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Showing papers on "Interferometry published in 1982"


Journal ArticleDOI
TL;DR: In this paper, a fast Fourier transform method of topography and interferometry is proposed to discriminate between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour generation techniques.
Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

3,650 citations


Journal ArticleDOI
TL;DR: In this article, a heterodyne signal recovery scheme for interferometric sensors based on frequency ramping of the laser diode source is described, and signals in the range 10?4 to 6 rad have been recovered, the system being linear over 5 decades.
Abstract: A heterodyne signal recovery scheme for interferometric sensors based on frequency ramping of the laser diode source is described. Using a PLL detector, signals in the range 10?4 to 6 rad have been recovered, the system being linear over 5 decades.

281 citations


Journal ArticleDOI
Morgan Cj1
TL;DR: It is shown that phase-extraction algorithms in phase-measurement interferometry can be developed from the principle of least-squares estimation, and it is demonstrated that this view can be taken to develop algorithms that estimate the phase in the presence of external perturbations.
Abstract: It is shown that phase-extraction algorithms in phase-measurement interferometry can be developed from the principle of least-squares estimation. It is then demonstrated that this view can be taken to develop algorithms that estimate the phase in the presence of external perturbations. To illustrate, an algorithm is developed that extracts the phase in the presence of a linear time-dependent drift.

251 citations


Journal ArticleDOI
TL;DR: Fiber-optic Fabry-Perot interferometers using monomode fibers are fabricated and their basic properties of finesse, polarization, and thermal response are studied as discussed by the authors.
Abstract: Fiber-optic Fabry-Perot interferometers using monomode fibers are fabricated and their basic properties of finesse, polarization, and thermal response are studied. Fiber-optic Fabry-Perot interferometers are applied to the sensors of temperature, mechanical vibration, acoustic wave including human voice, ac voltage, and ac and dc magnetic fields. It has been demonstrated that a fiber-optic Fabry-Perot interferometer can simplify the interferometric fiber sensor sys-tem and that high measurement sensitivity can be obtained by using a high-finesse and/or long-distance fiber Fabry-Perot interferometer.

186 citations


Journal ArticleDOI
TL;DR: Fiber-optic Fabry-Perot interferometers using monomode fibers are fabricated and their basic properties of finesse, polarization, and thermal response are studied.
Abstract: Fiber-optic Fabry-Perot interferometers using monomode fibers are fabricated and their basic properties of finesse, polarization, and thermal response are studied. Fiber-optic Fabry-Perot interferometers are applied to the sensors of temperature, mechanical vibration, acoustic wave including human voice, ac voltage, and ac and dc magnetic fields. It has been demonstrated that a fiber-optic Fabry-Perot interferometer can simplify the interferometric fiber sensor system and that high measurement sensitivity can be obtained by using a high-finesse and/or long-distance fiber Fabry-Perot interferometer.

183 citations


Journal ArticleDOI
TL;DR: In this article, a phase swept multicarrier demodulation (SMCD) technique was proposed to optimize the interferometer output, which employed synthetic-heterodyne (SHE) to optimize interferometric output.
Abstract: A new interferometric demodulation technique is described. This technique employs phase swept multicarrier demodulation (synthetic-heterodyne) to optimize the interferometer output.

121 citations


Journal ArticleDOI
TL;DR: The many methods suggested and (some of them) tried out experimentally and/or observationally for imaging celestial objects through the Earth's atmosphere are reviewed in this paper, where their theoretical and physical bases are examined.

118 citations


Journal ArticleDOI
TL;DR: Three different optical techniques which eliminate the signal fading problem are presented and experimentally verified and comparison of the three techniques in terms of their technical merits is presented.
Abstract: In single-mode optical fiber interferometer sensors environmental effects such as ambient temperature fluctuations and static pressure changes result in signal fading. Three different optical techniques which eliminate the signal fading problem are presented and experimentally verified. Comparison of the three techniques in terms of their technical merits is presented.

