are connected to two input ports of this coupler, the powers at the four output ports vary in phase quadrature. PMID:19738726

Niemeier, T; Ulrich, R

1986-10-01

8

Quantitative phase imaging using grating-based quadrature phase interferometer  

NASA Astrophysics Data System (ADS)

In this paper, we report the use of holographic gratings, which act as the free-space equivalent of the 3x3 fiber-optic coupler, to perform full field phase imaging. By recording two harmonically-related gratings in the same holographic plate, we are able to obtain nontrivial phase shift between different output ports of the gratings-based Mach-Zehnder interferometer. The phase difference can be adjusted by changing the relative phase of the recording beams when recording the hologram. We have built a Mach-Zehnder interferometer using harmonically-related holographic gratings with 600 and 1200 lines/mm spacing. Two CCD cameras at the output ports of the gratings-based Mach-Zehnder interferometer are used to record the full-field quadrature interferograms, which are subsequently processed to reconstruct the phase image. The imaging system has ~12X magnification with ~420µmx315µm field-of-view. To demonstrate the capability of our system, we have successfully performed phase imaging of a pure phase object and a paramecium caudatum.

Wu, Jigang; Yaqoob, Zahid; Heng, Xin; Cui, Xiquan; Yang, Changhuei

2007-03-01

9

Calculation method for a quadrature phase-shifting interferometer and its applications.  

PubMed

A calculation method for a quadrature phase-shifting interferometer is presented, and its applications to specular and speckle interferometers and digital holography are described. Two sets of quadrature phase-shifted interferograms are acquired, and the calculation method proposed gives the phase distribution of the interferograms. The principle of the calculation method with error analysis and experimental results for specular and speckle interferometers and digital holography are also given. PMID:23292421

Nakadate, Suezou; Sawada, Shinya; Kiire, Tomohiro; Shibuya, Masato; Yatagai, Toyohiko

2013-01-01

10

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

PubMed Central

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).

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

2012-01-01

11

An Innovative Interferometer for Industrial Laser Ultrasonic Inspection  

NASA Astrophysics Data System (ADS)

A novel interferometric scheme for robust and sensitive detection of ultrasound is presented. The proposed technique combines a classical Michelson interferometer design and an innovative multi-speckle processing technique. Multiple Michelson interferometers are integrated into a compact design, each interferometer operating on only few speckles. A compact design is achieved through the use of detector arrays and parallel processing. To overcome the requirement on path stabilization, quadrature demodulation is implemented. The performance of this multi-detector interferometer is described and its advantage for measurement in industrial environments is discussed.

Pouet, B.; Breugnot, S.; Clémenceau, P.

2005-04-01

12

Lattice Interferometer for Laser-Cooled Atoms  

SciTech Connect

We demonstrate an atom interferometer in which atoms are laser cooled into a 1D optical lattice, suddenly released, and later subjected to a pulsed optical lattice. For short pulses, a simple analytical theory predicts the signal. We investigate both short and longer pulses where the analytical theory fails. Longer pulses yield higher precision and larger signals, and we observe a coherent signal at times that can differ significantly from the expected echo time. The interferometer has potential for precision measurements of (Planck constant/2pi)/m{sub A}, and can probe the dynamics of atoms in an optical lattice.

Andersen, Mikkel F.; Sleator, Tycho [Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8424 (United States) and Jack Dodd Center for Quantum Technology, Department of Physics, University of Otago (New Zealand); Department of Physics, New York University, 4 Washington Place, New York, New York 10003 (United States)

2009-08-14

13

Arm Locking for the Laser Interferometer Space Antenna.  

National Technical Information Service (NTIS)

The Laser Interferometer Space Antenna (LISA) mission is a planned gravitational wave detector consisting of three spacecraft in heliocentric orbit. Laser interferometry is used to measure distance fluctuations between test masses aboard each spacecraft t...

J. Livas J. I. Thorpe P. G. Maghami

2009-01-01

14

The absolute measuring accuracy of technical laser interferometers  

NASA Astrophysics Data System (ADS)

The development of instruments and calibration methods for laser light sources for measurement of the refractive index of air and the calibration of laser interferometers are described. The development and calibration procedure for He-Ne stabilized lasers are described, with emphasis on the reproduction limits of this light source and the shift in the absorption lines. The measurement of the frequency of He-Ne laser light sources, including warming-up effects, stability and reproducibility, are discussed. An interference refractometer was developed and successfully tested for the calibration of automatic refractive index change compensators, used with technical laser interferometers. A procedure for the comparison of technical laser interferometers is presented; it has an accuracy better than 1 part in 10 million. A test procedure for the counting system of Zeeman laser interferometers is presented.

Schellekens, Petrus Henricus Johannes

15

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

SciTech Connect

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 nonrelativistic 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.

Roura, Albert; Brill, Dieter R.; Hu, B.L.; Misner, Charles W. [Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States); Phillips, William D. [Department of Physics, University of Maryland, College Park, Maryland 20742-4111 (United States); National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8424 (United States)

2006-04-15

16

Experimental generation of broadband quadrature entanglement using laser pulses  

SciTech Connect

We report on the generation of broadband pulsed quadrature entanglement by combining two squeezed vacua, which are generated from two degenerate optical parametric amplifiers (OPAs), on a beam splitter. With a single pass through OPA, in which a periodically poled lithium niobate waveguide is used as a nonlinear material, the noise reduction of 3.4{+-}0.2 dB below the shot noise limit is observed with a bandwidth of more than 200 MHz. The entanglement correlation or EPR correlation is confirmed with a sufficient criterion <{delta}{sup 2}(X{sub a}+X{sub b})>+<{delta}{sup 2}(Y{sub a}-Y{sub b})>=1.28<2.

Zhang, Yun; Furuta, Tatsuya; Okubo, Ryuhi; Takahashi, Kosuke; Hirano, Takuya [Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan CREST, Japan Science and Technology Agency, 1-9-9 Yaesu, Chuo-ku, Tokyo, 103-0028 (Japan)

2007-07-15

17

Dispersion Interferometer Based on CO{sub 2} Laser  

SciTech Connect

A dispersion interferometer based on CO{sub 2} laser for measurements of plasma line density in the gas dynamic trap (GDT) experiment has been developed with sensitivity {sub min} {approx} 1.10{sup 13} cm{sup -2}, temporal resolution {approx}50 ns. The main advantages of the interferometer are compactness and low sensitivity to vibrations. The interferometer does not require specific vibration isolation structure and can be mounted directly on the working chamber of the plasma device. The above mentioned advantages have been successfully demonstrated in the Gas Dynamic Trap experiments.

Bagryansky, P.A. [Budker Institute of Nuclear Physics (Russian Federation); Khilchenko, A.D. [Budker Institute of Nuclear Physics (Russian Federation); Lizunov, A.A. [Budker Institute of Nuclear Physics (Russian Federation); Maximov, V.V. [Budker Institute of Nuclear Physics (Russian Federation); Solomakhin, A.L. [Novosibirsk State University (Russian Federation); Voskoboynikov, R.V. [Budker Institute of Nuclear Physics (Russian Federation)

2005-01-15

18

Research of measurement assurance program (MAP) for laser interferometer  

NASA Astrophysics Data System (ADS)

A multi-parameter Measurement Assurance Program (MAP) aim at laser interferometer is discussed detailedly in this paper. Firstly, we summarize the basic implementation process of MAP. After analyzing the measurement parameters of the laser interferometer, we design a set of transfer standard and check standard. Then, the mathematical statistic model of the whole MAP process is presented including the statistic process control and the evaluation of the measurement uncertainty. Lastly, we demonstrate the MAP software we programmed for this process in order to facilitate the implementation. It's clear that our MAP implementation has greatly improved the attending laboratories' confidence for their measurement results.

Feng, Yue; Chen, Lingfeng; Ren, JianRong; Sha, Dingguo

2003-09-01

19

LIGO - The Laser Interferometer Gravitational-Wave Observatory  

Microsoft Academic Search

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,

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

20

Arm locking for the Laser Interferometer Space Antenna  

NASA Astrophysics Data System (ADS)

The Laser Interferometer Space Antenna mission is a planned gravitational wave detector consisting of three spacecraft in heliocentric orbit. Laser interferometry is used to measure distance fluctuations between test masses aboard each spacecraft to the picometer level over a 5 million kilometer separation. Laser frequency fluctuations must be suppressed in order to meet the measurement requirements. Arm-locking, a technique that uses the constellation of spacecraft as a frequency reference, is a proposed method for stabilizing the laser frequency. We consider the problem of arm-locking using classical optimal control theory and find that our designs satisfy the LISA requirements.

Maghami, P. G.; Thorpe, J. I.; Livas, J.

2009-08-01

21

Sinusoidal phase modulating laser diode interferometer using an additive operating type of integrating bucket method  

NASA Astrophysics Data System (ADS)

We propose a sinusoidal phase modulating laser diode interferometer using an additive operating type of integrating bucket method. In previous integrating bucket method, four images, which are integrated values of the interference pattern detected by a CCD image sensor, are required. According to additive and subtractive operations in a calculator, the quadrature signals can be calculated from these images. While these operations are associated with the technical computing software, such as MATLAB, in a personal computer, it is quite fast, even if the images possess large size. In a standard-alone system with a CPU, however, this kind of operation expends unbearable time. To lighten the burden of the calculator, we tried to simplify the operation. That is, on the basis of integrating bucket method, the subtraction in the signal processing is transformed to the addition by use of the phase shifting technique. All additive operations are achieved with the CCD image sensor. In this interferometer, not only the calculating quantity is reduced, but also the number of required images is reduced. The surface profile of a diamond-turned aluminum disk was measured. The repeatability in the measurements was 5.93 nm rms.

Zhao, Xuefeng; Suzuki, Takamasa; Sasaki, Osami

2002-09-01

22

Status of the GRACE Follow-On Laser Ranging Interferometer  

NASA Astrophysics Data System (ADS)

The Laser Ranging Interferometer (LRI) is an experimental instrument currently being developed for GRACE Follow-on by a US/German collaboration, with contributions from Australia. The LRI will be implemented such that it can operate in parallel with the microwave instrument which will provide the primary measurement of the inter-satellite range variations. In addition to providing additional ranging data with higher precision compared to the microwave instrument the LRI can also produce pointing information for the angles perpendicular to the line-of-sight between the two satellites. The laser interferometry technology that will be demonstrated by the LRI is of particular interest to future gravity field missions based on inter-satellite ranging. The LRI instrument is based on technology developed for GRACE 2 and the Laser Interferometer Space Antenna (LISA), a proposed space based gravitational wave detector. This presentation will give an overview of the design and current status of the development of the instrument.

Sheard, Benjamin

2013-04-01

23

Laser exposure analysis for a near-infrared ocular interferometer  

NASA Astrophysics Data System (ADS)

Ocular interferometry has potential value in a variety of ocular measurement applications, including measuring ocular thicknesses, topography of ocular surfaces or the wavefront of the eye. Of particular interest is using interferometry for characterizing corneal shape and irregular corneal features, making this technology attractive due to its inherent accuracy and spatial resolution. A particular challenge of designing an ocular interferometer is determining safe laser exposure levels to the eye, including both the retina and anterior segment. Described here are the laser exposure standards relevant in the interferometer design and the corresponding calculations and results. The results of this work can be used to aid in the design of similar laser-based systems for ocular evaluation.

Primeau, Brian C.; Goldstein, Goldie L.; Greivenkamp, John E.

2012-06-01

24

Measuring large amplitudes of mechanical vibrations with laser interferometers  

NASA Astrophysics Data System (ADS)

Heterodyne methods of laser interferometry are the most promising methods of measuring large mechanical vibrations, their main advantages being that they are contactless and remote operational, and their main features being high accuracy and reproducibility of readings. However, use of a square-law photodetector and a frequency detector with a laser interferometer requires conversion to single-frequency laser radiation to two-frequency one. An attendant problem is to provide a stable and efficient wideband heterodyne with wide dynamic range for a reference signal with a Doppler frequency shift sufficiently large relative to the frequency of the probing signal. One known method of such interferometry which meets these requirements involves use of an oscillograph and an electronic-counter frequency meter. The principle of this method is outlined on the example of one mirror of a two-beam interferometer, assuming that its vibrations are harmonic. The interferometer for this application consists of a light splitter, a reference mirror, and a movable mirror with a Teflon membrane controlled by a sine-wave generator. The light source is an LG-79/1 He-Ne laser. The photodetector is an FD-21 KP photodiode with a time constant of 6 ns. Vibrations are measured with a Ch3-34A frequency meter.

Bondarenko, A. N.; Trotsenko, V. P.

1984-09-01

25

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

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

26

Laser Interferometer for a spaceborne mapping of the Earth  

NASA Astrophysics Data System (ADS)

The Gravity Recovery and Climate Experiment (GRACE) is one of the present missions to map the Earth's gravity field. The aim of a GRACE follow-on mission is to map the gravitational field of the Earth with higher resolution over at least 6 years. This should lead to a deeper insight into geophysical processes of the Earth's system. One suggested detector for this purpose consists of two identical spacecraft carrying drag-free test masses in a low Earth orbit at an altitude of the order of 300 km, following each other with a distance of about 10 to 100 km. Changes in the Earth's gravity field will induce distance fluctuations between two test masses on separate spacecraft. These variations are to be monitored by a laser interferometer with nanometer precision in the frequency range between 1 mHz and 100 mHz. The relative velocity between the spacecraft induces a Doppler shift in the interferometer beatnote. This effect together with the large variations in the inter-spacecraft separation make heterodyne interferometry ideally suitable as the pathlength readout scheme. The round-trip Doppler shift introduces variations in the interferometer beatnote up to a few 100 kHz. A suitable heterodyne frequency is therefore between several hundred kHz and a few MHz, with the lower limit given by the maximal Doppler shift and the required control bandwidth of the offset phase lock. The upper limit is given by technical considerations concerning the photodiodes and the phasemeter. We benefit a lot from the current developments for the joint ESA-NASA space-based gravitational-wave detector "Laser Interferometer Space Antenna" (LISA) and its precursor mission LISA Pathfinder, such as a precise drag-free technology and the interferometric readout. We present preliminary results of an interferometric readout using a heterodyne configuration with polarising optics, demonstrating the required phase sensitivity.

Dehne, M.; Sheard, B.; Guzmán Cervantes, F.; Heinzel, G.; Danzmann, K.

2009-04-01

27

Using a laser interferometer to check measuring heads and transducers  

SciTech Connect

This paper describes the use of laser interferometers to check precision measuring heads and transducers. Laser interferometers combine high accuracy with a wide measurement range. The apparatus described in this paper uses a two-channel phase laser measuring system based on the IPL-10m.52 instrument. A diagram of the apparatus is shown. An LG-77 laser is used as the light source. The acousto-optic modulator is in the form of an optically transparent multihedral prism with an even number of faces filled with M-40 antifreeze, one of whose bases has a piezoelectric transmitter while the other has an absorber. The reflection coefficient of the ultrasonic wave does not exceed 0.0015. The error of this apparatus was found by first-class end measures by the pair method in ranges of 1, 10, 100 and 1000 micrometers. The obtained error values for these ranges did not exceed 7 nm. When the apparatus is used to check precision heads, the productivity is increased by a factor of four or five, as compared with checking with end measures of length.

Gorokhov, L.Ya.

1985-04-01

28

Investigations on the frequency measuring error of laser Doppler velocimeters using the quadrature demodulation technique  

NASA Astrophysics Data System (ADS)

We present the application of the quadrature demodulation technique (QDT) for time-resolved frequency measurements in laser Doppler velocimetry (LDV). In contrast to conventional frequency estimators like FFT, the QDT allows the determination of the Doppler frequency nearly independent of the number of the occurring signal periods, so that a high time resolution can be achieved. The resulting frequency error of the QDT is investigated in dependence on relevant LDV signal parameters like SNR and time duration. Furthermore, the optimum averaging time for the processing of gaussian burst signals was determined. The minimum frequency uncertainty of the QDT occurs for an averaging time of the approximately equals 1/e burst duration at the thermal noise, and the approximately equals 1/e2 burst duration at shot noise, respectively.

Czarske, Juergen W.; Doelle, O.

1999-07-01

29

Simultaneous reception of both quadratures of 40Gb\\/s DQPSK using a simple monolithic demodulator  

Microsoft Academic Search

We demonstrate a novel device that demodulates both quadratures of the optical differential quadrature phase shift keying (DQPSK) format in a single interferometer. We present simultaneous measurements of both DQPSK quadratures at 42.7-Gb\\/s.

C. R. Doerr; D. M. Gill; A. H. Gnauck; L. L. Buhl; P. J. Winzer; M. A. Cappuzzo; A. Wong-Foy; E. Y. Chen; L. T. Gomez

2005-01-01

30

Self-oscillating operating modes of a laser oscillating Mach-Zehnder interferometer  

Microsoft Academic Search

Operating modes of a laser oscillating Mach-Zehnder interferometer which is a simplified version of the fiber-optic laser oscillating Mach-Zehnder interferometer proposed by Grigor'yants et al. (1988) and Grigor'yants and Il'in (1989), were investigated experimentally. Out of the total set of possible operating modes of the interferometer, a single-frequency steady-state operating mode was identified. This mode is of paramount importance for

T. V. Babkina; V. V. Grigor'iants; Iu. B. Il'In; V. A. Prokof'ev

1991-01-01

31

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

SciTech Connect

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)

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

2011-07-31

32

The laser interferometer system for the large optics diamond turning machine  

SciTech Connect

The purpose of this report is to describe the Laser Interferometer System designed for the Large Optics Diamond Turning Machine (LODTM). To better understand the laser interferometer system, it is useful to begin with an overview of the LODTM metrology system.

Baird, E D; Donaldson, R R; Patterson, S R

1999-06-29

33

Multicomponent wavefield characterization with a novel scanning laser interferometer  

SciTech Connect

The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.

Blum, Thomas E.; Wijk, Kasper van [Department of Geosciences, Boise State University, 1910 University Drive, Boise, Idaho 83725 (United States); Pouet, Bruno; Wartelle, Alexis [Bossa Nova Technologies LLC, 606 Venice Blvd., Suite B, Venice, California 90291 (United States)

2010-07-15

34

LIGO: the Laser Interferometer Gravitational-Wave Observatory  

NASA Astrophysics Data System (ADS)

The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves (GWs) of astrophysical origin. Direct detection of GWs holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black holes 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 one part in 1021. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on GWs from a variety of potential astrophysical sources.

Abbott, B. P.; Abbott, R.; Adhikari, R.; Ajith, P.; Allen, B.; Allen, G.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Arain, M. A.; Araya, M.; Armandula, H.; Armor, P.; Aso, Y.; Aston, S.; Aufmuth, P.; Aulbert, C.; Babak, S.; Baker, P.; Ballmer, S.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barsotti, L.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Behnke, B.; Benacquista, M.; Betzwieser, J.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Bodiya, T. P.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Bridges, D. O.; Brinkmann, M.; Brooks, A. F.; Brown, D. A.; Brummit, A.; Brunet, G.; Bullington, A.; Buonanno, A.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Camp, J. B.; Cannizzo, J.; Cannon, K. C.; Cao, J.; Cardenas, L.; Caride, S.; Castaldi, G.; Caudill, S.; Cavaglià, M.; Cepeda, C.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Christensen, N.; Chung, C. T. Y.; Clark, D.; Clark, J.; Clayton, J. H.; Cokelaer, T.; Colacino, C. N.; Conte, R.; Cook, D.; Corbitt, T. R. C.; Cornish, N.; Coward, D.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Culter, R. M.; Cumming, A.; Cunningham, L.; Danilishin, S. L.; Danzmann, K.; Daudert, B.; Davies, G.; Daw, E. J.; DeBra, D.; Degallaix, J.; Dergachev, V.; Desai, S.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doomes, E. E.; Drever, R. W. P.; Dueck, J.; Duke, I.; Dumas, J.-C.; Dwyer, J. G.; Echols, C.; Edgar, M.; Effler, A.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Faltas, Y.; Fan, Y.; Fazi, D.; Fehrmenn, H.; Finn, L. S.; Flasch, K.; Foley, S.; Forrest, C.; Fotopoulos, N.; Franzen, A.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Garofoli, J. A.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grimaldi, F.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hammond, G. D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Haughian, K.; Hayama, K.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hodge, K. A.; Holt, K.; Hosken, D. J.; Hough, J.; Hoyland, D.; Hughey, B.; Huttner, S. H.; Ingram, D. R.; Isogai, T.; Ito, M.; Ivanov, A.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kanner, J.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khan, R.; Khazanov, E.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Kozak, D.; Krishnan, B.; Kumar, R.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lei, H.; Lei, M.; Leindecker, N.; Leonor, I.; Li, C.; Lin, H.; Lindquist, P. E.; Littenberg, T. B.; Lockerbie, N. A.; Lodhia, D.; Longo, M.; Lormand, M.; Lu, P.; Lubi?ski, M.; Lucianetti, A.; Lück, H.; Machenschalk, B.; MacInnis, M.; Mageswaran, M.; Mailand, K.; Mandel, I.; Mandic, V.; Márka, S.; Márka, Z.; Markosyan, A.; Markowitz, J.; Maros, E.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McIntyre, G.; McKechan, D. J. A.; McKenzie, K.; Mehmet, M.; Melatos, A.; Melissinos, A. C.; Menéndez, D. F.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miller, J.; Minelli, J.; Mino, Y.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Mohanty, S. D.; Mohapatra, S. R. P.; Moreno, G.; Morioka, T.; Mors, K.; Mossavi, K.; Mow Lowry, C.; Mueller, G.; Müller-Ebhardt, H.; Muhammad, D.; Mukherjee, S.; Mukhopadhyay, H.; Mullavey, A.; Munch, J.; Murray, P. G.; Myers, E.; Myers, J.; Nash, T.; Nelson, J.; Newton, G.; Nishizawa, A.; Numata, K.; O'Dell, J.; O'Reilly, B.; O'Shaughnessy, R.; Ochsner, E.; Ogin, G. H.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pan, Y.; Pankow, C.; Papa, M. A.; Parameshwaraiah, V.; Patel, P.; Pedraza, M.; Penn, S.; Perraca, A.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Postiglione, F.; Principe, M.; Prix, R.; Prokhorov, L.; Punken, O.; Quetschke, V.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raics, Z.; Rainer, N.; Rakhmanov, M.; Raymond, V.; Reed, C. M.; Reed, T.; Rehbein, H.; Reid, S.

2009-07-01

35

Multicomponent wavefield characterization with a novel scanning laser interferometer  

NASA Astrophysics Data System (ADS)

The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.

Blum, Thomas E.; van Wijk, Kasper; Pouet, Bruno; Wartelle, Alexis

2010-07-01

36

Cancellation of Laser Noise in Space-Based Interferometer Detectors of Gravitational Radiation.  

National Technical Information Service (NTIS)

We presented a time-domain procedure for accurately cancelling laser noise fluctuations in an unequal-arm Michelson interferometer. The method involves separately measuring the phase of the returning light relative to the phase of the transmitted light in...

M. Tinto

1999-01-01

37

Highly Sensitive Three Dimensional Measurement Using Ultrashort Pulse Fiber Laser and Fiber Interferometer  

Microsoft Academic Search

Three dimensional measurement system with high sensitivity of 99 dB and high longitudinal resolution of 10 ?m is demonstrated using ultrashort pulse fiber laser and fiber interferometer. Precise image is obtained from 1.5 m distance.

N. Nishizawa; T. Ohta; T. Goto

2005-01-01

38

Robust Laser Interferometer (RLI) Findings Relative Condition Monitoring and Diagnostics/Prognostics Engineering Management.  

National Technical Information Service (NTIS)

In recent years, a series of machinery condition and/or machinery health measurement projects have employed a Robust Laser Interferometer (RLI), a non-contact vibration measurement system introduced for wideband vibration measurements. The specific implem...

A. J. Hess M. F. Karchnak T. Goodenow

2001-01-01

39

Improvements of CO2 Laser Heterodyne Imaging Interferometer for Electron Density Profile Measurements on LHD  

Microsoft Academic Search

After installation of CO2 laser (wavelength 10.6 mum) heterodyne imaging interferometer (CO2 HI) in 2001, continuous developments have been carried out to improve the measurements capability and stability of operation. The CO2 HI works almost without phase jumping at high electron density (> 1 × 1020 m-3), where the existing far infrared laser (wavelength 118.9 mum) interferometer suffers from fringe

Kenji Tanaka; Clive Michael; Leonid Vyacheslavov; Andrei Sanin; Kazuo Kawahata; Shigeki Okajima; Takeshi Akiyama; Tokihiko Tokuzawa; Yasuhiko Ito

2008-01-01

40

Detection and active stabilization of beams position at a high-resolution laser interferometer  

NASA Astrophysics Data System (ADS)

In metrology applications of laser interferometers like a scale calibration of capacitive or inductive sensors, strictly linear positioning of the measuring mirror of the interferometer is necessary. It is maintained usually by a stage, which is based on principle of linear guide ways with ball carrier bearings. But possible imperfection of guides of the travel stage can cause deviations of the mirror plane from the right angle to the axis of traveling. Mentioned angle deviations lead to distortion of interference fringes in the output of the interferometer and by other words it causes non-linearity of the interferometer scale. Because the phenomenon is very random for this type of the travel stage the uncertainty of calibration of sensors is higher. In the work we present a method, which eliminates this usual problem by two ways. The first of them utilizes a special configuration of the laser interferometer where possible angle deviation of the mirror plane is compensated by second pass of the laser beam in the measuring arm of the interferometer. The next way is based on continual monitoring of spatial position of laser beams in the interferometer when the measuring mirror is positioned. It works with condition that the mirror can be slightly tilted by piezoelectric actuators in servo-loop mode with respect to detected spatial position.

?íp, Ond?ej; Buchta, Zden?k; ?ížek, Martin; Šmíd, Radek; Lazar, Josef

2008-10-01

41

Surface profile measurement of KB mirrors using Fizeau laser interferometer  

NASA Astrophysics Data System (ADS)

Fizeau interferometer is the most commonly used interferometer for testing optical components. The aim of this work is to apply this technique to the measurement of elliptical Kirkpatrick-Baez (KB) mirrors during their fabrication process. KB mirrors are widely used at synchrotron radiation facilities around the world for x-ray focusing. Fizeau interferometer can provide accurate measurements for KB mirrors. Recently a KB mirror that can focus X-ray down to 150 nm has been fabricated in the Argonne National Laboratory.

Qian, J.; Assoufid, L.; Liu, C.; Shi, B.; Liu, W.

2010-08-01

42

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

NASA Astrophysics Data System (ADS)

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.

Hilbert, Vinzenz; Blinne, Alexander; Fuchs, Silvio; Feigl, Torsten; Kämpfer, Tino; Rödel, Christian; Uschmann, Ingo; Wünsche, Martin; Paulus, Gerhard G.; Förster, Eckhart; Zastrau, Ulf

2013-09-01

43

Detection of low frequency hurricane emissions using a ring laser interferometer  

NASA Astrophysics Data System (ADS)

Over the last decade, large horizontally mounted ring laser interferometers have demonstrated the capacity to measure numerous geophysical effects. In this paper, responses from large ring laser interferometers to low frequency hurricane emissions are presented. Hurricanes create a broad spectrum of noise that extends into the millihertz range. In addition to microseisms, hurricanes with established eyewalls were found to create distinct frequency peaks close to 7 mHz as they came ashore or moved over shallow water. Selected emissions from Hurricanes Katrina, Wilma, and Dean are presented. The exact coupling mechanism between the ~7 mHz hurricane emissions and the ring lasers remains under active investigation.

Dunn, Robert W.; Slaton, William V.; Kendall, Lauren M.

2012-10-01

44

Delayed self-heterodyne interferometer measurements of narrow linewidth fiber lasers  

Microsoft Academic Search

Summary form only given. Narrow linewidth lasers are critical for many scientific applications, including sensing, coherent signal generation, the study of quantum phenomena, and phase-sensitive systems. One key practical technology for generating narrow linewidths is the fiber ring laser. The delayed self-heterodyne interferometer (DSHI), in which one arm is delayed to decorrelate the phases of the optical fields before recombination,

S. A. Havstad; Y. Xie; A. B. Sahin; Z. Pan; A. E. Willner; B. Fischer

2000-01-01

45

A simple phase-encoding electronics for reducing the nonlinearity error of a heterodyne interferometer  

Microsoft Academic Search

A phase-encoding electronics capable of compensating for the nonlinearity error in a heterodyne laser interferometer is described. The system consists of the phase demodulating electronics and the nonlinearity compensating electronics. For phase demodulation, we use the phase-quadrature mixing technique. For nonlinearity compensation, the offsets, the amplitudes and the phase of two output signals from the demodulator are adjusted electrically so

Tae Bong Eom; Jong Ahn Kim; Chu-Shik Kang; Byong Chon Park; Jae Wan Kim

2008-01-01

46

Gravitational Wave Science with Laser Interferometers and Pulsar Timing  

NASA Astrophysics Data System (ADS)

Within this decade, gravitational wave detection will open a new observational window on the Universe. Advanced ground-based interferometers covering the kilohertz frequency range will be online by 2016, and the announcement of a first detection within 5 years is foreseeable. At the same time, a worldwide effort for detecting low-frequency waves (in the nanohertz regime) by timing ultra-precise millisecond pulsars is rapidly growing, possibly leading to a positive detection within this decade. The millihertz regime, bridging these two windows, is the realm of space-based interferometers, which might be launched in the late 1920s. I provide here a short overview of the scientific payouts of gravitational wave astronomy, focusing the discussion on the low-frequency regime (pulsar timing and space-based interferometry). A detailed discussion of advanced ground-based interferometer can be found in Patrick Brady's contribution to this proceeding series.

Sesana, Alberto

2013-06-01

47

Virgo: a laser interferometer to detect gravitational waves  

Microsoft Academic Search

This paper presents a complete description of Virgo, the French-Italian gravitational wave detector. The detector, built at Cascina, near Pisa (Italy), is a very large Michelson interferometer, with 3 km-long arms. In this paper, following a presentation of the physics requirements, leading to the specifications for the construction of the detector, a detailed description of all its different elements is

T Accadia; F Acernese; M Alshourbagy; P Amico; F Antonucci; S Aoudia; N Arnaud; C Arnault; K G Arun; P Astone; S Avino; D Babusci; G Ballardin; F Barone; G Barrand; L Barsotti; M Barsuglia; A Basti; Th S Bauer; F Beauville; M Bebronne; M Bejger; M G Beker; F Bellachia; A Belletoile; J L Beney; M Bernardini; S Bigotta; R Bilhaut; S Birindelli; M Bitossi; M A Bizouard; M Blom; C Boccara; D Boget; F Bondu; L Bonelli; R Bonnand; V Boschi; L Bosi; T Bouedo; B Bouhou; A Bozzi; L Bracci; S Braccini; C Bradaschia; M Branchesi; T Briant; A Brillet; V Brisson; L Brocco; T Bulik; H J Bulten; D Buskulic; C Buy; G Cagnoli; G Calamai; E Calloni; E Campagna; B Canuel; F Carbognani; L Carbone; F Cavalier; R Cavalieri; R Cecchi; G Cella; E Cesarini; E Chassande-Mottin; S Chatterji; R Chiche; A Chincarini; A Chiummo; N Christensen; A C Clapson; F Cleva; E Coccia; P-F Cohadon; C N Colacino; J Colas; A Colla; M Colombini; G Conforto; A Corsi; S Cortese; F Cottone; J-P Coulon; E Cuoco; S DAntonio; G Daguin; A Dari; V Dattilo; P Y David; M Davier; R Day; G Debreczeni; G De Carolis; M Dehamme; R Del Fabbro; W Del Pozzo; M del Prete; L Derome; R De Rosa; R DeSalvo; M Dialinas; L Di Fiore; A Di Lieto; M Di Paolo Emilio; A Di Virgilio; A Dietz; M Doets; P Dominici; A Dominjon; M Drago; C Drezen; B Dujardin; B Dulach; C Eder; A Eleuteri; D Enard; M Evans; L Fabbroni; V Fafone; H Fang; I Ferrante; F Fidecaro; I Fiori; R Flaminio; D Forest; L A Forte; J-D Fournier; L Fournier; J Franc; O Francois; S Frasca; F Frasconi; A Freise; A Gaddi; M Galimberti; L Gammaitoni; P Ganau; C Garnier; F Garufi; M E Gáspár; G Gemme; E Genin; A Gennai; G Gennaro; L Giacobone; A Giazotto; G Giordano; L Giordano; C Girard; R Gouaty; A Grado; M Granata; V Granata; X Grave; C Greverie; H Groenstege; G M Guidi; S Hamdani; J-F Hayau; S Hebri; A Heidmann; H Heitmann; P Hello; G Hemming; E Hennes; R Hermel; P Heusse; L Holloway; D Huet; M Iannarelli; P Jaranowski; D Jehanno; L Journet; S Karkar; T Ketel; H Voet; J Kovalik; I Kowalska; S Kreckelbergh; A Krolak; J C Lacotte; B Lagrange; P La Penna; M Laval; J C Le Marec; N Leroy; N Letendre; T G F Li; B Lieunard; N Liguori; O Lodygensky; B Lopez; M Lorenzini; V Loriette; G Losurdo; M Loupias; J M Mackowski; T Maiani; E Majorana; C Magazzù; I Maksimovic; V Malvezzi; N Man; S Mancini; B Mansoux; M Mantovani; F Marchesoni; F Marion; P Marin; J Marque; F Martelli; A Masserot; L Massonnet; G Matone; L Matone; M Mazzoni; F Menzinger; C Michel; L Milano; Y Minenkov; S Mitra; M Mohan; J-L Montorio; R Morand; F Moreau; J Moreau; N Morgado; A Morgia; S Mosca; V Moscatelli; B Mours; P Mugnier; F-A Mul; L Naticchioni; I Neri; F Nocera; E Pacaud; G Pagliaroli; A Pai; L Palladino; C Palomba; F Paoletti; R Paoletti; A Paoli; S Pardi; G Parguez; M Parisi; A Pasqualetti; R Passaquieti; D Passuello; M Perciballi; B Perniola; G Persichetti; S Petit; M Pichot; F Piergiovanni; M Pietka; R Pignard; L Pinard; R Poggiani; P Popolizio; T Pradier; M Prato; G A Prodi; M Punturo; P Puppo; K Qipiani; O Rabaste; D S Rabeling; I Rácz; F Raffaelli; P Rapagnani; S Rapisarda; V Re; A Reboux; T Regimbau; V Reita; A Remilleux; F Ricci; I Ricciardi; F Richard; M Ripepe; F Robinet; A Rocchi; L Rolland; R Romano; D Rosi?ska; P Roudier; P Ruggi; G Russo; L Salconi; V Sannibale; B Sassolas; D Sentenac; S Solimeno; R Sottile; L Sperandio; R Stanga; R Sturani; B Swinkels; M Tacca; R Taddei; L Taffarello; M Tarallo; S Tissot; A Toncelli; M Tonelli; O Torre; E Tournefier; F Travasso; C Tremola; E Turri; G Vajente; C Van Den Broeck; S van der Putten; M Vasuth; M Vavoulidis; G Vedovato; D Verkindt; F Vetrano; O Véziant; A Viceré; J-Y Vinet; S Vilalte; S Vitale; H Vocca; R L Ward; K Yamamoto; M Yvert; J-P Zendri; Z Zhang

2012-01-01

48

Long-term monitoring crustal deformations in the North Caucasus by the laser interferometer  

Microsoft Academic Search

During several years SAI MSU carries out the long-term observation of crustal deformations in the North Caucasus, in one of the most active in geodynamic respect region of Russia. On the whole this region is characterized by the complex system of active faults, intensive movements of the Earth's crust and high seismicity. The wide-band laser interferometer strainmeter with a measurable

V. Milyukov; A. Kopaev; A. Kozyreva; B. Klyachko; A. Myasnikov

2003-01-01

49

A method for evaluating spindle rotation errors of machine tools using a laser interferometer  

Microsoft Academic Search

This paper presents a method for assessing radial and axial error motions of spindles. It uses the Hewlett Packard 5529A laser interferometer. The measurement is made using reflection directly from a high-precision sphere. Such object is used as the optical reflector. The sphere is affixed at the end of a wobble device, which is clamped in the spindle. The principle

H. F. F. Castro

2008-01-01

50

Compound pendulum test mass systems for laser interferometer gravitational wave detectors  

Microsoft Academic Search

Compound pendulum test mass suspensions for laser interferometer gravitational wave detectors offer a means of obtaining the maximum possible pendulum Q-factors and of avoiding violin string normal modes. Careful design can allow the transfer function to be equivalent to that of a simple pendulum. The suspension systems are also convenient for servo control of mirror orientation. We describe the design

L. Ju; D. G. Blair

1994-01-01

51

Retouching the Lenses of Large Objectives with the Aid of an Unequal Arm Laser Interferometer.  

National Technical Information Service (NTIS)

A description of a scheme for manually retouching the lenses of large objectives using an unequal arm interferometer which contains a gas laser as a source of monochromatic light is given. The proposed technique makes it possible to perform rapid quantita...

V. A. Savin V. N. Esina V. Y. Yurchenko

1972-01-01

52

Performance comparison of robust laser interferometer (RLI) and contact accelerometer technology in aviation health monitoring  

Microsoft Academic Search

Accelerometer systems are commonly employed in aviation health and usage monitoring systems (HUMS) and other aviation diagnostic and prognostic system approaches. Over the past decade, an research and development (R&D) robust laser interferometer (RLI) has been employed in a variety of aviation component health measurement situations, and in a variety of functional measurement situations of potential significance for aviation system

Theodore Goodenow; Martin Karchnak; Robert Shipman

2004-01-01

53

Low Cost Plane Parallel Plate Lateral Shearing Interferometer for Infrared Laser Beam Diagnostics  

SciTech Connect

In this paper we present and demonstrate, through laboratory measurements and computer ray tracing simulations, a low-cost Lateral Shearing Interferometer (LSI) use to measure the collimation and wave front quality of infrared lasers. The LSI is constructed using a single commercial off-the-shelf uncoated ZnSe window in conjunction with an infrared camera.

Bernacki, Bruce E.; Krishnaswami, Kannan; Anheier, Norman C.

2009-04-01

54

Calibration of a standard transducer using a laser interferometer (TTCP calibration round-robin)  

Microsoft Academic Search

A 10-MHz piezoelectric transducer with a half-inch diameter element and square gold target of 4.0 mm on a side was used in an interlaboratory project which consisted of measuring the amplitude of vibration of a standard transducer using a laser interferometer. The work should lead to the establishment of a reproducible procedure for the calibration of laser interferometric systems used

Andre Moreau

1992-01-01

55

Characterization of the high frequency response of LASER interferometer gravitational wave detectors  

NASA Astrophysics Data System (ADS)

This thesis describes a search for a stochastic background of gravitational waves at high frequency, 37.52 kHz. At this frequency the separation between the available instruments excludes the use of a correlation technique. Instead I rely on the spectral response of the LASER interferometer to isolate a possible signal from the underlying noise. This research was carried out at the LIGO (LASER Interferometer Gravitational Observatory) located in Hanford, WA and within the LIGO Scientific Collaboration (LSC). Chapter 1 serves as a general introduction to the present state of the search for gravitational waves (GW). I discuss the indirect observation of gravitational radiation as well as the expected sources for GW and their characteristics. I also discuss possible future developments, in particular the Advanced LIGO instruments and the LASER Interferometer Space Antenna (LISA). The characteristics of the large LASER interferometers, layout, terminology and necessary formulae are developed in Chapter 2. To carry out the proposed search it is essential that the frequency response of the interferometer be thoroughly understood, including possible noise sources. This was the subject of a series of experimental investigations using sideband injection and mirror excitations to characterize the IFO response in the region of the first free spectral range, which is at 37.52 kHz. The results of these experiments as well as their theoretical model are presented in Chapter 3. Contributions to the spectrum from mechanical noise are investigated in Chapter 4, and compared to the expected contribution thermal excitation. The results of my search are based on data obtained during the third science run of LIGO (S3) and are presented in Chapter 5. I show that a signal such as expected from a stochastic gravitational wave background is manifest in the data and compare it to the expected noise signal. This allows me to postulate a limit on a possible stochastic background. I also discuss further possible high sensitivity measurements at these high frequencies.

Butler, William E.

56

Efficient second harmonic conversion of broad-band high-peak-power Nd:glass laser radiation using large-aperture KDP crystals in quadrature  

Microsoft Academic Search

The authors have investigated the second-harmonic conversion efficiency of broadband Nd:glass laser light (??\\/c<30 cm-1 FWHM). Using two KDP crystals in a quadrature arrangement, they obtain energy conversion efficiencies of ≈55% with an initial bandwidth for the fundamental of ??\\/c≈17 cm-1 FWHM. For these conditions, a modest increase (≈70%) was observed in the harmonic bandwidth (FWHM) relative to the fundamental.

MARK S. PRONKO; ROBERT H. LEHMBERG; S. Obenschain; CARL J. PAWLEY; CHARLES K. MANKA; R. Eckardt

1990-01-01

57

Generation of vortex array laser beams with Dove prism embedded unbalanced Mach-Zehnder interferometer  

NASA Astrophysics Data System (ADS)

This paper introduces a scheme for generation of vortex laser beams from a solid-state laser with off-axis laser-diode pumping. The proposed system consists of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer configuration. This configuration allows controlled construction of p × p vortex array beams from Ince-Gaussian modes, IGep,p modes. An incident IGe p,p laser beam of variety order p can easily be generated from an end-pumped solid-state laser with an off-axis pumping mechanism. This study simulates this type of vortex array laser beam generation and discusses beam propagation effects. The formation of ordered transverse emission patterns have applications in a variety of areas such as optical data storage, distribution, and processing that exploit the robustness of soliton and vortex fields and optical manipulations of small particles and atoms in the featured intensity distribution.

Chu, Shu-Chun

2009-02-01

58

Laser-matter interaction studies using X-ray laser and double Lloyd's mirror interferometer  

NASA Astrophysics Data System (ADS)

Inertial confinement fusion (ICF) is one of the promising approaches how to get a new resource of energy. In order to model ICF implosions reliably, the measurements of the mass ablation rates are needed. Such a measurement was performed at PALS; using the Ne-like Zn X-ray laser (XRL) as a probe beam and the Double Lloyd's mirror interferometer as the main diagnostic. The Parylene N foil (200nm and 350nm) was heated by 250-ps pulse of 3? iodine laser with nominal energy of 1J. The size of the focal spot was ~300?m then the maximum resulting intensity was ~1012W/cm2. The plasma probed by XRL was imaged by Mo:Si spherical mirror to CCD detector with magnification 8. The expected phase shift for the chosen thicknesses, which corresponds to reasonable fringe visibility, was from ? to 2?. The recorded interferograms were taken for different time delays between the heating pulse and the probe.

