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Proceedings ArticleDOI

Edge enhancement of phase objects using a cyclic-path polarization interferometer

15 Jun 2015-Vol. 9654, pp 138-142

AbstractThe aim of this study is to model edge enhancement effect in purely phase samples. A self compensating interferometer similar to Sagnac’s, employed with a polarizing beam splitter where two counter propagating orthogonally polarized mutually coherent beams are modulated by the phase shifts introduced by a phase sample. An afocal imaging system is used to image the phase sample on the CCD so that one of the images is slightly defocused. Real-time subtraction of two images results in intensity modulation of phase interfaces.

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References
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Journal ArticleDOI
TL;DR: An approach is proposed for removing the wavefront curvature introduced by the microscope imaging objective in digital holography, which otherwise hinders the phase contrast imaging at reconstruction planes and it is shown that a correction effect can be obtained at all reconstruction planes.
Abstract: An approach is proposed for removing the wave front curvature introduced by the microscope imaging objective in digital holography, which otherwise hinders the phase contrast imaging at reconstruction planes. The unwanted curvature is compensated by evaluating a correcting wave front at the hologram plane with no need for knowledge of the optical parameters, focal length of the imaging lens, or distances in the setup. Most importantly it is shown that a correction effect can be obtained at all reconstruction planes. Three different methods have been applied to evaluate the correction wave front and the methods are discussed in detail. The proposed approach is demonstrated by applying digital holography as a method of coherent microscopy for imaging amplitude and phase contrast of microstructures.

376 citations

Journal ArticleDOI
TL;DR: A new technique for the simultaneous measurement of refractive index and wedge angle of optical windows using Fizeau interferometry and a cyclic path optical configuration (CPOC).
Abstract: We present a new technique for the simultaneous measurement of refractive index and wedge angle of optical windows using Fizeau interferometry and a cyclic path optical configuration (CPOC). Two laterally separated beams are obtained from an expanded collimated beam using an aperture containing two rectangular openings. The test wedge plate is placed in one of the two separated beams. Using CPOC, these two beams are made to overlap and interfere, producing interference fringes in the overlapping region. The beams reflected from the front and back surfaces of the test wedge plate interfere and produce Fizeau fringes. The refractive index is related to the spacing of the above two beam fringes. The wedge angle is determined from the evaluated values of the refractive index and Fizeau fringe spacing. The results obtained for a BK-7 optical window are presented.

13 citations

Journal ArticleDOI
TL;DR: The polarization phase shifting technique is used to generate four phase-shifted interferograms, which are utilized to evaluate the phase profile of the phase sample.
Abstract: A polarization phase shifting interferometer using a cyclic path configuration for measurement of phase nonuniformities in transparent samples is presented. A cube beam splitter masked by two linear polarizers is used to split the source wavefront into two counter propagating linearly polarized beams that pass through the sample. At the output of the interferometer, the two orthogonally polarized beams are rendered circularly polarized in the opposite sense through the use of a quarter wave plate. Finally, phase shifting is achieved by rotating a linear polarizer before the recording plane. In a rectangular path interferometer, although the two counter propagating wavefronts are laterally folded with respect to each other in the interferometer arms, the beams finally emerge mutually unfolded at the output of the interferometer. This phenomenon is utilized to create a reference if the sample is introduced in one lateral half of the beam in any one of the interferometer arms. The polarization phase shifting technique is used to generate four phase-shifted interferograms, which are utilized to evaluate the phase profile of the phase sample. Experimental results presented validate the proposed technique.

11 citations

Journal ArticleDOI
TL;DR: The results of the development of a much simpler optical configuration for the long-trace profiler (LTP) are presented, which employs a cyclic optical configuration to achieve zero optical path difference for the closely spaced, laterally separated laser beams.
Abstract: The results of the development of a much simpler optical configuration for the long-trace profiler (LTP) are presented. The current technique employs a cyclic optical configuration to achieve zero optical path difference for the closely spaced, laterally separated laser beams. The accuracy of measurement is found to remain as good as that in the case of the widely used LTP, although the geometrical alignment problem is simplified significantly.

9 citations

Journal ArticleDOI
TL;DR: Two compact cyclic interferometers which can be used for the testing of right-angle prisms are described; with some modifications they can also be use for testing convergent wave fronts.
Abstract: In this paper, we describe two compact cyclic interferometers which can be used for the testing of right-angle prisms; with some modifications they can also be used for testing convergent wave fronts.

8 citations