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A high-precision coherent peak localization method immune to spike noise

A technology of spike noise and positioning method, which is applied in the direction of instruments, measuring devices, optical devices, etc., can solve problems such as the influence of measurement results and achieve high positioning accuracy

Active Publication Date: 2019-12-24
BEIHANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In white light scanning interferometry, since the position of the coherence peak represents the relative height of the test surface, any positioning error of the coherence peak will affect the measurement results

Method used

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  • A high-precision coherent peak localization method immune to spike noise
  • A high-precision coherent peak localization method immune to spike noise
  • A high-precision coherent peak localization method immune to spike noise

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Embodiment Construction

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] figure 1 Shown is a schematic diagram of the principle of white light interference technology. The Koehler illumination system expands and collimates the light emitted by the light source, enters the beam splitting prism and divides it into two beams, which are respectively irradiated on the surface of the sample to be tested and the reference mirror, and reflected on the CCD. focal planes combine and interfere. Driven by the phase shifter, the reference mirror drives the interference fringes across the entire field of view at a uniform speed. The data recorded by the CCD is solved by means of an algorithm to obtain the surface topography.

[0018] The key to the algorithm in the system lies in the accurate positioning of the coherence peak. In the use of the system, a variety of factors can cause deviations in the coherence peak posit...

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Abstract

The invention discloses a high-precision coherent peak positioning method immune to peak noise, and belongs to the technical field of surface topography measurement. The high-precision coherent peak positioning method immune to the peak noise comprises the steps of generating an envelope curve for an interference curve through a self-defined Gaussian template function, performing function fittingon the envelope curve, and solving an extreme value of the continuous function, wherein the extreme value is the position of a coherent peak. The extreme value of the continuous function is solved, and thus the method is higher in coherent peak positioning precision compared with the traditional method of solving a discrete point extreme value and is not limited by the fluctuation in sampling frequency. The method is insensitive to the peak noise, and has a high anti-interference ability and high stability.

Description

technical field [0001] The invention relates to a high-precision coherent peak positioning method immune to spike noise, and belongs to the technical field of surface topography measurement. Background technique [0002] The emergence of white light scanning interferometry has brought great progress to ultra-precision detection technology, and the quality control of products in ultra-precision machining technology has become very convenient. However, white light scanning interferometry also faces new challenges, and people always hope that this method can continuously break through the original limitations and meet more, more sophisticated and complex testing needs. The algorithm in white light interference is the key to improve the test accuracy. [0003] White light interference signals are usually represented as modulated cosine signals. Therefore, its visibility is not constant and varies with different scanning positions. When the optical path difference between the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/24
CPCG01B11/24
Inventor 张春熹李豪伟李慧鹏宋凝芳
Owner BEIHANG UNIV