Polarization-shifting method for step interferometry
01 Jan 1998-Pure and Applied Optics: Journal of The European Optical Society Part A (IOP Publishing)-Vol. 7, Iss: 1, pp 53-60
TL;DR: In this article, a phase step interferometry system using polarization shifting is described, which is essentially a Mach-Zehnder interferometer in which the polarization of light travelling through one arm is orthogonal to the polarization travelling through the other arm.
Abstract: A phase step interferometry system using polarization shifting is described. The device is essentially a Mach-Zehnder interferometer in which the polarization of light travelling through one arm is orthogonal to the polarization of light travelling through the other arm. At the interferometer output we place a quarter-wave plate with its fast axis at with respect to the polarization directions and a polarizer. By rotating the polarizer, the interfering waves acquire an extra phase (of topological origin) to that expected from the calculations of optical path lengths, and thus, arbitrary phase shifts can be induced. Then, from a set of interferograms recorded while the reference phase is changed, the `dynamical' phase difference (e.g. the phase profile of an object placed in one of the interferometer arms) can be reconstructed by using techniques of phase-shifting interferometry.
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TL;DR: An extensive numerical and experimental analysis endorses the algorithm reliability and accuracy and confirms its usefulness for antennas having a general radiating (vector) behavior, i.e., either focusing or non-focusing.
Abstract: The problem of antenna characterization from phaseless near-field data is addressed by appropriate use of the available information on the Antenna Under Test (AUT) and on the scanning geometry to provide efficient representations for both the unknowns and the data. Such a strategy allows improving the reliability and the accuracy of the proposed characterization algorithm and, at the same time, shortens the overall measurement process. An extensive numerical and experimental analysis, together with a comparison with existing approaches, endorses the algorithm reliability and accuracy and confirms its usefulness for antennas having a general radiating (vector) behavior, i.e., either focusing or non-focusing.
67 citations
Cites background from "Polarization-shifting method for st..."
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TL;DR: A simple method for visualization of phase objects placed between a printed two-dimensional periodic pattern and a CCD camera that has potential application for detection of gas leaks in industrial environments.
Abstract: We describe a simple method for visualization of phase objects The phase object is placed between a printed two-dimensional periodic pattern and a CCD camera The ray deflection that is due to the phase object distorts the image of the pattern This image is subtracted from a reference image and then, by squaring and low-pass filtering, a measurement of the two-dimensional refractive-index changes is obtained Because the optical system does not require special alignment or illumination, the method presented has potential application for detection of gas leaks in industrial environments
35 citations
TL;DR: In this paper, the trajectories of the wave light polarization during the polarization process were determined using the Stokes vector representation, and it was shown that such trajectories are not always geodesics of the Poincare sphere as is usually thought.
Abstract: The polarization process when polarizers act on an optical field is studied. We give examples for two kinds of polarizers. The first kind presents an anisotropic absorption—as in a Polaroid film—and the second one is based on total reflection at the interface with a birefringent medium. Using the Stokes vector representation, we determine explicitly the trajectories of the wave light polarization during the polarization process. We find that such trajectories are not always geodesics of the Poincare sphere as is usually thought. Using the analogy between light polarization and special relativity, we find that the action of successive polarizers on the light wave polarization is equivalent to the action of a single resulting polarizer followed by a rotation achieved, for example, by a device with optical activity. We find a composition law for polarizers similar to the composition law for noncollinear velocities in special relativity. We define an angle equivalent to the relativistic Wigner angle which can be used to quantify the quality of two composed polarizers.
25 citations
TL;DR: In this paper, a robust one-beam interferometer with external phase-delay control is described, where the two arms are together in one collimated beam, and an additional phase delay is introduced by application of an electrical current to the Faraday rotator or by rotation of the polarizer (the latter being of topological origin).
Abstract: A robust one-beam interferometer with external phase-delay control is described. The device resembles a Mach-Zehnder interferometer in which the two arms are together in one collimated beam. However, the proposed device is not an amplitude-division interferometer but a wave-front division one. The phase-delay control occurs at the interferometer output with the help of two polarizing beam splitters, a quarter-wave plate, a Faraday rotator, and a polarizer. An additional phase delay is introduced by application of an electrical current to the Faraday rotator or by rotation of the polarizer (the latter is of topological origin), which permits the use of techniques of phase-stepping interferometry.
21 citations
TL;DR: In this paper, the polarization-to-phase conversion of space-variant polarized light waves was investigated and it was shown that using an azimuthally and radially variant polarizer combined with a circular analyzer, it is possible to induce spinto-orbital angular momentum exchange and to generate optical vortices of arbitrary charge.
Abstract: We investigate the polarization-to-phase conversion of space-variant polarized light waves. Our analysis can be considered as an extension of Pancharatnam's phase to the case of space-variant polarization. In two particular cases - azimuthally and radially variant polarization - we found striking consequences. Using an azimuthally variant polarizer combined with a circular analyzer, it is possible to induce spin-to-orbital angular momentum exchange and to generate optical vortices of arbitrary charge. Radially variant polarizers with linear or quadratic radial dependence of the transmission direction generate nondiffracting beams or focus light, respectively. Our results are potentially relevant for the design of achromatic wavefront forming (and correcting) elements based strictly on space-variant polarization optics.
13 citations
References
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TL;DR: In this article, an achromatic phase shifter operating on the geometric phase can be used to evaluate the fringe contrast directly and to locate the position of the zero-order white-light fringe along the scanning axis.
Abstract: Interferometric profilers suffer from phase ambiguities if the measurement range involves a change in the optical path difference greater than a wavelength This limitation has been overcome by using white light and scanning the object in height We show how an achromatic phase shifter operating on the geometric phase can be used to evaluate the fringe contrast directly and to locate the position of the zero-order white-light fringe along the scanning axis
70 citations
TL;DR: In this article, the same intensity data obtained with white light and an achromatic phase shifter in an interferometric surface profiler can be used to locate the peak of the visibility curve as the test surface is moved in steps along the height axis.
Abstract: Intensity data obtained with white light and an achromatic phase shifter in an interferometric surface profiler can be used to locate the peak of the visibility curve as the test surface is moved in steps along the height axis. We show that the same intensity data can also be used to find the fractional interference order at each point on the test surface, at the position of the test surface nearest to the visibility peak and, hence, its height at that point, with a high degree of accuracy.
33 citations
TL;DR: In this paper, a phase-shifting apparatus based on polarization techniques is developed, which changes phase only by rotating a polarizer using a precise step motor and a specially designed decelerator.
Abstract: A new computer-controlled phase-shifting apparatus based on polarization techniques is developed. This apparatus changes phase only by rotating a polarizer using a precise step motor and a specially designed decelerator. The precision of this method can be higher than other methods because of the accurate control of the rotating angle. Four applications of this technique to optical interlerometry and 3-D shape measurements are presented.
23 citations
TL;DR: This work proposes using a geometric phase modulator that is achromatic and does not suffer from bandwidth restrictions to measure the fringe visibility of stellar interferometers.
Abstract: In stellar interferometry the fringe visibility can be measured by modulating the optical path difference between the two arms of an interferometer. This approach yields accurate estimates of the fringe visibility only if the bandwidth is small, and this limits the sensitivity of the technique. We propose using a geometric phase modulator that is achromatic and does not suffer from bandwidth restrictions. Fringe detectors using geometric phase modulation have the potential of greatly increasing the sensitivity of optical stellar interferometers.
18 citations