Kozlová, M.; Nejdl, J.; Rus, B.; Sawicka, M.; Polan, J.; Gartside, L.; Rossall, A.; Tallents, G.

59

Laser-interferometer position-feedback for precision machine tools  

SciTech Connect

Diamond turning of off-axis parabolic mirrors is used to provide high-quality turning and focusing optics for the Los Alamos Scientific Laboratory's laser-fusion research. These mirrors are fabricated at the Oak Ridge Y-12 Plant on a large machine tool that incorporates lasers, air bearings, and linear-motor slide-drives to meet the part specifications of 0.63 ..mu..m (25 ..mu..in) on contour and 63 nm (2.5 ..mu..in) on surface finish. This report discusses the application of lasers to this machine and other precision machine tools.

Barkman, W.E.

1980-04-15

60

New-type active vibration isolation system with laser interferometer and piezoelectric displacement transducer  

Microsoft Academic Search

A new-type active vibration isolation system is developed for ultra-precision measuring system. It is composed of three sets of 3D Laser interferometer transducer and six groups of piezoelectric displacement executor to constrain six degrees of space movement and to realize real-time compensation of vibration. The active vibration isolation system can effectively eliminate low-frequency vibrations. Combined with passive vibration isolation system,

Boyin Lu; Meirong Zhao

1994-01-01

61

Laser Interferometer Used for Satellite—Satellite Tracking: an On-Ground Methodological Demonstration  

Microsoft Academic Search

A Chinese satellite gravity mission called SAGM (Space Advanced Gravity Measurements) is now taken into consideration. To meet its designed requirement, the measurement precision of the laser ranging system used to measure the inter-satellite distance change has to be better than 100nm\\/Hz1\\/2 within a broad bandwidth from 0.1 mHz to 1 Hz. An equal arm heterodyne Mach-Zehnder interferometer has been

Li Yu-Qiong; Luo Zi-Ren; Liu He-Shan; Dong Yu-Hui; Jin Gang

2012-01-01

62

Disturbance-free phase-shifting laser diode interferometer using adaptive feedback control  

SciTech Connect

A feedback-control-equipped phase-shifting laser diode interferometer that eliminates external disturbance is proposed. The feedback loop is stabilized by adaptive control of the polarity of the interference signal. Conventional phase-shifting interferometry can be used with the feedback control, resulting in simplified signal processing and accurate measurement. Several experiments confirm the stability of the feedback control with a measurement repeatability of 1.8 nm.

Suzuki, Takamasa; Takahashi, Tsutomu; Sasaki, Osami

2009-10-10

63

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

NASA Astrophysics Data System (ADS)

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.

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

64

Two-color CO2/HeNe laser interferometer for C-2 experiment.  

PubMed

A six-channel two-color interferometer has been developed for plasma electron density measurements in the C-2 field reversed configuration experiment. A CO(2) laser is utilized as the main probe beams, while copropagating visible HeNe laser beams are mainly sensitive to vibration. Density measurements in C-2 plasmas have shown that this is a reliable turn-key system. The maximum residual phase noise after vibration compensation is less than ±5°, corresponding to a line integral density of 3×10(18)?m(-2). The time resolution for routine operation is 2??s. PMID:21033871

Gornostaeva, O; Deng, B H; Garate, E; Gota, H; Kinley, J; Schroeder, J; Tuszewski, M

2010-10-01

65

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

PubMed

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. PMID:19876216

Chilla, J L; Rocca, J J; Martinez, O E; Marconi, M C

1996-07-01

66

Two-color CO{sub 2}/HeNe laser interferometer for C-2 experiment  

SciTech Connect

A six-channel two-color interferometer has been developed for plasma electron density measurements in the C-2 field reversed configuration experiment. A CO{sub 2} laser is utilized as the main probe beams, while copropagating visible HeNe laser beams are mainly sensitive to vibration. Density measurements in C-2 plasmas have shown that this is a reliable turn-key system. The maximum residual phase noise after vibration compensation is less than {+-}5 deg., corresponding to a line integral density of 3x10{sup 18} m{sup -2}. The time resolution for routine operation is 2 {mu}s.

Gornostaeva, O.; Deng, B. H.; Garate, E.; Gota, H.; Kinley, J.; Schroeder, J.; Tuszewski, M. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States)

2010-10-15

67

Modelling laser interferometers for the measurement of the Avogadro constant  

NASA Astrophysics Data System (ADS)

In dimensional measurements by laser interferometry, when the accuracy approaches 10-9 ?, wavefront aberra­ tions cause systematic variations of the fringe period. This paper illustrates how these effects are modeled and experimentally studied in the measurements of the lattice parameter and the topographical survey of 1 kg Si spheres, which measurements are necessary to "count" atoms and to make it possible to realize the kilogram from the Planck constant value.

Andreas, Birk; Mana, Giovanni; Massa, Enrico; Palmisano, Carlo

2013-05-01

68

Searching for a Stochastic Background of Gravitational Waves with the Laser Interferometer Gravitational-Wave Observatory  

NASA Astrophysics Data System (ADS)

The Laser Interferometer Gravitational-Wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new Bayesian 90% upper limit is ?GW×[H0/(72 km s-1 Mpc-1)2<6.5×10-5. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss the complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.

Abbott, B.; Abbott, R.; Adhikari, R.; Agresti, J.; Ajith, P.; Allen, B.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Araya, M.; Armandula, H.; Ashley, M.; Aston, S.; Aulbert, C.; Babak, S.; Ballmer, S.; Barish, B. C.; Barker, C.; Barker, D.; Barr, B.; Barriga, P.; Barton, M. A.; Bayer, K.; Belczynski, K.; Betzwieser, J.; Beyersdorf, P.; Bhawal, B.; Bilenko, I. A.; Billingsley, G.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bogue, L.; Bork, R.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brooks, A.; Brown, D. A.; Bullington, A.; Bunkowski, A.; Buonanno, A.; Burman, R.; Busby, D.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Casey, M. M.; Cepeda, C.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chin, D.; Chin, E.; Chow, J.; Christensen, N.; Cokelaer, T.; Colacino, C. N.; Coldwell, R.; Cook, D.; Corbitt, T.; Coward, D.; Coyne, D.; Creighton, J. D. E.; Creighton, T. D.; Crooks, D. R. M.; Cruise, A. M.; Cumming, A.; Cutler, C.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; de Vine, G.; DeBra, D.; Degallaix, J.; Dergachev, V.; Desai, S.; DeSalvo, R.; Dhurandar, S.; Di Credico, A.; Díaz, M.; Dickson, J.; Diederichs, G.; Dietz, A.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Ehrens, P.; Elliffe, E.; Etzel, T.; Evans, M.; Evans, T.; Fairhurst, S.; Fan, Y.; Fejer, M. M.; Finn, L. S.; Fotopoulos, N.; Franzen, A.; Franzen, K. Y.; Frey, R. E.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Goda, K.; Goetz, E.; Goggin, L.; González, G.; Gossler, S.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, J.; Gretarsson, A. M.; Grimmett, D.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, R.; Hage, B.; Hanna, C.; Hanson, J.; Hardham, C.; Harms, J.; Harry, G.; Harstad, E.; Hayler, T.; Heefner, J.; Heng, I. S.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hild, S.; Hindman, N.; Hirose, E.; Hoak, D.; Hoang, P.; Hosken, D.; Hough, J.; Howell, E.; Hoyland, D.; Hua, W.; Huttner, S.; Ingram, D.; Ito, M.; Itoh, Y.; Ivanov, A.; Jackrel, D.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Khalili, F. Ya.; Khan, A.; Kim, C.; King, P.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Kozak, D.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lee, B.; Lei, M.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Lockerbie, N. A.; Lormand, M.; Lubi?ski, M.; Lück, H.; Machenschalk, B.; MacInnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Márka, S.; Markowitz, J.; Maros, E.; Martin, I.; Marx, J. N.; Mason, K.; Matone, L.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McKenzie, K.; McNabb, J. W. C.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messaritaki, E.; Messenger, C. J.; Meyers, D.; Mikhailov, E.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Mohanty, S.; Moreno, G.; Mossavi, K.; MowLowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Müller-Ebhardt, H.; Mukherjee, S.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Newton, G.; Numata, K.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Pedraza, M.; Penn, S.; Pitkin, M.; Plissi, M. V.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D.; Radkins, H.; Rahkola, R.; Rakhmanov, M.; Rawlins, K.; Ray-Majumder, S.; Re, V.; Rehbein, H.; Reid, S.; Reitze, D. H.; Ribichini, L.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, D. I.; Robertson, N. A.; Robinson, C.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; de la Jordana, L. Sancho; Sandberg, V.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Schediwy, S.; Schilling, R.; Schnabel, R.; Schofield, R.; Schutz, B. F.; Schwinberg, P.; Scott, S. M.; Seader, S. E.; Searle, A. C.; Sears, B.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Shawhan, P.; Sheard, B.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Sintes, A. M.; Slagmolen, B.; Slutsky, J.; Smith, J.; Smith, M. R.; Sneddon, P.; Somiya, K.; Speake, C.; Spjeld, O.; Strain, K. A.; Strom, D. M.; Stuver, A.; Summerscales, T.; Sun, K.; Sung, M.; Sutton, P. J.; Tanner, D. B.; Tarallo, M.; Taylor, R.; Taylor, R.; Thacker, J.; Thorne, K. A.; Thorne, K. S.; Thüring, A.; Tokmakov, K. V.; Torres, C.; Torrie, C.; Traylor, G.; Trias, M.; Tyler, W.; Ugolini, D.; Ungarelli, C.; Vahlbruch, H.; Vallisneri, M.

2007-04-01

69

Experiments with an 834 m2 ring laser interferometer  

NASA Astrophysics Data System (ADS)

An ultralarge ring He-Ne ring laser gyroscope, UG-2, with area 834 m2 and dimensions 39.7×21 m2, has been built underground at Cashmere Cavern, Christchurch, New Zealand (latitude -43.575°). Earth rotation is sufficient to unlock it, giving a Sagnac frequency of 2.18 kHz. Supermirrors are used with transmission ~0.18 parts per million (ppm) and optical loss unexpectedly high at ~200 ppm per reflection. The cavity Q is 1.5×1012. Residual Sagnac frequency error caused by backscatter coupling is measured as <2 parts in 108. Its best stability is achieved for an averaging time of ~2000 s, for which the Allan Deviation of the Sagnac frequency is 0.08 mHz, or four parts in 108 of Earth rotation rate. The dominant processes generating the residual rotational noise are, for times <10 s, microseismic ground movements, and for times >1000 s, mechanical movement of the mirror assemblies, which act to change the geometrical dimensions and tilt. At all averaging times the residual rotational noise is well above the limit imposed by quantum phase fluctuations. It is concluded from comparisons among many large ring lasers that the excess mirror losses arise from high order aberrations, and UG-2 may be larger than the optimum size.

Hurst, R. B.; Stedman, G. E.; Schreiber, K. U.; Thirkettle, R. J.; Graham, R. D.; Rabeendran, N.; Wells, J.-P. R.

2009-06-01

70

Large-Optics white light interferometer for laser wavefront test: apparatus and application  

NASA Astrophysics Data System (ADS)

There is transmitting optics of 250mm aperture with about 8 microradians in SILEX system. This is often large aperture and diffraction-limited laser beam in the laser communications. Large-Optics white light interferometer using double-shearing structure has been submitted to analysis the laser wavefront before. Six optical plates of 490 millimeters apertures are manufactured now one of which is also aperture-divided so that the precision of measured wave front is higher than the full aperture design. It is suitable for measurement of minimum diffraction-limited laser wave front and any wavelength. The interference is happened between equal optical path of the reflection and the other. The plates are the basic structures which are precisely parallel or perpendicular needed for either two plates. There are several tools equipped with the interferometer including white light test source and collimators and so on to confirm the precision of several seconds angle. The apparatus and application is explained in detail in this paper. The adjustment is important for the realization of white light test.

Luan, Zhu; Liu, Liren; Wang, Lijuan; Liu, De'an

2008-08-01

71

CONTROL OF LASER RADIATION PARAMETERS: Device for enhancing the time contrast of utrashort laser pulses based on a polarisation Mach—Zehnder interferometer  

NASA Astrophysics Data System (ADS)

A polarisation Mach—Zehnder interferometer is considered containing identical cells with a nonlinear medium in different arms. A parallel wave beam propagates through one cell and a converging-diverging wave beam propagates through the other. It is shown that the interferometer transmission depends on the power of the laser pulse propagated through it. It is proposed to use this effect to enhance the time contrast of ultrashort and superhigh-power laser pulses, i.e. to suppress side (background) pulses.

Gitin, Andrey V.

2009-02-01

72

Low cost plane parallel plate lateral shearing interferometer for infrared laser beam diagnostics  

NASA Astrophysics Data System (ADS)

Few cost-effective methods exist for measuring the wave front of mid- and long-wave infrared beams that span 3-5 and 8-12 ?m, respectively. One obvious need within the infrared laser community is the ability to measure the degree of collimation of an infrared laser beam, e.g. that formed by a beam expanding telescope used with a CO2 laser or a system of lenses used to collimate a Quantum Cascade Laser (QCL). An ideal approach for this type of metrology is the use of a lateral shearing interferometer (LSI). An LSI uses various methods to displace ("shear") a beam with respect to itself to create an interferogram that can subsequently be used for diagnosing the wavefront quality of the beam. Since this type of interferometer is of the common path variety, it is insensitive to vibration making it ideal for field applications, where vibration isolation may neither be possible nor practical. In this paper we present and demonstrate, through laboratory measurements and computer ray tracing simulations, a low-cost LSI using a single commercial off-the-shelf uncoated ZnSe window in conjunction with an infrared camera. This plane parallel plate LSI configuration was used to interactively collimate a LWIR beam and also provide quantitative transmitted wavefront error data using static fringe analysis software. We also present a self-contained review of the theory of lateral shearing interferometry, including the necessary design equations as applicable to this LSI configuration, to enable researchers to construct a similar beam diagnostic shearing interferometer from readily available components.

Bernacki, Bruce E.; Krishnaswami, Kannan; Anheier, Norman C.

2009-05-01

73

LIGO: the Laser Interferometer Gravitational-Wave Observatory  

Microsoft Academic Search

The goal of the Laser Interferometric Gravitational-Wave\\u000a\\u0009\\u0009 Observatory (LIGO) is to detect and study gravitational\\u000a\\u0009\\u0009 waves (GWs) of astrophysical origin. Direct detection of\\u000a\\u0009\\u0009 GWs holds the promise of testing general relativity in the\\u000a\\u0009\\u0009 strong-field regime, of providing a new probe of exotic\\u000a\\u0009\\u0009 objects such as black holes and neutron stars and of\\u000a\\u0009\\u0009 uncovering unanticipated new astrophysics. {LIGO}, a joint\\u000a\\u0009\\u0009 Caltech-MIT

B. P. Abbott; R. Abbott; R. Adhikari; P. Ajith; B. Allen; G. Allen; R. S. Amin; S. B. Anderson; W. G. Anderson; M. A. Arain; M. Araya; H. Armandula; P. Armor; Y. Aso; S. Aston; P. Aufmuth; C. Aulbert; S. Babak; P. Baker; S. Ballmer; C. Barker; D. Barker; B. Barr; P. Barriga; L. Barsotti; M. A. Barton; I. Bartos; R. Bassiri; M. Bastarrika; B. Behnke; M. Benacquista; J. Betzwieser; P. T. Beyersdorf; I. A. Bilenko; G. Billingsley; R. Biswas; E. Black; J. K. Blackburn; L. Blackburn; D. Blair; B. Bland; T. P. Bodiya; L. Bogue; R. Bork; V. Boschi; S. Bose; P. R. Brady; V. B. Braginsky; J. E. Brau; D. O. Bridges; M. Brinkmann; A. F. Brooks; D. A. Brown; A. Brummit; G. Brunet; A. Bullington; A. Buonanno; O. Burmeister; R. L. Byer; L. Cadonati; J. B. Camp; J. Cannizzo; K. C. Cannon; J. Cao; L. Cardenas; S. Caride; G. Castaldi; S. Caudill; M. Cavaglià; C. Cepeda; T. Chalermsongsak; E. Chalkley; P. Charlton; S. Chatterji; S. Chelkowski; Y. Chen; N. Christensen; C. T. Y. Chung; D. Clark; J. Clark; J. H. Clayton; T. Cokelaer; C. N. Colacino; R. Conte; D. Cook; T. R. C. Corbitt; N. Cornish; D. Coward; D. C. Coyne; J. D. E. Creighton; T. D. Creighton; A. M. Cruise; R. M. Culter; A. Cumming; L. Cunningham; S. L. Danilishin; K. Danzmann; B. Daudert; G. Davies; E. J. Daw; D. DeBra; J. Degallaix; V. Dergachev; S. Desai; R. DeSalvo; S. Dhurandhar; M. Díaz; A. Dietz; F. Donovan; K. L. Dooley; E. E. Doomes; R. W. P. Drever; J. Dueck; I. Duke; J-C Dumas; J. G. Dwyer; C. Echols; M. Edgar; A. Effler; P. Ehrens; E. Espinoza; T. Etzel; M. Evans; T. Evans; S. Fairhurst; Y. Faltas; Y. Fan; D. Fazi; H. Fehrmenn; Lee Samuel Finn; K. Flasch; S. Foley; C. Forrest; N. Fotopoulos; A. Franzen; M. Frede; M. Frei; Z. Frei; A. Freise; R. Frey; T. Fricke; P. Fritschel; V. V. Frolov; M. Fyffe; V. Galdi; J. A. Garofoli; I. Gholami; J. A. Giaime; S. Giampanis; K. D. Giardina; K. Goda; E. Goetz; L. M. Goggin; G. González; M. L. Gorodetsky; S. Goßler; R. Gouaty; A. Grant; S. Gras; C. Gray; M. Gray; R. J. S. Greenhalgh; A. M. Gretarsson; F. Grimaldi; R. Grosso; H. Grote; S. Grunewald; M. Guenther; E. K. Gustafson; R. Gustafson; B. Hage; J. M. Hallam; D. Hammer; G. D. Hammond; C. Hanna; J. Hanson; J. Harms; G. M. Harry; I. W. Harry; E. D. Harstad; K. Haughian; K. Hayama; J. Heefner; I. S. Heng; A. Heptonstall; M. Hewitson; S. Hild; E. Hirose; D. Hoak; K. A. Hodge; K. Holt; D. J. Hosken; J. Hough; D. Hoyland; B. Hughey; S. H. Huttner; D. R. Ingram; T. Isogai; M. Ito; A. Ivanov; B. Johnson; W. W. Johnson; D. I. Jones; G. Jones; R. Jones; L. Ju; P. Kalmus; V. Kalogera; S. Kandhasamy; J. Kanner; D. Kasprzyk; E. Katsavounidis; K. Kawabe; S. Kawamura; F. Kawazoe; W. Kells; D. G. Keppel; A. Khalaidovski; F. Y. Khalili; R. Khan; E. Khazanov; P. King; J. S. Kissel; S. Klimenko; K. Kokeyama; V. Kondrashov; R. Kopparapu; S. Koranda; D. Kozak; B. Krishnan; R. Kumar; P. Kwee; P. K. Lam; M. Landry; B. Lantz; A. Lazzarini; H. Lei; M. Lei; N. Leindecker; I. Leonor; C. Li; H. Lin; P. E. Lindquist; T. B. Littenberg; N. A. Lockerbie; D. Lodhia; M. Longo; M. Lormand; P. Lu; M. Lubinski; A. Lucianetti; H. Lück; B. Machenschalk; M. MacInnis; M. Mageswaran; K. Mailand; I. Mandel; V. Mandic; S. Márka; Z. Márka; A. Markosyan; J. Markowitz; E. Maros; I. W. Martin; R. M. Martin; J. N. Marx; K. Mason; F. Matichard; L. Matone; R. A. Matzner; N. Mavalvala; R. McCarthy; D. E. McClelland; S. C. McGuire; M. McHugh; G. McIntyre; D. J. A. McKechan; K. McKenzie; M. Mehmet; A. Melatos; A. C. Melissinos; D. F. Menendez; G. Mendell; R. A. Mercer; S. Meshkov; C. Messenger; M. S. Meyer; J. Miller; J. Minelli; Y. Mino; V. P. Mitrofanov; G. Mitselmakher; R. Mittleman; O. Miyakawa; B. Moe; S. D. Mohanty; S. R. P. Mohapatra; G. Moreno; T. Morioka; K. Mors; K. Mossavi; C. Mow Lowry; G. Mueller; H. Müller-Ebhardt; D. Muhammad; S. Mukherjee; H. Mukhopadhyay; A. Mullavey; J. Munch; P. G. Murray; E. Myers; J. Myers; T. Nash; J. Nelson; G. Newton; A. Nishizawa; K. Numata; J. O'Dell; B. O'Reilly; R. O'Shaughnessy; E. Ochsner; G. H. Ogin; D. J. Ottaway; R. S. Ottens; H. Overmier; B. J. Owen; Y. Pan; C. Pankow; M. A. Papa; V. Parameshwaraiah; P. Patel; M. Pedraza; S. Penn; A. Perraca; V. Pierro; I. M. Pinto; M. Pitkin; H. J. Pletsch; M. V. Plissi; F. Postiglione; M. Principe; R. Prix; L. Prokhorov; O. Punken; V. Quetschke; F. J. Raab; D. S. Rabeling; H. Radkins; P. Raffai; Z. Raics; N. Rainer; M. Rakhmanov; V. Raymond; C. M. Reed; T. Reed; H. Rehbein; S. Reid; D. H. Reitze; R. Riesen; K. Riles; B. Rivera; P. Roberts; N. A. Robertson; C. Robinson; E. L. Robinson; S. Roddy; C. Röver; J. Rollins; J. D. Romano; J. H. Romie; S. Rowan; A. Rüdiger; P. Russell; K. Ryan; S. Sakata; L. Sancho de la Jordana; V. Sandberg; V. Sannibale; L. Santamaría; S. Saraf; P. Sarin; B. S. Sathyaprakash; S. Sato; M. Satterthwaite; P. R. Saulson; R. Savage; P. Savov; M. Scanlan; R. Schilling

2009-01-01

74

A simple phase-encoding electronics for reducing the nonlinearity error of a heterodyne interferometer  

NASA Astrophysics Data System (ADS)

A phase-encoding electronics capable of compensating for the nonlinearity error in a heterodyne laser interferometer is described. The system consists of the phase demodulating electronics and the nonlinearity compensating electronics. For phase demodulation, we use the phase-quadrature mixing technique. For nonlinearity compensation, the offsets, the amplitudes and the phase of two output signals from the demodulator are adjusted electrically so that their Lissajous figure is a circle. As a result, the correct phase can be obtained. An analysis of the nonlinearity in the heterodyne interferometer and the design of the phase-encoding electronics are presented. The experiment was performed in a Michelson-type interferometer using a transverse Zeeman stabilized He-Ne laser. We demonstrate that this method can encode the phase of a heterodyne interferometer with sub-nanometer accuracy.

Eom, Tae Bong; Kim, Jong Ahn; Kang, Chu-Shik; Chon Park, Byong; Kim, Jae Wan

2008-07-01

75

Dense plasma diagnostics with an amplitude-division soft-x-ray laser interferometer based on diffraction gratings.  

PubMed

We report the demonstration of an amplitude-division soft-x-ray interferometer that can be used to generate high-contrast interferograms at the wavelength of any of the saturated soft-x-ray lasers (5.6-46.9 nm) that are available at present. The interferometer, which utilizes grazing-incidence diffraction gratings as beam splitters in a modified Mach-Zehnder configuration, was used in combination with a tabletop 46.9-nm laser to probe a large-scale (~2.7-mm-long) laser-created plasma. PMID:18059879

Filevich, J; Kanizay, K; Marconi, M C; Chilla, J L; Rocca, J J

2000-03-01

76

Laser Interferometer Used for Satellite—Satellite Tracking: an On-Ground Methodological Demonstration  

NASA Astrophysics Data System (ADS)

A Chinese satellite gravity mission called SAGM (Space Advanced Gravity Measurements) is now taken into consideration. To meet its designed requirement, the measurement precision of the laser ranging system used to measure the inter-satellite distance change has to be better than 100nm/Hz1/2 within a broad bandwidth from 0.1 mHz to 1 Hz. An equal arm heterodyne Mach-Zehnder interferometer has been built on ground to demonstrate the measurement principle of a laser ranging system, which potentially can be used for both SAGM and future GW (gravitational wave) space antennas. Because of the equal arm length, the laser frequency noise has been significantly suppressed in the interferometer. Thus, the sensitivity better than 1nm/Hz1/2 in a frequency range of 0.15 mHz-0.375 Hz has been achieved. The result shows that the proposed methodology has very promising feasibility to meet the requirements of SAGM and of GW space antennas as well.

Li, Yu-Qiong; Luo, Zi-Ren; Liu, He-Shan; Dong, Yu-Hui; Jin, Gang

2012-07-01

77

Fast wavelength-scanning interferometry technique with derivative detection of quadrature signals  

NASA Astrophysics Data System (ADS)

We present a laser interferometer where a narrow-line width tuneable VCSEL laser (Vertical-Cavity Surface-Emitting Laser) working at 760 nm is used. For the detection of an absolute distance, we have used a fast wavelength-scanning interferometry technique. In the first part of the work we introduce the absolute laser interferometer as a demonstrator for research of a digital detection of quadrature signals (X-cos and Y-sin). This interferometer uses polarized beams and magnitude division of interference fringes. The wavelength of VCSEL laser is swept with the mode-hop free tuning range more than 1.2 nm, by means of the amplitude modulation of the injection current. At the same time, the operating temperature of the VCSEL is stabilized with a fast digital temperature controller. We control the wavelength value and whole tuning process of the laser with the frequency lock to selected modes of an external Fabry-Perot etalon. Except the frequency lock, the Fabry-Perot mode spectrum identifies wavelength-tuning interval of VCSEL during each sweep. A digital signal processor (DSP) is heart of the control and detection system. It samples intensity signal from Fabry-Perot etalon and X-Y quadrature signals from the detection unit of the interferometer. After 1 nm sweep of the VCSEL wavelength, we obtain a number of passed interference fringes and the number of passed Fabry-Perot resonance modes, at the same time. On basis of these measured quantities we are able to calculate the instantaneous value of the optical path length difference between the measuring and reference arm of the demonstrational interferometer. The other part of the work is oriented to research and experimental testing of the digital detection of quadrature signals (X-cos and Y-sin) processed only on basis of one intensity signal (X-axis) that is produced by a simple photo-detector. On basis of traditional inversion function arctan(Y/X) we are able to determine instantaneous phase between interference beams in each part of recorded signals. In the work the first introduction of the method and measured records are presented.

?íp, O.; Mikel, B.; Lazar, J.

2006-05-01

78

Switchable multiwavelength fiber laser by using a compact in-fiber Mach-Zehnder interferometer  

NASA Astrophysics Data System (ADS)

We propose a simple and compact method for implementing an in-fiber Mach-Zehnder interferometer, which is constructed with two optical paths, propagating through the core and the ring-shaped silica cladding modes in the double-cladding fibers. Strong cladding-mode resonance across the thin inner cladding is used to excite the cladding modes. The measured spectra fringe presents high-contrast interference from cascading a pair of well-overlapped resonant spectra dips. In combination with the nonlinear polarization rotation (NPR) technique, switchable and tunable multi-channel laser outputs are experimentally demonstrated with a fluctuation of less than 0.1 dB.

Zhang, Qianwu; Zeng, Xianglong; Pang, Fufei; Wang, Min; Wang, Tingyun

2012-04-01

79

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

Microsoft Academic Search

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

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

2010-01-01

80

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

SciTech Connect

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)

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

81

Calibration of a standard transducer using a laser interferometer (TTCP calibration round-robin)  

NASA Astrophysics Data System (ADS)

A 10-MHz piezoelectric transducer with a half-inch diameter element and square gold target of 4.0 mm on a side was used in an interlaboratory project which consisted of measuring the amplitude of vibration of a standard transducer using a laser interferometer. The work should lead to the establishment of a reproducible procedure for the calibration of laser interferometric systems used for displacement measurements. The experimental setup included a pulse/frequency generator for generating continuous excitation and a heterodyne Michelson interferometer with associated electronics. Three calibration methods were compared. The acoustic amplitude was measured as a function of horizontal position. The measurement error on the acoustic amplitude of a particular data point is estimated at + or - 1 picometer. The reproducibility agrees with the estimated measurement errors. Acoustic amplitude was also studied as a function of excitation voltage. To reduce the large variability in acoustic amplitude with position on the transducer surface, a special transducer assembly with reduced internal reflections was designed; preliminary tests show amplitude could be made uniform to within 10-20 percent over distances of several mm. This could probably be improved with further work.

Moreau, Andre

1992-09-01

82

Design of dispersed Rayleigh interferometer for grating mosaic in laser pulse compressors  

NASA Astrophysics Data System (ADS)

Dispersed Rayleigh Interferometer (DRI) is designed for 3 degree-of-freedom alignment of a grating pair contained in chirped-pulse-amplification laser pulse system. The working Gaussian pulse laser spectrally centered at 1053 nm with an FWHM bandwidth of 5 nm is utilized as the broadband light source. The relationship of DRI interferograms and alignment errors is simulated, based on which the alignment criteria by image processing method are determined. Structural parameters of the DRI are carefully designed according to the simulations. Theoretically, the final coarse measurement range for piston error is 5 mm, with positional sensitivity of 20 nm and angular sensitivity of 8 ?rad within a fine measurement range of 500 ?m.

Hu, Yao; Wang, Shanshan

2011-11-01

83

Design and performance of high laser power interferometers for gravitational-wave detection  

NASA Astrophysics Data System (ADS)

A prediction of Einstein's general theory of relativity, gravitational waves (GWs) are perturbations of the flat space-time Minkowski metric that travel at the speed of light. Indirectly measured by Hulse and Taylor in the 1970s through the energy they carried away from a binary pulsar system, gravitational waves have yet to be detected directly. The Laser Interferometer Gravitational-wave Observatory (LIGO) is part of a global network of gravitational-wave detectors that seeks to detect directly gravitational waves and to study their sources. LIGO operates on the principle of measuring the gravitational wave's physical signature of a strain, or relative displacement of inertial masses. An extremely small effect whose biggest of expected transient signals on Earth is on the order of one part in 1023, gravitational-wave strain can only be measured by detectors so sensitive to displacement as to encounter the effects of quantum physics. To improve their sensitivities and to demonstrate advanced technologies, the LIGO observatories in Hanford, WA and Livingston, LA underwent an upgrade between fall 2007 and summer 2009 called Enhanced LIGO. This study focuses on the experimental challenges of one of the goals of the upgrade: operating at an increased laser power. I present the design and characterization of two of the interferometer subsystems that are critical for the path towards higher laser power: the Input Optics (IO) and the Angular Sensing and Control (ASC) subsystems. The IO required a new design so its optical components would not be susceptible to high power effects such as thermal lensing or thermal beam drift. The ASC required a new design in order to address static instabilities of the arm cavities caused by increased radiation pressure. In all, I demonstrate the capability of an interferometric GW detector to operate at several times the highest of laser powers previously used. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Dooley, Katherine Laird

84

Direct near-field phase measurement of laser diodes employing a single-mode fiber interferometer.  

PubMed

A method of direct measurement of near-field phase and intensity distribution of laser diodes employing a single-mode fiber interferometer is proposed and demonstrated. The phase and intensity of the output beam of the laser in the vicinity of the output facet are measured directly via interferometry. Using a 980 nm laser diode as an example, we obtained a beam width of 0.9 and 3.6 ?m at the output facet in the vertical and horizontal axes, respectively. In addition, the phase information of the output beam was also obtained by using interferometry. This technique is particularly useful for laser diodes whose near-field phases are difficult to measure directly. The measured vertical and horizontal wavefront radius of curvatures of a laser diode are in good agreement with the calculation from Gaussian beam theory. Detailed understanding and measurement of the near-field phase and intensity distributions of light sources and optical components are essential for micro-optic designs with better mode matching to minimize the insertion loss. PMID:21042377

Lu, Yu-Kuan; Yeh, Pochi; Cheng, Wood-Hi

2010-11-01

85

Heterodyne interferometer laser source with a pair of two phase locked loop coupled He-Ne lasers by 632.8 nm  

NASA Astrophysics Data System (ADS)

Two He-Ne lasers are frequency and phase coupled by phase locking loop technique for a heterodyne laser interferometer. The heterodyne He-Ne laser is built of stabilized commercially used laser tubes. The two lasers create a high frequency stable heterodyne laser source with an output power of 2 mW. The laser source is coupled by two fibers (one fiber per laser) to the heterodyne laser head. This paper describes the configuration and the control theory basics of the laser system. The experimental setup and the equipment used are also described. First, experimental results with different parameters are represented. Then we discuss a novel heterodyne laser source which has achieved a master laser frequency stability of ?f1/f1 = 1 · 10-8 and a beat frequency stability of approximately ?fbeat/fbeat ? 4.5 · 10-5.

Sternkopf, C.; Diethold, C.; Gerhardt, U.; Wurmus, J.; Manske, E.

2012-07-01

86

A Tunable Er3+-Doped Fiber Laser by Use of an Integrated Optics Mach-Zehnder Interferometer  

Microsoft Academic Search

Wavelength tunability of an Er3+-doped fiber laser is reported by the use of an integrated optics Mach-Zehnder interferometer driven electro-optically. A pump laser threshold of 5 mW and a continuous tunable band from 1530 nm to 1554 nm are achieved with a drive voltage varying between 0 to +7 volts. An evaluation of the design and improvements are given based

N. Azami; A. Saïssy; M. P. de Micheli; G. Monnom; D. B. Ostrowsky; P. Mollier

2001-01-01

87

A Tunable Er3+-Doped Fiber Laser by Use of an Integrated Optics Mach-Zehnder Interferometer  

NASA Astrophysics Data System (ADS)

Wavelength tunability of an Er3+-doped fiber laser is reported by the use of an integrated optics Mach-Zehnder interferometer driven electro-optically. A pump laser threshold of 5 mW and a continuous tunable band from 1530 nm to 1554 nm are achieved with a drive voltage varying between 0 to +7 volts. An evaluation of the design and improvements are given based on the experimental and theoretical analysis.

Azami, N.; Saïssy, A.; de Micheli, M. P.; Monnom, G.; Ostrowsky, D. B.; Mollier, P.

88

Long-term monitoring crustal deformations in the North Caucasus by the laser interferometer  

NASA Astrophysics Data System (ADS)

During several years SAI MSU carries out the long-term observation of crustal deformations in the North Caucasus, in one of the most active in geodynamic respect region of Russia. On the whole this region is characterized by the complex system of active faults, intensive movements of the Earth's crust and high seismicity. The wide-band laser interferometer strainmeter with a measurable armlength of 75 m is disposed in an underground tunnel. The optical scheme of the interferometer is the two passes (N=2) Michelson-type interferometer with unequal arms. The long-term monitoring strains of the Earth is provided in tree frequency bands: below 0.1 Hz (low frequency channel), in the bandwidth of 1 Hz around frequency of 30 Hz (seismic channel) and in the bandwidth of 0.5 Hz around frequency of 1.62 kHz (acoustic channel). Pressure and temperature are monitored too. Unique geodynamical features of the region, the proximity of the Elbrus volcanic structure and existing long-term wide-band and high-quality observed timeseries of deformations allow to study a wide class of geophysical phenomenae. Time variation of the tidal deformation parameters indicates the correlation with local seismicity of the region. The large number of global earthquakes recorded by the Baksan interferometer during several years where analyzed. The data are used for estimating the parameters of the free oscillations of the Earth (FOE) and resonances of the Elbrus volcano magma source. After subtraction of FOE from the experimental spectrums the additional resonance peaks were interpreted as the eigen frequencies of the magma source of the Elbrus volcano. Slight changes of these frequencies may certainly indicate changes of magma state, its temperature and saturation by volcanic gases. Continuous monitoring over the spectra of eigen frequencies of the magma source provide additional data for the general warning system for volcanic hazard assessment. This work is supported by the Russian Foundation for Basic Research under Grant No 00-05-64882 and 02-05-65012.

Milyukov, V.; Kopaev, A.; Kozyreva, A.; Klyachko, B.; Myasnikov, A.

2003-04-01

89

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

SciTech Connect

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.

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

90

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

PubMed

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

Rodrigo, Peter John; Pedersen, Christian

2013-09-01

91

Robust, Accurate, and Non-Contacting Vibration Measurement Systems. Summary of Comparison Measurement of the Robust Laser Interferometer and Typical Accelerometer Systems.  

National Technical Information Service (NTIS)

Epoch Engineering, Incorporated (EEI) has completed a series of vibration measurements comparing their newly-developed Robust Laser Interferometer (RLI) with accelerometer instrumentation systems. EEI has successfully demonstrated, on several pieces of co...

T. C. Goodenow R. L. Shipman H. M. Holland

1995-01-01

92

Robust, Accurate, and Non-Contacting Vibration Measurement Systems. Supplemental Appendices Presenting Comparison Measurements of the Robust Laser Interferometer and Typical Accelerometer Systems.  

National Technical Information Service (NTIS)

Epoch Engineering, Incorporated (EEI) has completed a series of vibration measurements comparing their newly-developed Robust Laser Interferometer (RLI) with accelerometer instrumentation systems. EEI has successfully demonstrated, on several pieces of co...

T. C. Goodenow R. L. Shipman H. M. Holland

1995-01-01

93

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

Microsoft Academic Search

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

N V Baburin; Yu V Borozdov; Yu K Danileiko; B I Denker; A D Ivanov; Vyacheslav V Osiko; S E Sverchkov; A V Sidorin; V A Chikov; R Ifflander; R Hack; I Kertesz; N Kroo

1998-01-01

94

Precise density profile measurements by using a two color YAG/CO{sub 2} laser imaging Interferometer on LHD  

SciTech Connect

A multichannel imaging heterodyne interferometer is installed on Large Helical Device. Two branches of the interferometer: one with CO{sub 2} laser (wavelength {lambda}{sub i}=10.6 {mu}m) and other with diode pumped yttritium-aluminium-garnet (YAG) laser (wavelength {lambda}{sub i}=1.06 {mu}m) are used for electron density measurements and vibration compensation. Two slab beams and one circular beam are injected vertically. Liquid nitrogen cooled linear detector arrays are used for detection of slab beams and room temperature detector is employed for single circular beam for CO{sub 2} beams. Avalanche photodiodes record signals for YAG beams. Chordal resolution is from 15 to 22.5 mm, phase resolution is 10{sup -3} of CO{sub 2} fringe, which is determined by the electrical noise of phase counter. About 5x10{sup -3}{approx}10{sup -2} of CO{sub 2} fringe uncompensated signal remains after vibration compensation. Combining existing 13-channels far infrared (wavelength {lambda}{sub i}=119 {mu}m) laser interferometer, profile measurements at high density (>10{sup 20} m{sup -3}) become possible.

Tanaka, K.; Sanin, A.L.; Vyacheslavov, L.N.; Akiyama, T.; Kawahata, K.; Tokuzawa, T.; Ito, Y.; Okajima, S. [National Institute for Fusion Science, Toki 509-5962 (Japan); Budker Institute of Nuclear Physics, 630090, Novosibirsk (Russian Federation); Budker Institute of Nuclear Physics, 630090, Novosibirsk, Russia and Novosibirs State University, 630090, Novosibirsk (Russian Federation); National Institute for Fusion Science, Toki 509-5962 (Japan); Chubu University, Kasugai 487-8501 (Japan)

2004-10-01

95

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

NASA Astrophysics Data System (ADS)

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.

Higuchi, Sei

2009-10-01

96

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

SciTech Connect

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.

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

1991-02-01

97

Study of self-generated magnetic fields in laser produced plasmas using a three-channel polaro-interferometer  

SciTech Connect

Self-generated magnetic fields produced in laser plasmas at moderate laser intensities have been measured using a three-channel polaro-interferometer. The main elements of this device are two birefringent calcite wedges placed between two crossed polarizers. Using this device, the spatial profiles of (a) the rotation angle (polarometry), (b) the electron density (interferometry), and (c) the transmitted probe beam intensity (shadowgraphy) are recorded simultaneously using a digital camera with a large format CCD in a single laser shot. Magnetic fields of 2-4 MG had been estimated in aluminum plasma at laser intensities {approx}10{sup 13} W/cm{sup 2}. It is also possible to use this device in other configurations to get time resolved information.

Prasad, Y. B. S. R.; Barnwal, S.; Naik, P. A.; Kamath, M. P.; Joshi, A. S.; Kumbhare, S. R.; Gupta, P. D. [Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Bolkhovitinov, E. A.; Rupasov, A. A. [Laboratory of Plasma Diagnostics, P.N. Lebedev Physical Institute, 53 Leninsky Prospekt, Moscow 117924 (Russian Federation)

2011-12-15

98

Positive quadrature formulas III  

NASA Astrophysics Data System (ADS)

First we discuss briefly our former characterization theorem for positive interpolation quadrature formulas (abbreviated qf), provide an equivalent characterization in terms of Jacobi matrices, and give links and applications to other qf, in particular to Gauss-Kronrod quadratures and recent rediscoveries. Then for any polynomial t_n which generates a positive qf, a weight function (depending on n ) is given with respect to which t_n is orthogonal to mathbb{P}_{n-1} . With the help of this result an asymptotic representation of the quadrature weights is derived. In general the asymptotic behaviour is different from that of the Gaussian weights. Only under additional conditions do the quadrature weights satisfy the so-called circle law. Corresponding results are obtained for positive qf of Radau and Lobatto type.

Peherstorfer, Franz

2008-12-01

99

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

SciTech Connect

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.

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

1990-01-01

100

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

DOEpatents

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).

Buchenauer, C. Jerald (Los Alamos, NM)

1984-01-01

101

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

DOEpatents

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).

Buchenauer, C.J.

