Research On DMD-Based Dual Band Infrared Imaging Guidance Simulation System

Dynamic IR scene projection technology based on the digital micro-mirror device (DMD) has been developed and applied to infrared imaging guidance simulation system overseas; the key component of this technology is the digital micro-mirror device (DMD). The binary pulse width modulation technique was used to precisely control the step gray scale of the IR scene in this technology. DMD infrared scene projection technology can produce IR scene with high spatial resolution, high frame rates, no dead pixels, and excellent uniformity. In this paper, the application of DMD infrared scene projection technology for dual band infrared imaging guidance simulation is studied. The primary work is researching and designing the dual-waveband infrared optical system in order to satisfy the requirements of the two-color IR seeker, which is the most important component in the DMD infrared scene projection system.Firstly, the dual band infrared imaging guidance simulation system is briefly introduced; the structure and fundamental of the DMD infrared scene projection system is introduced. The operating principle of the DMD is presented, and the structure of the single chip DLP system is introduced. The predominance of DMD infrared scene projection technology is analyzed, and the key technologies was analyzed,such as temporal aliasing due to PWM, limited dynamic range due to diffraction of the small mirrors, and spectral transmission of the window covering the DMD, etc. A scheme of DMD dynamic infrared scene projection system was made.The optical part of the DMD dynamic infrared scene projection system was composed by two subsystems: illumination system and projection system. Infrared light was supplied by the illumination system, and illumined the DMD uniformly; infrared scene was projected to the entrance pupil of the under testing system by the projection system. Blackbody was used as source, which can produce uniform light, but the angle of divergence is a little big. In order to increase the usage of energy and sufficiently exert the action of the projection system, a convergence lens was designed. A half-reflector was used in this design, its material and size were given in the paper.One of the primary coverage of the design is projection system. The performance index of the object lens was analyzed, and a projection objective consisting of four lens with three materials was designed. The wave band are 3～5μm and 8～12μm, the F-number is 2.4, The half filed of view is 1.3°. The performance of the completed projection objective was analyzed, and the energy of the total system was checked, all of the index can satisfy the requirement.