Method and apparatus for measuring profile of object by double wavelength structural light

Abstract

The invention relates to a method and device of adopting dual wavelength structure light to measure object outline. It belongs to optical measurement technique field. The method includes the following steps: projector produces white light to make it irradiate to the object; the optical field is adjusted by the object; camera shoots the image. Its each image point phase difference is calculated by correlation method; the other wavelength is used to do sinusoidal modulation; the phase difference is gained as the same; twice sinusoidal modulation wavelength is combined to gain combination wavelength and combination phase difference; each image point depth is calculated. And it is un-envelope according to given continuity constraint condition to gain object actual three-dimensional shape. The device includes projector, camera, and computer. The invention has the advantages to good algorithmic stability and high measuring accuracy.

Description

technical field [0001] The invention relates to a method and device for measuring the contour of an object by using dual-wavelength structured light, and belongs to the technical field of optical (three-dimensional) measurement. Background technique [0002] Optical projection profilometry techniques can be divided into two broad categories: direct triangulation and phase measurement. Direct triangulation methods include laser point-by-point scanning method, binocular stereo vision method, structured light method (also known as light section method) and so on. The phase measurement method is based on measuring the phase of the grating image projected onto the object, and there are Moire's method, phase shifting method, Fourier transform method and so on. [0003] The binocular stereo vision method acquires two images of the same scene from different angles, just like the human eyes observe the scene. The computer obtains the depth information of the point of the object by ...

AI Technical Summary

Problems solved by technology

Autocorrelation can eliminate the interference of high-frequency noise, so the accuracy of the phase shift method is very high, but the unenveloping process has an uncertain solution to the step change.

[0006] To sum up, due to the use of proprietary projection devices in existing technologies, the three-dimensional scanning method is limited to a single technology, and there are insurmountable barriers in some aspects of the accuracy index

The binocular matching problem is very complicated, which makes it difficult to control the error

The fringe distance of the structured light method cannot be infinitely small, and the accuracy is limited

Due to the existence of arctangent transformation in the calculation process of phase method, a set of solutions can be obtained, and the only suitable solution can be found under the constraint of the continuity of the object surface, but this limits the range of step changes in the depth of adjacent points on the surface of the object to be measured. Applicability is limited

Images