Showing papers on "Interferometry published in 1991"
Journal Article•
1,653 citations
Journal Article•
TL;DR: In this article, a self-scanned 1024 element photodiode array and a minicomputer are used to measure the phase (wavefront) in the interference pattern of an interferometer to lambda/100.
Abstract: A self-scanned 1024 element photodiode array and minicomputer are used to measure the phase (wavefront) in the interference pattern of an interferometer to lambda/100. The photodiode array samples intensities over a 32 x 32 matrix in the interference pattern as the length of the reference arm is varied piezoelectrically. Using these data the minicomputer synchronously detects the phase at each of the 1024 points by a Fourier series method and displays the wavefront in contour and perspective plot on a storage oscilloscope in less than 1 min (Bruning et al. Paper WE16, OSA Annual Meeting, Oct. 1972). The array of intensities is sampled and averaged many times in a random fashion so that the effects of air turbulence, vibrations, and thermal drifts are minimized. Very significant is the fact that wavefront errors in the interferometer are easily determined and may be automatically subtracted from current or subsequent wavefrots. Various programs supporting the measurement system include software for determining the aperture boundary, sum and difference of wavefronts, removal or insertion of tilt and focus errors, and routines for spatial manipulation of wavefronts. FFT programs transform wavefront data into point spread function and modulus and phase of the optical transfer function of lenses. Display programs plot these functions in contour and perspective. The system has been designed to optimize the collection of data to give higher than usual accuracy in measuring the individual elements and final performance of assembled diffraction limited optical systems, and furthermore, the short loop time of a few minutes makes the system an attractive alternative to constraints imposed by test glasses in the optical shop.
1,300 citations
TL;DR: It is shown that gravitational waves from astronomical sources have a nonlinear erect on laser interferometer detectors on Earth, an erect which has hitherto been neglected, but which is of the same order of magnitude as the linear erects.
Abstract: It is shown that gravitational waves from astronomical sources have a nonlinear effect on laser interferometer detectors on Earth, an effect which has hitherto been neglected, but which is of the same order of magnitude as the linear effects. The signature of the nonlinear effect is a permanent displacement of test mases after the passage of a wave train.
537 citations
TL;DR: An atomic interferometers based on a Young's-type double-slit arrangement has been demonstrated and the good visibility of the observed fringes should make it possible to measure differential phase shifts in the interferometer of 1/3 rad in less than 10 min.
Abstract: An atomic interferometer based on a Young's-type double-slit arrangement has been demonstrated. A supersonic beam of metastable helium atoms passes through a 2-\ensuremath{\mu}m-wide slit in a thin gold foil. This transversely coherent beam impinges on a second microfabricated transmission structure, consisting of two 1-\ensuremath{\mu}m-wide slits at a lateral distance of 8 \ensuremath{\mu}m. This double slit defines two possible paths on which the atoms can reach the detector slit. The good visibility of the observed fringes should make it possible to measure differential phase shifts in the interferometer of 1/3 rad in less than 10 min.
510 citations
TL;DR: In this article, a two-pulse sequence of femtosecond duration phase-locked optical laser pulses is used to resonantly excite vibronic transitions of a molecule, where a definite optical phase angle between the pulses is maintained while varying the interpulse delay with interferometric precision.
Abstract: We introduce a novel spectroscopic technique which utilizes a two‐pulse sequence of femtosecond duration phase‐locked optical laser pulses to resonantly excite vibronic transitions of a molecule. In contrast with other ultrafast pump–probe methods, in this experiment a definite optical phase angle between the pulses is maintained while varying the interpulse delay with interferometric precision. For the cases of in‐phase, in‐quadrature, and out‐of‐phase pulse pairs, respectively, the optical delay is controlled to positions that are integer, integer plus one quarter, and integer plus one half multiples of the wavelength of a selected Fourier component. In analogy with a double slit optical interference experiment, the two the two pulse experiments reported herein involve the preparation and quantum interference of two nuclear wave packet amplitudes state of a molecule.These experiments are designed to be sensitive to the total phase evolution of the wave packet prepared by the initial pulse. The direct de...
