Three-window based common-path interference detecting method and device

Abstract

The invention relates to a three-window based common-path interference detecting method and a device and belongs to the field of optical interference detection. According to the method and the device, after parallel lights pass through three windows composed of a to-be-detected object and a rectangular window and then pass through a first lens, a one-dimensional periodic grating and a second lens in turn, the parallel lights are emitted toward an image sensor; the parallel lights are collected by the image sensor and a computer connected with the image sensor, thereby obtaining an interference image containing three patterns; the intensity distributions are respectively I-D/3, I0 and ID/3; and the intensity distributions are introduced into a formula, thereby calculating phase distribution of the to-be-detected object. The method and the device have the characteristics of excellent stability, low system complexity and simple phase recovering algorithm.

Description

technical field [0001] The invention belongs to the field of optical interference detection, in particular to a method and device for common optical path interference detection based on three windows. Background technique [0002] Optical detection method has become the main method in the field of metrology detection because of its non-contact and high sensitivity. Optical interferometry has attracted much attention in the field of precision and ultra-precision optical detection because its sensitivity can reach the order of one millionth of a wavelength. The current optical interferometry methods include Tieman-Green interferometry, Mach-Zehnder interferometry and shearing interferometry. Among them, Tieman-Green interferometry, Mach-Zehnder interferometry, etc. use separate optical path interference, that is, the reference beam and measuring beam interfere through different paths, which are easily affected by external vibrations, temperature fluctuations, etc.; shearing i...

AI Technical Summary

Problems solved by technology

This method uses two windows at the input end, one to place the measured object, and the other as a reference. By adjusting parameters such as the grating period and lens focal length, the interference pattern of the object can be obtained at the output end, and obtained by moving the grating axially or laterally. Interferograms with different phase shifts, and then the phase shift method can be used to restore the phase of the measured object, which has the advantages of simple principle and high control accuracy, but this method still needs to move the grating

[0004] Patent CN101451890B "A Three-wave Transverse Shearing Interference Device and Method for Extracting Differential Phase" uses three beams of copy light that are laterally staggered to generate transverse shearing interference, which has the advantages of compact structure, high control precision, and dynamic control. However, the method Eight shearing interferograms need to be obtained by eight-step phase-shifting method, which requires heavy detection workload and complex phase recovery algorithm

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