Large-aperture high-accuracy phase-shifting digital flat interferometer

Phase-shifting interferometry is widely used because it can measure phase with high accuracy. Changing optical path length with a PZT transducer and changing frequency of the optical source with a laser diode (LD) are two common methods to apply the desired phase shift between the arms in the interferometer. In any case, however, it is not easy to apply the desired shift accurately, and if not, measurement errors occur. In order to reduce the errors, the effect of the phase shift error has been analyzed numerically especially in the case with LD.

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Determination of Phase Shift by Digital Holography

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.888.43 ◽

2019 ◽

Vol 888 ◽

pp. 43-46

Author(s):

Yoshitaka Takahashi ◽

Masatoshi Saito ◽

Toru Nakajima ◽

Masakazu Shingu

Keyword(s):

Phase Shift ◽

Noise Reduction ◽

Digital Holography ◽

High Accuracy ◽

Measured Data ◽

Phase Shifting ◽

Surface Shape ◽

Shape Measurement ◽

Phase Shifting Interferometry

In phase shifting interferometry phase shift is applied by various ways, but applying it with high accuracy, especially by LD current modulation, is not easy. In order to determine the accurate phase shift a new method has been proposed that the value of LD current corresponding to π/2 phase shift can be determined by phase shifting digital holography. The measured data of standard in surface shape measurement were used for calibration, and the obtained value was confirmed to cause noise reduction and improvement of holographic reconstructed images in digital holography.

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Testing high accuracy optics using the phase shifting point diffraction interferometer

Fifth European Seminar on Precision Optics Manufacturing ◽

10.1117/12.2316330 ◽

2018 ◽

Author(s):

Nikolay B. Voznesenskiy ◽

Diwaker Jha ◽

Mariia Voznesenskaia

Keyword(s):

High Accuracy ◽

Phase Shifting

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Phase-Shifting Method with Unknown Intervals in Phase-Shifting Digital Holography

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.3-4.211 ◽

2006 ◽

Vol 3-4 ◽

pp. 211-216

Author(s):

T. Kita ◽

Yoshiharu Morimoto ◽

Motoharu Fujigaki ◽

Toru Matui

Keyword(s):

Phase Shift ◽

Intensity Distribution ◽

Digital Holography ◽

Phase Distribution ◽

Reference Beam ◽

Spherical Wave ◽

High Accuracy ◽

Displacement Measurement ◽

Phase Shifting ◽

Phase Shifting Method

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.

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