A Multi-Wavelength Interferometric Phase Detection Method for Point Diffraction Measurement System

Abstract

The invention discloses a multi-wavelength interference phase detection method for a point diffraction measurement system, which comprises three lasers for emitting the red light, the green light andthe blue light respectively. The light beams of the three lasers are combined into a beam through a frequency stabilizing and beam combining unit respectively. After that, the light beam is convergedto a pinhole diffraction plate through a converging lens. A high-precision spherical wave, generated by diffraction, is divided into two parts, namely a detection wave surface and a reference wave surface. The detection wave surface is reflected to the pinhole diffraction plate by a measured part, and is reflected again by the pinhole diffraction plate to be interfered with the reference wave surface. An interference image formed by the two coherent light beams is collected by a 3 CCD through an imaging lens set, and the 3 CCD is connected with a computer. The diffraction interference is carried out at the same time through three lasers, namely the red, green and blue lasers. Meanwhile, three interference images are obtained at the same time, and the interference images are solved by an iterative method. An iteration initial value is obtained through a statistical method and a Chinese remainder theorem, and finally the phase position is obtained. In this way, a light path after a pinhole is kept simple based on the point diffraction method. Moreover, multiple interference images are obtained at the same time, so that the anti-vibration performance is achieved.

Description

technical field [0001] The invention belongs to the technical field of surface shape measurement by optical interference method, in particular to a phase acquisition method that is anti-vibration and free from the use of a special phase shifting device, especially a multi-wavelength interference phase detection for a point diffraction measurement system method. Background technique [0002] Manufacturing large-caliber, high-precision, large-offset and high-precision aspheric surfaces requires higher-precision detection methods and equipment. The measurement accuracy of traditional Fizeau interferometers or Tieman Green interferometers is limited by the physical standard lens they use. Due to the limitation of accuracy, the measurement accuracy cannot be further improved. The point diffraction interferometry method can form a diffraction spherical wave with ultra-high precision through the diffraction of micron-sized holes (spherical error<λ / 10 5 ) as a reference wavefro...

AI Technical Summary

Problems solved by technology

This type of method requires complex optical devices to form a phase-shifting unit. For point diffraction interferometry, it can guarantee high-precision detection, on the one hand because of its high-precision diffraction of spherical waves, on the other hand because of its self-diffraction pinhole The rear optical path is very simple, except for the necessary imaging device placed in front of the CCD, there are no other optical components, and adding other devices will introduce additional errors

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