长波红外反远距物镜光学被动消热差设计

Optical Passive Athermalization Design of Long-Wavelength Infrared Inverted Telephoto Objective

为满足非制冷红外光学系统相对孔径大、长后工作距、温度适应性强的性能要求,采用反远距系统结构形式,设计了工作波段为8~12μm,F/#为2.5,全视场角为7.2°,焦距为100mm的长波红外物镜.通过光学被动式消热差方式,匹配光学材料及分配透镜光焦度,完成了红外物镜在-40^+65℃温度范围内的消热差设计,并对红外物镜的像质进行分析.仿真结果表明:不同温度下,系统各个视场内调制传递函数在奈奎斯特频率17lp·mm-1处均高于0.4,达到衍射极限,单个像元内能量均达到85%.系统整体无温度离焦,成像质量良好、结构紧凑,且适用于像元尺寸为30μm×30μm、像元数为320×240非制冷焦平面阵列探测器.

In order to fulfill the requirements of large relative aperture,long back-working distance and high temperature adaptability of the uncooled infrared optical system,an inverted telephoto optical system is adopted to realize the long-wavelength infrared objective design parameters：waveband of 8~12μm,F number of 2.5,field of view of 7.2°and focus length of 100 mm.In addition,the optical passive compensation method is used to realize an athermalized design in the temperature ranging from-40 ℃to＋65℃ by matching optical materials properly and distributing optical power of each lens-elements.The image quality of infrared objective is analyzed.The design results show that the modulation transfer function of all field of view of optical system is greater than 0.4at the Nyquist frequency of 17lp·mm-1,reaching the diffraction limit,and the energy ratios reach 85% within a single pixel in the different temperature.The whole system has an excellent image quality and compact structure.And the optical system applies to the uncooled focal plane array detector of 30μm ×30μm pixel size and 320×240pixel number.