Device and method of measuring surface topographies of mirror and mirror-like objects

A technology for object surface and shape measurement, which is applied in the direction of measuring devices, optical devices, instruments, etc., can solve the problems of unguaranteed convergence, multiple phase shifts of phase shift algorithms, and expensive laser trackers.

CN105783775AInactive Publication Date: 2016-07-20TSINGHUA UNIV
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2016-07-20
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention discloses a method and a device for measuring surface topographies of mirror and mirror-like objects. Phase measurement deflectometry is adopted to measure mirror and mirror-like surface shapes, a combination between a liquid crystal display and a planar mirror serves as a calibration plate, the liquid crystal display is fixed and can not move, the planar mirror moves freely for four times, an image reflected by the planar mirror is photographed by a CCD detector, linear solution and beam method adjustment are then used for completing calibration on inner parameters of the camera, global pose estimation is used for completing calibration on the relative relation between the liquid crystal display and the camera, and finally, a three-dimensional topography of a to-be-detected mirror surface is calculated and obtained through a gradient integral of the phase measurement deflectometry. According to the device and the method of the invention, defects that the calibration plate is needed and a precise positioning control point is attached to the planer mirror during the calibration process in the traditional method are overcome, the measurement cost is low, and he measurement speed is quick; and constraint conditions such as rotation matrix orthogonality during a perspective imaging process and a fourier transform method are introduced for corresponding point matching, and influences by high noise and multiframe processing on three-dimensional topography recovery can be overcome.
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Description

technical field

[0001] The invention belongs to the technical field of object surface topography measurement, in particular to a device and method for measuring the surface topography of mirror surfaces and mirror-like objects. Background technique

[0002] With the increasing application of highly reflective objects in industrial production, such as free mirrors in optical components, automotive metal bodies, solar mirrors, etc., accurate measurement and evaluation of the three-dimensional surface shape of mirrors and mirror-like surfaces has become an important tool for improving the processing surface. An important research content of quality and performance. However, due to the characteristic of specular reflection on the surface of highly reflective objects, it is difficult for the traditional computer vision-based 3D shape measurement technology to measure the surface shape of mirror objects.

[0003] The existing three-dimensional shape measurement methods of highly ...

Examples

Embodiment Construction

[0032]The implementation of the present invention will be described in detail below in conjunction with the drawings and examples.

[0033] The invention realizes the system calibration of the phase deflection technique on the basis of only using the free-moving plane mirror four times, and completes the matching of the same-named points by combining the absolute phase obtained by the Fourier transform method, and obtains the three-dimensional shape of the mirror object by using the gradient integral calculation. It greatly simplifies the system calibration process and realizes real-time and fast three-dimensional detection; at the same time, it ensures the authenticity of the measurement results and the ability to resist noise.

[0034] Such as figure 1 As shown, a device for measuring the surface topography of mirror surfaces and mirror-like objects includes: a liquid crystal display 1 for projecting checkerboard images 7-1 and two-dimensional sinusoidal stripes 7-2, and a C...