Design of Long-Wave Infrared Scan System with Rotating Dual-Wedge Prism

Abstract:

Due to the possession of advantages of passivity working mode, good disguise, and easy observation, infrared systems are used in a wide variety of applications. This paper using 640×480 uncooled detector designed a long-wave scan optical system with large field and large aperture working at 8.0μm～12μm, the Pixel Dimensions of the detector is 30μm. The F number of this system is 1.4 and focal length is 17mm, FOV is 63.6°, which extended to 143° by adopting dual-wedge prism rotating, the paper also given the extended field theory by the dual-wedge prism. Because there are a limited number of lens materials used in LWIR spectral bands, Germanium material and three aspheric surfaces were adopted to balance sphere aberrations and chromatic aberration. All above mentioned are intending to ensure the system has good imaging quality. The results show that the optical performance approximates to the diffraction limit and the design has better achromatic performance. The modulation transfer function (MTF) is above 0.5 at spatial frequency of 20lp/mm, energy concentration ratio is greater than 70% within the sensing element of the detector and Root Mean Square (RMS) value of spot diameter is smaller than the Pixel Dimensions. The system has advantages of simple structure, large aperture, high image quality etc.

• Periodical: Key Engineering Materials (Volume 552)
• Pages: 27-32
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.552.27
• Online since: May 2013
• Authors: Zhe Yuan Fan, Li Min Gao, Hong Tao Yang, Wei Ning Chen, Jian Zhong Cao, Jian Zhang, Zhi Zhang
• Keywords: Dual-Wedge Prism, LWIR, MTF, Optical System Design

References

[1] Zhao Xin-liang, Wang Hai-xia, Cui Li etc. Design of dual-field scanning LWIR optical system[J]. Infrared and Laser Engineering. 2011,40(8):1517-1520.

[2] FAN Zheyuan, CAO Jianzhong, YANG Hongtao etc. Design of high ratio middle infrared continuous zoom optical system. Proc. SPIE, 81931R1-81931R6

[3] Liu Jun, Li Jing, Gao Ming. Design of five-channel infrared panoramic optical system[J].Infrared and Laser Engineering. 2011,40(4):668-673.

[4] Xiang Jian-sheng, Pan Guo-qing. A Compact Low F# Infrared Optical System. Infrared Technology[J]. 2008,30(4):208-210.

[5] WEI Zhong-chao, XIONG Yan-wei, MO Wei etc. Analysis for refractive property of rotary dual-wedge prism system and 2-D scanning trace[J].Journal of Applied Optics. 2009,30(6):939-944.

[6] ZHANG Ming-yi, LI Bao-ping, WAN Zhong-nan etc. Design of the switch-zoom dual-field-of-view infrared optical system with hybrid refractive-diffractive[J]. Infrared and Laser Engineering. 2008,37(5):850-853.

[7] YU Dao-yin,TAN Heng-ying. Engineering optics[M]. Beijing: China Machine Press,2004.