Research of three-dimensional surface detection method based on grating projection

In tiny instrument structure design and treating, it is hotspot that three-dimensional surface of diffuse reflection is detected in recent years. Common Measurement method include: One is phase shift micro interference method. It has high measures accuracy to reaches nm lever. Its structure is complicated and measure range is small. Only it fits in tiny face of specula detecting. The other is projection method of computer optesthesia integration. This method is simple, convenient operation, big measurement range. But measurement accuracy is low, only be 0.1 mm lever. And the grating and the CCD repetition calibrate are difficult. A measuring 3-D diffuse reflection tiny instrument surface basing on grating projection method has been studied in this article. Measurement principle is triangle laser method. Using parallel light irradiate spatial light modulator (SLM) to produce amplitude grating with random period, through projection optics system´s image produces clear deform grating stripe. It is set up the mathematical model between three-dimensional tiny surfaces and deform grating stripe. It is processed the receive image and calculated three-dimensional information and regained three dimensional topography. Taking a tiny shape as example, the detecting method is validated though experimenting. Measure accuracy is one pixel. Using SLM to produce amplitude grating In this method, It is easy changing grating period or replacing different type amplitude grating, It isn´t need to calibrate grating repeat. This method has effectively resolved the grating difficult to repeat calibration. And it is true speedy real time online detecting.