Non-contact measurement method and system of high-reflection free-form surface

Abstract

The invention relates to a non-contact measurement method of a high-reflection free-form surface. The method includes the following steps that: 1) the coordinate and normal information of an object point is acquired by means of an LCD (liquid crystal display) and three cameras: the LCD is used to project encoding phase shift stripes, one of the cameras obtains the phase shift stripes on the LCD which are reflected by the surface of a measured object, incident light planes where incident light is located are obtained by means of position change of the LCD, the other two cameras are used to obtain two incident light planes, and the information of the incident light is obtained through intersecting the incident light planes, the coordinate information of the object point can be obtained through intersecting reflected light and the incident light planes, or intersecting the reflected light and the incident light, and the normal information of the object point is obtained through intersecting the reflected light and the incident light; and (2) interpolation or gradient integration is performed on the obtained coordinate and normal information of the object point through using a radial interpolation method or a gradient integration method, the accurate three-dimensional information of the object point can be obtained. The method of the invention has the advantages of high measuring speed, non-contact performance and no damage to the surface of a high-reflection object.

Description

technical field [0001] The invention relates to the field of optical measurement, in particular to a non-contact measurement method and system for a high-reflection free-form surface. Background technique [0002] Free-form surfaces refer to asymmetric and irregular surfaces, among which free-form surfaces with high reflection properties, especially ultra-precision processing parts with high reflection properties such as optical surfaces and blades, are used in aerospace, national defense, biomedicine, microelectronics, etc. Applications in the field of science and technology are becoming more and more extensive. Accurately measuring and evaluating the surface topography of ultra-precision processed highly reflective surfaces is of great significance for defect detection and improvement of processing technologies and methods. However, the high-precision measurement of highly reflective free-form surfaces has always been a difficult point in the field of ultra-precision mach...

AI Technical Summary

Problems solved by technology

The contact measurement method has its own defects: it is easy to destroy the surface characteristics of free-form surfaces

[0005] The phase deflection measurement system composed of a single projection device and a CCD camera has the disadvantage of solving the problem of 'non-unique normal', and the measurement system has a large error

At present, a variety of solutions based on phase deflection technology have been proposed to realize the topography measurement of the surface of highly reflective objects, but there are certain deficiencies.

For example, the measurement system proposed by Markus C.Knauer abroad is composed of LCD and two CCD cameras. The disadvantage is that the use of two cameras increases the cost; the measurement system proposed by Xiao Yongliang of Sichuan University consists of two LCD displays and a CCD camera. The disadvantage is that The positional relationship between CCD and LCD is not easy to calibrate; the measurement system proposed by Tao Tao of Shanghai University consists of an LCD display and a CCD camera placed on a precision guide rail. The disadvantage is that the auxiliary guide rail is used, which increases the motion error of the guide rail and reduces the measurement. precision

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