104 citations


Journal ArticleDOI
TL;DR: In this article, a technique of time-resolved interferometry capable of observing nonlinear optical phenomena down to 70 fs was presented, which can be readily extended to solids, in particular laser glasses.
Abstract: A technique of time‐resolved interferometry capable of observing nonlinear optical phenomena down to 70 fs is presented. We report the direct observation of the rotational contributions to the nonlinear refractive index of molecular liquids using this technique. The subpicosecond dynamics of such a nonlinearity in CS2 are investigated. This technique can be readily extended to solids, in particular laser glasses.

101 citations


Journal ArticleDOI
TL;DR: In this paper, a general theoretical description of modulated laser fields and power spectra for a current modulated single-mode laser is derived, taking into account both the intensity and frequency modulation (IM and FM) of the emitted light.
Abstract: A general theoretical description of modulated laser fields and power spectra for a current modulated single-mode laser is derived, taking into account both the intensity and frequency modulation (IM and FM) of the emitted light. The theory relies on an explicit knowledge of the modulus as well as the phase of the current-to-frequency modulation transfer function for the laser. Numerical examples are presented for sinusoidal, sawtooth, and square wave modulation considering broad-band and narrow-band FM cases with various amounts of IM. The IM causes a significant distortion of the pure FM spectrum, strongly dependent on the modulus and the phase of the current-to-frequency modulation transfer function. In general, it causes the FM spectrum to become asymmetrical with a change of the relative sideband level. The theoretical results have been confirmed experimentally by Fabry-Perot interferometer measurements on a temperature stabilized CSP injection laser. In the interpretation of the measurement results, the detailed characteristics of the interferometer, and the detection system are taken into account. The measurements include narrow-band and broad-band sinusoidal modulation as well as broad-band saw-tooth and square wave modulation.

91 citations


Journal ArticleDOI
TL;DR: In this article, a hybrid electro-optic oscillator is built up with an integrated Mach-Zehnder interferometer on LiNbO3 and an electrical feedback circuit.
Abstract: A hybrid electro‐optic oscillator is built up with an integrated Mach–Zehnder interferometer on LiNbO3 and an electrical feedback circuit. Oscillation frequencies up to 1.54 GHz are achieved due to the high‐frequency properties of the modulator. Oscillator operation as well as the synchronization behavior are analyzed by the describing function technique.


Journal ArticleDOI
TL;DR: Electronic speckle pattern interferometry (ESPI) as mentioned in this paper enables static and dynamic surface displacements to be measured in real time to an accuracy of the order of a wavelength of light.
Abstract: Electronic speckle pattern interferometry (ESPI) enables static and dynamic surface displacements to be measured in real time to an accuracy of the order of a wavelength of light. The principles of the technique are outlined and the different configurations of interferometers described. Some applications of the technique are discussed.

Journal ArticleDOI
TL;DR: In this paper, a holographic interferometer specially designed for measuring diffusion coefficients in transparent mixtures is described, and the diffusion coefficient is simply and directly measured from the interferograms using a finite fringe system intentionally introduced into the interFERometer.
Abstract: A holographic interferometer specially designed for measuring diffusion coefficients in transparent mixtures is described. The diffusion coefficient is simply and directly measured from the interferograms using a finite fringe system intentionally introduced into the interferometer. Preliminary results concerning the KCl-water diffusion system are in reasonable agreement with other methods. The results obtained for diffusion of diphenyl ether in hexadecane are also presented.

