Micro-topography measurement method based on white light interference zero optical path difference position picking algorithm

Abstract

The invention provides a micro-topography measurement method based on a white light interference zero optical path difference position picking algorithm. The micro-topography measurement method basedon the white light interference zero optical path difference position picking algorithm comprises the following steps: S1, obtaining a white light interference template curve; S2, vertically scanningan object to be measured, collecting interference fringes, and obtaining sampling points; S3, using a gravity center method or an extremum method to quickly and coarsely locate the zero optical path difference point; S4, determining a search range, taking a number of sampling points within a certain range around the zero optical path difference point as points to be matched; S5, matching the points to be matched with the template curve in the search range to obtain a finely positioned zero optical path difference point; and S6, obtaining the accurate relative height of the object surface topography according to a correlation between the zero optical path difference and the morphology height, thereby reconstructing the 3D shape of the object to be measured. The micro-topography measurementmethod based on the white light interference zero optical path difference position picking algorithm has simple algorithm, high speed, high precision and good anti-noise ability.

Description

technical field [0001] The invention relates to the technical field of precision optical measurement engineering, and more specifically, to a microscopic shape measurement method based on a white light interference zero optical path difference position picking algorithm. Background technique [0002] The microscopic topography of the surface of an object largely affects its quality and performance. With the continuous development of ultra-precision machining technology, the corresponding ultra-precision detection technology is becoming increasingly important. White light interferometry technology is one of the very important non-contact surface micro-topography optical measurement technologies, which solves the phase ambiguity problem of laser interferometer when the measured surface discontinuous height jump exceeds a quarter wavelength. The basic principle of white light interferometry is: the light emitted by the light source passes through a part of the optical path and...

AI Technical Summary

Problems solved by technology

The extreme value method directly uses the maximum light intensity value as the zero optical path point, which is very simple and fast, and the accuracy is mainly determined by the scanning step distance, and is easily affected by noise, resulting in poor accuracy; It is also susceptible to noise, and the accuracy is not high; the accuracy of the white light phase shift method is higher than that of the extreme value method and the center of gravity method, and lower than that of the envelope curve fitting method and the space frequency domain method, and the calculation speed is moderate; the envelope curve fitting method has Fourier transform Filtering method, Hilbert transform method, wavelet transform method and direct quadratic polynomial fitting method, etc., generally speaking, have high accuracy, but the calculation amount is large, time-consuming, and it is difficult to meet the requirements of online measurement; the spatial frequency domain method has relatively high High precision, but requires Fourier transform and least square fitting, and the amount of calculation is large

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