1981-09-23

102

Laser Interferometer Space Antenna double black holes: dynamics in gaseous nuclear discs  

NASA Astrophysics Data System (ADS)

We study the inspiral of double black holes, with masses in the Laser Interferometer Space Antenna (LISA) window of detectability, orbiting inside a massive circumnuclear, rotationally supported gaseous disc. Using high-resolution smoothed particle hydrodynamics simulations, we follow the black hole dynamics in the early phase when gas-dynamical friction acts on the black holes individually, and continue our simulation until they form a close binary. We find that in the early sinking the black holes lose memory of their initial orbital eccentricity if they corotate with the gaseous disc. As a consequence, the massive black holes bind forming a binary with a low eccentricity, consistent with zero within our numerical resolution limit. The cause of circularization resides in the rotation present in the gaseous background where dynamical friction operates. Circularization may hinder gravitational waves from taking over and leading the binary to coalescence. In the case of counter-rotating orbits, the initial eccentricity (if present) does not decrease, and the black holes may bind forming an eccentric binary. When dynamical friction has subsided, for equal mass black holes and regardless their initial eccentricity, angular momentum loss, driven by the gravitational torque exerted on the binary by surrounding gas, is nevertheless observable down to the smallest scale probed (~=1 pc). In the case of unequal masses, dynamical friction remains efficient down to our resolution limit, and there is no sign of formation of any ellipsoidal gas distribution that may further harden the binary. During inspiral, gravitational capture of gas by the black holes occurs mainly along circular orbits; eccentric orbits imply high relative velocities and weak gravitational focusing. Thus, the active galactic nucleus activity may be excited during the black hole pairing process and double active nuclei may form when circularization is completed, on distance scales of tens of parsecs.

Dotti, Massimo; Colpi, Monica; Haardt, Francesco

2006-03-01

103

CONTROL OF LASER RADIATION PARAMETERS: Q-switching of a high-power solid-state laser by a fast scanning Fabry---Perot interferometer  

Microsoft Academic Search

An investigation was made of the suitability of a Q-switch, based on a piezoelectrically scanned short-base Fabry---Perot interferometer, for an Nd3+: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

N. V. Baburin; Yu V. Borozdov; Yu K. Danileiko; B. I. Denker; A. D. Ivanov; R. Ifflander; I. Kertesz; N. Kroo; Vyacheslav V. Osiko; S. E. Sverchkov; A. V. Sidorin; R. Hack; V. A. Chikov

1998-01-01

104

A High-Quality Mach-Zehnder Interferometer Fiber Sensor by Femtosecond Laser One-Step Processing  

PubMed Central

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 104 nm/RIU, and the temperature sensitivity is 51.5 pm/°C at 200 ? 875 °C with a step of 25 °C.

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

2011-01-01

105

Phase-noise properties of an ytterbium-doped fiber amplifier for the Laser Interferometer Space Antenna  

NASA Astrophysics Data System (ADS)

Phase noise is a critical issue for the sensitivity of the interferometric gravitational-wave detector Laser Interferometer Space Antenna that requires laser sources with 1 W of output power. A low-power seed laser with a subsequent fiber amplifier is in discussion, and we report on spectrally resolved phase-noise measurements of an ytterbium-doped fiber amplifier emitting 1 W of output power from 10 mW of seed power. Phase-noise measurements for Fourier frequencies from 10-4 Hz to 100 kHz show 60 rad/Hz0.5 at 10-4 Hz and 0.2 mrad/Hz0.5 at 1 kHz. This measured excess phase noise is orders of magnitude below the free-running phase noise of nonplanar ring oscillators.

Tröbs, Michael; Wessels, Peter; Fallnich, Carsten

2005-04-01

106

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

NASA Astrophysics Data System (ADS)

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 × 1017 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.

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

107

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

SciTech Connect

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}.

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

108

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Fabry—Perot interferometer with resonant mirrors  

NASA Astrophysics Data System (ADS)

An analysis is made of the task of construction of an interferometer with an output signal weakly dependent on the frequency of the incident light and yet highly sensitive to a change in the distance between the mirrors. This can be achieved by the use of resonant dielectric mirrors with the reflection phase and amplitude strongly dependent on the frequency within the width of the response function of the interferometer. The interferometer can be reduced to a four-mirror configuration in the case of the proposed types of mirrors. The relevant expressions are derived for this configuration. It is shown that the distance between the mirrors can be considerably greater than has been assumed earlier. A system of parameters is introduced and specific examples are considered.

Troitskii, Yu V.

1995-06-01

109

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

SciTech Connect

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.

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

110

Dual surface interferometer  

DOEpatents

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.

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

1982-01-01

111

Dual surface interferometer  

DOEpatents

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.

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

1980-09-12

112

Optical quadrature demodulator for coherent detection and sensor applications  

NASA Astrophysics Data System (ADS)

A new device was designed, built and demonstrated which provides exceptional performance in a very small, potentially very low cost unit. Balanced quadrature detection for homodyne or heterodyne detection of phase or frequency encoded signal information is accomplished with microradian phase sensitivities over a broad range of environments and for a broad dynamic range of signal levels and frequencies. Results of current development testing are presented along with brief discussions of potential applications to coherent detection for interferometers, sensors, and communications.

Watanabe, S. F.; Joseph, A. A.; Turner, H. B.; Holmes, S. A.; Freidah, J. T.

1986-05-01

113

A laser probe based on a Sagnac interferometer with fast mechanical scan for RF surface and bulk acoustic wave devices.  

PubMed

This paper describes the development of a phasesensitive laser probe with fast mechanical scan for RF surface and bulk acoustic wave (SAW/BAW) devices. The Sagnac interferometer composed of micro-optic elements 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 insensitive to low-frequency vibration. This feature allows us to apply the fast mechanical scan to the interferometric measurement without badly sacrificing its SNR and spatial resolution. The system was applied to the visualization of a field pattern on the vibrating surface of an RF BAW resonator operating in the 2 GHz range. The field pattern was obtained in 17 min as a 2-D image (500 × 750 pixel with 0.4 ?m resolution and SNR of 40 dB). The system was also applied to the characterization of an RF SAW resonator operating in the 1 GHz range, and the applicability of the system was demonstrated. PMID:21244986

Hashimoto, Ken-ya; Kashiwa, Keiskue; Wu, Nan; Omori, Tatsuya; Yamaguchi, Masatsune; Takano, Osamu; Meguro, Sakae; Akahane, Koichi

2011-01-01

114

Uncertainty propagation: Quadrature  

NSDL National Science Digital Library

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.

Liao, David

115

A Comparison of Delayed Self-Heterodyne Interference Measurement of Laser Linewidth Using Mach-Zehnder and Michelson Interferometers  

PubMed Central

Linewidth measurements of a distributed feedback (DFB) fibre laser are made using delayed self heterodyne interferometry (DHSI) with both Mach-Zehnder and Michelson interferometer configurations. Voigt fitting is used to extract and compare the Lorentzian and Gaussian linewidths and associated sources of noise. The respective measurements are wL (MZI) = (1.6 ± 0.2) kHz and wL (MI) = (1.4 ± 0.1) kHz. The Michelson with Faraday rotator mirrors gives a slightly narrower linewidth with significantly reduced error. This is explained by the unscrambling of polarisation drift using the Faraday rotator mirrors, confirmed by comparing with non-rotating standard gold coated fibre end mirrors.

Canagasabey, Albert; Michie, Andrew; Canning, John; Holdsworth, John; Fleming, Simon; Wang, Hsiao-Chuan; Aslund, Mattias L.

2011-01-01

116

Fabrication of diffraction gratings for surface encoders by using a Lloyd's mirror interferometer with a 405 nm laser diode  

NASA Astrophysics Data System (ADS)

To fabricate a scale grating for a surface encoder in a cost-effective way, a blue laser diode with a wavelength of 405 nm is employed in a Lloyd's mirror interferometer to carry out interference lithography (IL) of the grating. The beams from the laser diode are collimated by an aspherical collimating lens to form beams with a diameter of 50 mm. These beams are then projected towards the Lloyd's mirror and the grating substrate, which are aligned perpendicularly with each other and are mounted on a rotary stage. One half of the beam directly goes to the grating substrate, and the other half reaches to the grating substrate after being reflected by the mirror. The direct beam and the reflected beam interference with each other to generate and expose the interference fringes, which correspond to the scale grating structures, on the substrate coated with a photoresist layer. The pitch and area of the grating structures are set to be 570 nm and around 300 mm2, respectively. The fabricated grating structures are evaluated with an AFM to investigate the influence of the spectrum width of the laser beam.

Li, Xinghui; Shimizu, Yuki; Ito, So; Gao, Wei; Zeng, Lijiang

2013-01-01

117

A Non-Linear Laser Interferometer Model And Its Use For Drag-Free System Verification  

NASA Astrophysics Data System (ADS)

A non-linear model of the Optical Metrology System (OMS) for the LISA Technology Package (LTP) on board LISA Pathfinder has been developed that covers main noise sources and accounts for large test masses' angular deviations; it allows for Drag-Free System verification in development and real-time-testing environments. Using this model a sequential approach for the LTP interferometer acquisition has been demonstrated. The acquisition has been completely designed in accelerometer mode; time-domain analyses demonstrate that angular positioning requirements are met in a timely manner.

Gerardi, D.; Fichter, W.; Brandt, N.; Braxmaier, C.; Heinzel, G.; Vitale, S.

2006-11-01

118

Correlation of terrestrial surface oscillations and ionosphere disturbances during the earthquakes according to laser interferometer and GPS data  

NASA Astrophysics Data System (ADS)

Process of earthquakes preparation occupies, as a rule, the significant period of time and consequently demands carrying out the long observations above the possible earthquake focus. The existing network of ground navigating stations allows performing such observations in the ionosphere state. It also enables to determine the ionospheric effects of earthquakes based on the analysis of an electron density of F2 layer. The navigating systems GPS and Glonass despite the complexity of detecting ionospheric variations caused by seismic effects can be adapted in the best way to the realization of the ionosphere monitoring. Large-scale spatial and temporal disturbances of the earth strain and the total electron contents (TEC) in the ionospheric F2 layer have been recently detected by our underground laser strainmeters and microwave ionospheric profile-meter based on the GPS data [1]. Here the technique of long-base laser interferometry measurements and dual frequency GPS data acquisition are presented and new results of data analysis are discussed. We have compared the strain-barometric variations recorded by the laser interferometers of 100 m and 300 m length at the IRE RAS testing site (Moscow region), and TEC drifts according to the local (distance up to 100-200 km) and remote (being 2000-7000 km apart) GPS stations. The utmost sensitivity of laser interferometers was dL/L=10(-11) to the earth strain and dP=10(-4) mbar to the barometric variations. The ionospheric data have been calculated with radio translucence algorithms application. The connection of undulating strain-barometric oscillations of a surface and atmospheric pressure in 1-10 mHz frequency band and synchronously recorded TEC variations was found during earthquakes (Japan 25.09.03, Ms=8.4 and Altai 27.09.03 Ms=7.3 - 6.7) and the velocities of the disturbances propagation have been determined. [1] M.N. Dubrov and V.M. Smirnov, IUGG2003, 30.06-11.07.2003, Sapporo, Japan, JSA02.

Dubrov, M. N.; Smirnov, V. M.

2008-09-01

119

Accurate image registration for quadrature tomographic microscopy.  

PubMed

This paper presents a robust and fully automated registration algorithm for registration of images of Quadrature Tomographic Microscopy (QTM), which is an optical interferometer. The need for registration of such images is to recognize distinguishing features of viable embryos to advance the technique for In Vitro Fertilization. QTM images a sample (live embryo) multiple times with different hardware configurations, each in turn producing 4 images taken by 4 CCD cameras simultaneously. Embryo movement is often present between imaging. Our algorithm handles camera calibration of multiple cameras using a variant of ICP, and elimination of embryo movement using a hybrid of feature- and intensity-based methods. The algorithm is tested on 20 live mouse embryos containing various cell numbers between 8 and 26. No failure thus far, and the average alignment error is 0.09 pixels, corresponding to the range of 639 and 675 nanometers. PMID:16686050

Tsai, Chia-Ling; Warger, William; DiMarzio, Charles

2005-01-01

120

Low cost plane parallel plate lateral shearing interferometer for infrared laser beam diagnostics  

Microsoft Academic Search

Few cost-effective methods exist for measuring the wave front of mid- and long-wave infrared beams that span 3-5 and 8-12 mum, respectively. One obvious need within the infrared laser community is the ability to measure the degree of collimation of an infrared laser beam, e.g. that formed by a beam expanding telescope used with a CO2 laser or a system

Bruce E. Bernacki; Kannan Krishnaswami; Norman C. Anheier

2009-01-01

121

Carbon fiber reinforced polymer dimensional stability investigations for use on the laser interferometer space antenna mission telescope.  

PubMed

The laser interferometer space antenna (LISA) is a mission designed to detect low frequency gravitational waves. In order for LISA to succeed in its goal of direct measurement of gravitational waves, many subsystems must work together to measure the distance between proof masses on adjacent spacecraft. One such subsystem, the telescope, plays a critical role as it is the laser transmission and reception link between spacecraft. Not only must the material that makes up the telescope support structure be strong, stiff, and light, but it must have a dimensional stability of better than 1 pm Hz(-1/2) at 3 mHz and the distance between the primary and the secondary mirrors must change by less than 2.5 ?m over the mission lifetime. Carbon fiber reinforced polymer is the current baseline material; however, it has not been tested to the pico meter level as required by the LISA mission. In this paper, we present dimensional stability results, outgassing effects occurring in the cavity and discuss its feasibility for use as the telescope spacer for the LISA spacecraft. PMID:22225234

Sanjuán, J; Preston, A; Korytov, D; Spector, A; Freise, A; Dixon, G; Livas, J; Mueller, G

2011-12-01

122

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

SciTech Connect

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.

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

123

Quadrature interferometry for nonequilbrium ultracold atoms in optical lattices  

NASA Astrophysics Data System (ADS)

We propose an interaction-based interferometric technique for making time-resolved measurements of quadrature operators of nonequilibrium ultracold atoms in optical lattices. The technique creates two subsystems of magnetic atoms in different spin states and lattice sites--the arms of the interferometer. A Feshbach resonance turns off atom-atom interactions in one spin subsystem, making it a well-characterized reference state, while atoms in the other subsystem undergo nonequilibrium many-body dynamics for a variable hold time. The nonequilibrium evolution can involve a variety of Hamiltonians, including systems with tunneling and spin-orbit couplings using artificial gauge fields. Interfering the subsystems via a second beam-splitting operation, time-resolved quadrature measurements are directly obtained by detecting relative spin populations. Analyzing a simple application of the interferometer, we obtain analytic predictions for quadratures for deep optical lattices with negligible tunneling. As a second, distinct application, we show that atom-atom interaction strengths can in principle be determined with super-Heisenberg scaling n-3/2 in the mean number of atoms per lattice site n, making it possible to test the physics of interaction-based quantum metrology.

Johnson, Philip; Tiesinga, Eite

2013-03-01

124

Multi-wavelength Operation of an Er3+-doped Fiber Laser at Room Temperature with a Novel Optical Fiber Mach-Zehnder Interferometer  

Microsoft Academic Search

A novel multi-wavelength erbium-doped fiber laser with a double-pass Mach-Zehnder fiber interferometer acting both as a comb filter and as a reflection mirror is demonstrated. The spatial hole burning effect introduced by the standing wave cavity configuration enables the simultaneous operation of multiple wavelengths in the homogeneously broadened erbium-doped fiber at room temperature. In the experiment, simultaneous oscillation of four

An Hong-Lin; Lin Xiang-Zhi; Liu Hong-Du

2000-01-01

125

Broad tunability from a compact, low-threshold Cr:LiSAF laser incorporating an improved birefringent filter and multiple-cavity Gires-Tournois interferometer mirrors  

Microsoft Academic Search

We demonstrate prismless tuning of a compact femtosecond Cr:LiSAF laser. The employed technique, which uses a specially designed birefringent filter in combination with dispersion compensation from a pair of multiple-cavity Gires-Tournois interferometer mirrors, provides tuning over 20 nm. We give the results of theoretical modeling of the tuning velocity and the spectral width of the central passband. We show, both

Barry Stormont; Alan J. Kemp; Iain G. Cormack; Ben Agate; C. Tom A. Brown; Wilson Sibbett; Robert Szipöcs

2005-01-01

126

Digital quadrature phase detection  

DOEpatents

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.

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

1989-08-17

127

Eliminating additional laser intensity modulation with an analog divider for fiber-optic interferometers  

NASA Astrophysics Data System (ADS)

Additional laser intensity modulation (LIM) will degrade performance of fiber-optic interferometric sensors in which phase generated carrier demodulation techniques are utilized. In this paper, a new method to eliminate the additional LIM of a sinusoidal modulated fiber ring laser through an analog divider is presented. Experimental results show not only LIM but also intensity noise peak caused by relax oscillation are eliminated simultaneously by the analog divider. System becomes more stable, and gets a higher performance with adoption of this method. Factors influencing system performance are also analyzed.

Wu, Xuqiang; Tao, Ran; Zhang, Qifa; Zhang, Gang; Li, Ling; Peng, Jun; Yu, Benli

2012-03-01

128

Analog-to-digital converters nonlinear errors correction in thermal diagnostics for the laser interferometer space antenna mission.  

PubMed

Low-noise temperature measurements at frequencies in the millihertz range are required in the laser interferometer space antenna (LISA) and LISA PathFinder missions. The required temperature stability for LISA is around 10 microK Hz(-1/2) at frequencies down to 0.1 mHz. In this paper we focus on the identification and reduction in a source of excess noise detected when measuring time-varying temperature signals. This is shown to be due to nonidealities in the analog-to-digital converter (ADC) transfer curve, and degrades the measurement by about one order of magnitude in the measurement bandwidth when the measured temperature drifts by a few approximately microK s(-1). In a suitable measuring system for the LISA mission, this noise needs to be reduced. Two different methods based on the same technique have been implemented, both consisting in the addition of dither signals out of band to mitigate the ADC nonideality errors. Excess noise of this nature has been satisfactorily reduced by using these methods when measuring temperature ramps up to 10 microK s(-1). PMID:19947750

Sanjuán, J; Lobo, A; Ramos-Castro, J

2009-11-01

129

Broad tunability from a compact, low-threshold Cr:LiSAF laser incorporating an improved birefringent filter and multiple-cavity Gires-Tournois interferometer mirrors  

NASA Astrophysics Data System (ADS)

We demonstrate prismless tuning of a compact femtosecond Cr:LiSAF laser. The employed technique, which uses a specially designed birefringent filter in combination with dispersion compensation from a pair of multiple-cavity Gires-Tournois interferometer mirrors, provides tuning over 20 nm. We give the results of theoretical modeling of the tuning velocity and the spectral width of the central passband. We show, both experimentally and theoretically, that a single birefringent plate can be used to control the oscillating bandwidth of the laser. The effect this has on the output-pulse duration has also been investigated.

Stormont, Barry; Kemp, Alan J.; Cormack, Iain G.; Agate, Ben; Brown, C. Tom A.; Sibbett, Wilson; Szipöcs, Robert

2005-06-01

130

Phase modulated self-mixing interferometer of a fiber laser system  

NASA Astrophysics Data System (ADS)

In this paper, self-mixing interference measurement based on phase modulation is demonstrated using a fiber laser system. The measurement setup is built by an erbium-doped fiber laser and an integrated-optic phase modulator. Optical feedback and phase modulated interference is theoretically analyzed, and the phase demodulation algorithm of the interference signal is implemented by Fourier analysis. Error sources induced by the distortion of the interference signal in the presence of optical feedback and the imperfect alignment between the polarization of the light and the electro-optically active axis are evaluated in detail. The system is experimentally applied to reconstruct the motion of a high-precision commercial PZT and a displacement measurement accuracy of ?/20 is obtained, providing a practically feasible solution for displacement measurement based on all optical-fiber sensing applications with high precision.

Hao, Hui; Wang, Ming; Xia, Wei; Guo, Dongmei; Lu, Huali

2013-10-01

131

Single-mode dye laser with a double-action Fizeau interferometer.  

PubMed

The peculiar properties of the high-reflectivity Fizeau wedge used in reflection are pointed out and used to obtain single-mode operation of a Nd:YAG-pumped dye laser. It is demonstrated that the reflecting Fizeau wedge can have, as a cavity output coupler, the double action of selective-feedback mirror and an output filter, thus producing a background-free tunable narrow line. PMID:19701347

Meyer, Y H; Nenchev, M N

1981-03-01

132

Design of Gires-Tournois Interferometer Mirror Used in Cr:LiSAF Femtosecond Lasers  

Microsoft Academic Search

An useful design used for the dispersion compensation in Cr:LiSAF femtosecond lasers is reported. It is composed of 58 alternating Ta2O5 and SiO2 layers. The first part, from layer 1 to layer 45, which have quarter-wave optical thickness serve as high reflectivity dielectric stack. The second part, from layer 46 to layer 58, whose thicknesses are obtained by computer optimization

Chunyan Liao

2010-01-01

133

Generalization of differential quadrature discretization  

NASA Astrophysics Data System (ADS)

The differential quadrature (DQ) is generalized. Various methods for generating the weighting coefficients are developed. The design of a grid model is flexible. Weighting coefficients for general multi-coordinate grid models with arbitrary configurations can also be calculated. The calculation of weighting coefficients is easy. Sample numerical procedures for constructing one-coordinate, two-coordinate and arbitrary finite-coordinate generic differential quadrature models are presented.

Chen, Chang-New

1999-12-01

134

Messages about the Messengers: Reception and Review of ``Astronomy's New Messengers,'' The Laser Interferometer Gravitational-wave Observatory's Interactive Public Exhibition  

NASA Astrophysics Data System (ADS)

The Laser Interferometer Gravitational-wave Observatory (LIGO) is an endeavor to directly confirm the existence of gravitational waves, funded by the National Science Foundation. As a publicly funded research project, it is both within its directive and within its best interest to educate and inform the public at large of its efforts. The Education and Public Outreach (EPO) group within LIGO, under the direction of Marco Cavaglià, has developed an interactive exhibit to educate, explain and showcase LIGO to the general public. The exhibit, entitled ``Astronomy's New Messengers,'' debuted at the World Science Festival in New York City, and includes features to explain gravitational waves and their possible sources, an interferometer, the space-time fabric model, and the difficulties in identifying a gravitational wave. The exhibit visitors were asked to complete a survey about their experience at ``Astronomy's New Messengers,'' and the presentation will report the survey results, and explore the full exhibit's reception by the general public.

Rankins, Brooke; Cavagliá, Marco

2010-10-01

135

Probing nontensorial polarizations of stochastic gravitational-wave backgrounds with ground-based laser interferometers  

SciTech Connect

In a general metric theory of gravitation in four dimensions, six polarizations of a gravitational wave are allowed: two scalar and two vector modes, in addition to two tensor modes in general relativity. Such additional polarization modes appear due to additional degrees of freedom in modified theories of gravitation or theories with extra dimensions. Thus, observations of gravitational waves can be utilized to constrain the extended models of gravitation. In this paper, we investigate detectability of additional polarization modes of gravitational waves, particularly focusing on a stochastic gravitational-wave background, with laser-interferometric detectors on the Earth. We found that more than three detectors can separate the mixture of polarization modes in detector outputs, and that they have almost the same sensitivity to each polarization mode of stochastic gravitational-wave background.

Nishizawa, Atsushi; Sakagami, Masa-aki [Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501 (Japan); Taruya, Atsushi [Research Center for the Early Universe, School of Science, The University of Tokyo, Tokyo 113-0033 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Hayama, Kazuhiro [Albert-Einstein-Institut (Max-Planck-Institut fuer Gravitationsphysik), Callinstrasse 38, D-30167 Hannover (Germany); Kawamura, Seiji [TAMA Project, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

2009-04-15

136

Fringe Visibility Estimators for the Palomar Testbed Interferometer  

Microsoft Academic Search

Visibility estimators and their performance are presented for use with the Palomar Testbed Interferometer (PTI). One operational mode of PTI is single-baseline visibility measurement using path length modulation with synchronous readout by a NICMOS-3 infrared array. Visibility is estimated from the fringe quadratures, either incoherently, or using source phase referencing to provide a longer coherent integration time. The visibility estimators

M. M. Colavita

1999-01-01

137

Holographic microscope interferometer  

NASA Astrophysics Data System (ADS)

A simple and easy to use holographic microscope interferometer (HMI) for biological and material science applications is described. The unit is based on an ordinary microscope accomplished by He-Ne laser, several optical elements, a photothermoplastic (PTP) recorder, and a CCD-camera. Blood and plant cells, as well as internal solid bodies defect images, are demonstrated. Characteristics and application of the unit are discussed.

Babenko, Veronika A.; Konst, Elena V.; Konstantinov, Vladimir B.

1995-02-01

138

Special quadrature rules for Laplace transform inversion  

NASA Astrophysics Data System (ADS)

Quadrature rules for Laplace transform inversion are studied that are adapted to the inversion of transforms corresponding to slowly varying long processes characteristic of linear viscoelasticity problems. The convergence of special quadrature rules for Laplace transform inversion is proved.

Lebedeva, A. V.; Ryabov, V. M.

2012-12-01

139

Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early universe  

NASA Astrophysics Data System (ADS)

We derive a general equation relating the gravitational-wave observables r and ?0gw(f); or the observables ?0gw(f1) and ?0gw(f2). Here, r is the so-called “tensor-to-scalar ratio,” which is constrained by cosmic-microwave-background experiments; and ?0gw(f) is the energy spectrum of primordial gravitational waves, which is constrained, e.g., by pulsar-timing measurements, laser-interferometer experiments, and the standard big bang nucleosynthesis bound. Differentiating this equation yields a new expression for the tilt dln??0gw(f)/dln?f of the present-day gravitational-wave spectrum. The relationship between r and ?0gw(f) depends sensitively on the uncertain physics of the early universe, and we show that this uncertainty may be encapsulated (in a model-independent way) by two quantities: w^(f) and n^t(f), where n^t(f) is a certain logarithmic average over nt(k) (the primordial tensor spectral index); and w^(f) is a certain logarithmic average over w˜(a) (the effective equation-of-state parameter in the early universe, after horizon re-entry). Here, the effective equation-of-state parameter w˜(a) is a combination of the ordinary equation-of-state parameter w(a) and the bulk viscosity ?(a). Thus, by comparing observational constraints on r and ?0gw(f), one obtains (remarkably tight) constraints in the {w^(f),n^t(f)} plane. In particular, this is the best way to constrain (or detect) the presence of a stiff energy component (with w>1/3) in the early universe, prior to big bang nucleosynthesis. (The discovery of such a component would be no more surprising than the discovery of a tiny cosmological constant at late times!) Finally, although most of our analysis does not assume inflation, we point out that if cosmic-microwave-background experiments detect a nonzero value for r, then we will immediately obtain (as a free by-product) a new upper bound w^?0.55 on the logarithmically averaged effective equation-of-state parameter during the “primordial dark age” between the end of inflation and the start of big bang nucleosynthesis.

Boyle, Latham A.; Buonanno, Alessandra

2008-08-01

140

Relating gravitational wave constraints from primordial nucleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early universe  

SciTech Connect

We derive a general equation relating the gravitational-wave observables r and {omega}{sub 0}{sup gw}(f); or the observables {omega}{sub 0}{sup gw}(f{sub 1}) and {omega}{sub 0}{sup gw}(f{sub 2}). Here, r is the so-called 'tensor-to-scalar ratio', which is constrained by cosmic-microwave-background experiments; and {omega}{sub 0}{sup gw}(f) is the energy spectrum of primordial gravitational waves, which is constrained, e.g., by pulsar-timing measurements, laser-interferometer experiments, and the standard big bang nucleosynthesis bound. Differentiating this equation yields a new expression for the tilt dln{omega}{sub 0}{sup gw}(f)/dlnf of the present-day gravitational-wave spectrum. The relationship between r and {omega}{sub 0}{sup gw}(f) depends sensitively on the uncertain physics of the early universe, and we show that this uncertainty may be encapsulated (in a model-independent way) by two quantities: w-circumflex(f) and n-circumflex{sub t}(f), where n-circumflex{sub t}(f) is a certain logarithmic average over n{sub t}(k) (the primordial tensor spectral index); and w-circumflex(f) is a certain logarithmic average over w-tilde(a) (the effective equation-of-state parameter in the early universe, after horizon re-entry). Here, the effective equation-of-state parameter w-tilde(a) is a combination of the ordinary equation-of-state parameter w(a) and the bulk viscosity {zeta}(a). Thus, by comparing observational constraints on r and {omega}{sub 0}{sup gw}(f), one obtains (remarkably tight) constraints in the {l_brace}w-circumflex(f),n-circumflex{sub t}(f){r_brace} plane. In particular, this is the best way to constrain (or detect) the presence of a stiff energy component (with w>1/3) in the early universe, prior to big bang nucleosynthesis. (The discovery of such a component would be no more surprising than the discovery of a tiny cosmological constant at late times{exclamation_point}) Finally, although most of our analysis does not assume inflation, we point out that if cosmic-microwave-background experiments detect a nonzero value for r, then we will immediately obtain (as a free by-product) a new upper bound w-circumflex < or approx. 0.55 on the logarithmically averaged effective equation-of-state parameter during the 'primordial dark age' between the end of inflation and the start of big bang nucleosynthesis.

Boyle, Latham A. [Canadian Institute for Theoretical Astrophysics (CITA), University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 3H8 (Canada); Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Buonanno, Alessandra [Maryland Center for Fundamental Physics, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2008-08-15

141

Baseband Digital Predistorter with Quadrature Error Correction  

Microsoft Academic Search

In this article simulation and measurement results of a FPGA implementation of a baseband digital complex gain predistorter with a quadrature modulator and demodulation error correction circuits are presented. Four different methods for finding the quadrature error correction values are compared and the effect of quadrature errors to predistortion is discussed. A 50 dB three stage power amplifier chain with

Ilari Teikari; Jouko Vankka; Kari Halonen

2006-01-01

142

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

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.

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

143

Quadrature interferometry for nonequilibrium ultracold atoms in optical lattices  

NASA Astrophysics Data System (ADS)

We develop an interferometric technique for making time-resolved measurements of field-quadrature operators for nonequilibrium ultracold bosons in optical lattices. The technique exploits the internal state structure of magnetic atoms to create two subsystems of atoms in different spin states and lattice sites. A Feshbach resonance turns off atom-atom interactions in one spin subsystem, making it a well-characterized reference state, while atoms in the other subsystem undergo nonequilibrium dynamics for a variable hold time. Interfering the subsystems via a second beam-splitting operation, time-resolved quadrature measurements on the interacting atoms are obtained by detecting relative spin populations. The technique can provide quadrature measurements for a variety of Hamiltonians and lattice geometries (e.g., cubic, honeycomb, superlattices), including systems with tunneling, spin-orbit couplings using artificial gauge fields, and higher-band effects. Analyzing the special case of a deep lattice with negligible tunneling, we obtain the time evolution of both quadrature observables and their fluctuations. As a second application, we show that the interferometer can be used to measure atom-atom interaction strengths with super-Heisenberg scaling n¯-3/2 in the mean number of atoms per lattice site, and standard quantum limit scaling M-1/2 in the number of lattice sites. In our analysis, we require M?1 and for realistic systems n¯ is small, and therefore the scaling in total atom number N=n¯M is below the Heisenberg limit; nevertheless, measurements testing the scaling behaviors for interaction-based quantum metrologies should be possible in this system.

Tiesinga, E.; Johnson, P. R.

2013-01-01

144

Short wavelength interferometer for ITER  

SciTech Connect

There is a need for a real time, reliable density measurement compatible with the restricted access and radiation environment on ITER. Due to the large plasma path length, high density and field, refraction and Faraday rotation effects makes the use of contemporary long wavelength (>50{mu}m) interferometers impractical. In this paper we consider the design of a short wavelength vibration compensated interferometer which allows operation without a prohibitively large vibration isolated structure and permits the optics to be conveniently mounted directly in or on the tokamak. A density interferometer design for ITER incorporating a 10.6 {mu}m CO{sub 2} interferometer with vibration compensation provided by a 3. 39 {mu}m HeNe laser is discussed. The proposed interferometer design requires only a small intrusion into the ITER tokamak without a large support structure, refraction and Faraday rotation problems are avoided, and it provides a density resolution of at least 0.5%. Results are presented from an interferometer installed on the DIII-D tokamak incorporating essential elements of the proposed ITER design including 10.6 and 3.39 {mu}m lasers, a retro-reflector mounted on the vacuum wall of the DIII-D tokamak and real-time density feedback control. In this paper we consider a short wavelength interferometer design that incorporates vibration compensation for use on ITER. Our primary concern is to develop a interferometer design that will produce a reliable real time density monitor. We use the ITER conceptual design activity report as the basis of the design.

Snider, R.T.; Carlstrom, T.N.

1992-04-01

145

Inhomogeneous phase-visibility modulating interferometry by space on-off non-quadrature amplitude modulation.  

PubMed

A new method in interferometry based on on-off non-quadrature amplitude modulation for object phase retrieval is presented. Although the technique introduces inhomogeneous visibility and phase variations in the interferogram, it is shown that the phase retrieval of a given object is still possible. This method is implemented by using three beams and two Mach-Zehnder interferometers in series. One of the arms of the system is used as a probe beam and the other two are used as reference beams, yielding from their sum the conventional reference beam of a two-beam interferometer. We demonstrate that, if there is a phase difference within the range of (0,?) between these two beams, the effect of modulation in both amplitude and phase is generated for the case of on-off non-quadrature amplitude modulation. An analytical discussion is provided to sustain this method. Numerical and experimental results are also shown. PMID:23938612

Rivera-Ortega, Uriel; Meneses-Fabian, Cruz; Rodriguez-Zurita, Gustavo

2013-07-29

146

Error analysis and correcting 3D profilometry based on quadrature demodulation  

NASA Astrophysics Data System (ADS)

In this paper, the errors of three-dimensioned profilometry based on quadrature demodulation are analyzed and the corrected results are present. We found the method had three primary errors: the error that is caused by speckle of laser interference system, the error that is caused by mixing in quadrature demodulation and the error that is caused by the cosine fringe distortion in the structure light. We analyzed these three errors by experiment and theory. At last, we gave the corrected results.

Su, Ting; Zhang, Yong-Lin

2002-09-01

147

dc readout experiment at the Caltech 40m prototype interferometer  

Microsoft Academic Search

The Laser Interferometer Gravitational Wave Observatory (LIGO) operates a 40m prototype interferometer on the Caltech campus. The primary mission of the prototype is to serve as an experimental testbed for upgrades to the LIGO interferometers and for gaining experience with advanced interferometric techniques, including detuned resonant sideband extraction (i.e. signal recycling) and dc readout (optical homodyne detection). The former technique

R. L. Ward; R. Adhikari; B. Abbott; R. Abbott; D. Barron; R. Bork; T. Fricke; V. Frolov; J. Heefner; A. Ivanov; O. Miyakawa; K. McKenzie; B. Slagmolen; M. Smith; R. Taylor; S. Vass; S. Waldman; A. Weinstein

2008-01-01

148

Quadrature formulas for Fourier coefficients  

NASA Astrophysics Data System (ADS)

We consider quadrature formulas of high degree of precision for the computation of the Fourier coefficients in expansions of functions with respect to a system of orthogonal polynomials. In particular, we show the uniqueness of a multiple node formula for the Fourier-Tchebycheff coefficients given by Micchelli and Sharma and construct new Gaussian formulas for the Fourier coefficients of a function, based on the values of the function and its derivatives.

Bojanov, Borislav; Petrova, Guergana

2009-09-01

149

Vibration Free Interferometer Mirror  

NASA Astrophysics Data System (ADS)

Optic tables may be an obstacle for the interferometric studies when they are exposed to mechanical vibrations in the particular frequency range. To reduce the mechanical noise, a moveable mirror of the FTIR spectrometer was used as an interferometer mirror. The vibration response of this mirror was investigated with a fiber optic Fabry-Perot interferometer that was built in our laboratory. The moveable mirror is mounted on a coil that is located between the permanent magnets. When the proper current is applied to the coil, the mirror becomes magnetically suspended and resistant to the mechanical vibrations. This work presents a non-contact vibration-monitoring technique with the extrinsic Fabry-Perot interferometric displacement sensor implemented using 4/125 ?m single-mode fiber with 3 dB fiber optic coupler. This device is based on a low finesse Fabry-Perot cavity which is formed by the end of a sensing optical fiber (fiber probe) and the magnetically-suspended mirror. The incoming light is emitted by a 660 nm laser diode. During the vibration test an ADC (NI 6070E) and a Labview software program were used. This technique helps to reduce the mechanical noise and to improve the stability of the interferometer.

Yaltkaya, S.

2007-04-01

150

Weighted quadrature rules for finite element methods  

NASA Astrophysics Data System (ADS)

We discuss the numerical integration of polynomials times non-polynomial weighting functions in two dimensions arising from multiscale finite element computations. The proposed quadrature rules are significantly more accurate than standard quadratures and are better suited to existing finite element codes than formulas computed by symbolic integration. We validate this approach by introducing the new quadrature formulas into a multiscale finite element method for the two-dimensional reaction-diffusion equation.

Oliveira, Saulo P.; Madureira, Alexandre L.; Valentin, Frederic

2009-05-01

151

Multipass-prism interferometer for fine-frequency-tuning, single-mode operation of TEA CO/sub 2/ lasers  

SciTech Connect

A novel inerferometric configuration has been used as an efficient, narrow-band output coupler for high-power lasers. Its application to a TEA CO/sub 2/ laser has resulted in extremely reliable (100%) single transverse- and longitudinal-mode operation of this laser with a fine-frequency tunability of up to 3 GHz.

Giuliani, G.; Palange, E.; Salvetti, G.

1984-09-01

152

Fiber optic acoustic hydrophone with double Mach–Zehnder interferometers for optical path length compensation  

Microsoft Academic Search

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;

T. K Lim; Y Zhou; Y Lin; Y. M Yip; Y. L Lam

1999-01-01

153

Gain characteristics of coherent optical amplifiers using a Mach-Zehnder interferometer with Kerr media  

Microsoft Academic Search

This paper investigates the gain characteristics of coherent optical amplifiers that amplify only one of two quadrature phase components in an input signal light according to the phase of pump light. It is constructed around a Mach-Zehnder interferometer with Kerr media. To heuristically obtain the design parameters of the coherent optical amplifier, small-signal analysis is adapted to the Mach-Zehnder interferometer

Wataru Imajuku; Atsushi Takada

1999-01-01

154

Fiber Grating Sensor Interrogation Using a Double-Pass Mach–Zehnder Interferometer  

Microsoft Academic Search

We propose an advanced quadrature sampling method for a fiber grating sensor interrogation. A Mach-Zehnder interferometer output is sampled at internal triggers which are generated at the zero-crossing points of a double-pass Mach-Zehnder interferometer output. Due to the phase relationship, the internal trigger signals assure a 90deg phase difference between the sampled signals even in the presence of environmental disturbances.

Hyoung-Jun Park; Minho Song

2008-01-01

155

Fabrication of an integrated optical Mach-Zehnder interferometer based on refractive index modification of polymethylmethacrylate by krypton fluoride excimer laser radiation  

NASA Astrophysics Data System (ADS)

It is known that deep ultraviolet (UV) radiation induces a refractive index increase in the surface layer of polymethylmethacrylate (PMMA) samples. This effect can be used for the fabrication of integrated optical waveguides. PMMA is of considerable interest for bio and chemical sensing applications because it is biocompatible and can be micromachined by several methods, e.g. structuring by photolithography, ablation and hot embossing. In the presented work direct UV irradiation of a common PMMA substrate by a krypton fluoride excimer laser beam through a contact mask has been used to write integrated optical Mach-Zehnder interferometers (MZI). MZI are used as sensitive bio and chemical sensors. The aim was to determine contact mask design and laser irradiation parameters for fabricating single-mode MZI for the infrared region from 1.30 ?m to 1.62 ?m. Straight and curved waveguides have been generated and characterized to determine the optical losses. The generation of channel waveguide structures has been optimized by a two step irradiation process to minimize the lithographic writing time and optical loss. By flood exposure to UV laser radiation in the first step the optical absorption of PMMA can be increased in the irradiated region. The required refractive index profile is then achieved with a second lithographic irradiation. The spectral behaviour of an unbalanced, integrated optical MZI fabricated by this excimer laser based contact mask method is shown for the first time. Further the optical intensity at the output port of a MZI has been measured while the optical path length difference was tuned by creating a temperature difference between the two arms of the MZI.

Koerdt, Michael; Vollertsen, Frank

2011-04-01

156

Error Analysis of Quadrature Rules. Classroom Notes  

ERIC Educational Resources Information Center

|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…

Glaister, P.

2004-01-01

157

CONTROL OF LASER RADIATION PARAMETERS: Measurements of small wave-front distortions using a three-wave lateral shearing interferometer  

NASA Astrophysics Data System (ADS)

The solution of the parabolic equation for radiation diffracted from a periodic hexagonal structure is analysed theoretically. It is shown that diffraction does not prevent high-precision measurements of wave-front distortions using a three-beam lateral shearing interferometer. The proposed measuring technique is based on the recording of interference-pattern distortions at arbitrary distances from a beam replicator. The results of numerical calculations supporting this technique are presented. The optical quality of an etalon plate is measured in an aperture of diameter 12 cm with a high degree of precision. By considering the example of a large-aperture KDP crystal, it is shown that the application of this method makes it possible to synthesise from individual measurements the wave front in an aperture considerably larger than the test beam aperture.

Sokolov, Viktor I.