484 citations
TL;DR: A calcium atomic beam excited in an optical Ramsey geometry was rotated about an axis perpendicular to the plane defined by the laser beams and the atomic beam and a frequency shift of the Ramsey fringes of several kHz has been measured.
Abstract: A calcium atomic beam excited in an optical Ramsey geometry was rotated about an axis perpendicular to the plane defined by the laser beams and the atomic beam. A frequency shift of the Ramsey fringes of several kHz has been measured which is proportional to the rotation frequency of the apparatus and to the distance between the laser beams. The results can be interpreted in three equivalent ways as the Sagnac effect in a calcium-atomic-beam interferometer: in the rotating frame of the laser beams either along straight paths or along the curved trajectories of the atoms, or in the inertial atomic frame.
436 citations
Proceedings Article•
12 May 1991TL;DR: An atom interferometer made from three 400 nm period transmission gratings with deBroglie wavelength 0.016 nm displayed an interference signal of 70 Hz on a 300 Hz background.
Abstract: We have demonstrated an atom interferometer made from three 400 nm period transmission gratings. Sodium atoms with deBroglie wavelength 0.016 nm displayed an interference signal of 70 Hz on a 300 Hz background.
408 citations
TL;DR: In this article, a three-grating geometry is used, in which the interfering beams are distinctly separated in both position and momentum, and the interference signal is 70 counts/s, which allows us to determine the phase to 0.1 rad in 1 min.
Abstract: We have demonstrated an interferometer for atoms. A three-grating geometry is used, in which the interfering beams are distinctly separated in both position and momentum. We used a highly collimated beam of sodium atoms with a de Broglie wavelength of 16 pm and high-quality 0.4-\ensuremath{\mu}m-period free-standing gratings which we fabricated using a novel method. The interference signal is 70 counts/s, which allows us to determine the phase to 0.1 rad in 1 min. Applications of atom interferometers are briefly discussed.
404 citations
375 citations
Book•
01 May 1991
TL;DR: Light scattering theory optical mixing spectroscopy photon correlation spectroscopic interferometry experimental methods methods of data analysis characterization of polymer molecular weight distribution (particle sizing) as discussed by the authors.
Abstract: Light scattering theory optical mixing spectroscopy photon correlation spectroscopy interferometry experimental methods methods of data analysis characterization of polymer molecular weight distribution (particle sizing).
Journal Article•
TL;DR: The advantages of the laser doppler interferometry (LDI) technique are high accuracy, high transversal resolution, and more comfort for the patient (it is a noncontact method; no anesthesia is needed).
Abstract: A new technique has been developed to determine the axial length of the human eye in vivo. Based on laser interferometry in conjunction with the Doppler technique, it uses partially coherent light. This new technique complies with laser safety regulations. High accuracy is achieved, the optical length (OL) can be determined within +/- 30 microns, and the reproducibility of the geometric eye length is greater than +/- 25 microns. Possible errors are discussed. First comparisons with the ultrasound technique yield good agreement for emmetropic subjects and for subjects with a myopia of up to 10 diopters. The advantages of the laser doppler interferometry (LDI) technique are high accuracy, high transversal resolution, and more comfort for the patient (it is a noncontact method; no anesthesia is needed). Possible future applications of LDI, like measurements of fundus profiles and of retinal thickness, are mentioned.
Patent•
29 Jul 1991TL;DR: In this article, a backscattered light in response to receiving the coherent light pulses is produced and coupled into an optical receiving fiber, which is detected by a photodetector.
