Paper
16 December 2019 Phase unwrapping and range enlargement in phase-shifting dual-wavelength digital holography
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Abstract
The dual wavelength interferometry in digital holography can eliminate 2π ambiguities with a large synthetic wavelength, but the measurement error tends to be amplified. In this paper, a new numerical algorithm is proposed to reduce the amplification error, and further expand the measurement range. The wrapped phase map associated with one wavelength is used to assist unwrapping the phase map associated with the other wavelength. Since these two phase maps correspond to the same step height, an exhaustive searching method is applied. The measurement error will not be amplified linearly with the synthetic wavelength, but controlled at the same level with the single wavelength interferometry. In consideration of the measurement errors such as the environmental vibration, instability of wavelength and so on, a tolerance is set to guarantee the stability of the solution. The performance and feasibility of the proposed algorithm is verified by the numerical demonstration.
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Yu Cheng, Xiangchao Zhang, He Yuan, Wei Wang, Shaoliang Li, and Siping Peng "Phase unwrapping and range enlargement in phase-shifting dual-wavelength digital holography", Proc. SPIE 11189, Optical Metrology and Inspection for Industrial Applications VI, 1118908 (16 December 2019); https://doi.org/10.1117/12.2537464
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KEYWORDS
Digital holography

Interferometry

Optical testing

Phase measurement

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