2001-10-01

158

Control of the laser frequency of the Virgo gravitational wave interferometer with an in-loop relative frequency stability of 1.0 × 10?21 on a 100 ms time scale  

Microsoft Academic Search

The measurement of the space-time structure variations induced by strong cosmic events (supernovae, coalescing binaries of neutron stars, etc.) requires an oscillator with a relative stability of 10-21 on time scales typically ap100 ms. We demonstrate that the Virgo interferometer with a wavelength of 1.064 degm has a laser frequency with an in-loop stability of 1.0 times 10-21 on a

F. Acernese; M. Alshourbagy; F. Antonucci; S. Aoudia; K. G. Arun; P. Astone; G. Ballardin; F. Barone; M. Barsuglia; T. S. Bauer; M. Beker; S. Bigotta; S. Birindelli; M. A. Bizouard; C. Boccara; F. Bondu; L. Bonelli; L. Bosi; S. Braccini; C. Bradaschia; A. Brillet; V. Brisson; H. J. Bulten; D. Buskulic; G. Cagnoli; E. Calloni; E. Campagna; B. Canuel; F. Carbognani; L. Carbone; F. Cavalier; R. Cavalieri; G. Cella; E. Chassande-Mottin; S. Chatterji; A. Chincarini; F. Cleva; E. Coccia; J. Colas; A. Colla; M. Colombini; C. Corda; A. Corsi; J.-P. Coulon; E. Cuoco; S. D'Antonio; A. Dari; V. Dattilo; M. Davier; R. Day; R. De Rosa; M. del Prete; L. Di Fiore; A. Di Lieto; M. Di Paolo Emilio; A. Di Virgilio; M. Drago; V. Fafone; I. Ferrante; F. Fidecaro; I. Fiori; R. Flaminio; J.-D. Fournier; J. Franc; S. Frasca; F. Frasconi; A. Freise; L. Gammaitoni; F. Garufi; G. Gemme; E. Genin; A. Gennai; A. Giazotto; M. Granata; V. Granata; C. Greverie; G. Guidi; H. Heitmann; P. Hello; S. Hild; D. Huet; P. La Penna; N. Leroy; N. Letendre; M. Lorenzini; V. Loriette; G. Losurdo; J.-M. Mackowski; E. Majorana; N. Man; M. Mantovani; F. Marchesoni; F. Marion; J. Marque; F. Martelli; A. Masserot; F. Menzinger; C. Michel; L. Milano; Y. Minenkov; M. Mohan; J. Moreau; N. Morgado; A. Morgia; S. Mosca; B. Mours; I. Neri; F. Nocera; G. Pagliaroli; C. Palomba; F. Paoletti; S. Pardi; A. Pasqualetti; R. Passaquieti; D. Passuello; G. Persichetti; M. Pichot; F. Piergiovanni; L. Pinard; R. Poggiani; M. Prato; G. A. Prodi; M. Punturo; P. Puppo; O. Rabaste; P. Rapagnani; V. Re; T. Regimbau; F. Ricci; F. Robinet; A. Rocchi; L. Rolland; R. Romano; P. Ruggi; F. Salemi; B. Sassolas; D. Sentenac; R. Sturani; B. Swinkels; R. Terenzi; A. Toncelli; M. Tonelli; E. Tournefier; F. Travasso; J. Trummer; G. Vajente; S. van der Putten; M. Vavoulidis; G. Vedovato; D. Verkindt; F. Vetrano; A. Vicere; J.-Y. Vinet; H. Vocca; M. Yvert

2009-01-01

159

Single and double superimposing interferometer systems  

DOEpatents

Interferometers which can imprint a coherent delay on a broadband uncollimated beam are described. The delay value can be independent of incident ray angle, allowing interferometry using uncollimated beams from common extended sources such as lamps and fiber bundles, and facilitating Fourier Transform spectroscopy of wide angle sources. Pairs of such interferometers matched in delay and dispersion can measure velocity and communicate using ordinary lamps, wide diameter optical fibers and arbitrary non-imaging paths, and not requiring a laser.

Erskine, David J. (Oakland, CA)

2000-01-01

160

Laser interferometry measurements of a high density propagating current sheet  

NASA Astrophysics Data System (ADS)

A helium-neon laser Mach-Zehnder quadrature interferometer is used to measure the electron number density in a propagating current sheet. In some cases the density rise rate was too high to be resolved by the system. Otherwise, the interferometer is used to measure time-resolved density at a particular location in the accelerator. The location of the beam is then moved between shots and, because of the repeatability of the discharge, multiple shots can be pieced together to create a temporally and spatially resolved view of the evolution of the sheet and of a wake of plasma that is left behind the sheet. The measurements confirm an emerging picture of the evolution of these structures that is based on high-speed photographs and current density measurements. They also reveal that the wake originates out of a bifurcation of the current sheet and that it is of comparable density to the sheet.

Berkery, J. W.; Markusic, T. E.; Choueiri, E. Y.

2007-05-01

161

Adaptive sparse grid quadrature filter for spacecraft relative navigation  

NASA Astrophysics Data System (ADS)

This paper explores a novel adaptive sparse grid quadrature filter. The sparse grid quadrature approach has been recently developed for nonlinear estimation problems to alleviate the curse-of-dimensionality issue of the Gauss-Hermite quadrature filter. Accuracy level of the sparse grid quadrature filter is an important tuning factor that affects desired performance. The proposed filter autonomously adjusts the accuracy level of the sparse grid quadrature rule in both prediction and update steps by increasing the level gradually until an adaptation criterion is satisfied. The adaptation criterion is derived based on a quadrature error estimator. The nestedness property of sparse grid quadrature rule enables efficient computation in adaptation by reusing quadrature points of the previous level sparse grid quadrature. An application to spacecraft relative navigation has been made to demonstrate the adaptive spare grid quadrature filter outperforming the extended Kalman filter and the unscented Kalman filter.

Baek, Kwangyul; Bang, Hyochoong

2013-06-01

162

Structured eigenvalue problems for rational gauss quadrature  

NASA Astrophysics Data System (ADS)

The connection between Gauss quadrature rules and the algebraic eigenvalue problem for a Jacobi matrix was first exploited in the now classical paper by Golub and Welsch (Math. Comput. 23(106), 221?230, 1969). From then on many computational problems arising in the construction of (polynomial) Gauss quadrature formulas have been reduced to solving direct and inverse eigenvalue problems for symmetric tridiagonals. Over the last few years (rational) generalizations of the classical Gauss quadrature formulas have been studied, i.e., formulas integrating exactly in spaces of rational functions. This paper wants to illustrate that stable and efficient procedures based on structured numerical linear algebra techniques can also be devised for the solution of the eigenvalue problems arising in the field of rational Gauss quadrature.

Fasino, Dario; Gemignani, Luca

2007-08-01

163

Quadrature demodulation technique for self-mixing interferometry displacement sensor  

NASA Astrophysics Data System (ADS)

A new, to the best of our knowledge, signal processing method based on quadrature demodulation technique is presented for laser diode self-mixing interferometry(LDSMI) displacement sensor. Phase modulation of the laser beam is obtained by an electro-optic modulator (EOM) in the external cavity. Detection of the target's displacement can be easily achieved by sampling the interference signal at those times which satisfied certain conditions. The major advantage of the technique is that it does not involve any complicated calculation and insensitive to the sampling error. Experimental results show that the proposed method can effectively improve the displacement measurement resolution of the laser diode self-mixing displacement sensor to a few nanometers.

Guo, Dongmei

2011-12-01

164

A multioctave active MMIC quadrature phase shifter  

Microsoft Academic Search

A 0.1-4.5-GHz GaAs monolithic quadrature phase shifter with very small phase error, based on a phase-locked loop system, was designed, fabricated, and tested. The phase shifter consists of two RC all-pass networks with FETs used as voltage-controlled resistors. It delivers four quadrature output signals as required for the operation of the double balanced mixers used in the receiver. The main

P. Coget; P. Philippe; V. Pauker; P. Dautriche; P. Jean

1989-01-01

165

Fabry-Perot sensors for dynamic studies using spectrally based passive quadrature signal processing  

Microsoft Academic Search

This paper describes a simple, optically passive detection scheme for in-line Fabry-Perot etalon (ILFE) sensors that is also\\u000a useful for intrinsic Fabry-Perot (IFP) and extrinsic Fabry-Perot interferometer (EFPI) sensors. This detection scheme is based\\u000a on two spectrally shiffed Bragg wavelengths from in-line Bragg gratings to produce two quadrature phase shifted signals from\\u000a the spectral transfer function of the Fabry-Perot sensor.

Y.-L. Lo; J. S. Sirkis

1997-01-01

166

A new differential quadrature methodology for beam analysis and the associated differential quadrature element method  

Microsoft Academic Search

This paper presents a computationally efficient and an accurate new methodology in differential quadrature analysis of beam elements. The methodology would overcome the difficulties in boundary conditions implementations of fourth-order differential equations encountered in such problems. The methodology benefited from defining the second-order derivatives along the boundaries as independent degrees of freedom would enable the differential quadrature method to exactly

G. Karami; P Malekzadeh

2002-01-01

167

Quadrature formulae for problems in mechanics  

NASA Astrophysics Data System (ADS)

The fast progress in recent years in symbolic computation and variable-precision arithmetic provide a possibility for generating the recursion coefficients in the three-term recurrence relation for orthogonal polynomials with respect to several nonclassical weight functions, as well as the construction of the corresponding quadrature rules of Gaussian type. Such quadratures are very important in many applications in engineering (fracture mechanics, damage mechanics, etc.), as well as in other computational and applied sciences. The boundary element method (BEM), finite element method (FEM), methods for solving integral equations, etc. very often require the numerical evaluation of one dimensional or multiple integrals with singular or near singular integrands with a high precision. In this paper we give some improvements of quadrature rules of Gaussian type with logarithmic and/or algebraic singularities. A numerical examples is included.

Milovanovi?, Gradimir V.; Igi?, Tomislav; Ton?ev, Novica

2012-09-01

168

Theory of the quadrature elliptic birdcage coil.  

PubMed

This paper presents the theory of the quadrature birdcage coil wound on an elliptic cylindrical former. A conformal transformation of the ellipse to a circular geometry is used to derive the optimal sampling of the continuous surface current distribution to produce uniform magnetic fields within an elliptic cylinder. The analysis is rigorous for ellipses of any aspect ratio and shows how to produce quadrature operation of the elliptic birdcage with a conventional hybrid combiner. Insight gained from the transformation is also used to analyze field homogeneity, find the optimal RF shield shape, and specify component values to produce the correct current distribution in practice. Measurements and images from a 16-leg elliptic birdcage coil at both low and high frequencies show good quadrature performance, homogeneity, and sensitivity. PMID:9358446

Leifer, M C

1997-11-01

169

The Palomar Testbed Interferometer  

Microsoft Academic Search

The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a testbed for interferometric techniques applicable to the Keck Interferometer. First fringes were obtained in 1995 July. PTI implements a dual-star architecture, tracking two stars simultaneously for phase referencing and narrow-angle astrometry. The three fixed 40 cm apertures can be combined

J. Kent Wallace; Andrew F. Boden; M. Mark Colavita; Philip J. Dumont; Yekta Gursel; Braden E. Hines; C. Koresko; S. R. Kulkarni; Fabien Malbet; Dean Palmer; Xiaopei Pan; Michael Shao; Gautam Vasisht; Gerard T. van Belle; Jeffrey W. Yu

1999-01-01

170

Optical fibre interferometer for monitoring tool wear  

NASA Astrophysics Data System (ADS)

A novel intrinsic optical fiber sensor for detection of acoustic emission (AE) has been designed, built, and tested. This sensor is intended for use in monitoring machine tool wear. An optical fiber is held between the transducer backing and the surface being probed. The coupling of AE waves through the fiber into the backing causes a phase change in the light transmitted by the fiber. This phase change is detected using a Mach-Zehnder interferometer, locked in quadrature with a phase servo. Acoustic emission during cutting is conveyed to the sensing fiber on the machine bed via either the tool or workpiece. Sensing of AE may then yield information on the wear state of the tool.

Zheng, S. X.; McBride, Roy; Hale, Ken F.; Jones, Barry E.; Barton, James S.; Jones, Julian D.

1991-08-01

171

Micromachined low-finesse Fabry-Perot interferometer for the measurement of DC and AC electrical currents  

Microsoft Academic Search

A micromachined low finesse Fabry-Perot interferometer for measuring DC and AC electrical current is presented. Interrogation of the microcavity is achieved by a dual-wavelength fiber Bragg grating technique working in quadrature. A linear relation between the DC electrical current and the optical phase defined by the microcavity was detected. Large enhancement of the sensitivity of the microcavities is presented with

R. L. Heredero; J. L. Santos; R. Ferndndez de Caleya; H. Guerrero

2003-01-01

172

Composite Gauss-Legendre Quadrature with Error Control  

ERIC Educational Resources Information Center

|We describe composite Gauss-Legendre quadrature for determining definite integrals, including a means of controlling the approximation error. We compare the form and performance of the algorithm with standard Newton-Cotes quadrature. (Contains 1 table.)|

Prentice, J. S. C.

2011-01-01

173

Coupled-Cavity Interferometer for the Optics Laboratory  

ERIC Educational Resources Information Center

|Describes the construction of a flexible coupled-cavity interferometer for student use. A helium-neon laser and phonograph turntable are the main components. Lists activities which may be performed with the apparatus. (Author/CP)|

Peterson, R. W.

1975-01-01

174

Fizeau interferometer without destructive interference fringes and speckles  

Microsoft Academic Search

The possibility of decreasing the depth of interference region in the Fizeau interferometer configuration with a semiconductor\\u000a laser is considered for problems concerned with inspection of plane-parallel plates.

V. P. Koronkevich; A. I. Lokhmatov; A. E. Matochkin; A. R. Gerent

2007-01-01

175

Microwave Interferometer for Non-Destructive Testing  

NASA Astrophysics Data System (ADS)

A K-band microwave interferometer for non-destructive sensing of high frequency low amplitude (nm) vibration is demonstrated. This sensor uses direct-conversion receiver architecture with a phase shifter to adjust its sensitivity while varying the target distance. Detection of nanoscale vibration and laser-generated ultrasound waves through thin aluminum plate are measured and then compared with the theoretical results.

Choi, J.; Breugnot, S.; Itoh, T.

2010-02-01

176

Ramsey-Bordé interferometer for electrons  

NASA Astrophysics Data System (ADS)

A scheme to realize an electron interferometer using low-intensity, bichromatic laser pulses as beam splitter is proposed. The splitting process is based on a modification of the Kapitza-Dirac effect, which produces a momentum kick for electrons with a specific initial momentum. A full interferometric setup in Ramsey-Bordé configuration is theoretically analyzed.

Marzlin, Karl-Peter

2013-10-01

177

Novel micro interferometer for length measurements  

Microsoft Academic Search

A novel micro interferometer for length and displacement measurements based on sampling an optical standing wave was developed. The interference of two laser beams propagating in opposite direction results in a sinusoidal light intensity profile, which can be detected by thin transparent photodiodes. Two detectors positioned on the optical axis of a standing wave allow bi-directional fringe counting. The operation

H. Stiebig; V. Mandryka; E. Bunte; H.-J. Büchner; K. H. Jun

2004-01-01

178

The AEI 10 m prototype interferometer  

NASA Astrophysics Data System (ADS)

A 10 m prototype interferometer facility is currently being set up at the AEI in Hannover, Germany. The prototype interferometer will be housed inside a 100 m3 ultra-high vacuum envelope. Seismically isolated optical tables inside the vacuum system will be interferometrically interconnected via a suspension platform interferometer. Advanced isolation techniques will be used, such as inverted pendulums and geometrical anti-spring filters in combination with multiple-cascaded pendulum suspensions, containing an all-silica monolithic last stage. The light source is a 35 W Nd:YAG laser, geometrically filtered by passing it through a photonic crystal fibre and a rigid pre-modecleaner cavity. Laser frequency stabilisation will be achieved with the aid of a high finesse suspended reference cavity in conjunction with a molecular iodine reference. Coating thermal noise will be reduced by the use of Khalili cavities as compound end mirrors. Data acquisition and control of the experiments is based on the AdvLIGO digital control and data system. The aim of the project is to test advanced techniques for GEO 600 as well as to conduct experiments in macroscopic quantum mechanics. Reaching standard quantum-limit sensitivity for an interferometer with 100 g mirrors and subsequently breaching this limit, features most prominently among these experiments. In this paper we present the layout and current status of the AEI 10 m Prototype Interferometer project.

Goßler, S.; Bertolini, A.; Born, M.; Chen, Y.; Dahl, K.; Gering, D.; Gräf, C.; Heinzel, G.; Hild, S.; Kawazoe, F.; Kranz, O.; Kühn, G.; Lück, H.; Mossavi, K.; Schnabel, R.; Somiya, K.; Strain, K. A.; Taylor, J. R.; Wanner, A.; Westphal, T.; Willke, B.; Danzmann, K.

2010-04-01

179

Rational Szego" quadratures associated with Chebyshev weight functions  

NASA Astrophysics Data System (ADS)

In this paper we characterize rational Szego" quadrature formulas associated with Chebyshev weight functions, by giving explicit expressions for the corresponding para-orthogonal rational functions and weights in the quadratures. As an application, we give characterizations for Szego" quadrature formulas associated with rational modifications of Chebyshev weight functions. Some numerical experiments are finally presented.

Bultheel, Adhemar; Cruz-Barroso, Ruyman; Deckers, Karl; Gonzalez-Vera, Pablo

2009-06-01

180

Error Bounds for Quadrature Methods Involving Lower Order Derivatives  

ERIC Educational Resources Information Center

|Quadrature methods for approximating the definite integral of a function f(t) over an interval [a,b] are in common use. Examples of such methods are the Newton-Cotes formulas (midpoint, trapezoidal and Simpson methods etc.) and the Gauss-Legendre quadrature rules, to name two types of quadrature. Error bounds for these approximations involve…

Engelbrecht, Johann; Fedotov, Igor; Fedotova, Tanya; Harding, Ansie

2003-01-01

181

Keck Interferometer nuller update  

Microsoft Academic Search

The Keck Interferometer combines the two 10 m Keck telescopes as a long baseline interferometer, funded by NASA, as a joint development among the Jet Propulsion Laboratory, the W. M. Keck Observatory, and the Michelson Science Center. Since 2004, it has offered an H- and K-band fringe visibility mode through the Keck TAC process. Recently this mode has been upgraded

M. M. Colavita; E. Serabyn; A. J. Booth; S. L. Crawford; J. I. Garcia-Gathright; E. R. Ligon; B. L. Mennesson; C. G. Paine; P. L. Wizinowich; S. Ragland; E. C. Appleby; B. C. Berkey; A. Cooper; W. Dahl; J. T. Gathright; M. A. Hrynevych; D. W. Medeiros; D. Morrison; T. Panteleeva; B. Smith; K. R. Summers; K. Tsubota; C. Tyau; E. Wetherell; J. M. Woillez; R. L. Akeson; R. Millan-Gabet; C. Felizardo; C. D. Koresko; J. S. Herstein

2008-01-01

182

Quadrature Clock Modulation Versus Binary and Quadrature Phase Shift Keying in the Presence of Intersymbol Interference.  

National Technical Information Service (NTIS)

Quadrature Clock Modulation (QCM) is a binary phase shift keying (BPSK) technique in which alternate bits are transmitted orthogonally. Compared to normal BPSK modulation, QCM improves the performance of a communication system which is limited by intersym...

G. A. White

1977-01-01

183

Calibration of a high spatial resolution laser two-color heterodyne interferometer for density profile measurements in the TJ-II stellarator  

SciTech Connect

A high spatial resolution two-color (CO{sub 2}, {lambda}=10.6 {mu}m, He-Ne, {lambda}=633 nm) interferometer for density profile measurements in the TJ-II stellarator is under development and installation, based in the currently operational single channel two-color heterodyne interferometer. To achieve the objectives of 32 channels, with 4-5 mm lateral separation between plasma chords, careful design and calibration of the interferometric waveforms for both the measurement and vibration compensation wavelengths are undertaken. The first step has been to set up in our laboratories an expanded-beam heterodyne/homodyne interferometer to evaluate the quality of both interferometric wavefronts, a reported source of poor vibration compensation and thus low resolution in the density profile measurements. This novel interferometric setup has allowed us to calibrate the spatial resolution in the profile measurements resulting in {approx}2 mm lateral resolution in the reconstruction of the interferometric wavefront.

Acedo, Pablo; Pedreira, P.; Criado, A. R.; Lamela, Horacio [Universidad Carlos III de Madrid, Avda. de la Universidad 30, Leganes, 28911 Madrid (Spain); Sanchez, Miguel; Sanchez, Joaquin [Laboratorio Nacional de Fusion por Confinamiento Magnetico-CIEMAT, Ciudad Universitaria s/n, 28040 Madrid (Spain)

2008-10-15

184

Rotative quadrature phase-shift keying  

NASA Astrophysics Data System (ADS)

A rotative quadrature phase-shift keying (RQPSK) modulation scheme is proposed. By rotating the QPSK signal constellation by pi/2, either clockwise or anticlockwise, during a symbol duration, the conventional QPSK scheme can be modified to transmit 3 bits per symbol to achieve both power and bandwidth efficiency.

Liu, J.; Kim, J.; Kwatra, S. C.; Stevens, G. H.

1992-06-01

185

Thin-thick quadrature frequency conversion  

SciTech Connect

The quadrature conversion scheme is a method of generating the second harmonic. The scheme, which uses two crystals in series, has several advantages over single-crystal or other two crystal schemes. The most important is that it is capable of high conversion efficiency over a large dynamic range of drive intensity and detuning angle.

Eimerl, D.

1985-02-07

186

Investigation of Shock-Like Density Variations with a Holographic High Speed Real Time Interferometer Verdichtungsstossuntersuchungen MIT Einem Holografischen Hochgeschwindigkeits-Real-Zeit-Interferometer.  

National Technical Information Service (NTIS)

Advantages of a laser interferometer over a Mach-Zehnder interferometer for detecting density variations in very unstable flows using a high speed camera, are shown. The system is based on phase holography and consists of an argon laser pulsed by an acous...

D. Basler

1982-01-01

187

Quadrature Formulae for the WISE Passbands  

NASA Astrophysics Data System (ADS)

I give linear quadrature formulae for WISE magnitudes in the form m = -2.5 log10([w1 F?(?1) +...+ wn F?(?n)]/F0) for the WISE passbands. With n=1, this formula can be exact for two different SEDs because there are two adjustable parameters, w1 and ?1. Choosing these SEDs to be a constant F? and Vega, these parameters give the isophotal wavelength and isophotal F0 given in Wright et al. (2010). But for very wide passbands like W3, n=1 does not give great accuracy for SEDs that differ from a constant F? or Vega. Wright et al. gives flux correction factors for such spectra, but for model spectra that are the sum of many different SEDs each term of the sum needs its own flux correction factor, making the magnitude difficult to compute. The linear quadrature formulae simplify the computation since the model can be computed without flux correction factors and then the quadrature formula can be applied. This is particularly useful for thermophysical models of asteroids, such as the rotating cratered model of Wright (2007) which gives the flux as a sum of over 60,000 weighted blackbodies of various temperatures. In this case the quadrature formula can be 1000 times faster than evaluating the response integral. The n=2 quadrature formulae are accurate to better than 0.5% for a wide range of power laws and blackbody temperatures for W1, W2 and W4. But n=3 is needed to reach this accuracy for W3.

Wright, Edward L.

2013-01-01

188

Analog processing based vibration measurement technique using michelson interferometer  

NASA Astrophysics Data System (ADS)

A Michelson interferometer based sensor, to monitor the displacement and vibration of a surface, is presented. The interference signals detected in quadrature are processed using analog electronics to find the direction of the motion of a vibrating surface in real-time. The complete instrumentation and signal processing are implemented for the interpretation of the amplitude as well as positive and negative excursion of the vibration cycles. This new technique is simpler as compared to the techniques commonly used in the interferometer based vibration sensors. Using this technique, we have measured mechanical vibrations having a magnitude of the order of nanometers and frequency in the range of 50 Hz to 500 Hz. By making small changes in the electronic circuit, the technique can be implemented for the extended range of the vibration frequencies and amplitude.

Hussain, Babar; Ahmed, Mushtaq; Hussain, Ghazanfar; Saleem, Muhammad; Nawaz, Muhammad

2013-06-01

189

A heterodyne interferometer for angle metrology  

SciTech Connect

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

Hahn, Inseob; Weilert, M.; Wang, X.; Goullioud, R. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

2010-04-15

190

Process control system using polarizing interferometer  

DOEpatents

A system for nondestructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figures.

Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

1994-02-15

191

Furnace control apparatus using polarizing interferometer  

DOEpatents

A system for nondestructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figures.

Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

1995-03-28

192

Multisite EPR oximetry from multiple quadrature harmonics.  

PubMed

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

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

2011-11-15

193

Polarized light by quadrature amplitude modulation  

NASA Astrophysics Data System (ADS)

A new method to create elliptically polarized light based on the quadrature amplitude modulation is proposed. This method begins from an unpolarized light and does not use any classical methods, as for instance those using polarizers and retarders or also by refraction, scattering, dichroism or birefringence effects. This method is based on the amplitude modulation of two optical waves in quadrature in order to modulate the field in amplitude and phase. With this idea, we show that any amplitude relation and relative phase difference between components can be created and therefore any polarization state can be carried out. A theoretical model will be shown, and it will be sustained with numerical simulations of several polarization examples.

Meneses-Fabian, Cruz; Rivera-Ortega, Uriel

2013-04-01

194

Phase shifting diffraction interferometer  

DOEpatents

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. 8 figs.

Sommargren, G.E.

1996-08-29

195

Design and fabrication of a high-damage threshold infrared Smartt interferometer  

NASA Astrophysics Data System (ADS)

A Smartt interferometer was investigated in terms of its use as a very precise alignment tool for infrared lasers. Particular emphasis was placed on its application to high power, fast pulse laser systems such as Helios and Antares. Results indicate that fabrication of structure with the unique optical characteristics of the Smartt interferometer combined with a very high optical damage threshold is necessary.

Hammond, R. B.; Gibbs, A. J.

1981-06-01

196

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

Microsoft Academic Search

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

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

1990-01-01

197

Fully remote generation and detection of ultrasonic waves for cure monitoring in epoxy materials using an Nd:YAG laser and optical fiber interferometer  

NASA Astrophysics Data System (ADS)

A fully remote all-optical technique for the generation and detection of ultrasonics in epoxy material. A sensitive wide-bandwidth optical fiber interferometer is used to remotely detect the arrival of these waves at the rear surface of the material. By monitoring the arrival time of these waves, the acoustic velocity can be determined. The technique has been used to monitor the acoustic velocity throughout the complete curing cycle of a rapid cure epoxy material.

Booth, David J.; Mitra, Biswanath

1998-07-01

198

Path matched vibration insensitive Fizeau interferometer  

NASA Astrophysics Data System (ADS)

An on-axis, vibration insensitive, polarization Fizeau interferometer is realized through the use of a novel pixelated mask spatial carrier phase shifting technique in conjunction with a low coherence source and a polarization path matching mechanism. In this arrangement, coherence is used to effectively separate out the orthogonally polarized test and reference beam components for interference. With both the test and the reference beams on-axis, the common path cancellation advantages of the Fizeau interferometer are maintained. Microwave modulation of a high powered red laser diode is used to create a 15 mW laser source having a coherence length of 250 um with minimal sidelobe ringing. With a 15 mW source, the maximum camera shutter speed, used when measuring a 4% reflector, was 150 usec, resulting in very robust vibration insensitivity. Additionally, stray light interference is substantially reduced due to the source's short coherence, allowing the measurement of thin transparent optics. Experimental results show the performance of this new interferometer to be within the specifications of commercial phase shifting interferometers. This work starts with a basic review of interferometry, phase shifting, and polarization as a lead in to a description of the theory and operation of the pixelated mask spatial carrier phase shifting technique. An analysis of the standard Fizeau Interferometer is then given. This is followed by detailed theoretical discussion of the path matched vibration insensitive (PMVI) Fizeau, which includes a theoretical model of the effects of multiple beam return from the test surface when measuring high value reflectors. The coherence properties of laser diodes are then discussed, a theoretical model for the effects of high frequency drive current is derived, and experimental results are given. Finally, the performance of the PMVI Fizeau is experimentally analyzed, potential error sources discussed, and suggestions for improvements provided.

Kimbrough, Bradley Trent

199

Collisional decoherence in trapped-atom interferometers that use nondegenerate sources  

NASA Astrophysics Data System (ADS)

The coherence time, and thus sensitivity, of trapped-atom interferometers that use nondegenerate gases are limited by the collisions between the atoms. An analytic model that describes the effects of collisions between atoms in an interferometer is developed. It is then applied to an interferometer using a harmonically trapped nondegenerate atomic gas that is manipulated with a single set of standing wave laser pulses. The model is used to find the optimal operating conditions of the interferometer and direct Monte Carlo simulation of the interferometer is used to verify the analytic model.

Stickney, James A.; Squires, Matthew B.; Scoville, James; Baker, Paul; Miller, Steven

2009-01-01

200

Interferometer-Type Structures for Guided Atoms  

Microsoft Academic Search

We experimentally demonstrate interferometer-type guiding structures for neutral atoms based on dipole potentials created by microfabricated optical systems. As a central element we use an array of atom waveguides being formed by focusing a red-detuned laser beam with an array of cylindrical microlenses. Combining two of these arrays, we realize X-shaped beam splitters and more complex systems like the geometries

R. Dumke; T. Müther; M. Volk; W. Ertmer; G. Birkl

2002-01-01

201

Optical tweezers based on polarization interferometer  

NASA Astrophysics Data System (ADS)

In this paper, we propose optical tweezers based on a biaxial crystal. To control the movement of opaque particles, we use the shift polarization interferometer. The results of experimental study of laser tweezers are shown. We demonstrates movement of a microparticle of toner using singular-optical trap, rotate a particle due to orbital momentum, conversion of two traps when changing the plane of polarizer transmission and converging of two traps.

Angelsky, Oleg V.; Maksimyak, Andrew P.; Maksimyak, Peter P.; Dominikov, Mykola M.

2013-06-01

202

Development of a Prototype Cryogenic Interferometer  

NASA Astrophysics Data System (ADS)

We have completed a cryostat system using two stages 4K Gifford-MacMahon cryocoolers for a prototype of cryogenic laser interferometer settled in ICRR. The first cooling down and vibration measurement on a mirror chamber of the cryostat system have been done. Results shows that temperature in the mirror chamber of 9K and 10-5Pa vacuum pressure achieved after four days cooling down. No excess vibration peak under 10 Hz due to the cryocooler was found.

Uchiyama, T.; Suzuki, T.; Yamamoto, A.; Shintomi, T.; Miyoki, S.; Taylor, C. T.; Ohashi, M.; Kuroda, K.; Shimonosono, T.

2002-12-01

203

PDX multichannel interferometer  

SciTech Connect

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.

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

1980-10-01

204

Keck interferometer autoaligner  

NASA Astrophysics Data System (ADS)

A key thrust of NASA's Origins program is the development of astronomical interferometers. Pursuing this goal in a cost-effective and expedient manner from the ground has led NASA to develop the Keck Interferometer, which saw first fringes between the twin 10m Keck telescopes in March of 2001. In order to enhance the imaging potential of this facility, and to add astrometric capabilities for the detection of giant planets about nearby stars, four 1.8 m 'outrigger' telescopes may be added to the interferometer. Robust performance of the multi-aperture instrument will require precise alignment of the large number of optical elements found in the six optical beamtrains spread about the observatory site. The requirement for timely and reliable alignments dictated the development of an automatic alignment system for the Keck Interferometer. The autoaligner consists of swing-arm actuators that insert light-emitting diodes on the optical axis at the location of each optical element, which are viewed by a simple fixed-focus CCD camera at the end of the beamtrain. Sub-pixel centroiding is performed upon the slightly out-of-focus target spots using images provided by a frame grabber, providing steering information to the two-axis actuated optical elements. Resulting mirror-to-mirror alignments are good to within 2 arcseconds, and trimming the alignment of a full beamtrain is designed to take place between observations, within a telescope repointing time. The interactions of the autoaligner with the interferometer delay lines and coude trains are discussed in detail. The overall design of the interferometer's autoaligner system is presented, examining the design philosophy, system sequencing, optical element actuation, and subsystem co-alignment, within the context of satisfying performance requirements and cost constraints.

van Belle, Gerard T.; Colavita, M. Mark; Ligon, Edgar R., III; Moore, James D.; Palmer, Dean L.; Reder, Leonard J.; Smythe, Robert F.

2003-02-01

205

Optical Thin Film Phase Quadrature Interferometry  

Microsoft Academic Search

An achromatic, fast time resolution, Michelson Doppler interferometric technique that is based on optical thin films and requires no scanning mechanisms has been developed. This was motivated by the pursuit to improve the time resolution of wide angle Michelson Doppler imaging interferometers for studies of the Earth's upper atmospheric winds and temperatures. The technique revolves around a mosaic of four

Susan H. C. P. McCall

1992-01-01

206

TRIO interferometer positioning  

NASA Astrophysics Data System (ADS)

The high accuracy positioning of each of the three satellites of the TRIO interferometer, with respect to the others and to the reference stars, is discussed. Based on ground interferometer experience, strategy guidelines are presented with related recommendations for spacecraft design. After star pointing, the two telescopes are aligned with respect to the central station so that the star images are within the central station field of view while optical path difference is smaller than the coherence length. Fine guidance is obtained from image superimposition on the central station focal plane, and from fringe contrast measurement.

Authier, B.

1985-04-01

207

Orbiting stellar interferometer for astrometry and imaging.  

PubMed

The orbiting stellar interferometer (OSI) is a concept for a first-generation space interferometer with astrometric and imaging goals and is responsive to the recommendations of the Astronomy and Astrophysics Survey Committee for an astrometric interferometer mission. The OSI, as developed at the Jet Propulsion Laboratory over the past several years, is a triple Michelson interferometer with articulating siderostats and optical delay lines. Two point designs for the instrument are described.

The 18-m design uses an 18-m maximum baseline and aperture diameters of 40 cm; the targeted astrometric performance is a wide-field accuracy of 10 microarsec for 16-mag objects in 100 s of integration time and for 20-mag objects in 1 h. The instrument would also be capable of synthesis imaging with a resolution of 5 marcsec, which corresponds to the diffraction limit of the 18-m base line. The design uses a deployed structure, which would fold to fit into an Atlas HAS shroud, for insertion into a 900-km sun-synchronous orbit In addition to the 18-m point design a 7-m point design that uses a shorter base line in order to simplify deployment is also discussed. OSI's high performance is made possible by utilizing laser metrology and controlled-optics technology.

PMID:20820313

Colavita, M M; Shao, M; Rayman, M D

1993-04-01

208

d-fold Hermite-Gauss quadrature  

NASA Astrophysics Data System (ADS)

We extend results presented in Gustafon and Hagler (J. Comput. Appl. Math. 105 (1999) 317-326); Hagler (Ph.D. Thesis, University of Colorado, 1997; J. Comput. Appl. Math. 104 (1999) 163-171; Hagler et al. (Lecture Notes in Pure and Applied Mathematics Series, Vol. 1999, Marcel Dekker, New York, 1998, pp. 187-208) by giving a construction of systems of orthogonal rational functions from systems of orthogonal polynomials and explicating the (2dn)-point d-fold Hermite-Gauss quadrature formula of parameters [gamma],[lambda]>0:where v[d]([gamma],[lambda])(x) is the d-fold composition of v([gamma],[lambda])(x)=(1/[lambda])(x-[gamma]/x) and where the abscissas hd,n,k([gamma],[lambda]) and weights Hd,n,k([gamma],[lambda]) are given recursively in terms of the abscissas and weights associated with the classical Hermite-Gauss quadrature. Error analysis, tables of numerical values for nodes, and examples and comparisons are included.

Hagler, Brian A.

2001-11-01

209

Polyphase quadrature filters--A new subband coding technique  

Microsoft Academic Search

A new method of implementing filter banks for subband coding of speech is presented. First, Esteban's Quadrature Mirror Filter principle is extended to allow the direct synthesis of filter banks with any number of equal size filter bands. Then, by combining the quadrature filter characteristic with the polyphase network implementation of filter banks, a new filter bank structure is obtained

J. Rothweiler

1983-01-01

210

Ultrasonic Interferometers Revisited  

ERIC Educational Resources Information Center

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…

Greenslade, Thomas B., Jr.

2007-01-01

211

Ultrasonic Interferometers Revisited  

ERIC Educational Resources Information Center

|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…

Greenslade, Thomas B., Jr.

2007-01-01

212

Excess noise reduction by optical technique in amplitude-sensitive heterodyne interferometer for small differential phase detection  

SciTech Connect

An amplitude-sensitive technique associated with a heterodyne interferometer for detecting small differential phase is reported. The excess noise with the amplitude-sensitive technique is reduced by optical subtraction instead of electronic subtraction. The differential phase introduced by the orthogonally polarized laser beams is converted to the amplitudes of two heterodyne interferometric signals, which presents amplitude and phase quadrature simultaneously. Thus the excess noise power and quantum noise power are both differential phase dependent. The advantages of differential and additive operations by optical technique and the real time differential phase determination without phase lock in are demonstrated experimentally. The theoretical signal-to-noise ratio (SNR) and minimum detectable differential phase are derived, which takes quantum noise and excess noise into consideration. The experimental results demonstrated the resolutions of differential phase detection closes to 10{sup -6} rad/{radical}Hz (10{sup -13} m/{radical}Hz) level over 100 kHz bandwidth and at 10{sup -8} rad/{radical}Hz (10{sup -15} m/{radical}Hz) level over 125 MHz bandwidth, respectively, under 2.5 mW incident power.

Teng, H.-K.; Lang, K.-C

2008-12-20

213

Distributed optical fiber perturbation sensing system based on Mach-Zehnder interferometer  

Microsoft Academic Search

A novel distributed optical fiber vibrationsensing system based on Mach-Zehnder interferometer has been designed and experimentally\\u000a demonstrated. Firstly, the principle of Mach-Zehnder optical path interferometer technique is clarified. The output of the\\u000a Mach-Zehnder interferometer is proportional to the phase shift induced by the perturbation. Secondly, the system consists\\u000a of the laser diode (LD) as the light source, fiber, Mach-Zehnder optical

Wengang Wang; Deming Liu; Hairong Liu; Qizhen Sun; Zhifeng Sun; Xu Zhang; Ziheng Xu

2009-01-01

214

Parametric oscillatory instability in a signal-recycled LIGO interferometer  

SciTech Connect

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)

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

2007-12-31

215

Non-Destructive Testing Using Two-Component Mixing Interferometer  

NASA Astrophysics Data System (ADS)

A new laser-based ultrasonic (LBU) receiver was recently introduced. The novel architecture is based on two-wave mixing in photorefractive materials and allows simultaneous measurement of in-plane and out-of-plane displacements (two- component). By taking advantage of recent developments in electronic processing and our knowledge on multi-channel interferometer, we achieved a compact optical system using only a single collecting aperture and a single laser probe beam. We will characterize the system performances and present experimental results demonstrating the capability for this compact two-component interferometer.

Wartelle, A.; Pouet, B.; Breugnot, S.

2011-06-01

216

New harmonic materials: index engineering. Thin-thick quadrature frequency conversion  

SciTech Connect

The quadrature conversion scheme is a method of generating the second harmonic. The scheme, which uses two crystals in series, has several advantages over single-crystal or other two crystal schemes. The most important is that it is capable of high conversion efficiency over a large dynamic range of drive intensity and detuning angle. Consider a pair of KDP crystals cut for type-II phase matching. In the quadrature scheme, the optic axes of the crystals are arranged so that the plans containing the direction of the laser beam and their optic axes (the kz planes) are mutually perpendicular. This arrangement has two important properties. First, in type-II phase matching, the incident wave is polarized at 45 deg to the kz plane of the crystal. This, in the quadrature scheme, if the incident wave is correctly polarized for efficient conversion in the first crystal, it is also correctly polarized for efficient conversion in the second crystal. Both crystals can therefore convert efficiently.

Eimerl, D.

1985-02-07

217

The Navy Prototype Optical Interferometer  

NASA Astrophysics Data System (ADS)

This paper announces the first closure phase measurements made with the Navy Prototype Optical Interferometer (NPOI) on stars. These are the first closure phase measurements made at optical wavelengths which exceed, by a factor of two to three, the resolution of the largest existing single optical telescope. The first observations were made on 1996 March 18 using three of the NPOI's four astrometric stations with baselines of 18.9, 22.2, and 37.5 meters. These data, the NPOI, and its current status will be discussed. The NPOI is a long baseline optical interferometer built by NRL, USNO, and Lowell Observatory on Anderson Mesa, near Flagstaff, AZ, USA. It is designed for astrometry and for imaging stellar surfaces. First fringe measurements with a single baseline were made in October 1994. The intervening time was spent adding a third telescope and making numerous upgrades to the equipment and software. The astrometric portion of the array consists of four stations in a Y-shaped configuration. The baselines between these stations are monitored by an extensive laser metrology system. The goal of this system is to catalog stellar positions with milliarcsecond accuracy. Baseline lengths range from 18.9 to 37.5 meters. The imaging portion of the array will contain 6 elements that can be deployed on any of 30 stations. These stations are also arranged in a Y configuration with a maximum baseline length of 435 meters. The wavelength coverage for both systems is 450 to 850 nm, divided into 32 spectral channels. The system incorporates active group delay fringe tracking and rapid tip-tilt angle tracking. There are plans for adding two micron capability. The maximum aperture is currently 12.5 cm. Beam compressors are planned to increase the apertures to 35 cm. So far, the faintest star on which we have tracked fringes is m_V = 4.0.

Benson, J. A.; Hutter, D. J.; Elias, N. M., II; Bowers, P.; Mozurkewich, D.; Armstrong, J. T.; White, N.; Hummel, C.

1996-05-01

218

Achromatic self-referencing interferometer  

DOEpatents

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.

Feldman, M.

1994-04-19

219

Achromatic self-referencing interferometer  

DOEpatents

A self-referencing Mach-Zehnder interferometer 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 ("first" 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.

Feldman, Mark (Pleasanton, CA)

1994-01-01

220

Dispersed Rayleigh interferometer  

NASA Astrophysics Data System (ADS)

In order to further improve the performance of Rayleigh Interferometer (RI) used for measurement of gas/liquid index, a Dispersed Rayleigh Interferometer (DRI), which uses a broadband source and disperses monochromatic interference pattern perpendicular to the direction of baseline, is proposed to expand measurement range and to acquire optical path difference dynamically by only one frame of interference pattern. At the same time, an algorithm used to analyse the interference pattern automatically is proposed. A DRI which uses a pair of transmissive phase plates used for generating optical path difference has been built up. The measurement range reaches 200?m, measurement error is less than 20nm and repeatability is better than 2nm in whole range. Good performance of DRI makes itself to be a suitable approach not only used in the conventional measurement of gas/quid index, but also in other aspects, for example, co-phasing of segmented mirrors for large telescopes.

