High Dynamic Range Imaging Technology And Research On Double Projection Measurement Based On Digital Micromirror Device Technology

Visual measurement is widely used in the field of mechanical testing because of its advantages.With the continuous development of the requirements of advanced manufacture,we need visual measurement to be higher accuracy,higher efficiency,more smart and more flexible.In practical industrial application,a large number of detected objects are all metal objects,and metal objects tend to cause specular reflection.Due to the limitation of camera’s dynamic range,image will have over-exposed area.In this area phase information can’t be acquired accurately,thus the precision of 3d shape measurement will be affected.In this paper based on the technology of digital micro-mirror device and the reflective imaging structure,we proposed a method of modulation processing before image formation.We applied high dynamic range imaging method to 3d vision measurement,and set up a high dynamic range imaging system.We calculated 3d coordinate based on high dynamic range image,in this way we can solve the problem of measurement accuracy affected by the quality of acquired image from the source.The main work done is as follows:We researched the method of modulation processing before image formation based on the technology of digital micro-mirror device.We achieved spatial light modulation using DMD,and described its system construction and optical principle.We proposed a method of matching and calibration between CCD and DMD elements by moiré fringe,and we designed an experiment of coordinate transformation to prove effectiveness of the method.We researched adaptive high dynamic range imaging technology for vision measurement.We designed the structure of double-armed adaptive HDR imaging system.By studying the produce principle of over-exposed area and its affection,we proposed a method of remove the over-exposed area by our system,then we can improve the accuracy of measuring system.An imaging experiment was also designed to prove it.We designed a double-projection measuring system.Based on the spatial light modulation characteristics of DMD,we designed a system which can project grating patterns form different directions,and then we build the 3d shape based on two images.By this way we can solve the block problem in the case that we measured a object of complicated shape.