紧凑型双波段无热化红外光学系统设计

摘要

针对红外双波段量子阱探测器，设计了一个可同时工作在4.4～5.4mm（中波段红外）和7.8～8.8mm（长波段红外）波段的仅含3片透镜的紧凑型双波段无热化光学系统，有效焦距为30 mm， f/#为2.1。对比先前报道的双波段无热化红外光学系统，此设计仅采用硫系玻璃材料Ge20Sb15Se65制备的两片镜片和常规红外材料ZnS制备的一片镜片，通过合理分配各个镜片的光焦度达到系统在中波红外及长波红外两个波段的无热化设计效果，且不含衍射面，整体结构紧凑，制备难度低。利用硫系玻璃易于精密模压制备非光学球面的特点，仅在一片硫系玻璃镜片上设计一处非球面。设计结果显示，系统在两个红外波段，－40℃～60℃温度范围内像质良好，且光学调制函数（MTF）接近衍射极限。%A compact dual-band athermalized infrared system is designed based on a QWIP dual-band infrared detector. The operating wavelengths of the system include the Medium Wavelength Infrared (MWIR, 4.4-5.4mm) and the Long Wavelength Infrared(LWIR, 7.8-8.8mm) regions, the effective focal length(EFL) is 30 mm, and thef/# is 2.1. The system is designed as a combination of two singlets fabricated with the chalcogenide glass Ge20Sb15Se65 and one singlet fabricated with the conventional infrared material Zinc Sulfide(ZnS). Utilizing the differences in the thermal-optical properties of the infrared materials, we realized an athermalized optical design by carefully adjusting the optical powers of the three singlets. Moreover, taking advantage of the superior property of chalcogenide glasses for molding preparation of aspherical surfaces, we are able to further improve the imaging quality of the design by introducing an aspherical surface on one of the chalcogenide singlets. The proposed system demonstrates imaging quality close to a diffraction-limited system for the designed operating wavelengths and for the temperature range from-40℃ to 60℃.