Design and testing of high contrast ratio MW/LW infrared dual-bands scene simulation system

For the requirements of performance testing and evaluation of IR guidence system which works in dual-bands of MW/LW, a DMD based dual-bands infrared scene simulation system was designed, including a projection lens and illumination optical system. The aberration characteristics of the aspherical surface and the projection system with long exit pupil relief and infinity projection was taken into account. Using common infrared materials with reasonable distribution of power and ashperical surface, it balanced the coma, astigmatism, distortion and chromatic aberration, introduced by the dual-bands and long exit pupil relief. In the design of the illumination system, directly irradiation combined with the Abbe illumination principle was adopted to achieve an uniform illumination in the case of oblique incidence, also the improvement of light energy utilization and suppression of the stray light as well. The design result shows that IR MW/LW scene simulator has a full field of view of 2, exit pupil relief of 190 mm, and exit pupil dimeter of 70 mm. The distortion of the lens is less than 0.2%, the modulation transfer function(MTF) is close to the diffraction limination at all the field of view in both the MWIR and LWIR; meanwhile, the relative illumination is higher than 95%. The test result shows, when blackbody temperature is 300 ℃, the lowest simulated temperature is 31.6 ℃, the highest temperature is 250 ℃, and the temperature difference reaches to 215.4 ℃, the system contrast ratio is higher than 0.98, and the relative illumination is higher than 98.1%. The simulation system has the characteristics of high contrast, wide temperature difference and realistic image.