Wang, Shanshan; Zhu, Qiudong; Cao, Genrui

2009-05-01

221

Multipulsed dynamic moire interferometer  

DOEpatents

An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

Deason, Vance A. (Idaho Falls, ID)

1991-01-01

222

Coaxial Mirau interferometer  

NASA Astrophysics Data System (ADS)

We describe a new interferometric configuration for optical coherence tomography that is based on the Mirau interferometer. It uses the photodetector included in a superluminescent diode package, which makes possible a highly miniaturized device. Other advantages of the configuration include its totally coaxial structure, confocal microscope operation, availability of the full working distance of the imaging objective, and no central obscuration. Fundamental characteristics such as resolution and dynamic range are discussed, and the result of measurement on a rough metallic surface is presented.

Dobroiu, Adrian; Sakai, Hiroshi; Ootaki, Hitoshi; Sato, Manabu; Tanno, Naohiro

2002-07-01

223

Optical and Infrared Interferometers  

NASA Astrophysics Data System (ADS)

Stellar interferometers achieve limiting angular resolution inaccessible to evennext-generation single-aperture telescopes. Arrays of small or modest apertureshave achieved baselines exceeding 300 m producing submilliarcsecond resolutionsat visible and near-infrared wavelengths. The technical cost and challenge inbuilding interferometric arrays is substantial due to the very high toleranceimposed by optical physics on the precision of beam combination and optical pathlength matching for two or more telescopes. This chapter presents the basic theoryand overall design considerations for an interferometer with an emphasis on thepractical aspects of constructing a working instrument that overcomes obstaclesimposed by the atmosphere, submicron path length matching requirements,limitations on number of telescopes and their layout, light losses throughmultiple reflections and transmissions necessary to superimpose telescopebeams in the beam-combining laboratory, and other realities of the art ofinterferometry. The basic design considerations for an interferometer arelaid out starting with site selection and telescope placement and thenfollowed through to beam combination and measurement of interferometricvisibility and closure phase after the encountering of numerous subsystems byincoming wavefronts. These subsystems include active wavefront sensing fortip/tilt correction or even full-up adaptive optics, telescope design fordirecting collimated beams over large distances, diffraction losses, polarizationmatching, optical path length insertion and active compensation, correctionfor atmospheric refraction and differential dispersion in glass and air,separation of light into visible and near-infrared channels, alignment over longoptical paths, high-precision definition of the three-dimensional layout of aninterferometric array, and, finally, a variety of beam-combining schemes fromsimple two-way combiners to multitelescope imaging combiners in thepupil and image planes. Much has been learned from a modest but robustcollection of successful interferometers over the last 25 years or so, andinterferometry is poised to become a mainstream technique for astrophysicalresearch.

ten Brummelaar, Theo A.; McAlister, Harold A.

224

Distributed fiber optic perturbation locating sensor based on dual Mach-Zehnder interferometer  

Microsoft Academic Search

This paper studies a distributed fiber optic perturbation locating sensor used for security system, which is based on dual Mach-Zehnder interferometers. This system consists of two Mach-Zehnder interferometers with the common sensing arm, reference arm, two couplers and one laser source. This kind of distributed fiber optic perturbation locating sensor is very suitable for the measurement of the phase shift

Guangming Luo; Chunxi Zhang; Lijing Li; Zongfeng Ma; Tian Lan; Chen Li; Wentai Lin

2008-01-01

225

Noncontact detection of laser-induced acoustic waves from buried absorbing objects using a dual-beam common-path interferometer  

Microsoft Academic Search

The feasibility of a noncontact all-optical probe for surface detection of laser-induced acoustic waves generated in buried absorbing objects was investigated. The goal is to detect subsurface optically absorbing objects, such as hemorrhages or vascularized tumors, which generate acoustic waves when slightly heated by a Q-switched laser pulse transported to an internal object by light diffusion within a turbid tissue.

Steven L. Jacques; Peter E. Andersen; Steen G. Hanson; Lars R. Lindvold

1998-01-01

226

Keck Interferometer nuller update  

NASA Astrophysics Data System (ADS)

The Keck Interferometer combines the two 10 m Keck telescopes as a long baseline interferometer, funded by NASA, as a joint development among the Jet Propulsion Laboratory, the W. M. Keck Observatory, and the Michelson Science Center. Since 2004, it has offered an H- and K-band fringe visibility mode through the Keck TAC process. Recently this mode has been upgraded with the addition of a grism for higher spectral resolution. The 10 um nulling mode, for which first nulling data were collected in 2005, completed the bulk of its engineering development in 2007. At the end of 2007, three teams were chosen in response to a nuller key science call to perform a survey of nearby stars for exozodiacal dust. This key science observation program began in Feb. 2008. Under NSF funding, Keck Observatory is leading development of ASTRA, a project to add dual-star capability for high sensitivity observations and dual-star astrometry. We review recent activity at the Keck Interferometer, with an emphasis on the nuller development.

Colavita, M. M.; Serabyn, E.; Booth, A. J.; Crawford, S. L.; Garcia-Gathright, J. I.; Ligon, E. R.; Mennesson, B. L.; Paine, C. G.; Wizinowich, P. L.; Ragland, S.; Appleby, E. C.; Berkey, B. C.; Cooper, A.; Dahl, W.; Gathright, J. T.; Hrynevych, M. A.; Medeiros, D. W.; Morrison, D.; Panteleeva, T.; Smith, B.; Summers, K. R.; Tsubota, K.; Tyau, C.; Wetherell, E.; Woillez, J. M.; Akeson, R. L.; Millan-Gabet, R.; Felizardo, C.; Koresko, C. D.; Herstein, J. S.

2008-07-01

227

The Keck Interferometer  

NASA Astrophysics Data System (ADS)

The Keck Interferometer (KI) combined the two 10 m W. M. Keck Observatory telescopes on Mauna Kea, Hawaii, as a long-baseline near- and mid-infrared interferometer. Funded by NASA, it operated from 2001 until 2012. KI used adaptive optics on the two Keck telescopes to correct the individual wavefronts, as well as active fringe tracking in all modes for path-length control, including the implementation of cophasing to provide long coherent integration times. KI implemented high sensitivity fringe-visibility measurements at H (1.6 ?m), K (2.2 ?m), and L (3.8 ?m) bands, and nulling measurements at N band (10 ?m), which were used to address a broad range of science topics. Supporting these capabilities was an extensive interferometer infrastructure and unique instrumentation, including some additional functionality added as part of the NSF-funded ASTRA program. This paper provides an overview of the instrument architecture and some of the key design and implementation decisions, as well as a description of all of the key elements and their configuration at the end of the project. The objective is to provide a view of KI as an integrated system, and to provide adequate technical detail to assess the implementation. Included is a discussion of the operational aspects of the system, as well as of the achieved system performance. Finally, details on V2 calibration in the presence of detector nonlinearities as applied in the data pipeline are provided.

Colavita, M. M.; Wizinowich, P. L.; Akeson, R. L.; Ragland, S.; Woillez, J. M.; Millan-Gabet, R.; Serabyn, E.; Abajian, M.; Acton, D. S.; Appleby, E.; Beletic, J. W.; Beichman, C. A.; Bell, J.; Berkey, B. C.; Berlin, J.; Boden, A. F.; Booth, A. J.; Boutell, R.; Chaffee, F. H.; Chan, D.; Chin, J.; Chock, J.; Cohen, R.; Cooper, A.; Crawford, S. L.; Creech-Eakman, M. J.; Dahl, W.; Eychaner, G.; Fanson, J. L.; Felizardo, C.; Garcia-Gathright, J. I.; Gathright, J. T.; Hardy, G.; Henderson, H.; Herstein, J. S.; Hess, M.; Hovland, E. E.; Hrynevych, M. A.; Johansson, E.; Johnson, R. L.; Kelley, J.; Kendrick, R.; Koresko, C. D.; Kurpis, P.; Le Mignant, D.; Lewis, H. A.; Ligon, E. R.; Lupton, W.; McBride, D.; Medeiros, D. W.; Mennesson, B. P.; Moore, J. D.; Morrison, D.; Nance, C.; Neyman, C.; Niessner, A.; Paine, C. G.; Palmer, D. L.; Panteleeva, T.; Papin, M.; Parvin, B.; Reder, L.; Rudeen, A.; Saloga, T.; Sargent, A.; Shao, M.; Smith, B.; Smythe, R. F.; Stomski, P.; Summers, K. R.; Swain, M. R.; Swanson, P.; Thompson, R.; Tsubota, K.; Tumminello, A.; Tyau, C.; van Belle, G. T.; Vasisht, G.; Vause, J.; Vescelus, F.; Walker, J.; Wallace, J. K.; Wehmeier, U.; Wetherell, E.

228

The Antarctic Plateau Interferometer  

NASA Astrophysics Data System (ADS)

The Antarctic Plateau Interferometer (API) is an instrument concept capable of extensive unique discovery space science in a variety of areas including exoplanets, accretion, YSO's, and AGNs. To study exoplanets in the habitable zone, API would use three 2 meter class telescopes, high-dynamic range spectroscopy, and differential closure phase to achieve 10-5 contrast ratio measurements. API would achieve this performance using proven technology at the best accessible site on Earth for infrared interferometry. At Dome C Antarctica, the combination of low levels of atmospheric turbulence (resulting in the best seeing ever measured) and low thermal background enable an interferometer with 2 m class telescopes to exceed substantially the performance of existing instruments. API will be packaged in shipping containers so that the instrument can be demonstrated on the sky in the northern hemisphere and then shipped, with a minimum of disassemble, to Dome C. The combination of using existing interferometer technology (adapted to the Antarctic environment) and containerized packaging makes it possible to begin operation at Dome C in 5 years. In addition to delivering a high-impact science program, API could test instrument technology for space interferometry missions such as Darwin and TPFI.

Lloyd, J. P.; Swain, M.; van Belle, G. T.; Coudé du Foresto, V.; Walker, C. K.; Traub, W. A.; Storey, J. W. V.

2004-12-01

229

Theoretical analysis of a single- and double-reflection atom interferometer in a weakly confining magnetic trap  

NASA Astrophysics Data System (ADS)

The operation of a BEC based atom interferometer, where the atoms are held in a weakly confining magnetic trap and manipulated with counterpropagating laser beams, is analyzed. A simple analytic model is developed to describe the dynamics of the interferometer. It is used to find the regions of parameter space with high and low contrast of the interference fringes for both single and double reflection interferometers. We demonstrate that for a double reflection interferometer the coherence time can be increased by shifting the recombination time. The theory is compared with recent experimental realizations of these interferometers.

Stickney, James A.; Kafle, Rudra P.; Anderson, Dana Z.; Zozulya, Alex A.

2008-04-01

230

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

NASA Astrophysics Data System (ADS)

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 pulsing at 20 J. Analytical and experimental analysis is conducted to determine the integrity of the phase front and the effect of multiple passes on the density measurements taken. The phase front quality is found to be acceptable for interferometric purposes and density measurements are taken for 2, 6, 14, and 18 passes in the Herriott cell. The advantage of the cell is obvious at late times when the external room vibrations induce an apparent phase shift in the same direction as neutral particles. Due to the same dependence on wavelength, 2 laser frequencies cannot be used to separate neutral and vibration contributions. The Herriott cell allows a density resolution increase linear with the number of passes that does not increase the vibrational component. Uncertainties from both vibrational sources and shot-to-shot variations of the thruster itself are investigated and characterized for this system. Due to variations in room vibrations on a day to day basis, the cell was unable to characterize the neutral density of the thruster. However, for single tests, neutral density measurements were acquired. The Herriott cell with 18 passes introduced a 9-fold increase in resolution over the standard 2-pass interferometric setup. At 200 microseconds for single tests at 14 and 18 passes (^20 shots averaged) neutral density at the exit plane was shown to be no more than 1*1016/cu cm. Peak electron density (4 microseconds) was shown to be 5.0*1015 +/- 1.1*1015/cu cm.

Antonsen, Erik; Burton, Rodney; Engelman, Scott; Spanjers, Greg

2000-06-01

231

Interferometer density measurements of a high-velocity plasmoid  

SciTech Connect

The plasmoid produced by a half-scale contoured gap coaxial plasma accelerator using ablative polyethylene capillary plasma injectors is measured using a quadrature heterodyne HeNe interferometer. The plasmoid is found to have a sharp rise in density at the leading edge, with a gradual falloff after the peak density. For this early test series, an average bulk density of 5x10{sup 14} cm{sup -3} is observed, with densities up to 8x10{sup 14} cm{sup -3} seen on some shots. Although plasmoid mass is only about 58 mug due to the low current and injected mass used in these tests, good shot-to-shot repeatability is attained making analysis relatively straightforward, thus providing a solid foundation for interpreting future experimental results.

Case, A.; Messer, S.; Bomgardner, R.; Witherspoon, F. D. [HyperV Technologies Corp., Chantilly, Virginia 20151 (United States)

2010-05-15

232

Experimental study of quadrature spring rate at tuned dry gyro  

NASA Astrophysics Data System (ADS)

A survey result on the mechanism of quadrature spring rate occurring at the tuned dry gyro is given. It is noted that the quadrature spring rate is a damping torque. This damping torque is similar to the spring reaction torque generated by the flexure displacement angles and drives the gyro rotor back to a balanced position. In order to investigate the mechanism of damping occurring at the gyro rotor, the relation between surrounding gas pressure and damping factor under gyro nonoperating was measured. Furthermore, the drag torque acting on the gyro rotor was measured by the back EMF method at different surrounding gas pressure. As a result of these testings, it was found out that the quadrature spring rate was generated by gas movement of the flexure around and drag forces due to bearing loss and windage loss, and the mechanism and magnitude of each damping torque which are contributor to the quadrature spring rate were extracted separately.

Hayakawa, Yoshiaki; Murayama, Naoshi

233

Quadrature demodulation: a new LDV burst-signal frequency estimator  

NASA Astrophysics Data System (ADS)

A novel frequency estimation method for the evaluation of LDA burst signals is presented. The new method is based on the measurement of time series of phase angles defined by a pair of quadrature signals (sine/cosine signal pair). Up to now quadrature techniques have preponderantly been used in the two beam interferometry for carrying out direction sensitive and high resolution measurements as well as in radio frequency applications. The quadrature demodulation technique can be considered as a straightforward development of the counter technique with the advantages of a higher resolution for a single burst evaluation and of directional discrimination. Compared with conventional signal processing techniques the application of the quadrature demodulation technique additionally allows a directional discrimination and the analysis of velocity fluctuations within single Doppler signal bursts with a higher accuracy by evaluating the measured time series of phase angle values.

Czarske, Juergen; Hock, Fromund; Mueller, H.

1993-08-01

234

An exponentially fitted quadrature rule over unbounded intervals  

NASA Astrophysics Data System (ADS)

A new class of quadrature formulae for the computation of integrals over unbounded intervals with oscillating integrand is illustrated. Such formulae are a generalization of the gaussian quadrature formulae by exploiting the Exponential Fitting theory. The coefficients depend on the frequency of oscillation, in order to improve the accuracy of the solution. The construction of the methods with 1, 2 and 3 nodes is described, together with the comparison of the order of accuracy with respect to classical formulae.

Conte, D.; Paternoster, B.; Santomauro, G.

2012-09-01

235

Numerical Modelling of Water Hammer Using Differential Quadrature Method  

NASA Astrophysics Data System (ADS)

In this research, Incremental Differential Quadrature Method (IDQM) is applied for modelling of unsteady flow (water hammer) in pipeline systems. This is considered as the first application of differential quadrature in this area. The implementation of the IDQM to the governing equations along with some numerical studies are presented. The main attractive feature of the proposed method compared with existing numerical techniques is unconditional stability.

Hashemi, M. R.; Abedini, M. J.

2007-09-01

236

Quadrature formulas for functions with a boundary-layer component  

NASA Astrophysics Data System (ADS)

Quadrature formulas for one-variable functions with a boundary-layer component are constructed and studied. It is assumed that the integrand can be represented as the sum of a regular and a boundary-layer component, the latter having high gradients that reduce the accuracy of classical quadrature formulas, such as the trapezoidal and Simpson rules. The formulas are modified so that their error is independent of the gradients of the boundary-layer component. Results of numerical experiments are presented.

Zadorin, A. I.; Zadorin, N. A.

2011-11-01

237

Quadrature Mismatch Shaping for Digital-to-Analog Converters  

Microsoft Academic Search

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

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

2006-01-01

238

FIR interferometer and scattering measurements of ATF  

SciTech Connect

A 15-channel far-infrared (FIR) interferometer system has been constructed to measure the electron densities on the ATF plasmas. The system consists of a pair of cw 214-..mu..m difluoromethane (CH/sub 2/F/sub 2/) lasers, optically pumped by separate CO/sub 2/ lasers. The large number of channels is achieved by the use of reflective beam expansion optics to create a beam of 2 cm /times/ 45 cm. After passing through the plasma discharge, the elongated beam produced by the cylindrical mirrors is dissected by an array of 15 off-axis paraboloid reflectors, each of which illuminates a single Schottky-diode detector. The use of the beam expanding optics system reduces the number of optical elements required for the interferometer to approximately 2-3 per channel. The FIR laser beams are transported from the laser room to the experimental area by 25 mm i.d. dielectric waveguides purged with dry nitrogen. The system can also be operated at a wavelength of 119-..mu..m by changing the gas in FIR laser cavities to methanol for high density experiments. Details of the system are described. A study is underway to determine the optimum design of a FIR scattering system for the ATF. This scattering system will be used to investigate density fluctuations with scale lengths from 0.1 cm to the plasma radius. The laser for this scattering system may be operated at wavelengths of 447, 307, 214, 184, and 119 ..mu..m with power levels of 100 to 500 mW. A summary of the study is presented. 6 refs., 1 fig.

Ma, C.H.; Hutchinson, D.P.; Fockedey, Y.; Vander Sluis, K.L.; Bennett, C.A.

1989-01-01

239

Quadrature mixture LO suppression via DSW DAC noise dither  

DOEpatents

A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1.2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither. The present dither technique can effectively produce a quadrature DC bias which has the precision required to adequately suppress the LO leakage. A calibration technique can be employed to calculate both the quadrature correction vectors and the LO-nulling DC offsets using the radar built-in test capability.

Dubbert, Dale F. (Cedar Crest, NM); Dudley, Peter A. (Albuquerque, NM)

2007-08-21

240

First gravity measurements using the mobile atom interferometer GAIN  

NASA Astrophysics Data System (ADS)

We present the compact Gravimetric Atom Interferometer (GAIN), based on laser-cooled 87Rb atoms, and discuss its first measurements of the local gravitational acceleration. In this context, we also describe an active vibration isolation system and a tip-tilt stage, which allow for a suppression of vibrational noise and systematic effects like the Coriolis force due to Earth's rotation.

Hauth, M.; Freier, C.; Schkolnik, V.; Senger, A.; Schmidt, M.; Peters, A.

2013-04-01

241

Fully balanced heat interferometer  

NASA Astrophysics Data System (ADS)

A tunable and balanced heat interferometer is proposed and analyzed. The device consists of two superconductors linked together to form a double-loop interrupted by three parallel-coupled Josephson junctions. Both superconductors are held at different temperatures, allowing the heat currents flowing through the structure to interfere. We demonstrate that thermal transport is coherently modulated through the application of a magnetic flux. Furthermore, such modulation can be tailored at will or even suppressed through the application of an extra control flux. Such a device allows for a versatile operation appearing as an attractive key to the onset of low-temperature coherent caloritronic circuits.

Martínez-Pérez, M. J.; Giazotto, F.

2013-03-01

242

dc readout experiment at the Caltech 40m prototype interferometer  

NASA Astrophysics Data System (ADS)

The Laser Interferometer Gravitational Wave Observatory (LIGO) operates a 40m prototype interferometer on the Caltech campus. The primary mission of the prototype is to serve as an experimental testbed for upgrades to the LIGO interferometers and for gaining experience with advanced interferometric techniques, including detuned resonant sideband extraction (i.e. signal recycling) and dc readout (optical homodyne detection). The former technique will be employed in Advanced LIGO, and the latter in both Enhanced and Advanced LIGO. Using dc readout for gravitational wave signal extraction has several technical advantages, including reduced laser and oscillator noise couplings as well as reduced shot noise, when compared to the traditional rf readout technique (optical heterodyne detection) currently in use in large-scale ground-based interferometric gravitational wave detectors. The Caltech 40m laboratory is currently prototyping a dc readout system for a fully suspended interferometric gravitational wave detector. The system includes an optical filter cavity at the interferometer's output port, and the associated controls and optics to ensure that the filter cavity is optimally coupled to the interferometer. We present the results of measurements to characterize noise couplings in rf and dc readout using this system.

Ward, R. L.; Adhikari, R.; Abbott, B.; Abbott, R.; Barron, D.; Bork, R.; Fricke, T.; Frolov, V.; Heefner, J.; Ivanov, A.; Miyakawa, O.; McKenzie, K.; Slagmolen, B.; Smith, M.; Taylor, R.; Vass, S.; Waldman, S.; Weinstein, A.

2008-06-01

243

Laser interferometry for satellite gravimetry  

Microsoft Academic Search

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

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

2010-01-01

244

Femtosecond laser ruler  

SciTech Connect

A new method for identifying interferometer pass bands used as marks on the femtosecond meter scale is proposed and realised. The possibility of creating a femtosecond laser ruler is demonstrated experimentally. (laser metrology)

Basnak, D V [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Dmitriev, A K; Lugovoy, A A [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Pokasov, P V [Novosibirsk State University, Novosibirsk (Russian Federation)

2008-02-28

245

Optical analysis and alignment applications using the infrared Smartt interferometer  

SciTech Connect

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.

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

1981-01-01

246

Optical analysis and alignment applications using the infrared Smartt interferometer  

NASA Astrophysics Data System (ADS)

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.

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

247

Keck Interferometer nuller instrument performance  

Microsoft Academic Search

The Keck Interferometer combines the two 10 m Keck telescopes as a long baseline interferometer. It is funded by NASA as a joint development among the Jet Propulsion Laboratory, the W. M. Keck Observatory, and the NASA Exoplanet Science Institute. In February 2008, the 10 um nulling mode began a 32 night observing program with three key science teams to

M. M. Colavita; E. Serabyn; S. Ragland; R. Millan-Gabet; R. L. Akeson

2010-01-01

248

Fiber-optic extrinsic Fabry-Perot interferometer sensors with three-wavelength digital phase demodulation.  

PubMed

A three-wavelength-based passive quadrature digital phase-demodulation scheme has been developed for readout of fiber-optic extrinsic Fabry-Perot interferometer vibration, acoustic, and strain sensors. This scheme uses a superluminescent diode light source with interference filters in front of the photodiodes and real-time arctan calculation. Quasi-static strain and dynamic vibration sensing with up to an 80-kHz sampling rate is demonstrated. Periodic nonlinearities owing to dephasing with increasing fringe number are corrected for with a suitable algorithm, resulting in significant improvement of the linearity of the sensor characteristics. PMID:18073795

Schmidt, M; Fürstenau, N

1999-05-01

249

High-accuracy sinusoidal phase-modulating self-mixing interferometer using an electro-optic modulator: development and evaluation.  

PubMed

A sinusoidal phase-modulating He-Ne laser subject to weak optical feedback has been used to develop an interferometer that is capable of performing real-time displacement measurement with nanometer accuracy. The principle and the signal processing method are introduced. A commercial dual-frequency interferometer is included in the displacement measurement in both small and large ranges to evaluate the performance of the developed interferometer. Experimental results show that the average errors and standard deviations of the interferometer are in good agreement with data obtained from the commercial interferometer. The resolution and the multiple feedback effect of the interferometer are discussed in detail. These results show that the development of the interferometer is reasonable and feasible. PMID:23385942

Xia, Wei; Wang, Ming; Yang, Zhenyu; Guo, Wenhua; Hao, Hui; Guo, Dongmei

2013-02-01

250

Laser-interference methods in hydroacoustic systems  

NASA Astrophysics Data System (ADS)

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 <>.

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

2008-05-01

251

Rational choices for the wavelengths of a two color interferometer  

SciTech Connect

If in a two color interferometer for plasma density measurements, the two wavelengths are chosen to have a ratio that is a rational number, and if the signals from each of the wavelengths are multiplied in frequency by the appropriate integer of the rational number and then heterodyned together, the resultant signal will have all effects of component motion nulled out. A phase measurement of this signal will have only plasma density information in it. With CO{sub 2} lasers, it is possible to find suitable wavelength pairs which are close enough to rational numbers to produce an improvement of about 100 in density resolution, compared to standard two color interferometers.

Jobes, F.C.

1995-07-01

252

Fiber-optic interferometer fringe projection using integrating bucket modulation.  

PubMed

A new fiber-optic interferometer fringe projection with the integrating bucket method is presented. This method is based on the sinusoidal phase-modulating technique and makes use of Mach-Zehnder interferometer structure and Young's double pinhole interference principle to achieve interference fringe projection. Here, we consider the modulated signal with the modulation intensity of laser (companion amplitude modulation) m in the calculation directly, adjust the optimal value of z to accommodate different m, and calculate the initial phase with phase generated carrier technology at the same time. Preliminary results from the optimum phase modulation z and initial phase ?(0) are discussed. PMID:23455903

Fajie, Duan; Changrong, Lv; Chao, Zhang; Xiaojie, Duan; Fukai, Zhang

2012-12-01

253

Fiber grating sensor array interrogation with direct-wavelength readout of a wavelength-scanned fiber laser  

NASA Astrophysics Data System (ADS)

We present a novel interrogation method to measure wavelength shifts in fiber Bragg grating sensor array. A fiber laser tuned by an intracavity FP (Fabry-Perot) filter was used to interrogate Bragg wavelength variations. To solve the linearity, stability, and accuracy problems caused by the nonlinear response of FP filter, we calculated the wavelength variation of the fiber laser using quadrature signal processing with an unbalanced M/Z (Mach-Zehnder) interferometer and time-delayed sampling technique. The phase modulated interferometric signal is sampled with time delay, generating quadrature phase-delayed signals. By applying arctangent demodulation and phase unwrapping algorithm to the signals, accurate wavelength readout is performed. The calculated wavelengths are mapped to corresponding temporal reflection peaks from the sensor array, which enables more accurate fiber grating interrogation without the problems from the FP filter"s nonlinear response. The wavelength resolution of ~ 20 pm was obtained in our experimental setup, which could have been greatly enhanced with faster phase modulation.

Song, Minho

2003-10-01

254

THE KECK INTERFEROMETER NULLER  

SciTech Connect

The Keck Interferometer Nuller (KIN), the first operational separated-aperture infrared nulling interferometer, was designed to null the mid-infrared emission from nearby stars so as to ease the measurement of faint circumstellar emission. This paper describes the basis of the KIN's four-beam, two-stage measurement approach and compares it to the simpler case of a two-beam nuller. In the four-beam KIN system, the starlight is first nulled in a pair of nullers operating on parallel 85 m Keck-Keck baselines, after which 'cross-combination' on 4 m baselines across the Keck apertures is used to modulate and detect residual coherent off-axis emission. Comparison to the constructive stellar fringe provides calibration. The response to an extended source is similar in the two cases, except that the four-beam response includes a term due to the visibility of the source on the cross-combiner baseline-a small effect for relatively compact sources. The characteristics of the dominant null depth errors are also compared for the two cases. In the two-beam nuller, instrumental imperfections and asymmetries lead to a series of quadratic, positive-definite null leakage terms. For the four-beam nuller, the leakage is instead a series of correlation cross-terms combining corresponding errors in each of the two nullers, which contribute offsets only to the extent that these errors are correlated on the timescale of the measurement. This four-beam architecture has allowed a significant ({approx}order of magnitude) improvement in mid-infrared long-baseline fringe-visibility accuracies.

Serabyn, E.; Mennesson, B.; Colavita, M. M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Koresko, C. [Argon ST, Inc., 1386 Connellsville Road, Lemont Furnace, PA 15456 (United States); Kuchner, M. J., E-mail: Gene.Serabyn@jpl.nasa.gov [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-03-20

255

Dual-modulation fiber Fabry-Perot interferometer with double reflection for slowly-varying displacements.  

PubMed

This Letter describes a dual-amplitude modulation technique incorporated into a double reflection extrinsic-type fiber Fabry-Perot interferometer to measure periodic, nonperiodic as well as quasi-static displacements. The modulation scheme simultaneously maintains the interference signal pair in quadrature and provides a reference signal for displacements inferior to a quarter of the source wavelength. The control and phase demodulation of the interferometer carried out via software enable quasi-real-time measurement and facilitates sensor alignment. The sensor system can be exploited in the low frequency range from 10(-3) to ?500 Hz and has a resolution better than 2.2 nm, targeting applications in geophysics. PMID:22825167

Seat, H C; Chawah, P; Cattoen, M; Sourice, A; Plantier, G; Boudin, F; Chéry, J; Brunet, C; Bernard, P; Suleiman, M

2012-07-15

256

Self-mixing interferometry based on quadrature demodulation technique for displacement measurement  

NASA Astrophysics Data System (ADS)

A new, to the best of our knowledge, method for the measurement of the micro-displacement of a remote target based on the laser diode self-mixing interferometry(LDSMI) is presented. Quadrature demodulation technique is introduced to improve the measurement accuracy. Phase modulation of the laser beam is obtained by an electro-optic modulator (EOM) in the external cavity. Detection of the target's displacement can be easily achieved by sampling the interference signal at those times which satisfied certain conditions. The major advantage of the technique is that it does not involve any complicated calculation and insensitive to the sampling error. Experimental results show that the proposed method can effectively improve the displacement measurement accuracy of the LDSMI system to a few nanometers.

Guo, Dongmei; Hao, Hui; Han, Daofu

2010-05-01

257

High data-rate atom interferometer for measuring acceleration  

NASA Astrophysics Data System (ADS)

Atom interferometers have the potential to be exceptional broadband inertial sensors in both translational and rotational degrees of freedom. The demonstrated performance of this technology rivals the best ring-laser gyroscopes and falling corner-cube gravimeters. However, compact and field-worthy manifestations of atom interferometers remain elusive using standard approaches. Furthermore, bandwidths have typically been limited to a few Hertz, which is insufficient for a broader application space. We demonstrate a high data-rate light-pulse atom interferometer for measuring acceleration. The device is optimized to operate at rates between 50 Hz to 330 Hz with sensitivities of 0.57 micro-g/rtHz to 36.7 micro-g/rtHz, respectively. Our method offers a dramatic increase in data rate and demonstrates a path to new applications in highly dynamic environments.

Rakholia, Akash; McGuinness, Hayden; Biedermann, Grant

2012-06-01

258

White light velocity interferometer  

DOEpatents

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.

Erskine, David J. (Oakland, CA)

1999-01-01

259

White light velocity interferometer  

DOEpatents

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.

Erskine, David J. (Oakland, CA)

1997-01-01

260

White light velocity interferometer  

DOEpatents

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.

Erskine, D.J.

1999-06-08

261

Single fringe pattern demodulation using local adaptable quadrature filters  

NASA Astrophysics Data System (ADS)

We propose a new approach to demodulate a single fringe pattern with closed fringes by using Local Adaptable Quadrature Filters (LAQF). Quadrature filters have been widely used to demodulate complete image interferograms with carrier frequency, however these have never being used to demodulate complete image interferogramas with out carrirer (with closed fringes). The idea, in this paper, is to demodulate the fringe pattern sequentially, using a fringe following scanning strategy. In particular we use linear robust quadrature filters to obtain a fast and robust demodulation method for single fringe pattern images with closed fringes. The proposed LAQF method does not require a previous fringe pattern normalization. Some tests with experimental interferograms are shown to see the performance of the method along with comparisons to its closest competitor, which is the Regularized Phase Tracker (RPT), and we will see that this method is tolerant to higher levels of noise.

Estrada, J. C.; Servin, M.

2007-06-01

262

Measurement of Differential Phasor Diagram of Multilevel DPSK Signals by Using an Adjustment-Free Delay Interferometer Composed of a 3 3 Optical Coupler  

Microsoft Academic Search

We develop an adjustment-free differential-phase demodulator based on a delay-interferometer (DI) made of a 3 times 3 optical coupler, which is used as a 120-degree optical hybrid, and demonstrate the possibility of using it as a phasor monitor for the multilevel differential phase-shift keyed (DxPSK) signal. The key features of the proposed demodulator are twofold: (a) in-phase and quadrature (I-Q)

Y. Takushima; H. Y. Choi; Y. C. Chung

2009-01-01

263

Polarizing optical interferometer having a dual use optical element  

DOEpatents

A system for nondestructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figures.

Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

1995-04-04

264

Image Reconstruction from Interferometer Data.  

National Technical Information Service (NTIS)

In blind tests, we successfully reconstructed images from data simulated to have some of the defects that data coming from the multi-aperture amplitude interferometer (MAAI) at the University of Maryland would have. We also successfully reconstructed good...

J. R. Fienup J. H. Seldin

1993-01-01

265

Error estimates for Gaussian quadratures of analytic functions  

NASA Astrophysics Data System (ADS)

For analytic functions the remainder term of Gaussian quadrature formula and its Kronrod extension can be represented as a contour integral with a complex kernel. We study these kernels on elliptic contours with foci at the points ±1 and the sum of semi-axes [varrho]>1 for the Chebyshev weight functions of the first, second and third kind, and derive representation of their difference. Using this representation and following Kronrod's method of obtaining a practical error estimate in numerical integration, we derive new error estimates for Gaussian quadratures.

Milovanovic, Gradimir V.; Spalevic, Miodrag M.; Pranic, Miroslav S.

2009-12-01

266

On spectral quadrature for linear-scaling Density Functional Theory  

NASA Astrophysics Data System (ADS)

We provide a unified description of the Fermi operator expansion and recursion methods within the technique of spectral quadrature. Through rigorous error estimates, we prove that this approach is linear-scaling, stable and exponentially convergent. We use this analysis to determine the influence of smearing, band-gap, position of Fermi energy, and spectral width of the Hamiltonian on the convergence rates obtained in practical calculations. Additionally, we establish that super-geometric convergence can be achieved when the erfc function is used for smearing. We validate the spectral quadrature method and the accuracy of our analysis by means of selected examples.

Suryanarayana, Phanish

2013-10-01

267

Current-biased Andreev interferometer  

NASA Astrophysics Data System (ADS)

We theoretically investigate the behavior of Andreev interferometers with three superconducting electrodes in the current-biased regime. Our analysis allows us to predict a number of interesting features of such devices, such as both hysteretic and nonhysteretic behavior, negative magnetoresistance, and two different sets of singularities of the differential resistance at subgap voltages. In the nonhysteretic regime we find a pronounced voltage modulation with the magnetic flux which can be used for improving the sensitivity of Andreev interferometers.

Galaktionov, Artem V.; Zaikin, Andrei D.

2013-09-01

268

Phase-referenced interferometer with subwavelength and subhertz sensitivity applied to the study of cell membrane dynamics  

Microsoft Academic Search

We report a highly sensitive means of measuring cellular dynamics with a novel interferometer that can mea- sure motional phase changes. The system is based on a modified Michelson interferometer with a composite laser beam of 1550-nm low-coherence light and 775-nm CW light. The sample is prepared on a coverslip that is highly ref lective at 775 nm. By referencing

Changhuei Yang; Adam Wax; Mariah S. Hahn; Kamran Badizadegan; Ramachandra R. Dasari; Michael S. Feld

2001-01-01

269

102({h_bar}/2{pi})k Large Area Atom Interferometers  

SciTech Connect

We demonstrate atom interferometers utilizing a novel beam splitter based on sequential multiphoton Bragg diffractions. With this sequential Bragg large momentum transfer (SB-LMT) beam splitter, we achieve high contrast atom interferometers with momentum splittings of up to 102 photon recoil momenta (102({h_bar}/2{pi})k). To our knowledge, this is the highest momentum splitting achieved in any atom interferometer, advancing the state-of-the-art by an order of magnitude. We also demonstrate strong noise correlation between two simultaneous SB-LMT interferometers, which alleviates the need for ultralow noise lasers and ultrastable inertial environments in some future applications. Our method is intrinsically scalable and can be used to dramatically increase the sensitivity of atom interferometers in a wide range of applications, including inertial sensing, measuring the fine structure constant, and detecting gravitational waves.

Chiow, Sheng-wey; Kovachy, Tim; Chien, Hui-Chun; Kasevich, Mark A. [Department of Physics, Stanford University, Stanford, California 94305 (United States)

2011-09-23

270

Polynomial Spline Functions on the Circle II. Monosplines and Quadrature Formulae.  

National Technical Information Service (NTIS)

The paper is a continuation of MRC Technical Summary Report No. 997. The connection between monosplines and quadrature formulae is used to determine the best quadrature formula for the integral of f(z)dz integrated along the unit circle. The quadrature fo...

I. J. Schoenberg

1971-01-01

271

A Simplified Quadrature Element Method to compute the natural frequencies of multispan beams and frame structures  

Microsoft Academic Search

In this paper a new version of the Modified Quadrature Element Method (MQEM) is proposed. Like MQEM, the proposed method overcomes the drawback of the distance ? of the Quadrature Element Method (QEM) without introducing further degrees of freedom at the ends of the element as in the Differential Quadrature Element Method (DQEM), but it makes the computational cost of

S. Tomasiello

2011-01-01

272

Two-chord interferometry using 3.39 {mu}m He-Ne laser on a flux-coil-generated FRC  

SciTech Connect

A two-chord {lambda}{sub IR}{approx}3.39 {mu}m He-Ne laser interferometer system was developed for a flux-coil-generated field-reversed configuration to estimate the electron density and the total temperature of the field-reversed configuration (FRC) plasma. This two-chord heterodyne interferometer system consists of a single {approx}2 mW infrared He-Ne laser, a visible ({lambda}{sub vis}{approx}632.8 nm) He-Ne laser for the alignment, a 40 MHz acousto-optic modulator, photodetectors, and quadrature phase detectors. Initial measurement was performed and the measured average electron densities were 2-10x10{sup 19} m{sup -3} at two different radial positions in the midplane. A time shift in density was observed as the FRC expands radially. The time evolution of the line-averaged density agrees with the density estimated from the in situ internal magnetic probes, based on a rigid-rotor profile model.

Gota, H.; Deng, B. H.; Gupta, D.; Kiyashko, V.; Knapp, K.; Mendoza, R.; Morehouse, M. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Bolte, N.; Roche, T.; Wessel, F. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States); Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

2010-10-15

273

An analytical formula for the design of quadrature mirror filters  

Microsoft Academic Search

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.

GIANCARLO PIRANI; VALERIO ZINGARELLI

1984-01-01

274

Gaussian rational quadrature formulas for ill-scaled integrands  

NASA Astrophysics Data System (ADS)

A flexible treatment of Gaussian quadrature formulas based on rational functions is given to evaluate the integral , when f is meromorphic in a neighborhood V of the interval I and W(x) is an ill-scaled weight function. Some numerical tests illustrate the power of this approach in comparison with Gautschi's method.

Illán González, J. R.

2009-12-01

275

Wave-Based Inversion & Imaging for the Optical Quadrature Microscope  

SciTech Connect

The Center for Subsurface Sensing & Imaging System's (CenSSIS) Optical Quadrature Microscope (OQM) is a narrow band visible light microscope capable of measuring both amplitude and phase of a scattered field. We develop a diffraction tomography, that is, wave-based, scattered field inversion and imaging algorithm, for reconstructing the refractive index of the scattering object.

Lehman, S K

2005-10-27

276

A DIFFERENTIAL QUADRATURE ANALYSIS OF VIBRATION FOR RECTANGULAR STIFFENED PLATES  

Microsoft Academic Search

Structures consisting of thin plates stiffened by a system of ribs or diaphragms form a class of structural elements of practical importance in various engineering applications. A differential quadrature analysis of free vibration of plates with eccentric stiffeners is presented. The plate and the stiffeners are treated separately. Simultaneous governing differential equations are derived from the plate dynamic equilibrium, the

H. Zeng; C. W. BERT

2001-01-01

277

A quadrature-based approach to improving the collocation method  

Microsoft Academic Search

Summary The collocation method is a popular method for the approximate solution of boundary integral equations, but typically does not achieve the high order of convergence reached by the Galerkin method in appropriate negative norms. In this paper a quadrature-based method for improving upon the collocation method is proposed, and developed in detail for a particular case. That case involves

Ian H. Sloan

1988-01-01

278

Quantitative Phase Measurements Using a Quadrature Tomographic Microscope  

Microsoft Academic Search

ABSTRACT The Quadrature Tomographic Microscope measures the amplitude and phase of an image. This information allows the user to see contrast features not available in other microscopes, and is critical to any three-dimensional reconstruction. We report on development and use of test objects to measure the accuracy and repeatability of phase measurements. A simple binary phase grating, a series of

Daniel J. Townsend; Kregg D. Quarles; Anthony L. Thomas; Willie S. Rockward; Carol M. Warner; Judith A. Newmark; Charles A. Dimarzio

279

Quantitative phase measurements using a quadrature tomographic microscope  

Microsoft Academic Search

The Quadrature Tomographic Microscope measures the amplitude and phase of an image. This information allows the user to see contrast features not available in other microscopes, and is critical to any three-dimensional reconstruction. We report on development and use of test objects to measure the accuracy and repeatability of phase measurements. A simple binary phase grating, a series of glass

Daniel J. Townsend; Kregg D. Quarles; Anthony L. Thomas; Willie S. Rockward; Carol M. Warner; Judith A. Newmark; Charles A. DiMarzio

2003-01-01

280

Thermodynamics of quadrature trajectories in open quantum systems  

NASA Astrophysics Data System (ADS)

We apply a large-deviation method to study the diffusive trajectories of the quadratures of light emitted from open 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 light quadratures 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 such phases. The formalism we introduce also allows us to analyze the properties of the light emitted in quantum-jump trajectories which deviate far from the typical dynamics.

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

2012-12-01

281

Development of an Interferometer Diagnostic for the Spheromak Turbulent Physics Experiment (STPX)  

NASA Astrophysics Data System (ADS)

Laser interferometry is a proven method for measuring electron density in fusion plasmas. Typically, far-infrared interferometers are used because of the large phase shift due to the change in the index of refraction of the plasma and their relative insensitivity to vibrations. A two-color (CO2: ?=10.6 ?m, HeNe: ?=633 nm) interferometer has been designed for installation on STPX. The interferometer is a Mach-Zehnder configuration with a single-chord, double pass probe beam. The laser beams copropagate along a 10-meter path for vibration subtraction along with frequency modulation for heterodyne detection. Detection is carried out using a HgCdTe photoconductor for the CO2 and a Si APD for the HeNe. The capabilities and challenges with the installation of the interferometer on STPX will be discussed.

Clark, Jerry; Titus, J.; Alexander, A. B.; Mezonlin, E. D.