Abstract: Apparatus for sensing intrusion into a predefined perimeter comprises means for producing a coherent pulsed light, which is injected into an optical sensing fiber having a first predetermined length and positioned along the predefined perimeter. A backscattered light in response to receiving the coherent light pulses is produced and coupled into an optical receiving fiber. The backscattered light is detected by a photodetector and a signal indicative of the backscattered light is produced. An intrusion is detectable from the produced signal as indicated by a change in the backscattered light. To increase the sensitivity of the apparatus, a reference fiber and an interferometer may also be employed.
TL;DR: In this article, a method for measuring submicrometer distances with an asymmetric fiber Michelson interferometer having an LED as a source of radiation is described, which is compatible with time domain sampling at the Nyquist rate.
Abstract: We describe a method for measuring submicrometer distances with an asymmetric fiber Michelson interferometer having an LED as a source of radiation. By measuring the phase slope of the Fourier components in the frequency domain, it is possible to locate the position of reflections with nanometer precision even in the presence of sample dispersion. The method is compatible with time domain sampling at the Nyquist rate which assures efficiency in data acquisition and processing.
Patent•
06 Nov 1991TL;DR: In this article, an optical coherence-domain reflectometry system provides an interferometer driven by a broadband incoherent light source with the device under test connected to one arm of the interferometers and a movable scanning mirror in the other arm providing a reference signal.
Abstract: An optical coherence-domain reflectometry system provides an interferometer driven by a broadband incoherent light source with the device under test connected to one arm of the interferometer and a movable scanning mirror in the other arm providing a reference signal. The mirror moves at a controlled velocity to produce a Doppler shift in the reference signal frequency. The reference signal arm also includes a piezoelectric transducer which modulates the phase of the reference signal at a given frequency, causing a further shift in the reference signal frequency. The interference signal is detected and measured by a polarization diversity receiver. A linear polarizer in the reference signal arm is adjusted to produce equal reference signal powers in each arm of the polarization diversity receiver in the absence of a reflection signal from the test arm. The measured reflectometry signal is substantially independent of the state of polarization of the reflected signal from the device under test.
Book•
26 Jul 1991
TL;DR: Blair et al. as discussed by the authors presented an introduction to Gravitational Waves and methods for their detection, including the sources of gravitational waves, detectors, and sources of internal friction in high Q materials.
Abstract: Part I. An Introduction to Gravitational Waves and Methods for their Detection: 1. Gravitational waves in general relativity D. G. Blair 2. Sources of gravitational waves D. G. Blair 3. Gravitational wave detectors D. G. Blair Part II. Gravitational Wave Detectors: 4. Resonant-bar detectors D. G. Blair 5. Gravity wave dewars W. O. Hamilton 6. Internal friction in high Q materials J. Ferreirinko 7. Motion amplifiers and passive transducers J. P. Richard 8. Parametric transducers P. J. Veitch 9. Detection of continuous waves K. Tsubono 10. Data analysis and algorithms for gravitational wave-antennas G. V. Paalottino Part III. Laser Interferometer Antennas: 11. A Michelson interferometer using delay lines W. Winkler 12. Fabry-Perot cavity gravity-wave detectors R. W. P. Drever 13. The stabilisation of lasers for interferometric gravitational wave detectors J. Hough 14. Vibration isolation for the test masses in interferometric gravitational wave detectors N. A. Robertson 15. Advanced techniques A. Brillet 16. Data processing, analysis and storage for interferometric antennas B. F. Schutz 17. Gravitational wave detection at low and very low frequencies R. W. Hellings.
TL;DR: In this paper, a polarisation-insensitive fiber optic Michelson interferometric sensor configuration is demonstrated based on the use of birefringence compensation in a retraced fibre path using Faraday rotator mirror elements.
Abstract: A polarisation-insensitive fibre optic Michelson interferometric sensor configuration is demonstrated. The approach is based on the use of birefringence compensation in a retraced fibre path using Faraday rotator mirror elements.<
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TL;DR: In this paper, the authors describe the implementation of time-resolved step-scan FT-IR spectroscopy with a commercial interferometer, with the use of the photoreaction of the biological system bacteriorhodopsin.
