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摘要:针对640×512长波红外制冷型探测器,设计了一种制冷型长波红外光学系统,用于对目标的红外跟踪探测。该光学系统采用二次成像结构以达到100%冷光阑效率,采用锗和硫化锌玻璃材料相结合,实现了像差校正和消色差设计,通过引入高次非球面,很好地校正了系统的高级像差,简化了系统结构。光学系统由6个镜片构成,焦距为400 mm,工作波段为7.7~9.3 μm,视场角为1.37°×1.10°, F数为2。设计结果表明:在空间频率33 lp/mm处,轴外视场MTF>0.24,接近衍射极限,具有较高的成像品质。在−35~+55 ℃工作温度范围内,通过内置调焦镜调焦来保证高温、低温环境下的成像质量,可用于宽温度范围内的红外跟踪探测。Abstract:Aiming at 640×512 long-wavelength infrared cooled detectors, a cooled long-wavelength infrared optical system was designed to track and detect an infrared target. The optical system adopts the secondary imaging structure to ensure 100% cold-shielding efficiency, and adopts a combination of optical material Ge and ZnS to achieve aberration correction and achromatic design. By introducing the high-order aspheric surface, the high aberration of the system is well-corrected, thus the system structure is simplified. The optical system is composed of 6 lenses. The focal length is 400 mm, the working bands are 7.7~9.3 μm, the field of view is 1.37°×1.10°, and the F-number is 2. The design results show that at a spatial frequency of 33 lp/mm, the MTF of off-axis field of view is more than 0.24, which approaches the diffraction limit and has high imaging quality. In the operating temperature range of −35~+55 ℃, the focusing lens is used to ensure the imaging quality under high and low temperature environments, which can be used for infrared tracking detection over a wide range of temperatures.
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Key words:
- cooled/
- the secondary imaging/
- high order aspheric surface/
- focusing lens
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表 1该红外系统的光学设计参数
Table 1.Design parameters of proposed infrared optical system
项目 参数 波段范围/μm 7.7~9.3 中心波段/μm 8.5 焦距/mm 400 F数 2 视场角(°) 1.37×1.10 靶面大小/mm 12.29 温度范围/℃ −35~+55 像元大小 15 μm×15 μm 表 2冷反射分析结果
Table 2.Analysis results of the narcissus effect
反射面 光瞳切趾 YNI I/IBAR 冷像立体角 冷像强度比 1 7(R) 32.3971 −21.550 0.012372 0.00072 2 7(R) −14.1678 −4.933 0.028289 0.00377 3 7(R) 8.9698 7.885 0.044679 0.00942 4 7(R) 2.3184 1.592 0.172476 0.13999 5 7(R) −9.9085 −6.533 0.040447 0.00772 6 7(R) −1.0371 −0.676 0.381728 0.67911 8 20(R) 1.5979 −10.228 0.423244 0.83253 9 20(R) −1.6151 −0.509 0.166312 0.13018 10 20(R) −3.5843 −0.801 0.108109 0.05508 11 20(R) −2.6479 −0.762 0.147997 0.10314 12 20(R) 1.1223 1.353 0.505261 1.17892 13 20(R) −2.7761 −0.861 0.163054 0.12515 -
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