Proceedings ArticleDOI
19 Nov 1982
TL;DR: In this article, an interferometer which provides for the precise figure measurement of optical surfaces through the interference of two pencil beams, reflected off the optical surface, is presented, and the accuracy of the figure measurement is ± 2 nm.
Abstract: An interferometer which provides for the precise figure measurement of optical surfaces through the interference of two pencil beams, reflected off the optical surface. Since reference surfaces are not required, the interferometer is also capable of analysing aspheric optical surfaces like axicons. The accuracy of the figure measurement is ± 2 nm.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Journal ArticleDOI
TL;DR: In this paper, the statistical theory of coherent speckle patterns is compared to classical coherence theory, and it is shown that the Hanbury Brown and Twiss effect is directly analogous to the Coherence effect.
Abstract: The statistical theory of fully developed, coherent speckle patterns is compared to classical coherence theory. It is shown that speckle correlations are directly analogous to the Hanbury Brown and Twiss effect. On that background a unified description is given for a number of measurement techniques based on intensity correlation measurements in scattered laser light: holographic interferometry, speckle pattern interferometry, speckle photography, stellar speckle interferometry, laser Doppler velocimetry and intensity correlation spectroscopy.

Journal ArticleDOI
TL;DR: In this paper, an integrated optical temperature sensor consisting of a parallel array of unequal arm-length waveguide interferometers in LiNbO3 has been designed and the key components have been demonstrated.
Abstract: An integrated optical temperature sensor requiring no electrical connection and consisting of a parallel array of unequal arm‐length waveguide interferometers in LiNbO3 has been designed and the key components have been demonstrated. The optical transmission of each interferometer varies sinusoidally with temperature with a period inversely proportional to the path length difference between the two arms. This device has a projected range and resolution of ≳700 °C and 2×10−3 °C, respectively, and would be particularly useful in applications requiring immunity to electrical noise.


Patent
10 Sep 1982
TL;DR: In this paper, the authors used retro-reflecting mirrors (16, 18) in a monolithic interferometer assembly, where the mirrors are not at 90 degrees to the propagation vector (29, 43) of the radiation, but rather at a small angle.
Abstract: State of the art Fourier transform spectrometers are useful scientific tools. But, they are very complex precision electro-optical-mechanical instruments. To simplify the instrument, the need for a mechanical slide mechanism to create a path difference has been eliminated by the use of retro-reflecting mirrors (16, 18) in a monolithic interferometer assembly (11) wherein the mirrors (16, 18) are not at 90 degrees to the propagation vector (29, 43) of the radiation (27), but rather at a small angle (49). The resulting interference fringes (51, 53) create a double-sided interferogram (33) of the source irradiance distribution which is detected by a charge-coupled device (CCD) array (23). The position of each CCD pixel (25) in the array is an indication of the path difference between the two retro-reflecting mirrors (16, 18) in the monolithic optical structure. The Fourier transform of the signals generated by the CCD array (23) provide the spectral irradiance distribution of the source. For imaging, the interferometer assembly (11) scans the source of irradiation by moving the entire instrument, such as would occur if it was fixedly mounted to a moving platform, e.g., a spacecraft. During scanning, the entrance slot (21) to the monolithic optical structure send different pixels to corresponding interferograms detected by adjacent columns of pixels at the CCD array (23).

Journal ArticleDOI
TL;DR: In this article, a new approach to the detection of rotation rate using the optical fiber Sagnac interferometer is described, and a prototype system has exhibited noise levels in the region of 100°/h, and improvement to the signal processing will soon improve on this figure.
Abstract: This paper describes a new approach to the detection of rotation rate using the optical fiber Sagnac interferometer. An inherently reciprocal heterodyne system gives the advantages in terms of signal-to-noise ratios (SNR's) of heterodyne detection, while independent electronic monitoring of each propagation path through the interferometer significantly enhances signal processing flexibility. The system may thus be used as a probe to evaluate fiber properties in a way compatible with other architectures, and these measurements should lead to advances in performance characteristics. A prototype system has exhibited noise levels in the region of 100°/h, and improvement to the signal processing will soon improve on this figure.

