Fringe-print-through error analysis and correction in snapshot phase-shifting interference microscope.

Yu Zhang,Rongguang Liang,Xiaobo Tian

doi:10.1364/oe.25.026554

Abstract

To reduce the environmental errors, a snapshot phase-shifting interference microscope (SPSIM) has been developed for surface roughness measurement. However, fringe-print-through (FPT) error widely exists in the phase-shifting interferometry (PSI). To ensure the measurement accuracy, we analyze the sources which introduce the FPT error in the SPSIM. We also develop a FPT error correction algorithm which can be used in the different intensity distribution conditions. The simulation and experiment verify the correctness and feasibility of the FPT error correction algorithm.

Highlights

Interferometry is the industry standard metrology method for optical surface [1] and roughness measurement [2]
The phase-shifting interferometer (PSI) was introduced by Brunning [3] to achieve accurate metrology in 1974, PSI and its variations have been widely used in optical measurement [1, 4, 5]
The simultaneous PSI based on polarization camera can avoid the instability error of the light source and environmental errors, the fringe-print-through (FPT) error [15] can be introduced by the defects in polarized components, such as polarization beam splitter (PBS), quarter-wave plate (QWP), and polarizer array (PA) in front of the pixels

Summary

Introduction

Interferometry is the industry standard metrology method for optical surface [1] and roughness measurement [2]. Since the phase-shifted interferograms are collected sequentially, the instabilities of light source intensity and frequency, vibration, and air turbulence in the working environment [8,9,10] will lead to the unavoidable and unknown phase error. To overcome these problems, two simultaneous PSIs were developed [11]. Liu et al [22] proposed a general algorithm to correct the phase error in PSI, where the points of a circle on the interferograms are used to create the Lissajous ellipse. The algorithms of correcting FPT error and generating Lissajous ellipse are introduced as well.

Principle of snapshot phase-shifting interference microscope

Error analysis

Method of generating Lissajous ellipse

Simulation

Findings

Conclusion