3D reconstruction of structured light based on infrared MEMS

The traditional 3D reconstruction process of structured light is based on a DLP visible light grating projection method; the DLP method has many flaws, including great bulk, and harmful to human eyes caused by visible light and so on. In this article, we propose a method based on infrared micro electro mechanical systems (MEMS) instead of DLP to generate programmable coded structured light. First, MEMS emits a laser beam by using a point-beam laser. Then, the laser beam is modulated by the optical system and transformed into a laser line, which is reflected by MEMS and projected onto the object to be measured. The grating pattern can be a square wave or a sinusoidal wave for different needs. Due to the speckle characteristics of the infrared laser, the phase error obtained by the traditional four-step phase-shifting method is very large. Therefore, an eight-step phase-shifting method based on the Gaussian filter is proposed to improve the decoding accuracy of the grating. An improved calibration method based on phase space is used to calibrate the monocular system. Finally, the 3D data of the object are obtained according to this method, and the 3D reconstruction accuracy is better than 0.1 mm.