Journal ArticleDOI
TL;DR: In this paper, a polyvinylidene fluoride (PVF 2 ) phase shifter is characterized in terms of amplitude response linearity, frequency response uniformity, and ultimate sensitivity to electric field.
Abstract: A polyvinylidene fluoride (PVF 2 ) phase shifter is characterized in terms of amplitude response linearity, frequency response uniformity, and ultimate sensitivity to electric field. Phase-drift compensation with this PVF 2 device is demonstrated in a Mach-Zehnder fiber interferometer. The compensator can be operated at the \pi/2 -phase mode for maximum sensitivity in detection applications, or the π-phase mode for maximum frequency mixing efficiency.

Journal ArticleDOI
TL;DR: Nonreciprocal phase shift has been predicted and observed in a fiber-optic gyroscope based on a Sagnac interferometer when the intensities of the counterpropagating beams are unequal and the data are consistent with theoretical predictions based on four-wave mixing in the quartz fiber.
Abstract: Nonreciprocal phase shift has been predicted and observed in a fiber-optic gyroscope based on a Sagnac interferometer when the intensities of the counterpropagating beams are unequal. The magnitude of this intensity-induced phase shift is 1.4 rad/W power difference. At 1-μW power difference, this is equivalent to a rotation rate of 0.2°/h in our 200-m-long fiber with a core radius of 2.25 μm that is wound around a spool of 19-cm diameter. The data are consistent with theoretical predictions based on four-wave mixing in the quartz fiber.

Journal ArticleDOI
TL;DR: Effectiveness of moire interferometry near the theoretical limit was proved and in-plane displacement fringes of excellent definition were obtained throughout the 76 x 51-mm field of view.
Abstract: The theoretical upper limit of moire interferometry is approached as the reference grating pitch approaches lambda/2 and its frequency approaches 2/lambda. This work demonstrates the method at 97.6% of the theoretical limit. A virtual reference grating of 4000 lines/mm (101,600 lines/in.) was used in conjunction with a phase type reflection grating of half of that frequency on the specimen. Sensitivity was 0.25 microm/fringe (9.8 microin./fringe). In-plane displacement fringes of excellent definition were obtained throughout the 76 x 51-mm (3 x 2-in.) field of view. They were very closely packed, exhibiting a maximum fringe density of 24 fringes/mm (610 fringes/in.). Effectiveness of moire interferometry near the theoretical limit was proved.

Patent
05 Nov 1982
TL;DR: In this paper, a two-dimensional, long baseline (D) direction finding interferometer (12) is provided for obtaining unambiguous spatial position of an object, which comprises four antenna receiving means, (A1, A2, A3, A4) arranged in a 2D planar fashion.
Abstract: A two-dimensional, long baseline (D) direction finding interferometer (12) is provided for obtaining unambiguous spatial position of an object. The interferometer comprises four antenna receiving means, (A1, A2, A3, A4) which are arranged in a two-dimensional, planar fashion. Three of the antenna means (A1, A2, A3) are positioned on two orthogonal axes (D, D2). The remaining antenna (A4) means is positioned on a third axis (D1) which is arranged asymmetrically and nonorthogonally to the orthogonal axes, whereby the unambiguous spatial position of the object is determined.

Patent
22 Oct 1982
TL;DR: In a surface profile interferometer, a test surface is illuminated by a beam having components at orthogonal directions of polarization which are focused at different axial distances so that the areas of intersection with the surface differ by a factor of ten or more, and any phase difference introduced by reflection by the surface is sensed by an interference technique as discussed by the authors.
Abstract: In a surface profile interferometer, a test surface is illuminated by a beam having components at orthogonal directions of polarization which are focused at different axial distances so that the areas of intersection with the surface differ by a factor of ten or more, and any phase difference introduced by reflection by the surface is sensed by an interference technique. Alternatively, the beam components are focused at equal distances but are laterally separated.

Journal ArticleDOI
TL;DR: In this article, the minimum dispersion spectrum of a singlemode silica fiber was measured with 0.1 ps resolution by a crosscorrelation method using a CW halogen lamp source and a Mach-Zehnder fibre interferometer configuration.
Abstract: The minimum-dispersion spectrum of a single-mode silica fibre has been measured with 0.1 ps resolution by a crosscorrelation method using a CW halogen lamp source and a Mach-Zehnder fibre interferometer configuration.

