紧凑型长波红外光学系统无热化设计

Athermalization of a compact LWIR optical system

对于工作环境温度在-40~60℃之间的长波红外折射光学系统来说,由于红外光学材料受温度变化影响非常大,光学系统必须进行无热化设计。在介绍了无热化系统的种类,分析了温度变化对红外光学系统的影响基础之上,基于非制冷型焦平面探测器,设计了工作在长波红外8~12μm,F#为2,视场角为6.8°的摄远型物镜系统。采用添加棱镜的方法,使系统在不添加特殊面型的情况下达到无热化的目的,同时使系统结构紧凑,摄远比达到0.69。透镜面型均为标准球面,利于加工、装调、检测。设计结果表明,光学系统的调制传递函数在每个规定温度下均能接近衍射极限,满足了设计要求。

Athermal design is necessary to design a LWIR optical system for working under temperature range of-40-＋60 ℃, because the infrared optical materials could transform extremely with the change of temperature. On the basis of introduction of athermal system and analysis on the effects of optical elements, an infrared telephoto objective lens was designed in the way of optical passive compensating, which working waveband was 8-12 μm long wave infrared band, F# was 2, the field of view was 6.8°, uncooled focal plane array was adopted. A prism was added in the system to achieve athermalization and compact structure without adding a special surface, the telephoto ratio of this system was 0.69. All of the surfaces were designed to be standard sphere, which was of benefit to processing, alignment and testing. The result of design indicates that the optical transfer functions are close to the diffraction limit in the required temperature range and the design requirement is met.