根据外场测试要求, 设计一套精确变焦的大口径投影光学系统, 为系统性能测试评估提供远场至近场的目标成像模拟, 系统由精确变焦系统和大口径投影系统两部分组成。根据被测系统口径及所成像点大小要求, 在保证光瞳衔接和口径匹配的前提下, 对大口径投影光学系统和精确变焦系统进行了光学参数计算和像质优化。变焦系统工作波段为8 μm ~12 μm, 变倍比为16x, 大口径投影光学系统口径为300 mm, 模拟实验结果表明, 该系统在变焦过程中像面稳定, 各焦距位置MTF曲线接近衍射极限, 满足外场测试实验要求。

According to the validation requirements of the field test, a large aperture optical system with precisely zooming was designed, in order to provide target imaging simulation from near field to far field to test and evaluate the system performance. The system has two parts: zoom system and projection system. Based on the requirements of beam aperture and image size on the unit to be tested, and with the precondition of pupil connection and aperture matching principle, the optical parameters of projection system and zoom system were calculated and the image quality was optimized. The zoom system works between 8 μm ~12 μm in far-infrared band with a 16x zoom ratio. The large-aperture projection system has a 300mm aperture. Simulation experiment results show that, the image position is stable and the modulation transfer function (MTF) curve of each focal length is close to the diffraction limit during zoom process, which could meet the test requirement exactly.