Cosine fringe field projection module

Abstract

The invention relates to the technical field of 3D measurement, and provides a cosine fringe field projection module. The cosine fringe field projection module is particularly suitable for being usedin miniaturized 3D measuring equipment. According to the cosine fringe field projection module, binarized cosine patterns are adopted, the problem of inaccurate transmittance in the process of manufacturing a transmission-type cosine optical grating is solved, and meanwhile the manufacturing cost is greatly reduced; the four binarized cosine patterns satisfying a 90-degree phase shift relationshipare designed on a same negative film, and then through a projection imaging camera lens and an expansion camera lens, in cooperation with a channel selection circuit, four cosine fringe fields satisfying four-step phase shift are obtained. The cosine fringe field projection module is simple in structure and control, small in size and particularly suitable for 3D measuring equipment requiring whole-machine size miniaturization; meanwhile, based on the simple structure and control and low-cost components, the cost of the projection module is far lower than that of a programmable projection method.

Description

technical field [0001] The present invention relates to the technical field of 3D measurement, and mainly relates to a 3D measurement technology using cosine fringe structured light, specifically a cosine fringe field projection module. Background technique [0002] Structured light 3D measurement equipment projects structured light onto the target to be measured, shoots the target with a camera, and realizes 3D measurement by processing the captured pictures; there are many types of projected structured light, among which the cosine fringe light field is the most commonly used structured light one. For the case of projecting a cosine fringe light field, the four-step phase shift method is one of the commonly used methods. Four cosine fringe fields with the same frequency but with a phase increment of 90° are used to irradiate the target, and four photos are obtained. After processing, the height values ​​of each point are obtained. Corresponding to 3D measurement results. ...

AI Technical Summary

Problems solved by technology

The devices used in programmable projection technology are expensive and relatively complex to control, and because the stripes are actually realized by the different brightness of multiple pixels, and the pixels have a certain size limit, so they are projected The period of the fringe pattern on the display cannot be too small, but it is not suitable for the situation where a small area needs to be detected

In practical applications, in many cases, the application scenarios are relatively fixed and do not require complex projections. The advantages of programmable projections are not obvious. In contrast, the use of negatives can make the process more refined, so the size can be smaller , but the cost is lower; however, the production of the standard transmission cosine grating film is difficult, mainly because the transmittance is difficult to guarantee. At present, the main production method is photolithography, and the production cost is high. At the same time, the phase shift The realization of is cumbersome and requires fine mechanical movement to achieve

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