Abstract: The implementation of time-resolved step-scan FT-IR spectroscopy with a commercial interferometer is described. With the use of the photoreaction of the biological system bacteriorhodopsin as an example which exhibits infrared spectral changes smaller than 10−2 absorbance units, the quality of the method is demonstrated. A comparison with conventional flash-photolysis experiments with a monochromatic infrared monitoring beam clearly demonstrates the multiplex advantage. The advantage of covering the total time course of the reaction allows for a variety of data analysis, such as forming difference spectra between intermediates of the reaction and the deduction of time courses of absorbance changes at selected wavenumbers. The mirror stability is better than ±1.5 nm, which is sufficient for the reliable measurement of small absorbance changes.
TL;DR: The performance of thermally distorted interferometers is treated quantitatively, and the two schemes for increasing the optical path, the delay-line and Fabry-P\'erot methods, are compared.
Abstract: The ultimate sensitivity of interferometric gravitational-wave detectors requires extremely high light powers sensing the separation of test masses. Absorption of light at the optical components causes wave-front distortions via the thermally deformed substrates or via thermal lensing. The performance of thermally distorted interferometers is treated quantitatively, and the two schemes for increasing the optical path, the delay-line and Fabry-P\'erot methods, are compared.
TL;DR: In this paper, a generalized phase-shifting interferometry for which the reference phases are directly evaluated at each time that the interference fringe data are read is described. But the reference phase evaluation is not considered in this paper.
Abstract: We describe a generalized phase-shifting interferometry for which the reference phases are directly evaluated at each time that the interference fringe data are read. The reference phases are obtained from the additional straight fringes on the interfering plane by the fast-Fourier-transform method. According to error estimation, the repeatabilities in the measurements of optical surfaces are λ/500 rms, when the generalized algorithm with eight data acquisitions is used.
Journal Article•
TL;DR: In this paper, periodic phase changes in the 10−6 -rad region were induced and detected in a single-mode all-fiber Mach-Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10−4 Hz.
Abstract: Periodic phase changes in the 10(-6) -rad region have been induced and detected in a single-mode all-fiber Mach- Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10(4) Hz.
TL;DR: In this article, a detailed analysis of the method of picosecond acoustic interferometry to study attenuation and velocity of longitudinal acoustic phonons in transparent materials in the Brillouin frequency range with pico-cond laser pulses is presented.
Abstract: A detailed analysis of the method of picosecond acoustic interferometry to study attenuation and velocity of longitudinal acoustic phonons in transparent materials in the Brillouin frequency range with picosecond laser pulses is presented. Experimental results for fused quartz from 90 to 300 K show good agreement with previous Brillouin scattering data. Measurements on a borosilicate glass (Corning 7059) and sapphire have also been made. This method makes these measurements possible under conditions where conventional approaches are not applicable.
TL;DR: In this paper, an interferometric fiber-optic sensor using a light-emitting diode (LED) as the optical source is analyzed and demonstrated using two Fabry-Perot interferometers (FPIs) in series, one for sensing and one which serves as a reference.
Abstract: An interferometric fiber-optic sensor using a light-emitting diode (LED) as the optical source is analyzed and demonstrated. The sensor arrangement employs two Fabry-Perot interferometers (FPIs) in series, one for sensing and one which serves as a reference. The optical output from the LED is spectrally modulated by reflection from the sensing FPI. Then, reflection or transmission by the reference FPI produces an interferometric beat response similar to that observed when a laser is used with the sensing interferometer alone. Best fringe visibility is obtained when the optical path lengths of the two interferometers are matched, and the fringes disappear when the path length difference becomes substantially greater than the coherence length of the LED. >
TL;DR: In this article, the optical thickness of the retina at the macula and the optical length of the eye has been measured and a precision of ± 0·03 mm has been obtained.
