Phase shift point-diffraction interference detection device and method based on reflecting grating

Abstract

The invention belongs to the technical field of optical interference detection and particularly relates to a phase shift point-diffraction interference detection device and method based on a reflecting grating. The phase shift point-diffraction interference detection device based on the reflecting grating comprises a light source, a collimation and beam expanding system, a window, an object to be detected, a first lens, an unpolarized splitting prism, the reflecting grating, a small-hole reflector, a second lens and an image sensor. A light beam emitted by the light source enters the collimation and beam expanding system, the outgoing beam subjected to collimation and beam expanding of the collimation and beam expanding system enters the first lens through the window and the object to be detected, and the light beam subjected to focusing of the first lens is divided into a bundle of reference light and a bundle of object light by the unpolarized splitting prism. The reference light irradiates to the small-hole reflector, and the object light irradiates to the reflecting grating. The phase shift point-diffraction interference detection device based on the reflecting grating is low in system complexity and cost, simple in structure, flexible and convenient to operate and free of special optical elements of a polarizer group and the like.

Description

Technical field [0001] The invention belongs to the technical field of optical interference detection, and specifically relates to a phase shift point diffraction interference detection device and a detection method based on a reflection grating. Background technique [0002] Because of its unique characteristics such as non-contact, high resolution, and no special processing of samples, optical interference detection has been widely used in the detection of optical surfaces, deformation and thickness. The current optical interference detection structure can be divided into two types: split optical path and common optical path: split optical path interferometers, such as Tymann-Green interferometer, Mach-Zehnder interferometer, etc. Because the reference beam and the measurement beam interfere through different paths, it is easy to Affected by external vibration, temperature fluctuations, etc. Compared with the split optical path interferometer, the common optical path interfero...

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Problems solved by technology

This method only needs to collect one interferogram to obtain quantitative phase information, and the measurement efficiency is high. However, because of the off-axis structure, the spatial bandwidth and spatial sampling capability of the camera are sacrificed, which in turn limits the spatial resolution of the system and is easy to lose. High-frequency information of the measured sample

[0004] Patent 201310206690.1 "A Reflective Point Diffraction Off-Axis Synchronous Phase-Shifting Interference Detection Device and Detection Method" introduces the light-splitting synchronous orthogonal phase-shift technology based on the polarization beam splitter prism, and obtains two orthogonal phase-shifts through one exposure acquisition. While improving the measurement efficiency, the measurement resolution of the system is improved, but the system is complex and the utilization rate of the camera's field of view is low

[0005] Guo Rongli of Xi'an Institute of Optics and Mechanics proposed a reflective point-diffraction coaxial micro-interferometer (R.Guo, B.Yao, P.Gao, J.Min, J.Zheng, T.Ye. "Reflective Point- diffraction microscope interferometer with long term stability."COL 2011,9(12):120002.), through the introduction of polarization phase shift technology, four phase shifted interferograms are collected in time sequence exposure, the field of view utilization rate is high, but because at least 4 The plate polarizing element realizes the phase shift, and the system complexity is high

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