Journal ArticleDOI
TL;DR: An optical theory is developed to calculate the power transmission of a Gaussian beam through a hollow circular dielectric waveguide, and the results agree well with theoretical relations derived from propagation constants of modes.
Abstract: An optical theory is developed to calculate the power transmission of a Gaussian beam through a hollow circular dielectric waveguide. This theory uses Fresnel formulas of wave reflection on a dielectric wall and approximate formulas of Gaussian beam diffraction through a circular aperture. The calculation is valid for low-loss waveguides and for beams weakly diffracted by the guide aperture. These conditions are fulfilled in most of the usual cases. The results agree well with theoretical relations derived from propagation constants of modes. An application is made to the waveguides used in the infrared interferometer for the JET tokamak.

Journal ArticleDOI
TL;DR: The Heterodyne holographic interferometry system was used to measure temperature and specie-concentration distribution in natural convection boundary layers in air adjacent to heated surfaces through which a second gas is emitted or injected.
Abstract: Heterodyne holographic interferometry is employed to measure refractive-index distributions in transparent media. A system using a He–Ne laser and relatively modest electronic instrumentation is described. The system was used to measure temperature and specie-concentration distribution in natural convection boundary layers in air adjacent to heated surfaces through which a second gas is emitted or injected.

Book ChapterDOI
TL;DR: In this paper, the authors present a survey of the Fourier optical transfer theory and discuss the problems connected with off-axis holography, and the problems associated with the use of offaxis holograms.
Abstract: Publisher Summary The chapter introduces a new method called holography, the actual purpose is to invent an electron optical device able to produce strongly magnlfied images, the aberrations of that can be eliminated afterward by light optical processing. The shadow electron microscope of Boersch can be used for the electron optical step. The optics of this system is identical with that of a modern scanning transmission electron microscope, using a fixed and slightly defocused electron probe. The chapter reveals that the electron holograms can be taken in a conventional electron microscope by applying large defocusings. The chapter presents the survey of the Fourier optical transfer theory. In the course of these considerations, it has become clear that the range of application of Gabor's method is restricted either to pure weak amplitude objects or to pure weak phase objects. The extension of this method to strong objects, however, is not possible and the problems are discussed in the chapter. The problems connected with off-axis holography are also discussed. The chapter explains that the object and reference waves in the electron microscope is created by splitting the illumination wave, using an electrostatic biprism. But in close analogy to the current light optical reconstruction methods, object and reference waves can also be generated by means of a scattering foil, and the interferometric method employing amplitude splitting by crystal diffraction instead of wave front splitting was recently brought to a successful conclusion by Matteucci. The chapter deals with recent investigations in this field.

Journal ArticleDOI
TL;DR: In this paper, the dispersion of the second virial coefficients B(T) was determined in the case of neopentane at four different temperatures between 283 and 363 K. Berthelot's equation gave the best overall-fit of reasonable experimental ß(r)-values of NEOPENTANE in the extended range 283 < 7" < 550.
Abstract: Scanning-wavelength interferometry is proposed as a method for precise investigations of the (complex) index of refraction of gases in dependence on wavelength A, temperature and pressure p. At — 293 the (real) index of refraction of the gases He, Ne, Ar, H2, N2, 02 and CH4 has been investigated in dependence on (0 < < 1.4 bar) and (400 nm < < 700 nm) in order to determine the dispersion of the mean molecular polarizabilities a(i). In the case of neopentane C(CH3)4 corresponding measurements are accomplished at four different temperatures between 283 and 363 K. In addition to the hitherto unknown dispersion of ( ) second virial coefficients B(T) are determined. Berthelot's equation gave the best overall-fit of reasonable experimental ß(r)-values of neopentane in the extended range 283 < 7" < 550 . For this gas the influence of temperature on a(A) and the influence of gas Sorption on B(T)measurements are discussed.