Two-path white light interference differential measurement device and method

Abstract

The invention discloses a dual-path white light interference differential measurement device and method. The dual-path white light interference differential measurement device comprises a broadband light source module, a first optical path modulation and demodulation module and a dual-path differential light intensity detection and recording module; the broadband light source module provides an input light signal; the first optical path modulation and demodulation module receives an input optical signal, provides two paths of white light interference signals by using a white light interference principle and a double-path differential detection principle and adopting a method of constructing an optical path difference, and converts the two paths of white light interference signals into electric signals; and the double-path differential light intensity detection and recording module receives the two paths of electric signals, differential response signals are obtained after differential detection, and an absolute reference position and a measurement position are obtained according to the differential response signals. The method is high in positioning precision, high in sensitivity and convenient in signal demodulation, and can be widely applied to quantitative measurement of information such as thickness and surface appearance of the micro-nano device.

Description

technical field [0001] The design of the invention belongs to the technical field of optical measurement, and specifically relates to a two-way white light interference differential measurement device and method. Background technique [0002] In the field of optics, the measurement of sample thickness is an important means to observe the three-dimensional shape of the sample surface, and it has important applications in precision manufacturing, test measurement and other fields. According to the contact mode between the measuring device and the sample, it is generally divided into two types: contact measurement and non-contact measurement. The measuring device of contact measurement is in direct contact with the sample to be tested, which directly wears the surface of the sample to be tested, causing irreversible damage to it and affecting the measurement accuracy. has certain limitations. Non-contact measurement methods can be divided into magnetic methods, capacitance met...

AI Technical Summary

Problems solved by technology

In 2014, Jia Chuanwu of Shandong University and others disclosed a system for measuring film thickness by wide-spectrum optical interferometry (Chinese patent application number: 201410290494.1). High, but easy to cause abrasion to the film surface

[0005] The corresponding slope at the central fringe position of the white light interference signal is zero, the theoretical sensitivity is the worst, and its positioning accuracy is easily affected by noise

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