外视场拼接的单镜头大视场中波红外成像系统的实现

Realized large field of view infrared imaging system of single lens with external field splicing

基于外视场拼接原理,研制一套大视场中波红外原理样机。设计一制冷型中波红外光学系统。采用光学系统出瞳与冷屏重合的二次成像结构形式,保证系统具有100%冷光阑效率。工作波段为3.7~4.8μm,焦距为40 mm,相对孔径为1:2,全视场角为21.74°×17.46°(27.88°),系统总长145 mm。采用孔/反射镜分时成像的外视场拼接,实现2×1视场扩展。设计结果表明:在空间频率21 lp/mm处,轴外视场MTF>0.68,接近衍射极限。系统结构紧凑,成像质量较高。利用原理样机完成可行性和合理性验证。

Based on the principle of external field splicing, a principle prototype of large-field mid-wave infrared was developed. A cooled mid-wave infrared optical system was designed. The secondary imaging structure of the optical exit aperture coincides with the cold screen was adopted to make sure 100% cold shielding efficiency of the system. The working wave band was 3.7-4.8 μm, the focus was 40 mm, the relative aperture was 1:2, the full field of view was 21.74°×17.46°(27.88°), the total length of the system was 145 mm. The principle of external field splicing with time-sharing exposure imaging of holes/mirrors was adopted, 2×1 field of view expansion was realized. The design result show that MTF>0.68 of the off-axis field of view at spatial frequency of 21 lp/mm,which closes to the diffraction limited. The system has compact constructure and has high imaging quality. The feasibility and rationality of the splicing principle were verified using prototype.