Papers by Keyword: Phase-Shifting Digital Holography

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Authors: Terutake Hayashi, Masaki Michihata, Yasuhiro Takaya
Abstract: The nondestructive, non-contact, three-dimensional evaluation of optical glass has been important to the manufacturing of high-precision optical components. In order to achieve high-precision nondestructive evaluation of optical heterogeneity, we develop a versatile evaluation system using the parallel phase- shift digital holography, which enables measurements of the optical path differences at a nanometer-scale resolution. The amplitude and phase distributions of the object wave can be reconstructed directly from a single hologram by using the parallel phase-shift digital holography system. The optical heterogeneity of a sample is determined quantitatively based on the distribution of the optical path differences quantitatively.
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Authors: Hitomi Matsukawa, Motoharu Fujigaki, Toru Matui, Yoshiharu Morimoto
Abstract: Phase-shifting digital holography can be used for displacement measurement instead of strain gauge. Our research group is developing the measurement equipment for phase-shifting digital holography. Generally, in the measurement equipment, piezo stages are used as phaseshifting devices. But the piezo stage is expensive. Cheaper and smaller phase-shifting device is required in order to put the measurement equipment into practical use. In this paper, we, therefore, propose a phase-shifting device using the deflection of a cantilever and we verify whether this phase-shifting device can be usedfor digital holography.
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Authors: T. Kita, Yoshiharu Morimoto, Motoharu Fujigaki, Toru Matui
Abstract: Displacement measurement can be performed with high accuracy using phase-shifting method. In phase-shifting method, it is often used four steps of phase-shifting for one cycle. In conventional method, to measure the displacement of an object by an interferometer, the phase of a reference beam should be shifted by every π/2 in the four-step phase-shifting. In this paper, a phase-shifting method with unknown intervals is proposed. This method does not need to shift a phase by every π/2. It can detect an intensity distribution and a phase distribution from five fringe images with equal intervals even if the phase-shift amount is unknown. Using this method, we propose a displacement measurement of phase-shifting digital holographic interferometry using spherical wave as reference wave.
211
Authors: S. Okazawa, Motoharu Fujigaki, Yoshiharu Morimoto, Toru Matui
Abstract: In this paper, we apply phase-shifting digital holographic interferometry to simultaneous measurement for out-of-plane and in-plane displacements by employing two beam illuminations for an object. Phase-shifted holograms before and after displacements of the object using each of two beams are recorded by a CCD camera, separately. The complex amplitude at each pixel of the CCD plane is analyzed from the holograms taken with phase-shifting. The complex amplitude of he object is reconstructed from the complex amplitude distribution on the CCD plane using the Fresnel diffraction integral. Each directional phase difference distribution is obtained by calculating the phases before and after deformation for each directional beam. The phase distribution for out-of-plane displacements is obtained by calculating the sum of the two phase difference distributions. The phase distribution for in-plane displacements is obtained by calculating the difference of the two phase difference distributions. The phase values provide accurate displacement distribution information. Actually, when the object deforms in both out-of-plane and in-plane directions, it is possible to analyze the displacement distribution in each direction. The theory and an experiment are shown.
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