2012-10-01

282

An overview of the Keck Interferometer Nuller  

NASA Astrophysics Data System (ADS)

The first high dynamic range interferometry mode planned to come on line at the Keck Observatory is mid-infrared nulling interferometry. In this paper, an overview is given of the goals and experimental configuration of the Keck Interferometer Nuller (KIN). After an introduction to the science enabled by mid-infrared nulling interferometry on the Keck Interferometer's baseline, a system level overview of the experiment is provided, which includes a discussion of the optical path-length matching and stabilization approaches. This is followed by brief tours of both the nulling beam-combiner breadboard and the mid-infrared camera to be used in the experiment. The paper concludes with a discussion of the performance levels attained to date with the mid-infrared nullers built at the Jet Propulsion Laboratory. These symmetric nullers, all based on the modified Mach-Zehnder beamcombiner configuration, have now experimentally verified the predicted dual-polarization nulling capability of a reversed beamsplitter pair arrangement. To date, the JPL nulling beamcombiners have nulled broadband thermal mid-infrared radiation to the 10-4 level, and monochromatic (10.6 ?m CO2 laser) radiation to the 10-6 level.

Serabyn, Eugen

2003-10-01

283

Sub-50 nm patterning by immersion interference lithography using a Littrow prism as a Lloyd's interferometer.  

PubMed

We present a simple setup that combines immersion lithography with a Lloyd's mirror interferometer. Aiming for smaller structure sizes, we have replaced the usual Lloyd's interferometer by a triangular Littrow prism with one metal-coated side, which acts as a mirror. Because of the higher refractive index of the prism, the wavelength and, thus, the attainable structure sizes, are decreased significantly. Using a laser with a wavelength of 244nm, we could produce line patterns with a period of less than 100nm and a width of 45nm. The introduced setup retains all the advantages of a Lloyd's mirror interferometer, in particular the flexibility in periodicity. PMID:20967096

de Boor, Johannes; Kim, Dong Sik; Schmidt, Volker

2010-10-15

284

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

SciTech Connect

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.

Preissner, C.; Assoufid, L.; Shu, D.; Experimental Facilities Division (APS)

2004-01-01

285

Fiber interferometer for calibration of electron density profile measured by Thomson scattering in LHD  

NASA Astrophysics Data System (ADS)

An electron density (ne) calibration method using a fiber-based interferometer (FI) for Thomson scattering (TS) diagnostics is proposed. An interferometer probe laser is injected into the plasma from the back face of a TS final bend mirror that has a transparency at the wavelength of the FI probe beam. The coaxial line electron density is measured by the FI, making it possible to calibrate neL from TS without either misalignment or optical loss in the collective optics of the TS system. In this paper, we report the conceptual design, wavelength selection of FI and potential issues in calibration of the fiber-based interferometer system.

Yasuhara, R.; Akiyama, T.; Yamada, I.; Kawahata, K.; Tokita, S.

2012-01-01

286

A simple air wedge shearing interferometer for studying exploding wires  

NASA Astrophysics Data System (ADS)

A new type of shearing interferometer using an air wedge is described. This interferometer is based on a beam splitter constructed using two 90-degree prisms. A small air gap, which varies in spacing from top-to-bottom, separates the second prism from the first and forms the air wedge. The single incident laser beam is focused near the gap, and the two primary reflections from the long sides of each prism form the two coherent virtual sources necessary for interferometry. The shift between the two images of the object at the detector, as well as the orientation and frequency of the fringes, can be independently adjusted by altering the air gap thickness and angle, as well as the position of the laser focus in the gap. This interferometry scheme is inexpensive and easily aligned, and has been successfully and reliably used in exploding wire experiments.

Pikuz, S. A.; Romanova, V. M.; Baryshnikov, N. V.; Hu, Min; Kusse, B. R.; Sinars, D. B.; Shelkovenko, T. A.; Hammer, D. A.

2001-01-01

287

Reduction of quantum noise in optical interferometers using squeezed light  

NASA Astrophysics Data System (ADS)

We study the photon counting noise in optical interferometers used for gravitational wave detection. In order to reduce quantum noise a squeezed vacuum state is injected into the usually unused input port. Here, we specifically investigate the so-called "dark port case," when the beam splitter is oriented close to 90° to the incoming laser beam, such that nearly all photons go to one output port of the interferometer, and only a small fraction of photons is seen in the other port ("dark port"). For this case it had been suggested that signal amplification is possible without concurrent noise amplification [R. Barak and Y. Ben-Aryeh, J. Opt. Soc. Am. B 25, 361 (2008)]. We show that by injection of a squeezed vacuum state into the second input port, counting noise is reduced for large values of the squeezing factor, however the signal is not amplified. Signal strength only depends on the intensity of the laser beam.

Weyrauch, M.; Voronov, V. G.

2011-11-01

288

A new method for determining the plasma electron density using three-color interferometer  

NASA Astrophysics Data System (ADS)

A new method for determining the plasma electron density using the fractional fringes on three-color interferometer is proposed. Integrated phase shift on each interferometer is derived without using the temporal history of the fractional fringes. The dependence on the fringe resolution and the electrical noise are simulated on the wavelengths of CO2 laser. Short-time integrations of the fractional fringes enhance the reliability of this method.

Arakawa, Hiroyuki; Kawano, Yasunori; Itami, Kiyoshi

2012-06-01

289

Polarization-independent silica-on-silicon Mach-Zehnder interferometers  

Microsoft Academic Search

The birefringence induced by compressive strain in silica waveguides on silicon substrates is compensated with a silicon nitride patch placed below the core. We demonstrate Mach-Zehnder interferometers with polarization-independent spectral response, including a compensated Mach-Zehnder interferometer suitable for stabilization of multiple laser sources in a dense wavelength division multiplexed fiber optic communication network. Furthermore, we show how silicon nitride can

Henry H. Yaffe; Charles H. Henry; Rudolf F. Kazarinov; Michele A. Milbrodt

1994-01-01

290

Measurement of the carrier envelope offset frequency of a femtosecond frequency comb using a Fabry-Perot interferometer  

SciTech Connect

A method for measuring the carrier envelope offset (CEO) frequency of the femtosecond frequency comb with a bandwidth of less than one octave by using a Fabry-Perot interferometer is proposed and experimentally demonstrated. (laser components)

Basnak, D V; Bikmukhametov, K A; Dmitrieva, N I [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Dmitriev, Aleksandr K; Lugovoi, A A [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Pokasov, P V; Chepurov, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

2010-10-15

291

Dual-wavelength parallel interferometer with superhigh resolution  

NASA Astrophysics Data System (ADS)

A dual-wavelength parallel interferometer for subnanometer displacement measurement is introduced. A synthetic wavelength is used to subdivide the fringes formed by a single wavelength. An experimental setup that uses a heat-stabilizing dual-wavelength 633-nm He-Ne laser as the light source is established. The primary experimental result shows that a resolution of 0.210 nm over a 350-nm range has been achieved.

Zhao, Yang; Cheng, Xiaohui; Li, Dacheng

2002-04-01

292

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

SciTech Connect

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.

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

293

Phase-modulation interferometer for ICF-target characterization  

SciTech Connect

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.

Cooper, D.E.

1981-01-01

294

Desktop interferometer for optical synthesis imaging  

Microsoft Academic Search

A simple desktop optical interferometer is described and demonstrated as a teaching tool for concepts of long-baseline stellar interferometry. The interferometer is compact, portable, and easily aligned. It sits on a base 8\\

Peter R. Lawson; Donald M. A. Wilson; John E. Baldwin

2003-01-01

295

Astrophysics with the Laser Interferometer Space Antenna  

NASA Astrophysics Data System (ADS)

LISA will detect gravitational radiation with frequencies between roughly 0.1 mHz and 10 mHz. In this range are known and postulated objects that will probe many frontiers of physics and astrophysics. These frontiers include tests of models of strong gravity, hierarchical assembly of black holes and galaxies, precision cosmography, and the properties of very compact Galactic binaries such as the possible precursors of Type Ia supernovae. I will review the prospects for fundamental discovery with LISA as well as the expected rich interplay of information from LISA with electromagnetic observations.

Miller, Cole

296

Lasers.  

ERIC Educational Resources Information Center

|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)|

Schewe, Phillip F.

1981-01-01

297

Lasers.  

ERIC Educational Resources Information Center

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)

Schewe, Phillip F.

1981-01-01

298

White Light Extended Source Shearing Interferometer  

Microsoft Academic Search

A grating lateral shear interferometer is described that can be used with a white light source. The use of the interferometer with certain types of extended sources is also demonstrated. In a recent paper a simple double frequency grat- ing shearing interferometer, similar to a Ronchi in- terferometer, was described for use with a quasi- monochromatic point light source. l

J. C. Wyant

1974-01-01

299

Accurate Computation of Gaussian Quadrature for Tension Powers  

NASA Astrophysics Data System (ADS)

We consider Gaussian quadrature formulæ which exactly integrate a system of tension powers 1,x,x2,...,xn-3, sinh(px), cosh(px), on a given interval [a,b], where n>=4 is an even integer and p>0 is a given tension parameter. In some applications it is essential that p can be changed dynamically, and we need an efficient ``on-demand'' algorithm that calculates the nodes and weights of Gaussian quadrature formulas for many different values of p, which are not known in advance. It is an interesting numerical challenge to achieve the required full machine precision accuracy in such an algorithm, for all possible values of p. By exploiting various analytic and numerical techniques, we show that this can be done efficiently for all reasonably low values of n that are of any practical importance.

Singer, Saša

2007-09-01

300

Quadrature formulae for classes of functions of low smoothness  

SciTech Connect

For Sobolev and Korobov spaces of functions of several variables a quadrature formula with explicitly defined coefficients and nodes is constructed. This formula is precise for trigonometric polynomials with harmonics from the corresponding step hyperbolic cross. The error of the quadrature formula in the classes W{sup {alpha}}{sub p}[0,1]{sup n}, E{sup {alpha}}[0,1]{sup n} is o((ln M){sup {beta}}/M{sup {alpha}}), where M is the number of nodes and {beta} is a parameter depending on the class. The problem of the approximate calculation of multiple integrals for functions in W{sup {alpha}}{sub p}[0,1]{sup n} is considered in the case when this class does not lie in the space of continuous functions, that is, for {alpha}{<=}1/p.

Nursultanov, E D [Kazakhstan Branch of Lomonosov Moscow State University, Astana (Kazakhstan); Tleukhanova, N T [Eurasian National University named after L.N.Gumilev, Astana (Kazakhstan)

2003-10-31

301

Keck Interferometer status and plans  

Microsoft Academic Search

ABSTRACT Keck Interferometer is a NASA-funded project to combine ,the two 10 m Keck telescopes for high sensitivity near- infrared fringe visibility measurem ents, nulling interferometry at 10 µm to measure the quantity of exozodiacal emission around nearby stars, and differential-phase measurements to detect \\

M. Mark Colavita; Peter L. Wizinowich; Rachel L. Akeson

302

Keck Interferometer status and plans  

Microsoft Academic Search

Keck Interferometer is a NASA-funded project to combine the two 10 m Keck telescopes for high sensitivity near-infrared fringe visibility measurements, nulling interferometry at 10 mum to measure the quantity of exozodiacal emission around nearby stars, and differential-phase measurements to detect \\

M. M. Colavita; Peter L. Wizinowich; Rachel L. Akeson

2004-01-01

303

Common interferometer control systems architecture  

NASA Astrophysics Data System (ADS)

Astronomical interferometry at the JPL has grown rapidly in the last two years. JPL is now engaged in a number of interferometry projects and is also developing a number of internal testbeds to support those projects. While each of these projects and testbeds has its own unique properties, they do share a lot of common features, and JPL is striving, through its interferometer technology program (ITP), to develop common components, software, and hardware that can be reused by multiple projects. The discipline where this commonality is probably most apparent is in the area of realtime control systems, specifically the software and electronics that drive the instrument control loops and sequence the subsystems. To this end, within the ITP, JPL has developed the realtime interferometer control systems testbed (RICST) as a facility where a common software and electronics core, essentially a control system for a generic interferometer, can be developed. The realtime control (RTC) team in the ITP program consists of about 20 full-time equivalent engineers, technicians, quality assurance personnel, architects, and managers. The remainder of this paper will describe the interferometry landscape at JPL, the RTC effort, an overview of the RICST testbed, and the generic interferometer control system architecture that has been developed.

Hines, Braden E.; Johnson, Richard L.; Starr, Kenneth M.

1998-07-01

304

The Navy Prototype Optical Interferometer  

Microsoft Academic Search

This paper announces the first closure phase measurements made with the Navy Prototype Optical Interferometer (NPOI) on stars. These are the first closure phase measurements made at optical wavelengths which exceed, by a factor of two to three, the resolution of the largest existing single optical telescope. The first observations were made on 1996 March 18 using three of the

J. A. Benson; D. J. Hutter; N. M. Elias II; P. Bowers; D. Mozurkewich; J. T. Armstrong; N. White; C. Hummel

1996-01-01

305

Overview of the Keck Interferometer.  

National Technical Information Service (NTIS)

This is a presentation about the Keck Interferometer which is being constructed on top of Mauna Kea, Hawaii. This includes using the world's largest telescopes for optical and near-infrared astronomy, the twin 10 meter Keck telescopes. The two Keck telesc...

G. vanBelle

1999-01-01

306

Best quadrature formula on Sobolev class with Chebyshev weight  

NASA Astrophysics Data System (ADS)

Using best interpolation function based on a given function information, we present a best quadrature rule of function on Sobolev class KWr[-1,1] with Chebyshev weight. The given function information means that the values of a function f[set membership, variant]KWr[-1,1] and its derivatives up to r-1 order at a set of nodes x are given. Error bounds are obtained, and the method is illustrated by some examples.

Xie, Congcong

2008-05-01

307

Some new applications of truncated Gauss-Laguerre quadrature formulas  

NASA Astrophysics Data System (ADS)

We show how truncated Gauss-Laguerre quadrature formulas can be used to produce accurate approximations and high rates of convergence, also when they are applied to integrand functions having only an algebraic type decay to zero at infinity. The approach presented in the paper is proposed for the computation of integrals and for the construction of Nyström type interpolants for some second kind integral equations.

Mastroianni, G.; Monegato, G.

2008-12-01

308

Quadrature-fed wideband circularly polarized dielectric resonator antenna  

Microsoft Academic Search

A quadrature-fed wideband CP rectangular DRA has been investigated. The Ansoft HFSS and the DWM were used in the analysis. As similar to the LP case, the fundamental TEm mode, together with the higher-order TE113 mode, of the DRA can be simultaneously excited. Since each mode can generate a CP wave, the impedance and AR bandwidth can be increased by

Bin Li; Xin-Qing Sheng

2008-01-01

309

New embedded boundary-type quadrature formulas for the simplex  

NASA Astrophysics Data System (ADS)

In this paper we consider the problem of the approximation of the integral of a smooth enough function f(x,y) on the standard simplex {intlimits_{Delta _{2} } {f{left( {x,y} right)}dxdy} } = {sumlimits_{alpha = 1}^3 {{sumlimits_{i,j} {A_{{alpha ij}} frac{{alpha ^{{i + j}} }}{{alpha x^{i} alpha y^{j} }}f{left( {x_{alpha } ,y_{alpha } } right)} + E{left( f right)}} }} } where the nodes are the vertices of the simplex. Such kind of quadratures belong to a more general class of formulas for numerical integration, which are called boundary-type quadrature formulas. We discuss three classes of such formulas that are exact for algebraic polynomials and generate embedded pairs. We give bounds for the truncation errors and conditions for convergence. Finally, we show how to organize an algorithm for the automatic computation of the quadratures with estimate of the errors and provide some numerical examples.

Costabile, F.; Dell'Accio, F.

2007-08-01

310

Fast evaluation of quadrature formulae on the sphere  

NASA Astrophysics Data System (ADS)

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.

Keiner, Jens; Potts, Daniel

2008-03-01

311

Quadrature Hartley VCO and Injection-Locked Frequency Divider  

NASA Astrophysics Data System (ADS)

Novel low phase noise quadrature voltage-controlled oscillator (QVCO) and quadrature injection locked frequency divider (QILFD) with two coupled Hartley VCOs are proposed and implemented using the standard TSMC 0.18?m CMOS 1P6M process. The QVCO employs pMOS as the core to reduce the up-conversion of low-frequency device noise to RF phase noise. It uses super-harmonic coupling technique to couple two differential Hartley VCOs and four small-size coupling transistors to set the directivity of quadrature output phases. At the 1.7V supply voltage, the output phase noise of the QVCO is -124dBc/Hz at 1MHz offset frequency from the carrier frequency of 4.12GHz, and the figure of merit is -185dBc/Hz. At the supply voltage of 1.7V, the total power consumption is 13.1mW. At the supply voltage of 1.5V, the tuning range of the free-running QILFD is from 2.05GHz to 2.36GHz, about 310MHz, and the locking range of the ILFD is from 3.99 to 5.19GHz, about 1.20GHz, at the injection signal power of 0dBm.

Jang, Sheng-Lyang; Chang, Chia-Wei; Wu, Sheng-Chien; Lee, Chien-Feng; Tsai, Lin-Yen; Huang, Jhin-Fang

312

Standing waves in fiber-optic interferometers.  

PubMed

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

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

2011-10-10

313

A display technology based on Fabry Perot interferometer array  

NASA Astrophysics Data System (ADS)

The performances of a display chip based on Fabry-Perot interferometer (FPI) array was stimulated theoretically. Lighting by a single frequency laser, the grayscale of image pixels can be manipulated by transmission intensity modulation of the FPIs which act as chip pixels. The F-P cavities were constructed by Lithium Niobate thin layer. The cavity mirrors were deposited directly on the crystal surfaces. Using the converse piezoelectric effect of Lithium Niobate, the cavity length was scanned by changing the applied voltage. Therefore, the single frequency laser transmission was controlled. The electrodes were coated locally for corresponding chip pixel. A theoretical model for a display chip with an array of 64×64 FPIs was built. The main parameters of the chip were optimized and the performances were stimulated. The influences of mirror flatness, parallel of the cavity mirrors, linewidth and frequency stability of the lighting laser were discussed. The simulation results indicated that this technique is promising for laser display.

Otmani, Aicha; Wang, Xin; Wang, Hongjie; Li, Zhuo

2013-09-01

314

Non-destructive testing using two-component/two-wave mixing interferometer  

SciTech Connect

A new laser-based ultrasonic (LBU) receiver was recently introduced. The novel architecture is based on two-wave mixing in photorefractive materials and allows simultaneous measurement of in-plane and out-of-plane displacements (two- component). By taking advantage of recent developments in electronic processing and our knowledge on multi-channel interferometer, we achieved a compact optical system using only a single collecting aperture and a single laser probe beam. We will characterize the system performances and present experimental results demonstrating the capability for this compact two-component interferometer.

Wartelle, A.; Pouet, B.; Breugnot, S. [Bossa Nova Technologies, Venice, CA 90291 (United States)

2011-06-23

315

Stabilized fiber-optic Mach-Zehnder interferometer for carrier-frequency rejection.  

PubMed

We have demonstrated stabilization of a fiber-optic Mach-Zehnder interferometer, with a centimeter-scale path difference, to the transmission minimum for the carrier wave of a frequency-modulated laser beam. A time-averaged extinction of 32 dB, limited by the bandwidth of the feedback, was maintained over several hours. The interferometer was used to remove the carrier wave from a 780 nm laser beam that had been phase modulated at 2.7 GHz. PMID:23938423

Cooper, Nathan; Woods, Jonathan; Bateman, James; Dunning, Alexander; Freegarde, Tim

2013-08-10

316

Multi-channel far-infrared HL-2A interferometer-polarimeter.  

PubMed

An HL-2A interferometer is upgraded to a multi-channel interferometer?polarimeter, which includes four chords for the interferometer and four chords for the polarimeter. The far-infrared lasers (at ? = 432.5 ?m and 30 mW power) are used to probe plasmas horizontally in the midplane of HL-2A. A conventional heterodyne technique is used for the interferometer. Two counter-rotating circularly polarized waves are used to measure the Faraday rotation effect. A fast-phase comparator with temporal resolution of 1 ?s and phase resolution 0.1° is developed. Further, the distortion of the polarization caused by the beam-splitters and the other optical components is also investigated. PMID:23126994

Zhou, Y; Deng, Z C; Li, Y G; Yi, J

2012-10-01

317

Single and double reflection Michelson atom interferometers in a weakly-confining magnetic trap  

NASA Astrophysics Data System (ADS)

We analyze the operation of a BEC based atom interferometer, where the atoms are held in a weakly-confining magnetic trap and manipulated with diffraction gratings produced by counter-propagating laser beams. A simple analytic model is developed to describe the dynamics of the interferometer. It is used to find the region of parameters corresponding to high values of the interference fringe contrast for both single and double reflection geometries. We demonstrate that for a double reflection interferometer the coherence time can be increased by shifting the recombination time. Finally, we compare the theory with recent experimental realizations of these interferometers and estimate when phase diffusion and finite temperature phase fluctuations become important.

Kafle, Rudra; Stickney, James; Anderson, Dana; Zozulya, Alex

2008-03-01

318

Analyzing algorithms for nonlinear and spatially nonuniform phase shifts in the liquid crystal point diffraction interferometer. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports  

SciTech Connect

Phase-shifting interferometry has many advantages, and the phase shifting nature of the Liquid Crystal Point Diffraction Interferometer (LCPDI) promises to provide significant improvement over other current OMEGA wavefront sensors. However, while phase-shifting capabilities improve its accuracy as an interferometer, phase-shifting itself introduces errors. Phase-shifting algorithms are designed to eliminate certain types of phase-shift errors, and it is important to chose an algorithm that is best suited for use with the LCPDI. Using polarization microscopy, the authors have observed a correlation between LC alignment around the microsphere and fringe behavior. After designing a procedure to compare phase-shifting algorithms, they were able to predict the accuracy of two particular algorithms through computer modeling of device-specific phase shift-errors.

Jain, N. [Pittsford Sutherland High School, NY (United States)

1999-03-01

319

Development of a multichannel dispersion interferometer at TEXTOR.  

PubMed

The design and main characteristics of 14-channel dispersion interferometer for plasma profile measurement and control in TEXTOR tokamak are presented. The diagnostic is engineered on the basis of modular concept, the 10.6 microm CO(2) laser source and all optical and mechanical elements of each module are arranged in a compact housing. A set of mirrors and retroreflectors inside the TEXTOR vacuum vessel provides full coverage of the torus cross section with 12 vertical and two diagonal lines of sight, no rigid frame for vibration isolation is required. Results of testing of the single-channel prototype diagnostic and the pilot module of the multichannel dispersion interferometer are presented. PMID:19044526

Lizunov, A; Bagryansky, P; Khilchenko, A; Kovalenko, Yu V; Solomakhin, A; Biel, W; Lambertz, H T; Krasikov, Yu; Mitri, M; Schweer, B; Dreier, H

2008-10-01

320

A Fiber Interferometer for the Magnetized Shock Experiment  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

321

A Fiber Interferometer for the Magnetized Shock Experiment  

SciTech Connect

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.

Yoo, Christian [Los Alamos National Laboratory

2012-08-30

322

Development of a multichannel dispersion interferometer at TEXTOR  

SciTech Connect

The design and main characteristics of 14-channel dispersion interferometer for plasma profile measurement and control in TEXTOR tokamak are presented. The diagnostic is engineered on the basis of modular concept, the 10.6 {mu}m CO{sub 2} laser source and all optical and mechanical elements of each module are arranged in a compact housing. A set of mirrors and retroreflectors inside the TEXTOR vacuum vessel provides full coverage of the torus cross section with 12 vertical and two diagonal lines of sight, no rigid frame for vibration isolation is required. Results of testing of the single-channel prototype diagnostic and the pilot module of the multichannel dispersion interferometer are presented.

Lizunov, A.; Bagryansky, P.; Khilchenko, A.; Kovalenko, Yu. V.; Solomakhin, A. [Budker Institute of Nuclear Physics, Novosibirsk 630090 (Russian Federation); Biel, W.; Lambertz, H. T.; Krasikov, Yu.; Mitri, M.; Schweer, B. [Forschungszentrum Juelich GmbH, Association EURATOM-FZ Juelich, Institut fuer Plasmaphysik, Trilateral Euregio Cluster, 52425 Juelich (Germany); Dreier, H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)

2008-10-15

323

On deriving a locally corrected Nystrom scheme from a quadrature sampled moment method  

Microsoft Academic Search

A novel high-order method of moment procedure with quadrature point-based discretization is presented. The scheme is equivalent to a moment method employing smooth basis and testing functions applying a fixed-point numerical quadrature approximation for the outer integral. Mapping the current to the quadrature points then leads to a formulation that is equivalent to that derived via the locally corrected Nystrom

Stephen D. Gedney

2003-01-01

324

A Low Phase Noise Quadrature LC VCO Using Capacitive Common-Source Coupling  

Microsoft Academic Search

A low phase noise quadrature LC VCO with inherent tail-current shaping is presented. Two identical differential LC VCOs are locked in quadrature with a capacitor connected between their common-source nodes. This capacitor further drives the oscillators into a tail-current shaping mode, which increases their oscillation amplitude and reduces their phase noise. A multi-band 1.9 GHz differential nMOS quadrature LC VCO

B. Soltanian; P. Kinget

2006-01-01

325

Optical field's quadrature excitation studied by new Hermite-polynomial operator identity  

NASA Astrophysics Data System (ADS)

We study the optical field's quadrature excitation state Xm|0>, where X = (a + a†)/?2 is the quadrature operator. We find it is ascribed to the Hermite-polynomial excitation state. For the first time, we determine this state's normalization constant which turns out to be a Laguerre polynomial. This is due to the integration method within the ordered product of operators (IWOP). The normalization for the two-mode quadrature excitation state is also completed by virtue of the entangled state representation.

Fan, Hong-Yi; He, Rui; Da, Cheng; Liang, Zu-Feng

2013-08-01

326

Status of the LBT interferometer  

NASA Astrophysics Data System (ADS)

The Large Binocular Telescope Interferometer, a thermal infrared imager and nulling interferometer for the LBT, is currently being integrated and tested at Steward Observatory. The system consists of a general purpose or universal beamcombiner (UBC) and three camera ports, one of which is populated currently by the Nulling and Imaging Camera (NIC). Wavefront sensing is carried out using pyramid-based "W" units developed at Arcetri Observatory. The system is designed for high spatial resolution, high dynamic range imaging in the thermal infrared. A key project for the program is to survey nearby stars for debris disks down to levels which may obscure detection of Earth-like planets. During 2007-2008 the UBC portion of the LBTI was assembled and tested at Steward Observatory. Initial integration of the system with the LBT is currently in progress as the W units and NIC are being completed in parallel.

Hinz, Philip M.; Bippert-Plymate, Teresa; Breuninger, Andy; Connors, Tom; Duffy, Brian; Esposito, Simone; Hoffmann, William; Kim, Jihun; Kraus, Joe; McMahon, Thomas; Montoya, Manny; Nash, Richard; Durney, Olivier; Solheid, Elliott; Tozzi, Andrea; Vaitheeswaran, Vidhya

2008-07-01

327

Keck Interferometer nuller instrument performance  

NASA Astrophysics Data System (ADS)

The Keck Interferometer combines the two 10 m Keck telescopes as a long baseline interferometer. It is funded by NASA as a joint development among the Jet Propulsion Laboratory, the W. M. Keck Observatory, and the NASA Exoplanet Science Institute. In February 2008, the 10 um nulling mode began a 32 night observing program with three key science teams to perform a survey of nearby stars for exozodiacal dust. This program has recently concluded, and has been followed by nuller observing on a variety of science topics through the standard proposal process. We provide a review and update of the nuller implementation, and describe the data reduction process, including the calibration approach. We then review the technical performance of the instrument based on the full key science data set, including sensitivity and systematic errors. We also provide some summary data on atmospheric effects applicable to the cophasing approach.

Colavita, M. M.; Serabyn, E.; Ragland, S.; Millan-Gabet, R.; Akeson, R. L.

2010-07-01

328

An X\\/Ku-band frequency synthesizer using a 9Bit quadrature DDS  

Microsoft Academic Search

This paper presents an X\\/Ku-band fine-tuning frequency synthesizer using a quadrature DDS implemented in a 0.18 mum SiGe BiCMOS technology. The frequency synthesizer comprises a 9-bit quadrature DDS, an 11.7 GHz quadrature VCO and image rejection mixers. The outputs of the quadrature DDS are down-converted to 9.4~11.7 GHz and up-converted to 11.7~14.0 GHz, respectively. The die area of the synthesizer

Xuefeng Yu; Fa Foster Dai; Dayu Yang; J. David Irwin; Richard C. Jaeger

2008-01-01

329

Fiber-optic extrinsic Fabry-Perot interferometer vibration sensor with two-wavelength passive quadrature readout  

Microsoft Academic Search

A new fiber-optic extrinsic Fabry-Perot microinterferometer cantilever beam type vibration sensor (EFPI-V) is described. For eliminating signal fading effects a two-wavelength demodulation scheme is implemented. The theoretical model of this sensor with pronounced eigenfrequency spectrum in the acoustic range is confirmed by experimental results. Initial field tests in an experimental airport ground traffic surveillance system for vehicle defection via monitoring

Norbert Furstenau; Markus Schmidt

1997-01-01

330

Experimental demonstration of microring quadrature phase-shift keying modulators.  

PubMed

Advanced optical modulation formats are a key technology to increase the capacity of optical communication networks. Mach-Zehnder modulators are typically used to generate various modulation formats. Here, we report the first experimental demonstration of quadrature phase-shift keying (QPSK) modulation using compact microring modulators. Generation of 20 Gb/s QPSK signals is demonstrated with 30 ?m radius silicon ring modulators with drive voltages of ~6 V. These compact QPSK modulators may be used in miniature optical transponders for high-capacity optical data links. PMID:22466187

Dong, Po; Xie, Chongjin; Chen, Long; Fontaine, Nicolas K; Chen, Young-kai

2012-04-01

331

Noise-cancelling quadrature magnetic position, speed and direction sensor  

DOEpatents

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.

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

1996-01-01

332

Runge-Kutta methods for parabolic equations and convolution quadrature  

SciTech Connect

We study the approximation properties of Runge-Kutta time discretizations of linear and semilinear parabolic equations, including incompressible Navier-Stokes equations. We derive asymptotically sharp error bounds and relate the temporal order of convergence, which is generally noninteger, to spatial regularity and the type of boundary conditions. The analysis relies on an interpretation of Runge-Kutta methods as convolution quadratures. In a different context, these can be used as efficient computational methods for the approximation of convolution integrals and integral equations. They use the Laplace transform of the confolution kernal via a discrete operational calculus. 23 refs., 2 tabs.

Lubich, Ch.; Ostermann, A.

1993-01-01

333

Statistical frequency measuring error of the quadrature demodulation technique for noisy single-tone pulse signals  

NASA Astrophysics Data System (ADS)

The standard deviation of the centre frequency of a signal is investigated for the quadrature demodulation technique (QDT). Signal frequencies can be measured by QDT unaffected by the amount of available signal periods. It can be used for the measurement of nonstationary signals generated by laser Doppler velocimeters. The dependence of the frequency measuring error on the averaging time of noisy single-tone Gaussian pulse signals is analysed. Assuming a quantum noise process, it is shown that the minimum measuring error results for an averaging time of approximately 1/ e2 of the pulse duration of the signal. Alternatively, defined weighting of the measured values leads to a monotonically decreasing measuring error with increasing averaging time until the Cramer-Rao lower bound is reached. Therefore, the weighted QDT provides the lowest measuring error of all linear unbiased frequency estimators. It allows the evaluation of small frequency changes of laser Doppler signals, e.g. from micro-turbulent flows. The theory presented here is verified by Monte Carlo simulations and experiments.

Czarske, Jürgen W.

2001-05-01

334

The AEI 10 m prototype interferometer  

Microsoft Academic Search

A 10 m prototype interferometer facility is currently being set up at the AEI in Hannover, Germany. The prototype interferometer will be housed inside a 100 m3 ultra-high vacuum envelope. Seismically isolated optical tables inside the vacuum system will be interferometrically interconnected via a suspension platform interferometer. Advanced isolation techniques will be used, such as inverted pendulums and geometrical anti-spring

S. Goßler; A. Bertolini; M. Born; Y. Chen; K. Dahl; D. Gering; C. Gräf; G. Heinzel; S. Hild; F. Kawazoe; O. Kranz; G. Kühn; H. Lück; K. Mossavi; R. Schnabel; K. Somiya; K. A. Strain; J. R. Taylor; A. Wanner; T. Westphal; B. Willke; K. Danzmann

2010-01-01

335

Scanning force microscope using point diffraction interferometer  

NASA Astrophysics Data System (ADS)

A new optical interferometer suitable for the scanning force microscope is presented in this paper. The cantilever itself is used as a micro interferometer element. The deflection of the cantilever is detected by the interference between the geometrical reflected wave and the backward diffracted wave. This interferometer has a very simple structure, fewer optical components, lower cost, and complete common light path. 0.01 nm vertical resolution is gotten by this instrument.

Mou, Xu-Dong; You, Yifeng; Zhuo, Yong-Mo; Yang, Yong-Ying; Xu, Ming

1998-06-01

336

Holographic visualization of laser-induced plume in pulsed laser welding  

Microsoft Academic Search

High-speed holographic interferometry was applied to the experimental study of a laser-induced plasma plume in pulsed laser welding. We adopted two kinds of holographic interferometers for visualizing and imaging the refractive index distribution of the plume and vaporized metal; a real-time holographic interferometer with a high-speed camera and a double-pulsed holographic interferometer with a dual-reference-beam module. The high-speed photographs of

Sung-Hoon Baik; Seung-Kyu Park; Cheol-Jung Kim; Soo-Yong Kim

2001-01-01

337

Visible light interferometer for EUVL system alignment  

NASA Astrophysics Data System (ADS)

A visible wavelength interferometer has been developed for the alignment of an extreme ultraviolet lithography (EUVL) camera. Although the EUVL camera will operate at 13.4 nm, the alignment is far more conveniently done at visible wavelengths, at ambient pressure. Traditional visible interferometers are not capable of reaching the better than 1 nm accuracy required for EUVL camera alignment; so a phase shifting diffraction-limited interferometer was constructed and used to align and quantify the EUVL wavefront to an accuracy better than (lambda) visible/2000. The interferometer and alignment process are described, and camera wavefront measurements presented.

Gaughan, Richard J.

1999-11-01

338

Stable single-photon interference in a 1 km fiber-optic Mach-Zehnder interferometer with continuous phase adjustment  

Microsoft Academic Search

We experimentally demonstrate stable and user-adjustable single-photon interference in a 1 km long fiber- optical Mach-Zehnder interferometer, using an active phase control system with the feedback provided by a classical laser. We are able to continuously tune the single-photon phase difference between the interferometer arms using a phase modulator, which is synchronized with the gate window of the single-photon detectors.

G. B. Xavier; J. P. von der Weid

2011-01-01

339

Instrument-Based Noncontact Doppler Radar Vital Sign Detection System Using Heterodyne Digital Quadrature Demodulation Architecture  

Microsoft Academic Search

In this paper, we present a fast solution to build a Doppler radar system for noncontact vital sign detection (VSD) using instruments that are generally equipped in radio-frequency and communication laboratories. This paper demonstrates the feasibility of conducting research on VSD in ordinary radio-frequency laboratories. The system is designed with a heterodyne digital quadrature demodulation architecture that helps mitigate quadrature

Changzhan Gu; Changzhi Li; Jenshan Lin; Jiang Long; Jiangtao Huangfu; Lixin Ran

2010-01-01

340

Voltage Synthesis Using Dual Virtual Quadrature Sources - A New Concept in AC Power Conversion  

Microsoft Academic Search

Dynamic control of amplitude and phase of AC line voltage will allow node voltage and branch current in meshed systems. This has traditionally required the use of inverters with energy storage, and\\/or AC\\/AC converters with multiple phases. This paper presents a novel concept wherein dual virtual quadrature sources are used to synthesize both a direct and quadrature component of the

Deepak Divan; Jyoti Sastry

2007-01-01

341

A Family of Exponential Fitting Direct Quadrature Methods for Volterra Integral Equations  

NASA Astrophysics Data System (ADS)

A new class of direct quadrature methods for the solution of Volterra Integral Equations with periodic solution is illustrated. Such methods are based on an exponential fitting gaussian quadrature formula, whose coefficients depend on the problem parameters, in order to better reproduce the behavior the analytical solution. The construction of the methods is described, together with the analysis of the order of accuracy.

Cardone, A.; Ferro, M.; Ixaru, L. Gr.; Paternoster, B.

2010-09-01

342

An IMT-type quadrature formula with the same asymptotic performance as the DE formula  

NASA Astrophysics Data System (ADS)

We propose an IMT-type quadrature formula which achieves the same asymptotic error estimate as the DE formula. The point of the idea is to optimize the parameters of the IMT-type transformation depending on the number of sampling points. We also show the performance of our IMT-type quadrature formula by numerical examples.

Ooura, Takuya

2008-03-01

343

General n-dimensional quadrature transform and its application to interferogram demodulation.  

PubMed

Quadrature operators are useful for obtaining the modulating phase phi in interferometry and temporal signals in electrical communications. In carrier-frequency interferometry and electrical communications, one uses the Hilbert transform to obtain the quadrature of the signal. In these cases the Hilbert transform gives the desired quadrature because the modulating phase is monotonically increasing. We propose an n-dimensional quadrature operator that transforms cos(phi) into -sin(phi) regardless of the frequency spectrum of the signal. With the quadrature of the phase-modulated signal, one can easily calculate the value of phi over all the domain of interest. Our quadrature operator is composed of two n-dimensional vector fields: One is related to the gradient of the image normalized with respect to local frequency magnitude, and the other is related to the sign of the local frequency of the signal. The inner product of these two vector fields gives us the desired quadrature signal. This quadrature operator is derived in the image space by use of differential vector calculus and in the frequency domain by use of a n-dimensional generalization of the Hilbert transform. A robust numerical algorithm is given to find the modulating phase of two-dimensional single-image closed-fringe interferograms by use of the ideas put forward. PMID:12747439

Servin, Manuel; Quiroga, Juan Antonio; Marroquin, Jose Luis

2003-05-01

344

Polynomial and harmonic differential quadrature methods for free vibration of variable thickness thick skew plates  

Microsoft Academic Search

An examination of the accuracy and convergence behaviors of polynomial basis function differential quadrature (PDQ) and harmonic basis function differential quadrature (HDQ) for free vibration analysis of variable thickness thick skew plates will be carried out. The plate governing equations are based on the first-order shear deformation theory including the effects of rotary inertia. Arbitrary thickness variations will be assumed

P. Malekzadeh; G. Karami

2005-01-01

345

Arctangent Demodulation With DC Offset Compensation in Quadrature Doppler Radar Receiver Systems  

Microsoft Academic Search

Direct-conversion microwave Doppler radar can be used to detect cardiopulmonary activity at a distance. One challenge for such detection in single channel receivers is demodulation sensitivity to target position, which can be overcome by using a quadrature receiver. This paper presents a mathematical analysis and experimental results demonstrating the effectiveness of arctangent demodulation in quadrature receivers. A particular challenge in

Byung-Kwon Park; Olga Boric-Lubecke; Victor M. Lubecke

2007-01-01

346

Modeling of Transmission Lines with EM Wave Coupling by Finite Difference Quadrature Methods  

Microsoft Academic Search

This paper proposes an efficient numerical approxi- mation technique, called the Finite Difference Quadrature (FDQ) Method, which has been adapted to model transmission lines (TL's) with external EM wave coupling. The finite difference quadrature method can quickly compute finite differences be- tween adjacent grid points by estimating a weighted linear sum of derivatives at a set of points belonging to

Qinwei Xu; Pinaki Mazumder

347

General n-dimensional quadrature transform and its application to interferogram demodulation  

NASA Astrophysics Data System (ADS)

Quadrature operators are useful for obtaining the modulating phase ? in interferometry and temporal signals in electrical communications. In carrier-frequency interferometry and electrical communications, one uses the Hilbert transform to obtain the quadrature of the signal. In these cases the Hilbert transform gives the desired quadrature because the modulating phase is monotonically increasing. We propose an n-dimensional quadrature operator that transforms cos(f) into -sin(f) regardless of the frequency spectrum of the signal. With the quadrature of the phase-modulated signal, one can easily calculate the value of f over all the domain of interest. Our quadrature operator is composed of two n-dimensional vector fields: One is related to the gradient of the image normalized with respect to local frequency magnitude, and the other is related to the sign of the local frequency of the signal. The inner product of these two vector fields gives us the desired quadrature signal. This quadrature operator is derived in the image space by use of differential vector calculus and in the frequency domain by use of a n-dimensional generalization of the Hilbert transform. A robust numerical algorithm is given to find the modulating phase of two-dimensional single-image closed-fringe interferograms by use of the ideas put forward.

Servin, Manuel; Quiroga, Juan Antonio; Marroquin, Jose Luis

2003-05-01

348

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

ERIC Educational Resources Information Center

|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…

Rudmin, J. W.; And Others

1980-01-01

349

Monitoring bending motions of piezoceramic plates with homodyne interferometer based on adaptive photodetectors  

Microsoft Academic Search

We report on simple high-sensitivity interferometric technique of detecting vibrations of piezoceramic plates using adaptive photodetectors. It enables efficient direct conversion of high-frequency phase modulation of speckle-like optical wave reflected from vibrating plate into an output electrical signal with concomitant setting of optimal operation point of the interferometer and suppression of amplitude laser noise.

Igor A. Sokolov; Victor V. Khorenko; Sergei I. Stepanov

1994-01-01

350

Optical acoustic detector based on a fiber Fabry-Perot interferometer.  

PubMed

We describe a novel optical acoustic detector based on a bias-controlled fiber Fabry-Perot interferometer. The detector has a broad bandwidth from 10 Mhz to a few gigahertz and higher sensitivity than conventional systems, which are useful for noncontact characterization of microsamples based on laser ultrasound. PMID:15726943

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

2005-02-01

351

Note: Higher resolution Brillouin spectroscopy by offset stabilization of a tandem Fabry-Pérot interferometer.  

