满足双视场需求的红外模拟光学系统的设计

Design of scene simulation optics for dual field angle infrared imagers

简述了红外场景产生的技术背景以及基于液晶光阀实现可见光到红外视频图像转换的模拟器的总体结构。重点介绍了一种适用于两种不同视场的红外光电系统测试与评估的动态红外场景模拟器光学系统的设计,其中包括变倍透镜的选择和准直投射光学系统的设计。从理论上分析了利用变倍透镜的变化写入不同放大倍率的可见光图像,来满足视场变化需要的方法;从光学指标的确定,结构、材料的选取到最终光学性能,阐述了准直投射光学系统的设计。此投射光学系统工作在8～12μm,焦距271.69 mm,视场为±4,°入瞳距150mm,后工作距离139.2 mm,点列图和传递函数曲线表明此投射光学系统像质达到理想状态。最后分析了光学系统性能参数与指标要求的符合。在满足设计指标的前提下,和变焦系统相比,该光学系统结构简单、成本低、可行性高。

The design of the optical systems of simulator for testing of infrared imaging system is described, which has field angle of 6° or 8°. Infrared scene simulator technologies are outlined. The optical systems include projection optics and a variable magnification lens. The lens between the LCD panel and liquid crystal light valve （LCLV） produces visible image at varying magnifications on LCLV. The projection optics collimates infrared image from LCLV to generate infrared scene from infinity. The varying image size meets the need of the test optics. The projection optics is designed for a constant field angle and entrance pupil. Thus image always fills entrance aperture and view field of the test optical system. The effective focal length of the system is about 271.69 mm.There is sufficient exit pupil distance to match simulator exit pupil to the LWIR imagery system entrance pupil. A long working distance between LCLV and simulator ensures the mechanical and the optical assembly. The Modulation Transfer Function （MTF） and the geometric blur spot show the perfect image quality of the projection optics. In contrast with zoom system, the simple optics systems meet the requirements of low cost and high feasibility.