Author
Nandini Ghosh
Bio: Nandini Ghosh is an academic researcher from University of Calcutta. The author has contributed to research in topics: Phase (waves) & Interferometry. The author has an hindex of 2, co-authored 2 publications receiving 18 citations.
Papers
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TL;DR: A full-field technique for simultaneous measurement of the magnitude of birefringence and its orientation is presented using a monolithic bireFringence sensitive interferometer where the interference fringes carry the information of both the biretringence phase and the orientation of the fast axis of an optically transmissive anisotropic material placed at the output of the interferometers.
Abstract: A full-field technique for simultaneous measurement of the magnitude of birefringence and its orientation is presented. This is achieved using a monolithic birefringence sensitive interferometer where the interference fringes carry the information of both the birefringence phase and the orientation of the fast axis of an optically transmissive anisotropic material placed at the output of the interferometer. The interferometer consists of a suitably polarization-masked cube beam splitter, orientated as in the Gates interferometer, which serves to generate a pair of orthogonally polarized and collinearly propagating light beams. Experimental results are obtained through an algorithm incorporating eight polarization phase-shifted interferograms.
12 citations
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TL;DR: In this article, an interferometric technique for three-dimensional phase measurement of optically transparent microscopic phase samples is presented, which uses an obliquely aligned polarizer-masked cube beam-splitter, an infinity-corrected microscope objective, and a couple of simple polarization phase-shifting components.
Abstract: An interferometric technique for three-dimensional phase measurement of optically transparent microscopic phase samples is presented. An obliquely aligned polarizer-masked cube beam-splitter, an infinity-corrected microscope objective, and a couple of simple polarization phase-shifting components serve as the setup for such a measurement. Surface phase profiles are then extracted using standard phase-shifting algorithms. The salient features of the proposed technique are its simple design, in-line configuration, possibility of integration with standard microscopic systems, and inherent compensation of the substrate phase. Experimental results are presented. The overall lateral magnification is restricted due to the low numerical aperture offered by the microscope objective and cube beam-splitter combination.
9 citations
Cited by
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TL;DR: Three efficient algorithms are proposed for fast phase retrieval in slightly off-axis digital holography using spectrum cropping, spatial multiplexing, and complex encoding to speed up the previously proposed retrieval method with the assistance of specimen-free holograms.
24 citations
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TL;DR: In this paper, a full-field polarization phase shifting interferometric technique, based on the Twyman-Green interferometer, was proposed for the purpose of calibration of phase in spatial light modulators.
Abstract: Calibration of phase in spatial light modulators is a prerequisite for applications where a prespecified phase distribution needs to be imple- mented over the surface of the modulator. The present work proposes a full-field polarization phase shifting interferometric technique, based on the Twyman-Green interferometer, for the purpose. © 2013 Society of Photo-Optical
24 citations
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TL;DR: In this article, an interferometric phase microscopy (IPM) was proposed using slightly-off-axis reflective point diffraction interferometry for quantitative phase imaging, where a retro-reflector consisting two mirrors was used to generate an angle between the object beam and reference beam, and a 45° tilted polarizing beam splitter was employed to split the horizontal and vertical components of the both beams.
17 citations
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TL;DR: In this article, a novel interferometric method for the simultaneous measurement of the phase and state of polarization of a light wave with arbitrary polarization is presented, in particular, it can be varying elliptical.
Abstract: This publication presents what we believe is a novel interferometric method for the simultaneous measurement of the phase and state of polarization of a light wave with arbitrary polarization; in particular, it can be varying elliptical. The measurement strategy is based on variations of the reference wave, concerning phase and polarization and processing the interference patterns so obtained. With this method, which is very similar to classical phase-shifting interferometry, the general analysis of spatially variant states of polarization and their phase fronts can be done in one measurement cycle. Furthermore, the analysis of different optical elements regarding the impact on the polarization and phase of the incoming light can be realized. After the theoretical description of the method and the mathematical discussion of different algorithms, the realized measurement setup is presented. Afterward, the accuracy of the method is discussed.
13 citations
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TL;DR: A high-accuracy and automatic magnification calibration method that could be applied to different types of microscopes is proposed that is capable of performing the calibration over a wide range of magnifications while maintaining identical precision.
Abstract: Microscopes are widely applied in characterizing feature sizes at the micro-/nanoscale, and magnification calibration plays a key role in achieving precise measurements. However, it is difficult to obtain accurate results by using the general magnification calibration method if comparing the displayed size of a test-piece under microscope and its original one. In this study, a high-accuracy and automatic magnification calibration method that could be applied to different types of microscopes is pro- posed. A standard grating is employed as the reference, and a high-res- olution discrete Fourier transform is used to analyze the images captured under various magnifications in this method. With utilization of the high- order harmonic component in the Fourier spectrum, the proposed method is capable of performing the calibration over a wide range of magnifica- tions while maintaining identical precision. The relative error of the pro- posed method can be theoretically limited to 0.01%; moreover, the image noise can be tolerated. Furthermore, the validation and extensive adaptability of this method are demonstrated by calibrating the magnifica- tion of a scanning electron microscope and an optical microscope. © 2013 Society of Photo-Optical Instrumentation Engineers (SPIE) (DOI: 10.1117/1.OE.52.11.114102) Subject terms: magnification calibration; microscope; discrete Fourier transform; harmonic component.
9 citations