Abstract: The application of partially coherent laser light to measure intraocular optical distances is discussed In a first step the optical thickness of the retina at the macula and the optical length of the eye has been measured and a precision of ± 0·03 mm has been obtained The results of a comparison with the acoustically determined eye length and first fundus profile measurements are presented
TL;DR: In this article, it was shown that each interfering photon was essentially in an n-1 Fock state, by means of a beam splitter following the interferometer combined with a triple-coincidence technique.
Abstract: Coincidence detection of photon pairs produced in parametric fluorescence, in conjunction with a Michelson interferometer in which one member of each pair acquired a geometrical phase due to a cycle in polarization states, has allowed the first observation of Berry's phase at the single-photon level. We have verified that each interfering photon was essentially in an n=1 Fock state, by means of a beam splitter following the interferometer combined with a triple-coincidence technique. The results can be interpreted in terms of a nonlocal collapse of the wave function.
TL;DR: In this article, the Mark III optical interferometer was used to determine the angular diameters of 12 stars at wavelengths of 450 and 800 nm, and the results showed good agreement between these measurements and previously published data.
Abstract: Angular diameters determined with the Mark III Optical Interferometer are presented for 12 stars at wavelengths of 450 and 800 nm. The uniform disk diameters resulting from fits to the visibility observations have rms residuals of order 1 percent for the 800 nm measurements and less than 3 percent for the 450 nm measurements. The improvement over previous observations with this instrument is due to improved data analysis and the use of a wider range of baseline lengths. An analysis of the calibration systematics for the Mark III Optical Interferometer is included. There is good agreement between these measurements and previously published data. The changes in uniform disk diameter between wavelengths of 450 and 800 nm agree with models of stellar atmospheres.
TL;DR: This paper shows how measurement errors in phase shifting interferometry (PSI) can be described to a high degree of accuracy in a linear approximation.
Abstract: This paper shows how measurement errors in phase shifting interferometry (PSI) can be described to a high degree of accuracy in a linear approximation. System error sources considered here are light source instability, imperfect reference phase shifting, mechanical vibrations, nonlinearity of the detector, and quantization of the detector signal. The measurement inaccuracies resulting from these errors are calculated in linear approximation for several formulas commonly used for PSI. The results are presented in tables for easy calculation of the measurement error magnitudes for known system errors. In addition, this paper discusses the measurement error reduction which can be achieved by choosing an appropriate phase calculation formula.
TL;DR: Sensitive interferometry is proposed and demonstrated that permits the separation of the real and imaginary parts of the nonlinear susceptibility with a femtosecond time resolution by a single measurement.
Abstract: We propose and demonstrate sensitive interferometry that permits the separation of the real and imaginary parts of the nonlinear susceptibility with a femtosecond time resolution by a single measurement. A special reference interferometer compensates for any fluctuations of the fringe and provides high sensitivity to detect a fringe shift as small as 0.025 rad (lambda/250) by averaging only 100 shots with a low-repetition-rate laser. This method can be applied to materials with optical anisotropy and/or absorption with high sensitivity. We apply the method to two materials, CS(2) and CdS(x)Se(1-x) microcrystallite-doped glass.
Journal Article•
TL;DR: In this article, a laser interferometer transducer for a long, wideband, laser-linked gravitational radiation antenna was constructed and tested using 80 microW from a single mode Spectra-Physics 119 laser on a vibration isolation table in a quiet room.
Abstract: We have constructed and tested a laser interferometer transducer for a long, wideband, laser-linked gravitational radiation antenna. Photon-noise-limited performance was achieved using 80 microW from a single mode Spectra-Physics 119 laser in a modified Michelson interferometer on a vibration isolation table in a quiet room. A piezoelectric driver on one of the interferometer mirrors was used to generate subangstrom (3 x 10(-14)-m) vibrations of known amplitude. The measured displacement sensitivity of the system in the kilohertz region was 1.3 x 10(-14)m/Hz(1/2), which compares well with the calculated photon noise limit of 1.06 x 10(-14) m/Hz(1/2). This is the smallest vibrational displacement measured directly with a laser to date.