A four-step phase-shifted sinusoidal fringe field projection module based on liquid crystal plate

Abstract

The invention belongs to the technical field of 3D measurement, and provides a four-step phase-shifted sinusoidal fringe projection module based on a liquid crystal film, which is particularly suitable for use in miniaturized 3D measurement equipment; the invention uses a liquid crystal film, which only includes two COM electrodes and two SEG electrodes display sinusoidal binary filling patterns by applying a driving voltage to the electrodes, and then project sinusoidal stripes through the projection imaging lens and expansion lens; choose different power-on combinations, and the liquid crystal film can display four images that meet the four-step phase shift relationship. The similar sinusoidal binary filling pattern, so as to project four sinusoidal fringe fields satisfying four-step phase shift through time-sharing control. The present invention has simple structural control and small size, and is especially suitable for 3D measuring equipment that requires miniaturization of the overall volume; meanwhile, based on simple structure and control and low-cost components, the projection module of the present invention is relatively easy to reduce costs.

Description

Technical field [0001] The present invention belongs to the field of 3D measurement, mainly involving structural light 3D measurement techniques utilizing sine stripes, specifically a four-step phase shift string stripe field projecting module based on a liquid crystal film. Background technique [0002] The structural light 3D is measured as a non-contact measurement, and the 3D measurement is achieved by projecting a specific structural light to the measured target, and the camera is photographed, and then the photographing is taken. The projected structure light has a variety of types, including the string striped field Is one of the most commonly used structural lights, the most important technique for 3D measurements using a sinusoidal stripe, including Fourier transform silicoside (FTP) and phase measurement contour (PMP), where FTP only requires a stripe. As a result, when the target reflective pattern is complex and the topography is stressful, it will result in a large m...

AI Technical Summary

Problems solved by technology

Miniaturized 3D measurement based on phase-shifted sinusoidal fringes requires miniaturized sinusoidal fringe projection. The current widely used DFP projection technology uses high device costs and relatively complicated control, which is not conducive to reducing equipment costs. Equipment with a small overall size is not suitable, and in actual applications, the application scenarios are relatively fixed in many cases, and complex projection is not required, and the advantages of DFP projection are not obvious

In addition, the liquid crystal Ronchi grating method requires out-of-focus projection, and the method of mechanically moving the grating, the laser interference fringe method, and the existing various channel selection methods are not convenient for projection miniaturization

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