长焦距小型无热化电视光机系统设计

Design of long-focal length athermal NIR TV optomechanical system

针对长焦距小型化电视的设计要求,采用摄远型光学结构压缩系统的轴向尺寸,使摄远比达到了0.53,并对系统进行了消杂光及光机无热化设计,通过合理地设置光阑减少系统的杂散光,选择合适的结构材料与光学材料相匹配,在整个工作温度范围(-40℃^+65℃),像面漂移量在焦深范围内,20lp/mm时系统的MTF在0.7以上,点列斑4.7μm,小于探测器的像元尺寸6μm,光轴稳定性达到了0.04mrad,系统无需调焦便可满足高低温等恶劣环境下的像质和光轴稳定性要求。试验结果表明:探测和识别特定目标距离均达到了指标要求。

In order to achieve the target of long-focal length miniaturized near-infrared (NIR) system ,the telephoto optical structure was adopted to compress the axial dimension ,and the telephoto ratio reached 0 .53 .Furthermore ,the stray light was eliminated by properly setting the stop ,and by choosing appropriate mechanical and optical materials ,the athermal design was realized .In working temperature(-40 ℃ ~ +65 ℃) ,the image surface drift is smaller than focal depth ,the modulation transfer function(MTF) ≥0 .7 at 20 lp/mm ,the spot is 4 .7 μm which is smaller than CCD pixel of 6 μm ,and the optical axis stability is 0 .04 mrad .The sys-tem can gain good imaging quality and optical axis stability in worsened environment without focusing .Test result shows both the detection and recognition distances meet the requirements .