Three-dimensional refractive index measurement of special optical fiber based on optical vortex phase-shifting digital holographic microscopy

Wei-Ping Wang; Sujuan Huang; Yi Chen; Jia-Wen Wang; Cheng Yan

doi:10.1117/1.OE.58.3.034108

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23 March 2019 Three-dimensional refractive index measurement of special optical fiber based on optical vortex phase-shifting digital holographic microscopy

Wei-Ping Wang, Sujuan Huang, Yi Chen, Jia-Wen Wang, Cheng Yan

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Optical Engineering, 58(3), 034108 (2019). https://doi.org/10.1117/1.OE.58.3.034108

Abstract

We propose an approach for three-dimensional (3-D) refractive index (RI) measurement of special optical fiber by phase-shifting digital holographic microscopy based on optical vortex. The experimental system consists of a modified Mach–Zehnder interferometer and related lab-developed software. The phase shifts are obtained by loading different computer-generated spiral phase holograms on a liquid-crystal spatial light modulator with digital blazed grating, which is more accurate than the traditional phase-shift methods. The optical vortex generated in +1 diffraction order of the diffraction field is utilized as the reference beam. Eight digital holograms with the phase-shift increments of 0, π / 2, π, and 3π / 2 are recorded by a CCD before and after the tested optical fiber is placed in the experimental system. Then, a four-step phase-shifting algorithm and phase unwrapping algorithm are adopted to extract the phase distribution from the holograms. Based on a filtered backprojection algorithm, the 3-D RI distribution of the tested fiber is obtained at high accuracy. Experimental results demonstrate the feasibility of the proposed method for 3-D RI measurement of special optical fiber.

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Wei-Ping Wang, Sujuan Huang, Yi Chen, Jia-Wen Wang, and Cheng Yan "Three-dimensional refractive index measurement of special optical fiber based on optical vortex phase-shifting digital holographic microscopy," Optical Engineering 58(3), 034108 (23 March 2019). https://doi.org/10.1117/1.OE.58.3.034108

Received: 2 December 2018; Accepted: 7 March 2019; Published: 23 March 2019

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