PubMed

A simple modification to a Sandercock-type tandem Fabry-Pérot interferometer is demonstrated. By adding an independent reference laser with temperature tunability, narrow Brillouin lines that are tens GHz shifted from the Rayleigh line can be recorded with much higher frequency resolution than in the original system. PMID:22225258

Koreeda, Akitoshi; Saikan, Seishiro

2011-12-01

352

Note: Higher resolution Brillouin spectroscopy by offset stabilization of a tandem Fabry-Pérot interferometer  

NASA Astrophysics Data System (ADS)

A simple modification to a Sandercock-type tandem Fabry-Pérot interferometer is demonstrated. By adding an independent reference laser with temperature tunability, narrow Brillouin lines that are tens GHz shifted from the Rayleigh line can be recorded with much higher frequency resolution than in the original system.

Koreeda, Akitoshi; Saikan, Seishiro

2011-12-01

353

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

Microsoft Academic Search

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.

Alvarado Tarun; Julius Jecong; Caesar Saloma

2005-01-01

354

Optical zooming interferometer for subnanometer positioning using an optical frequency comb  

SciTech Connect

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.

Kajima, Mariko; Minoshima, Kaoru

2010-10-20

355

Quantum noise in optical interferometers  

SciTech Connect

We study the photon counting noise in optical interferometers used for gravitational wave detection. In order to reduce quantum noise, a squeezed vacuum is injected into the usually unused input port. It is investigated under which conditions the gravitational wave signal may be amplified without increasing counting noise concurrently. Such a possibility was suggested as a consequence of the entanglement of the two output ports of a beam splitter. We find that amplification without concurrent increase of noise is not possible for reasonable squeezing parameters. Photon distributions for various beam splitter angles and squeezing parameters are calculated.

Voronov, Volodymyr G.; Weyrauch, Michael [Faculty of Physics, Taras Shevchenko National University of Kyiv, 03022 Kyiv (Ukraine); Physikalisch-Technische Bundesanstalt, D-38116 Braunschweig (Germany)

2010-05-15

356

A multipulsed dynamic moire interferometer  

DOEpatents

An improved dynamic moire interferometer is described that is comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event. 5 figs.

Deason, V.A.

1989-06-10

357

Optical accelerometer based on grating interferometer with phase modulation technique.  

PubMed

In this paper, an optical accelerometer based on grating interferometer with phase modulation technique is proposed. This device architecture consists of a laser diode, a sensing chip and an optoelectronic processing circuit. The sensing chip is a sandwich structure, which is composed of a grating, a piezoelectric translator and a micromachined silicon structure consisting of a proof mass and four cantilevers. The detected signal is intensity-modulated with phase modulation technique and processed with a lock-in amplifier for demodulation. Experimental results show that this optical accelerometer has acceleration sensitivity of 619 V/g and high-resolution acceleration detection of 3 ?g in the linear region. PMID:23052079

Zhao, Shuangshuang; Zhang, Juan; Hou, Changlun; Bai, Jian; Yang, Guoguang

2012-10-10

358

Hand held phase-shifting diffraction moire interferometer  

DOEpatents

An interferometer in which a coherent beam of light is generated within a remote case and transmitted to a hand held unit tethered to said remote case, said hand held unit having optical elements for directing a pair of mutually coherent collimated laser beams at a diffraction grating. Data from the secondary or diffracted beams are then transmitted to a separate video and data acquisition system for recording and analysis for load induced deformation or for identification purposes. Means are also provided for shifting the phase of one incident beam relative to the other incident beam and being controlled from within said remote case.

Deason, Vance A. (Idaho Falls, ID); Ward, Michael B. (Idaho Falls, ID)

1994-01-01

359

Hand held phase-shifting diffraction Moire interferometer  

DOEpatents

An interferometer is described in which a coherent beam of light is generated within a remote case and transmitted to a hand held unit tethered to said remote case, said hand held unit having optical elements for directing a pair of mutually coherent collimated laser beams at a diffraction grating. Data from the secondary or diffracted beams are then transmitted to a separate video and data acquisition system for recording and analysis for load induced deformation or for identification purposes. Means are also provided for shifting the phase of one incident beam relative to the other incident beam and being controlled from within said remote case. 4 figs.

Deason, V.A.; Ward, M.B.

1994-09-20

360

An overview of the Keck Interferometer Nuller  

Microsoft Academic Search

The first high dynamic range interferometry mode planned to come on line at the Keck Observatory is mid-infrared nulling interferometry. In this paper, an overview is given of the goals and experimental configuration of the Keck Interferometer Nuller (KIN). After an introduction to the science enabled by mid-infrared nulling interferometry on the Keck Interferometer's baseline, a system level overview of

Eugen Serabyn

2003-01-01

361

The measuring element of a superconducting interferometer  

Microsoft Academic Search

The main component of a superconducting quantum interferometer (SQUID) is the superconducting ring with weak links. The size of the contact forming the weak link is so small (not exceeding 1000 A) that sufficient mechanical rigidity is required when constructing an interferometer in which a point contact is used between bulk superconductors. The design of a SQUID element is described

M. S. Legkostupov

1976-01-01

362

CIST....CORRTEX interferometer simulation test  

SciTech Connect

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.

Heinle, R.A.

1994-12-01

363

Feedback sharpening of Josephson interferometer switching characteristics  

SciTech Connect

Transfer characteristics of Josephson interferometers made with nonhysteretic junctions can be improved using positive feedback. Numerical calculations show that an interferometer's continuous current transfer characteristic can be sharpened to a step function by sending some of the output current back through a control current path. Logic circuits using feedback should have fairly wide operating margins. In some configurations parallel fanout is possible.

Howard, R.E.; Jackel, L.D.; Epworth, R.W.

1980-11-01

364

Dual-prism interferometer for collimation testing  

SciTech Connect

An air-wedge lateral-shear interferometer using two prisms is presented. With a variable shear, the interferometer is suitable for testing collimation of a wide range of beam sizes down to a few millimeters in diameter. No antireflection coatings are necessary. Collimation for a light source with short coherent length is also demonstrated.

Hii, King Ung; Kwek, Kuan Hiang

2009-01-10

365

Rotation Sensing with an Atom Interferometer  

Microsoft Academic Search

We have measured the phase shift induced by rotation of an atom interferometer at rates of -2 to +2 earth rates and obtained 1% agreement with the predicted Sagnac phase shift for atomic matter waves. The rotational rms noise of our interferometer was 42 milliearth rates for 1 sec of integration time, within 9% of shot noise. The high sensitivity

Alan Lenef; Troy D. Hammond; Edward T. Smith; Michael S. Chapman; Richard A. Rubenstein; David E. Pritchard

1997-01-01

366

Orientational atom interferometers sensitive to gravitational waves  

SciTech Connect

We present an atom interferometer that differs from common atom interferometers as it is not based on the spatial splitting of electronic wave functions, but on orienting atoms in space. As an example we present how an orientational atom interferometer based on highly charged hydrogen-like atoms is affected by gravitational waves. We show that a monochromatic gravitational wave will cause a frequency shift that scales with the binding energy of the system rather than with its physical dimension. For a gravitational wave amplitude of h=10{sup -23} the frequency shift is of the order of 110 {mu}Hz for an atom interferometer based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current atom interferometers in 1 s.

Lorek, Dennis; Laemmerzahl, Claus; Wicht, Andreas [Center of Applied Space Technology and Microgravity, University of Bremen, Am Fallturm, D-28359 Bremen (Germany); Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, D-12489 Berlin (Germany); Humboldt-Universitaet zu Berlin, Institut fuer Physik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

2010-02-15

367

Lasers in Machine Tool Controls.  

National Technical Information Service (NTIS)

A system is described for measuring those parameters which determine the dynamic characteristics of a numerically controlled machine; and, a system to correct for those errors. Both systems utilize a laser interferometer as the measurement transducer. The...

R. R. Burleson

1979-01-01

368

Quadrature uncertainty and information entropy of quantum elliptical vortex states  

NASA Astrophysics Data System (ADS)

We study the quadrature uncertainty of the quantum elliptical vortex state using the associated Wigner function. Deviations from the minimum uncertainty states were observed due to the absence of Gaussianity. We further observed that there exists an optimum value of ellipticity which gives rise to the maximum entanglement of the two modes of the quantum elliptical vortex states. In our study of entropy, we noticed that with increasing vorticity, entropy increases for both the modes. A further increase in ellipticity reduces the entropy thereby resulting in a loss of information carrying capacity. We check the validity of the entropic inequality relations, namely the subaddivity and the Araki-Lieb inequality. The latter was satisfied only for a very small range of the ellipticity of the vortex, while the former seemed to be valid at all values.

Banerji, Anindya; Panigrahi, Prasanta K.; Pratap Singh, Ravindra; Chowdhury, Saurav; Bandyopadhyay, Abir

2013-06-01

369

Exact quantum correlations of conjugate variables from joint quadrature measurements  

NASA Astrophysics Data System (ADS)

We demonstrate that for two canonically conjugate operators qˆ, pˆ, the global correlation -2, and the local correlations (p)- and (q)- can be measured exactly by Von Neumann-Arthurs-Kelly joint quadrature measurements. Here (q) and (p) denote the conditional expectation values of momentum at a given position, and position at a given momentum respectively. These correlations provide a sensitive experimental test of quantum phase space probabilities quite distinct from the probability densities of q, p. E.g. for EPR states, and entangled generalized coherent states, phase space probabilities which reproduce the correct position and momentum probability densities have to be modified to reproduce these correlations as well.

Roy, S. M.

2013-11-01

370

Relations between bosonic quadrature squeezing and atomic spin squeezing  

SciTech Connect

We study relations between bosonic quadrature squeezing and atomic spin squeezing, and find that the latter reduces to the former in the limit of a large number of atoms for even and odd states. We demonstrate this reduction by treating even and odd spin coherent states, for which analytical solutions are readily obtained, and prove that even spin coherent states always exhibit spin squeezing, whereas odd spin coherent states do not, analogous to the squeezing characteristic of even and odd bosonic coherent states. Finally, we examine the squeezing transfer between photons and atoms via the Dicke Hamiltonian, where a perfect transfer of squeezing is demonstrated in the limit of a large number of atoms.

Wang, Xiaoguang [Department of Physics and Australian Centre of Excellence for Quantum Computer Technology, Macquarie University, Sydney, New South Wales 2109, (Australia); Department of Physics and Center for Nonlinear Studies, Hong Kong Baptist University, Hong Kong, (China); Sanders, Barry C. [Department of Physics and Australian Centre of Excellence for Quantum Computer Technology, Macquarie University, Sydney, New South Wales 2109, (Australia); Quantum Information Science Group, Department of Physics and Astronomy, University of Calgary, Alberta, Canada T2N 1N4 (Canada)

2003-09-01

371

Extreme Ultraviolet Interferometer Using High-Order Harmonic Generation from Successive Sources  

NASA Astrophysics Data System (ADS)

We present a new interferometer technique whereby multiple extreme ultraviolet light pulses are generated at different positions within a single laser focus (i.e., from successive sources) with a highly controllable time delay. The interferometer technique is tested with two generating media to create two extreme ultraviolet light pulses with a time delay between them. The delay is found to be a consequence of the Gouy phase shift. Ultimately the apparatus is capable of accessing unprecedented time scales by allowing stable and repeatable delays as small as 100 zs.

Laban, D. E.; Palmer, A. J.; Wallace, W. C.; Gaffney, N. S.; Notermans, R. P. M. J. W.; Clevis, T. T. J.; Pullen, M. G.; Jiang, D.; Quiney, H. M.; Litvinyuk, I. V.; Kielpinski, D.; Sang, R. T.

2012-12-01

372

Extreme ultraviolet interferometer using high-order harmonic generation from successive sources.  

PubMed

We present a new interferometer technique whereby multiple extreme ultraviolet light pulses are generated at different positions within a single laser focus (i.e., from successive sources) with a highly controllable time delay. The interferometer technique is tested with two generating media to create two extreme ultraviolet light pulses with a time delay between them. The delay is found to be a consequence of the Gouy phase shift. Ultimately the apparatus is capable of accessing unprecedented time scales by allowing stable and repeatable delays as small as 100 zs. PMID:23368563

Laban, D E; Palmer, A J; Wallace, W C; Gaffney, N S; Notermans, R P M J W; Clevis, T T J; Pullen, M G; Jiang, D; Quiney, H M; Litvinyuk, I V; Kielpinski, D; Sang, R T

2012-12-26

373

A first study of environmental noise coupling to the Virgo interferometer  

NASA Astrophysics Data System (ADS)

During the commissioning of the Virgo interferometer, a search for environmental noise contributions to the dark fringe signal was undertaken. Dedicated tests have been performed to identify major sources of disturbances and to understand the coupling mechanism with the interferometer. The major effect is due to seismic/acoustic noise coupling to the laser beam before the input mode cleaner, then propagating as beam power noise to the ITF dark fringe output signal. In this paper we illustrate the tests performed and preliminary results of our investigation. Presented by I Fiori for the Virgo Collaboration.

Acernese, F.; Amico, P.; Al-Shourbagy, M.; Aoudia, S.; Avino, S.; Babusci, D.; Ballardin, G.; Barillé, R.; Barone, F.; Barsotti, L.; Barsuglia, M.; Beauville, F.; Bizouard, M. A.; Boccara, C.; Bondu, F.; Bosi, L.; Bradaschia, C.; Braccini, S.; Brillet, A.; Brisson, V.; Brocco, L.; Buskulic, D.; Calloni, E.; Campagna, E.; Cavalier, F.; Cavalieri, R.; Cella, G.; Chassande-Mottin, E.; Corda, C.; Clapson, A. C.; Cleva, F.; Coulon, J. P.; Cuoco, E.; Dattilo, V.; Davier, M.; De Rosa, R.; Di Fiore, L.; Di Virgilio, A.; Dujardin, B.; Eleuteri, A.; Enard, D.; Ferrante, I.; Fidecaro, F.; Fiori, I.; Flaminio, R.; Fournier, J. D.; Frasca, S.; Frasconi, F.; Freise, A.; Gammaitoni, L.; Gennai, A.; Giazotto, A.; Giordano, G.; Giordano, L.; Gouaty, R.; Grosjean, D.; Guidi, G.; Hebri, S.; Heitmann, H.; Hello, P.; Holloway, L.; Kreckelbergh, S.; La Penna, P.; Loriette, V.; Loupias, M.; Losurdo, G.; Mackowski, J. M.; Majorana, E.; Man, C. N.; Mantovani, M.; Marchesoni, F.; Marion, F.; Marque, J.; Martelli, F.; Masserot, A.; Mazzoni, M.; Milano, L.; Moins, C.; Moreau, J.; Morgado, N.; Mours, B.; Pai, A.; Palomba, C.; Paoletti, F.; Pardi, S.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Perniola, B.; Piergiovanni, F.; Pinard, L.; Poggiani, R.; Punturo, M.; Puppo, P.; Qipiani, K.; Rapagnani, P.; Reita, V.; Remillieux, A.; Ricci, F.; Ricciardi, I.; Ruggi, P.; Russo, G.; Solimeno, S.; Spallicci, A.; Stanga, R.; Taddei, R.; Tombolato, D.; Tonelli, M.; Toncelli, A.; Tournefier, E.; Travasso, F.; Vajente, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Vinet, J. Y.; Vocca, H.; Yvert, M.; Zhang, Z.

2005-09-01

374

Increase in the amplitude of a saturated absorption resonance in an active interferometer  

SciTech Connect

The behaviour of the amplitude of a saturated absorption resonance observed in laser radiation propagated through an active interferometer with nonlinear amplifying and absorbing media is studied experimentally for the first time. Upon variation of the gain in the amplifying medium and preserving a constant saturating field in the interferometer, a nonlinear increase in the amplitude of the saturated absorption resonance was observed. In this case, an increase in the detected signal exceeded an increase in the noise, i.e., the signal-to-noise ratio also increased. (nonlinear optical phenomena)

Primakov, D Yu; Pokasov, P V; Bagaev, Sergei N [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2005-02-28

375

Impact of anomalous dispersion on the interferometer measurements of plasmas  

SciTech Connect

For many decades optical interferometers have been used to measure the electron density of plasmas. During the last ten years X-ray lasers in the wavelength range 14 to 47 nm have enabled researchers to use interferometers to probe even higher density plasmas. The data analysis assumes that the index of refraction is due only to the free electrons, which makes the index of refraction less than one and the electron density proportional to the number of fringe shifts. Recent experiments in Al plasmas observed plasmas with an index of refraction greater than one and made us question the validity of the usual formula for calculating the index of refraction. Recent calculations showed how the anomalous dispersion from the bound electrons can dominate the index of refraction in many types of plasma and make the index greater than one or enhance the index such that one would greatly overestimate the electron density of the plasma using interferometers. In this work we calculate the index of refraction of C, Al, Ti, and Pd plasmas for photon energies from 0 to 100 eV (12.4 nm) using a new average-atom code. The results show large variations from the free electron approximation under many different plasma conditions. We validate the average-atom code against the more detailed OPAL code for carbon and aluminum plasmas. During the next decade X-ray free electron lasers and other sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential.

Nilsen, J; Johnson, W R; Iglesias, C A; Scofield, J H

2004-12-16

376

Solving the vibrational Schrödinger equation using bases pruned to include strongly coupled functions and compatible quadratures  

NASA Astrophysics Data System (ADS)

In this paper, we present new basis pruning schemes and compatible quadrature grids for solving the vibrational Schrödinger equation. The new basis is designed to include the product basis functions coupled by the largest terms in the potential and important for computing low-lying vibrational levels. To solve the vibrational Schrödinger equation without approximating the potential, one must use quadrature to compute potential matrix elements. For a molecule with more than five atoms, the use of iterative methods is imperative, due to the size of the basis and the quadrature grid. When using iterative methods in conjunction with quadrature, it is important to evaluate matrix-vector products by doing sums sequentially. This is only possible if both the basis and the grid have structure. Although it is designed to include only functions coupled by the largest terms in the potential, the new basis and also the quadrature for doing integrals with the basis have enough structure to make efficient matrix-vector products possible. When results obtained with a multimode approximation to the potential are accurate enough, full-dimensional quadrature is not necessary. Using the quadrature methods of this paper, we evaluate the accuracy of calculations made by making multimode approximations.

Avila, Gustavo; Carrington, Tucker

2012-11-01

377

Beam shuttering interferometer and method  

DOEpatents

A method and apparatus resulting in the simplification of phase shifting interferometry by eliminating the requirement to know the phase shift between interferograms or to keep the phase shift between interferograms constant. The present invention provides a simple, inexpensive means to shutter each independent beam of the interferometer in order to facilitate the data acquisition requirements for optical interferometry and phase shifting interferometry. By eliminating the requirement to know the phase shift between interferograms or to keep the phase shift constant, a simple, economical means and apparatus for performing the technique of phase shifting interferometry is provide which, by thermally expanding a fiber optical cable changes the optical path distance of one incident beam relative to another.

Deason, Vance A. (Idaho Falls, ID); Lassahn, Gordon D. (Idaho Falls, ID)

1993-01-01

378

Beam shuttering interferometer and method  

DOEpatents

A method and apparatus resulting in the simplification of phase shifting interferometry by eliminating the requirement to know the phase shift between interferograms or to keep the phase shift between interferograms constant. The present invention provides a simple, inexpensive means to shutter each independent beam of the interferometer in order to facilitate the data acquisition requirements for optical interferometry and phase shifting interferometry. By eliminating the requirement to know the phase shift between interferograms or to keep the phase shift constant, a simple, economical means and apparatus for performing the technique of phase shifting interferometry is provide which, by thermally expanding a fiber optical cable changes the optical path distance of one incident beam relative to another.

Deason, V.A.; Lassahn, G.D.

1993-07-27

379

A laser siderostat  

NASA Astrophysics Data System (ADS)

The Mark III Astrometric Interferometer is an instrument designed to improve on our ability to measure angular positions of stars by more than an order of magnitude. The instrument makes extensive use of active optics, digital signal processing and control, and laser metrology. This report describes the efforts of the first year of a four-year program to build the Mark III interferometer, as well as obstacles to technical progress due to Navy administrative procedures.

Shao, M.

1985-06-01

380

Universal quadratures for boundary integral equations on two-dimensional domains with corners  

NASA Astrophysics Data System (ADS)

We describe the construction of a collection of quadrature formulae suitable for the efficient discretization of certain boundary integral equations on a very general class of two-dimensional domains with corner points. The resulting quadrature rules allow for the rapid high-accuracy solution of Dirichlet boundary value problems for Laplace’s equation and the Helmholtz equation on such domains under a mild assumption on the boundary data. Our approach can be adapted to other boundary value problems and certain aspects of our scheme generalize to the case of surfaces with singularities in three dimensions. The performance of the quadrature rules is illustrated with several numerical examples.

Bremer, James; Rokhlin, Vladimir; Sammis, Ian

2010-11-01

381

Sensitivity of the Lanczos recurrence to Gaussian quadrature data: How malignant can small weights be?  

NASA Astrophysics Data System (ADS)

Stability of passing from Gaussian quadrature data to the Lanczos recurrence coefficients is considered. Special attention is paid to estimates explicitly expressed in terms of quadrature data and not having weights in denominators. It has been shown that the recent approach, exploiting integral representation of Hankel determinants, implies quantitative improvement of D. Laurie's constructive estimate. It has also been demonstrated that a particular implementation on the Hankel determinant approach gives an estimate being unimprovable up to a coefficient; the corresponding example involves quadrature data with a small but not too small weight. It follows that polynomial increase of a general case upper bound in terms of the dimension is unavoidable.

Knizhnerman, Leonid

2010-01-01

382

Admissible Crosstalk Limits in a Two Colour Interferometers for Plasma Density Diagnostics. A Reduction Algorithm  

SciTech Connect

Mid Infrared (10,6 {mu}m CO{sub 2} laser lines) interferometers as a plasma density diagnostic must use two-colour systems with superposed interferometers beams at different wavelengths in order to cope with mechanical vibrations and drifts. They require a highly precise phase difference measurement where all sources of error must be reduced. One of these is the cross-talk between the signals which creates nonlinear spurious periodic mixing products. The reason may be either optical or electrical crosstalk both resulting in similar perturbations of the measurement. In the TJII interferometer a post-processing algorithm is used to reduce the crosstalk in the data. This post-processing procedure is not appropriate for very long pulses, as it is the case for in new tokamak (ITER) or stellarator (W7-X) projects. In both cases an on-line reduction process is required or--even better--the unwanted signal components must be reduced in the system itself CO{sub 2} laser interferometers which as the second wavelength use the CO laser line (5,3 {mu}m), may apply a single common detector sensitive to both wavelengths and separate the corresponding IF signals by appropriate bandpass filters. This reduces complexity of the optical arrangement and avoids a possible source of vibration induced phase noise as both signals share the same beam path. To avoid cross talk in this arrangement filtering must be appropriate. In this paper we present calculations to define the limits of crosstalk for a desired plasma density precision. A crosstalk reduction algorithm has been developed and is applied to experimental results from TJ-II pulses. Results from a single detector arrangement as under investigation for the CO{sub 2}/CO laser interferometer developed for W7-X are presented.

Sanchez, M.; Esteban, L. [Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, E-28040 Madrid (Spain); Kornejew, P.; Hirsch, M. [Max-Planck-Institut fuer Plasmaphysik, TB Physik, Wendelsteinstr. 1, G-17491 Greifswald (Germany)

2008-03-19

383

Classes and configurations of atom interferometers  

SciTech Connect

We establish the fundamental properties of two classes of interferometers: those forming a pattern in momentum space, based on the superposition of two different momentum states and described by their relative propagation, and those forming a pattern in real space, based on two or more interferometer arms and described by the propagation between their local ends. These two classes are characterized by different sensitivity functions and different noise sources; we will compare the sensitivity functions of two possible configurations of atom interferometer and identify the most promising realization, with a view to applications to tests of general relativity and investigations of alterations of the spacetime curvature.

D'Ambrosio, Erika [Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, Via Bruno Rossi 1/3-50019 Sesto Fiorentino (Italy)

2009-02-15

384

X-ray Interferometer Using Prism Optics  

NASA Astrophysics Data System (ADS)

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.

Suzuki, Yoshio

2004-05-01

385

X-ray Interferometer Using Prism Optics  

SciTech Connect

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.

Suzuki, Yoshio [JASRI/SPring-8 Mikazuki, Hyogo 6791-5198 (Japan)

2004-05-12

386

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

SciTech Connect

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.

Tarun, Alvarado; Jecong, Julius; Saloma, Caesar

2005-12-01

387

Lasers.  

National Technical Information Service (NTIS)

The optical laser was first developed in 1960. Among the first medical applications for lasers was the dermatologic application of this Ruby laser in 1964. Since that time, the application of lasers in medical and surgical uses has grown quite extensively...

J. A. Werkhaven R. H. Ossoff D. Harris

1991-01-01

388

Recent applications and advances in laser manipulation of atoms  

Microsoft Academic Search

A series of experiments which owe their existence to advances in laser cooling and trapping of atoms will be presented. Emphasis will be given to the demonstration of an interferometer for atoms using laser cooled sodium atoms and the mechanical effects of velocity sensitive stimulated Raman transitions. This interferometer, configured as an accelerometer, was used to measure the acceleration due

Kasevich

1993-01-01

389

Composite low-coherence interferometer for imaging of immersed tissue with high accuracy  

NASA Astrophysics Data System (ADS)

Imaging and measurement of the surface profile of an object with high resolution has become essential in both of biological research and industry application. Many samples under investigation such as cultured cells are usually immersed in liquid. Although the techniques such as scanning electron microscope and atomic force microscope can provide imaging or measurement of the surface profile with nanometer resolution, it is difficult for them to image an immersed object with their typical types. Recently, we have proposed and demonstrated a new technique based on composite interferometer which can perform imaging and measurement of the surface profile of an object with accuracy in the axial direction within 5 nm through a self-phase-compensation mechanism. In this research, an optical system based on the concept of combination of optical coherence microscopy (OCM) and composite interferometer was built for imaging of biological tissue immersed in water with axial accuracy at nanometer scale. In the system, a Ti:sapphire laser with center wavelength at 800 nm and spectral width of 140 nm was used as the light source. The composite interferometer comprises two Michelson interferometers sharing common light source, reference arm and photodetector. One of the two interferometers served as a typical OCM system and the other was used to measure the phase shift in the reference arm in each axial scan with the sample being a fixed reflection mirror. The system was used to image the surface profiles of various immersed biological samples with accuracy at nanometer scale through the self-phasecompensation mechanism.

Chang, Chun-Wei; Hsu, I.-Jen

2012-09-01

390

Corner cube reflector lateral displacement evaluation simultaneously with interferometer length measurement  

NASA Astrophysics Data System (ADS)

The novel corner cube reflector (CCR) system for a distance measuring interferometer is presented. The proposed system allows reflector lateral displacement evaluation (relative to the beam axis) simultaneously with the interferometer length measurement. Laser beam in measuring arm of the interferometer is divided into two parallel beams that are used for the interferometer distance measurement and lateral shifts of the assembly in relation to the beam axis.The CCR assembly is based on applying a position sensitive detector placed behind the CCR that has truncated vertex. Due to the proposed configuration of the cube corner and photodetector, the rotations of the CCR assembly does not cause error in the lateral displacement measurement in relation to the beam axis.The theoretical analysis and experimental verification of the system metrological feasibilities are presented. The general limitations and design problems are shown. The proposed system can be used basically for measurement and compensation of global or local cosine errors especially in short range of the interferometer displacement measurement, where known techniques are ineffective. Possible applications of the system for Coordinate Measuring Machines accuracy testing are indicated.

Zamiela, Grzegorz; Dobosz, Marek

2013-09-01

391

Differential Phase Mode with the Keck Interferometer.  

National Technical Information Service (NTIS)

We describe the differential phase mode of the Keck Interferometer. The scientific goal of this mode is the direct detection and spectroscopic characterization of hot, Jupiter mass planets. We describe the differential phase effect, the basic observationa...

R. Akeson M. Swain

2000-01-01

392

On numerical integration with high-order quadratures: with application to the Rayleigh-Sommerfeld integral  

NASA Astrophysics Data System (ADS)

The paper focusses on the advantages of using high-order Gauss-Legendre quadratures for the precise evaluation of integrals with both smooth and rapidly changing integrands. Aspects of their precision are analysed in the light of Gauss' error formula. Some "test examples" are considered and evaluated in multiple precision to ? 200 significant decimal digits with David Bailey's multiprecision package to eliminate truncation/rounding errors. The increase of precision on doubling the number of subintervals is analysed, the relevant quadrature attribute being the precision increment. In order to exemplify the advantages that high-order quadrature afford, the technique is then used to evaluate several plots of the Rayleigh-Sommerfeld diffraction integral for axi-symmetric source fields defined on a planar aperture. A comparison of the high-order quadrature method against various FFT-based methods is finally given.

Evans, W. A. B.; Torre, A.

2012-11-01

393

Quantum-mechanical noise in an interferometer  

Microsoft Academic Search

The interferometers now being developed to detect gravitational waves work by measuring the relative positions of widely separated masses. Two fundamental sources of quantum-mechanical noise determine the sensitivity of such an interferometer: (i) fluctuations in number of output photons (photon-counting error) and (ii) fluctuations in radiation pressure on the masses (radiation-pressure error). Because of the low power of available continuous-wave

Carlton Caves

1981-01-01

394

Continuous phase amplification with a Sagnac interferometer  

SciTech Connect

We describe a phase-amplification technique using a Sagnac interferometer. We monitor the relative phase between two paths of a precisely misaligned interferometer by measuring the average position of a split-Gaussian mode in the dark port. Although we monitor only the dark port, we show that the signal varies linearly with phase and that we can obtain similar sensitivity to balanced homodyne detection. We derive the source of the amplification using classical wave optics.

Starling, David J.; Dixon, P. Ben; Williams, Nathan S.; Jordan, Andrew N.; Howell, John C. [Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)

2010-07-15

395

Numerical solution of moment-transformed population balance equation with fixed quadrature points  

Microsoft Academic Search

A solution to the moment-transformed population balance equation is presented. The method is based on calculating integrals with fixed quadrature points and corresponding moment-conserving weights. The quadrature points are fixed in the sense that their relative locations along the internal coordinate are determined based on a pre-determined condition. One such condition is choosing them as zeros of orthogonal polynomials. The

Ville Alopaeus; Marko Laakkonen; Juhani Aittamaa

2006-01-01

396

On the detection and classification of quadrature digital modulations in broad-band noise  

Microsoft Academic Search

Optimal and suboptimal decision rules for the detection of constant-envelope quadrature digital modulations in broadband noise are derived and analyzed. The effect of various stochastic models for the carrier phase is examined in detail, while no epoch or frequency uncertainty is assumed. The delay-and-multiply type of detector is considered. A new binary\\/quadrature phase shift keying (BPSK\\/QPSK) classifier is compared to

A. Polydoros; K. Kim

1990-01-01

397

Design of an X-band broad-band lumped-element quadrature hybrid  

Microsoft Academic Search

A method for synthesizing a two-section inductively-coupled lumped-element quadrature hybrid for broad-band applications is first proposed. Based on this analysis, a two-section inductively-coupled lumped-element quadrature hybrid operated at X-band is presented. The measured magnitude imbalance and phase difference are 2.4dB and 90°± 4° over the frequency band of 8–12GHz, respectively. Results show good agreement with the theoretical predictions.

Fangyue Ma; Yangyang Peng; Xiaoying Wang; Saier Liu; Jin Lan; Wenquan Sui

2011-01-01

398

Toward a spaceworthy picometer laser gauge  

Microsoft Academic Search

Metrology will be an enabling technology for a new generation of astronomical missions having large and distributed apertures and delivering unprecedented performance. The x-ray interferometer Black Hole Imager, the UV interferometer Stellar Imager, and other missions will require measurements of incremental distance as accurate as 0.1 picometer, and absolute distance capability. Our Tracking Frequency laser distance Gauge (TFG) was developed

James D. Phillips; Robert D. Reasenberg

2004-01-01

399

Lamb wave mode decomposition using annular transducers and quadrature signals  

NASA Astrophysics Data System (ADS)

Many nondestructive evaluation techniques employ surface-mounted piezoelectric transducers to produce Lamb waves to interrogate structures. However, the multimodal nature of the Lamb waves can make it difficult to obtain meaningful information from signal processing strategies that assume a single mode is present. This problem is typically addressed by a combination of narrowband excitations and careful transducer selection, which can result in acceptable mode purity at specific frequencies. Here a Lamb wave mode decomposition technique for two-element annular transducers is described, which is based upon the method developed by Yeum et al. [Wave Motion 48 p. 358, 2011]. The proposed technique performs the mode separation via constrained least squares optimization on time windowed direct arrivals from different transmitter-receiver element pairs. This method is advantageous for two reasons: (1) chirp excitations are utilized, allowing mode decomposition to be performed at multiple frequencies using a single set of signals, and (2) quadrature signals are included, which improves phase matching and thus can result in improved mode purity.

Dawson, Alexander J.; Michaels, Jennifer E.

2013-01-01

400

High-speed diagnostic interferometer  

Microsoft Academic Search

An Integrated Beam Control Demonstration (IBCD) is being fabricated by Hughes Danbury Optical Systems (HDOS) for the Strategic Defense Initiative Organization under the direction of the Naval Surface Warfare Center. The IBCD will validate critical technologies for the space based laser Advance Beam Control System (ABCS) Program. One of the system requirements is to provide a means of independently sense

Jacobus M. Oschmann; James Kiraly

1992-01-01

401

Towards a matter wave interferometer on a sounding rocket  

NASA Astrophysics Data System (ADS)

Applications of coherent matter waves are high resolution interferometers for measuring inertial and gravitational forces as well as testing fundamental physics, for which they may serve as a laser like source with mesoscopic quantum features. Out of possible applications, the test of the principle of equivalence in the quantum domain is selected as a target with the highest scientific interest on timescales of a microgravity experiment at the ISS or on a free flyer (ATV, FOTON or other satellites). The QUANTUS project demonstrated the technological feasibil-ity of coherent matter waves in microgravity. As a next step, the consortium will prepare and procure a sounding rocket mission to demonstrate technologies for matter wave interferome-try based on the broad experience of former developments with experiments in the droptower. Therefore, the experiment has to withstand strong requirements concerning environmental con-ditions (Temperature, shock, environmental pressure, etc.) and needs to be designed to fit in a 600 l volume (diameter 35 cm, length 160 cm). It is considered as an important step towards the technology required for the ISS and other platforms. These experiments will give further insights on the potential of inertial sensors based on atom interferometers and the technology is for example of interest for applications in earth observation and geodesy. They could replace classical techniques relying on test masses and promise a further improvement in the accuracy of such devices.

van Zoest, Tim; Peters, Achim; Ahlers, Holger; Wicht, Andreas; Vogel, Anika; Wenzlawski, Anderas; Deutsch, Christian; Kajari, Endre; Gaaloul, Naceur; Dittus, Hansjürg; Hartwig, Jonas; Herr, Waldemar; Herrmann, Sven; Reichel, Jakob; Bongs, Kai; Koenemann, Thorben; Laemmerzahl, Claus; Lewoczko-Adamczyk, Wojtek; Schiemangk, Max; Müntinga, Hauke; Meyer, Nadine; Rasel, Ernst Maria; Walser, Reinhold; Resch, Andreas; Rode, Christina; Seidel, Stephan; Sengstock, Klaus; Singh, Yeshpal; Schleich, Wolfgang; Ertmer, Wolfgang; Rosenbusch, Peter; Wilken, Tobias; Goeklue, Ertan

402

Measurements of gravitational acceleration from an echo atom interferometer  

NASA Astrophysics Data System (ADS)

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.

Mok, C.; Carew, A.; Barrett, B.; Berthiaume, R.; Kumarakrishnan, A.

2012-06-01

403

Optimal Beam Combiner Design for Nulling Interferometers  

NASA Astrophysics Data System (ADS)

A scheme to optimally design a beam combiner is discussed for any predetermined fixed geometry nulling interferometer aimed at detection and characterization of exoplanets with multiple telescopes or a single telescope (aperture masking). We show that considerably higher order nulls can be achieved with 1D (one-dimensional) interferometer geometries than possible with 2D (two-dimensional) geometries with the same number of apertures. Any 1D interferometer with N apertures can achieve a 2(N - 1)-order null, while the order of the deepest null for a random 2D aperture geometry interferometer is the order of the Nth term in the Taylor expansion of ei(x2+y2) around x=0, y=0 (2nd order null for N=2,3; 4th order null for N=4,5,6). We also show that an optimal beam combiner for nulling interferometry relies on only 0 or ? phase shifts. Examples of nulling interferometer designs are shown to illustrate these findings.

Guyon, Olivier; Mennesson, Bertrand; Serabyn, Eugene; Martin, Stefan

2013-08-01

404

Measurement of a Michelson interferometer mirror velocity with a time interval analyzer  

Microsoft Academic Search

This report documents the design, construction, and implementation of a time interval analyzer (TIA). The TIA is a precision counter that measures the dynamic variation in the time intervals (i.e., frequency) of a signal. The helium-neon (HeNe) laser signal from the servo-mirror control circuitry of the interferometer provides a nearly constant frequency source. The HeNe signal frequency is directly proportional

R. J. Combs; R. B. Knapp; C. T. Cathey

1992-01-01

405

Large cross-section pulsed TEA-CO/sub 2/ interferometer for plasma diagnostics  

SciTech Connect

A large cross-section Mach-Zehnder interferometer is illuminated by a 30-nsec CO/sub 2/ laser pulse. The line-integrated density sensitivity is 2 x 10/sup 10/ m/sup -2/. Spatial features down to 150 ..mu..m can be identified within a usable field of view of 50 mm. An example of a typical interference pattern obtained on a plasma column is shown together with its corresponding Abel deconvoluted density profile.

Lachambre, J.L.; Decoste, R.; Robert, A.

1982-07-15

406

Large cross-section pulsed TEA-CO(2) interferometer for plasma diagnostics.  

PubMed

A large cross-section Mach-Zehnder interferometer is illuminated by a 30-nsec CO(2) laser pulse. The line-integrated density sensitivity is 2 x 10(19) m(-2). Spatial features down to 150 microm can be identified within a usable field of view of 50 mm. An example of a typical interference pattern obtained on a plasma column is shown together with its corresponding Abel deconvoluted density profile. PMID:20396071

Lachambre, J L; Decoste, R; Robert, A

1982-07-15

407

An alternative optical switch using Mach Zehnder interferometer and two ring resonators  

Microsoft Academic Search

In this paper, we present an experimental investigation of all-optical switch using a symmetric Mach-Zehnder interferometer (MZI) combined with double fiber ring resonators. Here, we replace the ordinary-fiber ring resonator on one arm of MZI by a 980 nm-laser pumped erbium-doped fiber (EDF) ring resonator to form an EDFA. When adjusting the EDF pump power up we note increasing in

P. P. Yupapin; P. Saeung; P. Chunpang

2008-01-01

408

An Alternative Optical Switch Using Mach Zehnder Interferometer and Two Ring Resonators  

Microsoft Academic Search

In this paper, we present an experimental investigation of all-optical switch using a symmetric Mach-Zehnder interferometer (MZI) combined with double fiber ring resonators. Here, we replace the ordinary-fiber ring resonator on one arm of MZI by a 980 nm-laser pumped erbium-doped fiber (EDF) ring resonator to form an EDFA. When adjusting the EDF pump power up we note increasing in

P. P. Yupapin; P. Saeung; P. Chunpang

2008-01-01

409

Remote upconversion in microwave fiber optic links employing an unbalanced Mach-Zehnder interferometer  

Microsoft Academic Search

We present a new technique for remote upconversion by inserting a passive all-optical device in the microwave (MW) fiber-optic link. Using a semiconductor laser directly modulated by two MW signals and an unbalanced Mach-Zehnder interferometer (UMZ) to convert optical frequency modulation into intensity modulation, mixing is achieved after photodetection. Experiments with a UMZ integrated on glass- substrate have demonstrated the

Ghislaine Maury; A. Hilt; B. Cabon; V. Girod; L. Degoud

1999-01-01

410

Adopting our heterodyne interferometer with sub-nm sensitivity for industrial position metrology  

NASA Astrophysics Data System (ADS)

The laser interferometer space antenna (LISA) mission utilizes as current baseline a high sensitivity optical readout for measuring the relative position and tilt of a free flying proof mass with respect to the satellite housing. The required sensitivities are ~5pm/? Hz for the translation measurement and ~20 nrad/?Hz for the tilt measurement. For this purpose, EADS Astrium GmbH - in collaboration with the Humboldt-University Berlin and the University of Applied Sciences Konstanz - develops a fiber-coupled heterodyne interferometer including differential wavefront sensing for the tilt measurement. The interferometer is based on a highly symmetric design where both, measurement and reference beam have the same optical pathlength, frequency and polarization. We realized a mechanically highly stable and compact setup which is located in a temperature stabilized vacuum chamber and utilizes frequency stabilization of the laser and intensity stabilization of the heterodyne frequencies at the fibre outputs. Noise levels below 5 pm/? Hz in translation movement and below 10 nrad/?Hz in tilt movement (both for frequencies above 10-2 Hz) were measured. While this setup is developed with respect to the requirements of the LISA space mission, it also has potential applications beyond: In industry, high precision position measurements - with ever increasing sensitivity - are needed e.g. for guaranteeing very small tolerances for automobile industry components. While current systems developed for this purpose use for instance whitelight-interferometry with resulting sensitivities in the nm-range, our interferometer opens the possibility to further improve the sensitivity. Here, we discuss possible implementations of our interferometer for industrial applications.

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

2007-06-01

411

First results from the J-TEXT high-resolution three-wave polarimeter-interferometer  

NASA Astrophysics Data System (ADS)

A laser-based far-infrared polarimeter-interferometer system utilizing the three-wave technique has been implemented on the J-TEXT tokamak. The polarimeter determines the Faraday effect by measuring the phase difference between two collinear, counter-rotating, circularly polarized laser beams. The first results of the polarimeter-interferometer designed for J-TEXT have been obtained in the most recent J-TEXT experimental campaign. Simultaneous polarimetric and interferometric measurement is achieved, with phase resolution up to 0.1°, at bandwidth of 50 kHz. The temporal resolution, which is dependent on the laser's frequency offset, is ~1 ?s. Continual spatial measurement covering 45 cm (80% of the plasma cross-section) is realized by utilizing 1D parabolic beam expansion optics. Three initial test chords are installed and future plans call for expansion up to 30 chords with 1.5 cm chord spacing, providing high spatial resolution for measurement of electron density and current density profiles. Reliability of both polarimetric and interferometric measurement is confirmed by comparison with computation and data from a hydrocyanic acid (HCN) interferometer. With the high temporal and phase resolution, perturbations associated with the sawtooth cycle and MHD activity have been observed.

