红外双波段谐衍射光学系统设计

Optical Design of a Dual-Band Infrared System Based on Harmonic Diffraction

为提高红外系统探测能力,满足探测器在红外中长波双波段同时成像的要求,提出一种基于谐衍射的光学系统设计。根据谐衍射透镜的特点,通过合理选择谐衍射波长和衍射级次,采用折射式共光路构型成功完成了中/长波双波段光学系统的设计。系统在3.7～4.8μm和7.7～9.5μm两个波段成像,F数为2,视场角10°。优化结果表明,成像质量接近衍射极限,具有良好的消色差能力,光学传递函数长波波段大于0.56,中波波段大于0.72。同时系统仅采用4片透镜,一个衍射透镜面,其余均为球面,大大降低了工艺要求,结构紧凑,透过率高。

To improve the detection capability of IR system effectively and satisfy the imaging requirement of the detector at MWIR and LWIR at the same time,an optical design based on harmonic diffraction is put forward.Based on the characteristics of harmonic diffractive elements,a MWIR/LWIR dual-band infrared optical system using refractive dual-band structure is designed by choosing the appropriate harmonic diffraction wave and diffraction level.The system images at wavebands of 3.7～4.8μm and 7.7～9.5μm.The number of F is 2 and the angle of field is 10°.The results show that the optical performance approximates to the diffraction limit and the design has better achromatic performance.The MTF is higher than 0.56 in LWIR and higher than 0.72 in MWIR.The system has four lenses,only one piece of that is harmonic diffraction,the others are sphere,which debases the demands to technical level and has the advantages of compacted structures and high rate of transmission.