Design of zoom LWIR projection system based on DMD

The infrared scene simulator based on digital micro-mirror device(DMD) can test the performance of infrared imaging system by simulating the infrared radiation of the real object and environment in the indoor environment. A set of the infrared zoom projection system with dispersion prism was designed by ZEMAX optical software. The system can match the different viewing angle of the system and avoid overlapping between projection systems and illumination systems on the space. The system can work for the band of 8-12 m. The F number of the system is 2.7. A zoom optical compensation way was used in the system. And the system can realize the focal lengths of 50/100/150/200 mm through four zoom blocks. According to the principles and Gaussian optics formula of four-component system sub-group compensation, the optical parameters of the system were counted; the initial structure which was similar to the optical parameters was adopted and then optimized. The design results show that the image position is stable and the modulation transfer function(MTF) curve at 20 lp/mm of each focal length is closed to the diffraction limit during zoom process,which could conform to the requirements.