Chen, J.; Zhuang, G.; Wang, Z. J.; Gao, L.; Li, Q.; Chen, W.; Brower, D. L.; Ding, W. X.

2012-10-01

412

First tests of the interferometer in the micro-arcsecond metrology testbed (MAM)  

NASA Astrophysics Data System (ADS)

The Space Interferometry Mission (SIM) relies on interferometry and metrology capable of measuring the change in the optical path difference with picometer accuracy. For the last two years we designed and built the Micro-Arcsecond Metrology Testbed, the key technology demonstration for SIM. In a parallel effort the data analysis code was written. The interferometer was first used in a modified configuration; white light and light from a HeNe-laser was emerging from a fiber, collimated and split into the two arms with their respective delay lines. The recombined light was then dispersed onto the CCD camera. The tests done using this interferometer resulted in data on the effects that influence the accurate determination of the fringe phase delay: (1) alignment effects; (2) CCD camera parameters; (3) path length stability, and (4) analysis related inaccuracies. While offsetting the interferometer from equal arm length, the OPD was dithered using PZT-actuated mirrors. The white-light fringe was captured for each step. At the same time the (HeNe) laser light was monitored with two photo detectors--one serving as an intensity monitor, the second one monitoring the interfered laser light. This technique was used to accurately measure the path length changes by analyzing the linear parts of the HeNe sinusoidal interference signal normalized by the HeNe intensity signal. This simple metrology system is designed to determine the optical path length changes to about 100 pm.

Kuhnert, Andreas C.; Shaklan, Stuart B.; Shen, Janice; Carlson, Andrew E.; Azevedo, L. Steven

2000-07-01

413

First results from the J-TEXT high-resolution three-wave polarimeter-interferometer  

SciTech Connect

A laser-based far-infrared polarimeter-interferometer system utilizing the three-wave technique has been implemented on the J-TEXT tokamak. The polarimeter determines the Faraday effect by measuring the phase difference between two collinear, counter-rotating, circularly polarized laser beams. The first results of the polarimeter-interferometer designed for J-TEXT have been obtained in the most recent J-TEXT experimental campaign. Simultaneous polarimetric and interferometric measurement is achieved, with phase resolution up to 0.1 Degree-Sign , at bandwidth of 50 kHz. The temporal resolution, which is dependent on the laser's frequency offset, is {approx}1 {mu}s. Continual spatial measurement covering 45 cm (80% of the plasma cross-section) is realized by utilizing 1D parabolic beam expansion optics. Three initial test chords are installed and future plans call for expansion up to 30 chords with 1.5 cm chord spacing, providing high spatial resolution for measurement of electron density and current density profiles. Reliability of both polarimetric and interferometric measurement is confirmed by comparison with computation and data from a hydrocyanic acid (HCN) interferometer. With the high temporal and phase resolution, perturbations associated with the sawtooth cycle and MHD activity have been observed.

Chen, J.; Zhuang, G.; Wang, Z. J.; Gao, L.; Li, Q.; Chen, W. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Brower, D. L.; Ding, W. X. [Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095 (United States)

2012-10-15

414

Improved common-path fast-scanning heterodyne interferometer system as potential dense-plasma diagnostics  

SciTech Connect

An improved common-path fast-scanning heterodyne interferometer system has been developed. The mechanical vibration is one of the most critical error sources in typical interferometry system. These errors can be mostly eliminated in a common-path interferometry using a full common-mode rejection scheme. Taking advantage of it, the common-path interferometry is suitable for the measurements in noisy environments and can be applied even to the scanning interferometry. A prototype common-path interferometer system with He-Ne laser has been constructed with the capability of fast scanning by adding a rotating polygon mirror. A test of this system has been completed successfully by measuring the thickness profile of the scratched glass. In this study, the interferometer system is proposed and discussed as a potential density profile diagnostics for dense plasmas. By using a CO{sub 2} laser instead of a He-Ne laser, it may also be applied to get the time evolution of steep density profiles of plasma transport barriers in tokamak plasmas.

Nam, Y.U.; Cheon, M.S.; Ha, J.H.; Hwang, Y.S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2004-10-01

415

Local adaptable quadrature filters to demodulate single fringe patterns with closed fringes  

NASA Astrophysics Data System (ADS)

We propose a new approach to demodulate a single fringe pattern with closed fringes by using Local Adaptable Quadrature Filters (LAQF). Quadrature filters have been widely used to demodulate complete image interferograms with carrier frequency. However, in this paper, we propose the use of quadrature filters locally, assuming that the phase is locally quasimonochromatic, since quadrature filters are not capable to demodulate image interferograms with closed fringes. The idea, in this paper, is to demodulate the fringe pattern with closed fringes sequentially, using a fringe following scanning strategy. In particular we use linear robust quadrature filters to obtain a fast and robust demodulation method for single fringe pattern images with closed fringes. The proposed LAQF method does not require a previous fringe pattern normalization. Some tests with experimental interferograms are shown to see the performance of the method along with comparisons to its closest competitor, which is the Regularized Phase Tracker (RPT), and we will see that this method is tolerant to higher levels of noise.

Estrada, J. C.; Servin, M.; Marroquín, J. L.

2007-03-01

416

Telescope alignment with the absolute distance interferometer  

NASA Astrophysics Data System (ADS)

Achieving optimal performance from a multiple element telescope is critically dependent on an element position sensing and control system. We first discuss the design of a novel absolute distance measuring interferometer with performance suitable for such a sensing system, and secondly describe how it can be simply integrated into the telescope. Features of the interferometer include an extended ambiguity range, high temporal bandwidth, and very high accuracy. The concept for the overall optical alignment system is expected to compensate in part for local atmospheric distortions as well as mechanical vibrations while not interfering with the optical performance of the telescope.

Massie, N. A.; Dunn, M. R.

1982-10-01

417

Bayesian estimation of differential interferometer phase  

SciTech Connect

We apply Bayesian logic to optimally estimate the differential phase in a discrete-time, dual-interferometer measurement. This method is particularly relevant to the case of a gravity gradiometer, where the gravity gradient between cold-atom fountain interferometers can be estimated from the differential phase, despite the presence of large common phase (acceleration) fluctuations. Given an accurate model, the bias-free algorithm we present is optimal and leverages experimental knowledge of the system noise, classical or quantum, to outperform other typical estimators, including ellipse-fitting techniques.

Stockton, John K.; Wu Xinan; Kasevich, Mark A. [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)

2007-09-15

418

Nulling Measurements with the Keck Interferometer  

SciTech Connect

The Keck Interferometer provides a mid-infrared nulling capability that is designed to detect faint mid-infrared emission from the immediate vicinity of bright stars. The Keck Interferometer Nuller (KIN) has now been used to carry out initial shared-risk science observations, followed by three nulling key-science projects performed in the 2008 observing semesters. This paper describes the novel measurement technique employed by the KIN, and lists some of the initial observations obtained with it. These data sets are now in the process of being analyzed, and results should begin emerging in the near future.

Serabyn, Eugene [Jet Propulsion Laboratory, MS 171-113, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91125 (United States)

2009-08-05

419

BioCD: Self-referencing interferometer for biosensing  

NASA Astrophysics Data System (ADS)

The holy-grail of modern medical science is to provide personalized health-care. An individual's state of health can be correlated to the pattern of concentration of several 'marker' molecules, for e.g. the presence of Prostate Specific Antigen (PSA) beyond a certain threshold in the body is a strong indication of prostate cancer. To realize the dream of personalized healthcare, a large number of markers have to be identified and correlated to the state of health across diverse populations. The identified markers have to be quantified subsequently to define an individual's state of health. The technology used to achieve the above should be sensitive, accurate, reliable, high-throughput and should be cheap and simple enough to be able to be available in a clinician's office. Interferometry has been used as a sensitive metrology tool in fields ranging from semiconductor inspection to astronomy. This thesis demonstrates a self-referencing interferometric biosensor (BioCD) with a surface normal design potentially capable of scaling up to thousands of tests per sensor substrates. The sensor concept is similar to an optical CD in that gold microstructures fabricated on the BioCD surface act as wavefront splitting interferometers. In contrast to the optical CD, the BioCD operates in a condition called quadrature, which provides maximum linear response to small phase changes caused by protein binding events. The gold microstructures generate a carrier wave when the BioCD is spun, and protein binding is detected as a modulation of an envelope of the carrier wave pattern created by the immobilized capture proteins. By immobilizing reference and target proteins, differential measurements that automatically subtract out non-specific binding can be obtained. We have demonstrated a detection limit of about 1 ng/ml with this technology, which is a clinically relevant figure for many human and veterinary applications. The specific and non-specific binding signals are separated by 4 orders of magnitude implying that potentially as many simultaneous tests can be performed with a single substrate.

Varma, Manoj

420

Long-baseline optical fiber interferometer instruments and science  

Microsoft Academic Search

Developments of fiber linked optical interferometer are reported. This interferometer is a part of MIRA-I.2 interferometer (Mitaka InfraRed and optical Array). MIRA-I.2 is an optical interferometer with a 30 meters long baseline. It consists of two 30cm siderostats, tip-tilt mirrors, vacuum pipes delay lines and detectors. We plan to use two 60 meters long polarization-maintaining fibers for arms of the

Takayuki Kotani; Jun Nishikawa; Koichi Sato; Masanori Yoshizawa; Naoko Ohishi; Toshio Fukushima; Yasuo Torii; Ko Matsuda; Koichi Kubo; Hikaru Iwashita; Shunsaku Suzuki

2003-01-01

421

X-ray shearing interferometer and generalized grating imaging  

SciTech Connect

X-ray shearing interferometers with three gratings are analyzed on the basis of generalized grating imaging theory. The result of this analysis is applied to an already proposed interferometer. The contrast of the imaging fringes in the interferometer is calculated quantitatively. It is also applied to explain the spatial resolution of the image.

Iwata, Koichi

2009-02-10

422

Pulse regime of nonlinear spin wave interferometer operation  

Microsoft Academic Search

Summary form only given. Spin wave devices may find various application for microwave signal processing. Recently an interest to investigate ferrite-film spin wave interferometers was shown. In particular, a linear spin wave interferometer has been used for obtaining a bistable microwave device. We have reported the results on continuous wave measurements of the nonlinear spin wave interferometer (NSWI) (Ustinov et

A. B. Ustinov

2002-01-01

423

On the spectrum of field quadratures for a finite number of photons  

NASA Astrophysics Data System (ADS)

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 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.

Pisanty, E.; Nahmad-Achar, E.

2012-10-01

424

Generation of pure electrical quadrature amplitude modulation with photonic vector modulator.  

PubMed

A photonic vector modulator architecture for generating pure quadrature amplitude modulation (QAM) signals is presented. An electrical quadrature-modulated signal at microwave-millimeter-wave frequencies is generated from its corresponding baseband in-phase (I) and quadrature (Q) components. In the proposed scheme, no electrical devices apart from the electrical tone oscillator are needed in the generation process. In addition, the purity of the generated signal is increased, and the hardware requirements are reduced when compared with previously proposed architectures so a highly compact low-cost architecture can be implemented. A pure 1.25 Gbit/s 4-QAM signal has been experimentally generated at a 42 GHz carrier frequency. PMID:18552936

Corral, Juan L; Sambaraju, Rakesh; Piqueras, Miguel A; Polo, Valentín

2008-06-15

425

Spindle error motion measurement using concentric circle grating and phase modulation interferometers  

NASA Astrophysics Data System (ADS)

In the conventional methods to measure radial, axial and angular motions of spindles, complicated artifacts with relative large volume (such as two balls linked with a cylinder) are required. Small volume artifact is favorable from the viewpoint of the accurate and practical measurement of the spindle motion. This paper describes a concurrent measurement of spindle radial, axial and angular motions using concentric circle grating and phase modulation interferometers. In the measurement, the concentric circle grating with fine pitch is installed on top of the spindle of interest. The grating is a reference artifact in the method. Three optical sensors are fixed over the concentric circle grating, and observe the proper positions of the grating. The optical sensor consists of a frequency modulated laser diode as a light source, and two interferometers. One interferometer observes an interference fringe between reflected light form a fixed mirror and 0-th order diffraction light from the grating to measure the axial motion. Another interferometer observes an interference fringe between +/-2nd diffraction lights from the grating to measure the radial motion. Using three optical sensors, three radial displacements and three axial displacements of the proper observed position of the grating can be measured. From these measured displacements, radial, axial and angular motions of the spindle can be calculated concurrently. In the paper, a measurement instrument, a novel fringe interpolation technique by sinusoidal phase modulation and experimental results are discussed.

Aketagawa, M.; Madden, M.; Uesugi, S.; Kumagai, T.; Maeda, Y.; Okuyama, E.

2012-11-01

426

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

NASA Astrophysics Data System (ADS)

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 warms up; in another experimental step, they confront the issue of the photodetection system's electronic bandwidth. We also provide a review of Gaussian beam formulas and detail their use in mode-matching calculations.

Nachman, Paul; Bernstein, Aaron C.

1997-03-01

427

Discrete variable representation in electronic structure theory: Quadrature grids for least-squares tensor hypercontraction  

NASA Astrophysics Data System (ADS)

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.

Parrish, Robert M.; Hohenstein, Edward G.; Martínez, Todd J.; Sherrill, C. David

2013-05-01

428

Discrete variable representation in electronic structure theory: quadrature grids for least-squares tensor hypercontraction.  

PubMed

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. PMID:23697409

Parrish, Robert M; Hohenstein, Edward G; Martínez, Todd J; Sherrill, C David

2013-05-21

429

Fiber-optic extrinsic Fabry-Perot vibration-isolated interferometer for use in absolute gravity meters.  

PubMed

In an absolute gravity meter, a laser interferometer measures the position of a test mass that is falling ina vacuum. The calculated value of gravity is the average acceleration of the mass during a set ofdrops. Since systematic accelerations of the optical system will bias the measured value of gravity,various interferometer geometries have been implemented in the past to isolate the optical system fromground motion. We have developed and tested a low-finesse fiber-optic extrinsic Fabry-Perotinterferometer that is fixed to the mass of a critically damped seismometer in which the effects ofsystematic ground motion and acoustic vibrations are reduced. PMID:21102741

Canuteson, E L; Zumberge, M

1996-07-01

430

High resolution laser-interferometric probing of SAW devices  

Microsoft Academic Search

Measurements on the surface-acoustic wave profiles in various SAW devices have been performed with a scanning laser interferometer. SAW profiles at frequencies up to 1 GHz are obtained with our interferometer. Fast automatic computer control enables high-resolution scans with a large number of measuring points at speeds up to 10 000 points\\/hour. Our interferometer can detect below one Angstrom vibrations

J. Knuuttila; P. Tikka; T. Thorvaldsson; K.-Y. Hashimoto; M. M. Salomaa

1998-01-01

431

Use of a Radial Shear Interferometer as a Self Reference Interferometer in Adaptive Optics  

NASA Astrophysics Data System (ADS)

A radial shear interferometer (rsi) is produced by the interference of two different sized images of the test wavefront. When the center of curvature of the wavefronts are at the same location, they produce a shear in the radial direction. The rsi has a unique attribute which distinguishes it from other wavefront shear interferometers. For sufficiently large shears S, where S = R1/R2, R being the radius of inner or outer beam, the interferometric fringe pattern is almost identical to a Michelson amplitude splitting interferometer. The usual conversion of measured phase tilt to wavefront phase, as required in other shear interferometers, is avoided. The resultant wavefront reconstruction is eliminated, and the radial shear interferogram can be treated as a direct phase measurement. Developed for optical testing in prelaser days, the radial shear interferometer was a prime candidate for our use with the black fringe wavefront sensor (bfwfs) described in a companion presentation at this conference.1 We also considered a point diffraction interferometer (pdi) as a self reference interferometer, which led to a testing program to analyze the attributes of each of these optical designs for their later incorporation into an adaptive optics control system with the bfwfs. The rsi has several advantages over the pdi, including more efficient use of the input light from the test wavefront and insensitivity to vibration and environmental disturbances, due to the common path nature of the coincident wavefronts. However, the radial shear interferometer is hampered by at least two issues in its implementation: the measured wavefront is only an approximation to the true input wavefront (based on the shear ratio), and it cannot be used with a centrally obscured telescope because of the radial shear. The remainder of the presentation will summarize an experimental investigation in which various wavefront aberrations are introduced at the input of a radial shear interferometer and the resultant wavefront error map obtained. This phase map will be compared with that obtained when similar aberrations are input to a point diffraction interferometer. There is a common theme to the recent successful applications of curvature sensing, image sharpness algorithms, and stochastic optimization techniques in adaptive optics. All aberrations do not need to be corrected to obtain either better images or corrected outgoing wavefronts, and averaging techniques can be a viable alternative for adaptive optics correction in severely degraded atmospherically generated or high flow conditions. The use of a radial shear interferometer, combined with a black fringe wavefront sensor is finally described as an alternative method to correct for many of these aberrations, and, to the best of our knowledge, represents the first use of an rsi for atmospheric correction.

Tansey, R.; Phenis, A.; Shu, K.

432

Fast Sweeping Interferometer with Digital Data Integration.  

National Technical Information Service (NTIS)

Accurate frequency and time resolution for solar dekameter observation is obtained with an interferometer which steps within 50 msec through the band from 24 to 48 MHz using 160 kHz frequency increments. Alternatively adding and subtracting the two antenn...

B. W. Reinisch K. Bibl R. K. Temple

1970-01-01

433

Automated planning for interferometer configuration and control  

Microsoft Academic Search

In this paper, we discuss Artificial Intelligence (AI) planning and scheduling technology and its application to interferometer configuration and control. Scientific demand and technical requirements necessitate streamlining and optimizing the operation of these instruments. However, it is difficult, often impossible, to achieve this streamlining manually. Moreover, harsh operating environments make manual operation impractical, further motivating the use of automation. We

Gregg Rabideau; Leonard Reder; Steve Chien; Andrew Booth

2001-01-01

434

Electronic transmittance phase extracted from mesoscopic interferometers  

PubMed Central

The usual experimental set-up for measuring the wave function phase shift of electrons tunneling through a quantum dot (QD) embedded in a ring (i.e., the transmittance phase) is the so-called ‘open’ interferometer as first proposed by Schuster et al. in 1997, in which the electrons back-scattered at source and the drain contacts are absorbed by additional leads in order to exclude multiple interference. While in this case one can conveniently use a simple two-path interference formula to extract the QD transmittance phase, the open interferometer has also a number of draw-backs, such as a reduced signal and some uncertainty regarding the effects of the extra leads. Here we present a meaningful theoretical study of the QD transmittance phase in ‘closed’ interferometers (i.e., connected only to source and drain leads). By putting together data from existing literature and giving some new proofs, we show both analytically and by numerical simulations that the existence of phase lapses between consecutive resonances of the ‘bare’ QD is related to the signs of the corresponding Fano parameters - of the QD + ring system. More precisely, if the Fano parameters have the same sign, the transmittance phase of the QD exhibits a ? lapse. Therefore, closed mesoscopic interferometers can be used to address the ‘universal phase lapse’ problem. Moreover, the data from already existing Fano interference experiments from Kobayashi et al. in 2003 can be used to infer the phase lapses.

2012-01-01

435

The Virgo Interferometer for Gravitational Wave Detection  

Microsoft Academic Search

The Virgo interferometer for gravitational wave detection is described. During the commissioning phase that followed the first scientific data taking run an unprecedented sensitivity was obtained in the range 10-60 Hz. Since then an upgrade program has begun, with the aim of increasing the sensitivity, mainly through the introduction of fused silica wires to suspend mirrors and by increasing the

T. Accadia; F. Acernese; F. Antonucci; P. Astone; G. Ballardin; F. Barone; M. Barsuglia; Th. S. Bauer; M. G. Beker; A. Belletoile; S. Birindelli; M. Bitossi; M. A. Bizouard; M. Blom; C. Boccara; F. Bondu; L. Bonelli; R. Bonnand; V. Boschi; L. Bosi; B. Bouhou; S. Braccini; C. Bradaschia; A. Brillet; V. Brisson; R. Budzynski; T. Bulik; H. J. Bulten; D. Buskulic; C. Buy; G. Cagnoli; E. Calloni; E. Campagna; B. Canuel; F. Carbognani; F. Cavalier; R. Cavalieri; G. Cella; E. Cesarini; E. Chassande-Mottin; A. Chincarini; F. Cleva; E. Coccia; C. N. Colacino; J. Colas; A. Colla; M. Colombini; A. Corsi; J.-P. Coulon; E. Cuoco; S. D'Antonio; V. Dattilo; M. Davier; R. Day; R. De Rosa; G. Debreczeni; M. Del Prete; L. di Fiore; A. di Lieto; M. di Paolo Emilio; A. di Virgilio; A. Dietz; M. Drago; V. Fafone; I. Ferrante; F. Fidecaro; I. Fiori; R. Flaminio; J.-D. Fournier; J. Franc; S. Frasca; F. Frasconi; A. Freise; M. Galimberti; L. Gammaitoni; F. Garufi; M. E. Gáspár; G. Gemme; E. Genin; A. Gennai; A. Giazotto; R. Gouaty; M. Granata; C. Greverie; G. M. Guidi; J.-F. Hayau; H. Heitmann; P. Hello; S. Hild; D. Huet; P. Jaranowski; I. Kowalska; A. Królak; N. Leroy; N. Letendre; T. G. F. Li; M. Lorenzini; V. Loriette; G. Losurdo; E. Majorana; I. Maksimovic; N. Man; M. Mantovani; F. Marchesoni; F. Marion; J. Marque; F. Martelli; A. Masserot; C. Michel; L. Milano; Y. Minenkov; M. Mohan; J. Moreau; N. Morgado; A. Morgia; S. Mosca; V. Moscatelli; B. Mours; I. Neri; F. Nocera; G. Pagliaroli; L. Palladino; C. Palomba; F. Paoletti; S. Pardi; M. Parisi; A. Pasqualetti; R. Passaquieti; D. Passuello; G. Persichetti; M. Pichot; F. Piergiovanni; M. Pietka; L. Pinard; R. Poggiani; M. Prato; G. A. Prodi; M. Punturo; P. Puppo; D. S. Rabeling; I. Rácz; P. Rapagnani; V. Re; T. Regimbau; F. Ricci; F. Robinet; A. Rocchi; L. Rolland; R. Romano; D. Rosinska; P. Ruggi; B. Sassolas; D. Sentenac; L. Sperandio; R. Sturani; B. Swinkels; A. Toncelli; M. Tonelli; O. Torre; E. Tournefier; F. Travasso; G. Vajente; S. van der Putten; M. Vasuth; M. Vavoulidis; G. Vedovato; D. Verkindt; F. Vetrano; A. Viceré; J.-Y. Vinet; H. Vocca; M. Yvert

2011-01-01

436

Reconfigurable electronics at the IOTA interferometer  

Microsoft Academic Search

We describe the new control system for the PICNIC near-infrared camera and the visible star tracker, implemented at the IOTA interferometer, based on the ALTERA Complex Programmable Logic Device (CPLD) technology. These digital components provide an adaptive interface between the control system and the cameras used at IOTA, allowing flexibility when connecting very different devices. In particular the clocking and

Ettore Pedretti; Rafael Millan-Gabet; John D. Monnier; S. Morel; Wesley A. Traub; Nathaniel P. Carleton; Jean-Philippe Berger; P. Schloerb; Michael K. Brewer; Sam Ragland; Marc G. Lacasse

2003-01-01

437

Differential Phase Mode with the Keck Interferometer  

NASA Astrophysics Data System (ADS)

We describe the differential phase mode of the Keck Interferometer. The scientific goal of this mode is the direct detection and spectroscopic characterization of hot, Jupiter mass planets. We describe the differential phase effect, the basic observational mode, and the expected differential phase signatures for the extrasolar planets discovered through radial velocity searches.

Akeson, Rachel; Swain, Mark

2000-01-01

438

A Microwave Interferometer on an Air Track.  

ERIC Educational Resources Information Center

Uses an air track and microwave transmitters and receivers to make a Michelson interferometer. Includes three experiments: (1) measuring the wavelength of microwaves, (2) measuring the wavelength of microwaves by using the Doppler Effect, and (3) measuring the Doppler shift. (MVL)

Polley, J. Patrick

1993-01-01

439

Monte Carlo Simulation of an Atomic Interferometer  

Microsoft Academic Search

A direct measurement of the gravitational acceleration of antimat- ter has never before been performed. Recently, such an experiment has been proposed, using antihydrogen with an atom interferometer. This paper describes a computer model of the proposed experiment, which is used to test basic assumptions and optimize certain param- eters. A Monte Carlo routine for generation of trial data sets

Ethan Neil

440

A Microwave Interferometer on an Air Track.  

ERIC Educational Resources Information Center

|Uses an air track and microwave transmitters and receivers to make a Michelson interferometer. Includes three experiments: (1) measuring the wavelength of microwaves, (2) measuring the wavelength of microwaves by using the Doppler Effect, and (3) measuring the Doppler shift. (MVL)|

Polley, J. Patrick

1993-01-01

441

Quantum Theory of the Nonlinear Interferometer,  

National Technical Information Service (NTIS)

A full quantum theory of the Mach-Zehnder interferometer with nonlinear Kerr media in both arms is presented. The nonlinear operator equations can be integrated, and the result can be normal-ordered. This permits the evaluation of the factorial moments of...

M. Shirasaki H. A. Haus D. L. Wong

1989-01-01

442

A matricial computation of rational quadrature formulas on the unit circle  

NASA Astrophysics Data System (ADS)

A matricial computation of quadrature formulas for orthogonal rational functions on the unit circle, is presented in this paper. The nodes of these quadrature formulas are the zeros of the para-orthogonal rational functions with poles in the exterior of the unit circle and the weights are given by the corresponding Christoffel numbers. We show how these nodes can be obtained as the eigenvalues of the operator Möbius transformations of Hessenberg matrices and also as the eigenvalues of the operator Möbius transformations of five-diagonal matrices, recently obtained. We illustrate the preceding results with some numerical examples.

Bultheel, Adhemar; Cantero, Maria-José

2009-09-01

443

Positivity of the weights of interpolatory quadrature formulae with Bernstein-Szegö abscissae  

NASA Astrophysics Data System (ADS)

We consider interpolatory quadrature formulae, relative to the Legendre weight function w(t) = 1 on [ - 1,1], having as nodes the zeros of any one of the nth degree orthogonal polynomials relative to the Bernstein-Szegö weight functions w_{?}^{(± 1/2}(t)D {(1-t^{2})^{± 1/2}} {1-{4?}/{(1+?)^{2}}t^{2}}, -1 We derive semiexplicit formulae for the quadrature weights and show that the weights are almost all positive; exceptions occur only for the weight corresponding to the node at 0 when n is odd and are carefully identified.

Notaris, Sotirios

2008-12-01

444

On the remainder term of Gauss-Radau quadratures for analytic functions  

NASA Astrophysics Data System (ADS)

For analytic functions the remainder term of Gauss-Radau quadrature formulae can be represented as a contour integral with a complex kernel. We study the kernel on elliptic contours with foci at the points ±1 and a sum of semi-axes [varrho]>1 for the Chebyshev weight function of the second kind. Starting from explicit expressions of the corresponding kernels the location of their maximum modulus on ellipses is determined. The corresponding Gautschi's conjecture from [On the remainder term for analytic functions of Gauss-Lobatto and Gauss-Radau quadratures, Rocky Mountain J. Math. 21 (1991), 209-226] is proved.

Milovanovic, Gradimir V.; Spalevic, Miodrag M.; Pranic, Miroslav S.

2008-09-01

445

Quadrature formulas on the unit circle with prescribed nodes and maximal domain of validity  

NASA Astrophysics Data System (ADS)

In this paper we investigate the Szego-Radau and Szego-Lobatto quadrature formulas on the unit circle. These are (n+m)-point formulas for which m nodes are fixed in advance, with m=1 and m=2 respectively, and which have a maximal domain of validity in the space of Laurent polynomials. This means that the free parameters (free nodes and positive weights) are chosen such that the quadrature formula is exact for all powers zj, -p<=j<=p, with p=p(n,m) as large as possible.

Bultheel, Adhemar; Daruis, Leyla; González-Vera, Pablo

2009-09-01

446

Remote preparation of a single-mode photonic qubit by measuring field quadrature noise.  

PubMed

An electromagnetic field quadrature measurement, performed on one of the modes of the nonlocal single-photon state alpha|1,0>-beta|0,1>, collapses it into a superposition of the single-photon and vacuum states in the other mode. We use this effect to implement remote preparation of arbitrary single-mode photonic qubits conditioned on observation of a preselected quadrature value. The preparation efficiency of the resulting qubit can be higher than that of the initial single photon. PMID:14995409

Babichev, S A; Brezger, B; Lvovsky, A I

2004-01-29

447

A Gaussian quadrature for the calculation of generalized Fermi-Dirac integrals  

NASA Astrophysics Data System (ADS)

In a recent paper, Pichon has addressed the problem of computing generalized Fermi-Dirac integrals with the use of a Gauss-Laguerre type quadrature. As an alternative solution, we investigate Gaussian quadrature based on weight functions of the form xk/(ex + 1), for k = 1/2, 3/2, 5/2, and show that the required number of functional evaluations for a desired accuracy is superior in some instances to the properly parametrized Gauss-Laguerre rule. Moreover, the method presented here is independent of parameter adjustment as opposed to the case of the Gauss-Laguerre.

Sagar, Robin P.

1991-09-01

448

Machine Precision Evaluation of Singular and Nearly Singular Potential Integrals by Use of Gauss Quadrature Formulas for Rational Functions  

Microsoft Academic Search

A new technique for machine precision evaluation of singular and nearly singular potential integrals with 1\\/R singularities is presented. The numerical quadrature scheme is based on a new rational expression for the integrands, obtained by a cancellation procedure. In particular, by using library routines for Gauss quadrature of rational functions readily available in the literature, this new expression permits the

Roberto D. Graglia; Guido Lombardi

2008-01-01

449

Feasibility of heart rate variability measurement from quadrature Doppler radar using arctangent demodulation with DC offset compensation.  

PubMed

This paper describes the experimental results of the beat-to-beat interval measurement from a quadrature Doppler radar system utilizing arctangent demodulation with DC offset compensation techniques. The comparison in SDNN and in RMSDD of both signals demonstrates the potential of using quadrature Doppler radar for HRV analysis. PMID:18002288

Massagram, Wansuree; Hafner, Noah M; Park, Byung-Kwan; Lubecke, Victor M; Host-Madsen, Anders; Boric-Lubecke, Olga

2007-01-01

450

Integrated optical interferometer with a stacked waveguide structure.  

PubMed

An integrated optical interferometer consisting of Al(2)O(3) waveguides placed upon an oxidized Si substrate is presented. The two waveguides forming the branches of the interferometer are stacked on top of each other with a SiO(2) buffer layer in between. The interferometer further contains two directional couplers which are realized by bending the upper waveguide toward the lower one. A masked evaporation technique is introduced to fabricate the directional couplers. The operation of the interferometer is confirmed in temperature-sensing experiments while the application of the interferometer to humidity measurement is discussed. PMID:20555887

Wu, S; Frankena, H J

1989-10-15

451

Stable single-photon interference in a 1 km fiber-optic Mach-Zehnder interferometer with continuous phase adjustment.  

PubMed

We experimentally demonstrate stable and user-adjustable single-photon interference in a 1 km long fiber-optic Mach-Zehnder interferometer, using an active phase control system with the feedback provided by a classical laser. We are able to continuously tune the single-photon phase difference between the interferometer arms using a phase modulator, which is synchronized with the gate window of the single-photon detectors. The phase control system employs a piezoelectric fiber stretcher to stabilize the phase drift in the interferometer. A single-photon net visibility of 0.97 is obtained, yielding future possibilities for experimental realizations of quantum repeaters in optical fibers and violation of Bell's inequalities using genuine energy-time entanglement. PMID:21593883

Xavier, G B; von der Weid, J P

2011-05-15

452

[Lasers].  

PubMed

Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. PMID:23260518

Passeron, T

2012-11-01

453

Lasers.  

PubMed

Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. PMID:23522632

Passeron, T

2012-12-01

454

Design of a digital holographic interferometer for the ZaP Flow Z-Pinch  

NASA Astrophysics Data System (ADS)

The ZaP Flow Z-Pinch experiment investigates how flow shear stabilizes MHD modes. An upgrade to a high energy-density plasma experiment would allow exploration of flow shear's effectiveness in this operating regime. The experiment's upgrade would include the addition of a digital holographic interferometer to measure electron density with fine spatial resolution. The design uses a pulsed Korad ruby laser with a consumer digital camera to generate and record holograms, which are then numerically reconstructed to obtain the phase shift caused by the interaction of the laser beam with the plasma. The numerical reconstruction provides a two-dimensional map of chord-integrated electron density without employing labor-intensive physical reconstruction techniques. The interferometer's accuracy has been validated with comparisons to measurements from an existing four-chord HeNe interferometer. The new diagnostic will allow the ZaP team to search for structures such as plasma shocks that were not previously resolvable. It would also be able to resolve the density profile of the smaller, high-energy pinch.

Ross, Michael; Shumlak, Uri; Nelson, Brian; Golingo, Raymond; Hughes, Michal; Knecht, Sean; Paliwoda, Matt

2012-10-01

455

Measurement of the thickness of the tympanic membrane in cat using a heterodyne interferometer  

NASA Astrophysics Data System (ADS)

The thickness of the tympanic membrane has to be known for the formulation of mathematical ear models. Using a commercial confocal laser scanning microscope we have found that the tympanic membrane has parts thinner than 10 micron. In this study we were forced to excise the tympanic membranes and due the restricted working distance of the microscope objective, we had to flatten the tympanic membrane onto a glass plate. Although we were able to measure thickness in fresh samples, thickness could still have been altered by the preparation procedure. S. Khanna developed over the years a powerful heterodyne interferometer with confocal pinholes in the illumination and observation arms. Thanks to its sectioning capabilities it can measure vibrations of structures embedded within other tissue without the need to expose the structure. While using this equipment in measuring vibrations in the middle ear, the idea grew that the interferometer could also be used to measure thickness, by tracking the carrier level of the interferometer while the laser focus is driven through the membrane. The method looks full of promises as measurements on animals with the tympanic membrane still in its original niche are possible without a prior preparation of the membrane.

Decraemer, Willem F. S.; Khanna, Shyam M.; Dirckx, Joris J. J.

2004-06-01

456

Single-shot electron bunch length measurements using a spatial electro-optical autocorrelation interferometer  

SciTech Connect

A spatial, electro-optical autocorrelation (EOA) interferometer using the vertically polarized lobes of coherent transition radiation (CTR) has been developed as a single-shot electron bunch length monitor at an optical beam port downstream the 100 MeV preinjector LINAC of the Swiss Light Source. This EOA monitor combines the advantages of step-scan interferometers (high temporal resolution) [D. Mihalcea et al., Phys. Rev. ST Accel. Beams 9, 082801 (2006) and T. Takahashi and K. Takami, Infrared Phys. Technol. 51, 363 (2008)] and terahertz-gating technologies [U. Schmidhammer et al., Appl. Phys. B: Lasers Opt. 94, 95 (2009) and B. Steffen et al., Phys. Rev. ST Accel. Beams 12, 032802 (2009)] (fast response), providing the possibility to tune the accelerator with an online bunch length diagnostics. While a proof of principle of the spatial interferometer was achieved by step-scan measurements with far-infrared detectors, the single-shot capability of the monitor has been demonstrated by electro-optical correlation of the spatial CTR interference pattern with fairly long (500 ps) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses in a ZnTe crystal. In single-shot operation, variations of the bunch length between 1.5 and 4 ps due to different phase settings of the LINAC bunching cavities have been measured with subpicosecond time resolution.

Suetterlin, Daniel [PUBLICA Swiss Federal Pension Fund, CH-3000 Berne (Switzerland); Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Erni, Daniel [General and Theoretical Electrical Engineering (ATE), Faculty of Engineering, University of Duisburg-Essen, D-47048 Duisburg (Germany); Schlott, Volker [Department of Large Research Facilities, Paul Scherrer Institute, CH- 5232 Villigen (Switzerland); Sigg, Hans [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH- 5232 Villigen (Switzerland); Jaeckel, Heinz [Department of Information Technology and Electrical Engineering, Electronics Laboratory, ETHZ, CH-8092 Zurich (Switzerland); Murk, Axel [Department of Microwave Physics, Institute of Applied Physics, University of Berne, CH-3012 Berne (Switzerland)

2010-10-15

457

A Milestone for the VLT Interferometer  

NASA Astrophysics Data System (ADS)

Less than one month after "First Light" for the fourth 8.2-m YEPUN telescope ( ESO PR 18/00 ), another special moment occurred at ESO's Paranal Observatory. This time, it was the first truly "underground" event, in the 168-metre long Interferometric Tunnel that has been dug beneath the platform at the top of the mountain. As one staff member remarked on this occasion, it was something like "the first scheduled trip of the Paranal metro"! With the successful integration of the first Delay Line on Monday, September 25th, 2000, ESO has accomplished another important step towards the VLT Interferometer (VLTI). It will be followed by the integration of the second Delay Line by the end of November and the third is scheduled for February 2001; both are now in their final development phase in Europe. "VLTI First Light" is then expected to take place soon thereafter, by means of two small special telescopes ("siderostats"). The combination of the light beams from two of the 8.2-m Unit Telescopes will happen in mid-2001. The VLTI Delay Lines The VLTI Delay Lines form essential parts of this very complicated optical system. They serve to ensure that the light beams from several telescopes arrive in phase at the common interferometric focus. Details about how they function may be found in ESO PR 04/98. In order to achieve the necessary performance, ESO has worked with two Dutch contractors, Fokker Space and TNO-TPD - Netherlands Organization for Applied Scientific Research - Institute of Applied Physics , to arrive at a totally new Delay Line concept. Another Dutch participant in the VLTI project is the Nova-ESO VLTI Expertise Centre (NEVEC) , cf. ESO PR 14/00. The installation at Paranal The last twelve months have been very busy for the integration team, with much preparatory work at the VLTI buildings for the final installation of the Delay Line systems. The assembly of the translation mechanisms for the first two Delay Lines in the tunnel started in mid-2000. This included the alignment of their rails and supports to the extreme accuracy of about 0.25 mm over a total distance of 66.7 metres ( PR Photos 26a-b/00 ). To achieve such an unusually high precision, ESO - in collaboration with the French company FOGALE - developed a measurement system that is based on the water-level principle. The delicate assembly and alignment of the critical sub-systems of the Delay Line were undertaken with the support of Fokker Space and TPD/TNO ( PR Photo 26e/00 ). Also for this, state-of-the-art methods were required in order to ensure a stringent performance of the system. This includes optical alignment of the optics with an accuracy at the arcsec level and positioning of the linear motors at the 0.01 mm (10 µm) level. The Delay Line is one of the key systems in the VLT Interferometer. It is responsible for the compensation of the length of the optical path that is different from the individual telescopes. Extreme accuracy needed In the case of the VLT, this accuracy of the path length compensation must be within a tolerance of only 0.05 µm (0.00005 mm) over a distance of 120 metres. The present concept by ESO and the Dutch contractors is based on a retro-reflector (a "Cat's Eye") that is fixed on a carriage that runs on two stainless steel rails ( PR Photos 26c-d/00 ). The motion on these rails is performed by a 60 metres linear motor and a piezo-transducer element. They are controlled by a laser metrology system that measures the instantaneous distances betwen the mirrors with the required accuracy. This carriage is 2.5 metres long and weighs 250 kg. The total friction force is less than 50 grammes, thanks to the extreme accuracy of the rail alignment and special ball bearings. Because of this, the total power required for the Delay Line operation is only about 15 W. The mirrors of the retro-reflector are made of aluminium by REOSC (France). They have been coated with a single layer of gold for the best possible reflection at infrared wavelengths. This is the caption to ESO PR Pho

2000-10-01

458

Demonstration of improved sensitivity of echo interferometers to gravitational acceleration  

NASA Astrophysics Data System (ADS)

We have developed two configurations of an echo interferometer that rely on standing-wave excitation of a laser-cooled sample of rubidium atoms. Both configurations can be used to measure acceleration a along the axis of excitation. For a two-pulse configuration, the signal from the interferometer is modulated at the recoil frequency and exhibits a sinusoidal frequency chirp as a function of pulse spacing. In comparison, for a three-pulse stimulated-echo configuration, the signal is observed without recoil modulation and exhibits a modulation at a single frequency as a function of pulse spacing. The three-pulse configuration is less sensitive to effects of vibrations and magnetic field curvature, leading to a longer experimental time scale. For both configurations of the atom interferometer (AI), we show that a measurement of acceleration with a statistical precision of 0.5% can be realized by analyzing the shape of the echo envelope that has a temporal duration of a few microseconds. Using the two-pulse AI, we obtain measurements of acceleration that are statistically precise to 6 parts per million (ppm) on a 25 ms time scale. In comparison, using the three-pulse AI, we obtain measurements of acceleration that are statistically precise to 0.4 ppm on a time scale of 50 ms. A further statistical enhancement is achieved by analyzing the data across the echo envelope so that the statistical error is reduced to 75 parts per billion (ppb). The inhomogeneous field of a magnetized vacuum chamber limited the experimental time scale and resulted in prominent systematic effects. Extended time scales and improved signal-to-noise ratio observed in recent echo experiments using a nonmagnetic vacuum chamber suggest that echo techniques are suitable for a high-precision measurement of gravitational acceleration g. We discuss methods for reducing systematic effects and improving the signal-to-noise ratio. Simulations of both AI configurations with a time scale of 300 ms suggest that an optimized experiment with improved vibration isolation and atoms selected in the mF=0 state can result in measurements of g statistically precise to 0.3 ppb for the two-pulse AI and 0.6 ppb for the three-pulse AI.

Mok, C.; Barrett, B.; Carew, A.; Berthiaume, R.; Beattie, S.; Kumarakrishnan, A.

2013-08-01

459

Differential quadrature solution for the free vibration analysis of laminated conical shells with variable stiffness  

Microsoft Academic Search

The free vibration analysis of laminated conical shells with variable stiffness is presented using the method of differential quadrature (DQ). The stiffness coefficients are assumed to be functions of the circumferential coordinate that may be more close to the realistic applications. The first-order shear deformation shell theory is used to account for the effects of transverse shear deformations. In the

Chih-Ping Wu; Chia-Ying Lee

2001-01-01

460