• Optics and Precision Engineering
  • Vol. 31, Issue 9, 1285 (2023)
Wenxiong LI1,2,3, Junli SHEN1,3,*, Xingxiang ZHANG1, Zhenyu LU1,3..., Zhisheng LI4, Hasiaoqier HAN1,3 and Qingwen WU1,3|Show fewer author(s)
Author Affiliations
  • 1Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun30033, China
  • 2University of Chinese Academy of Sciences, Beijing100049, China
  • 3CAS Key Laboratory of On-orbit Manufacturing and Integration for Space Optics System, Changchun100, China
  • 4Beijing Leyfond Vacuum Tech.co., LTD, Beijing10002, China
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    DOI: 10.37188/OPE.20233109.1285 Cite this Article
    Wenxiong LI, Junli SHEN, Xingxiang ZHANG, Zhenyu LU, Zhisheng LI, Hasiaoqier HAN, Qingwen WU. Design of low temperature infrared off-axis three-mirror collimation system[J]. Optics and Precision Engineering, 2023, 31(9): 1285 Copy Citation Text show less

    Abstract

    An off-axis three-mirror collimating optical system is designed to test the infrared equipment in a vacuum 100-K cryogenic environment. The system adopts athermal design, and the whole structure adopts SiC material. A C-shaped opening expansion sleeve is used as a flexible structure to compensate for low-temperature deformation at the connection between the mirror body and the support structure. The whole system is partially wrapped in a radiation cooling panel, except for the reflecting mirror. The low-thermal conductivity thermal insulation support structure plays a thermal shielding role in the heat conduction chain to realize the thermal insulation support and rapid refrigeration of the system. In the 100-K low-temperature environment, according to a system simulation analysis, the primary, secondary, and tertiary mirror wavefront error is <λ/50; an analysis of the whole structure indicates that the wavefront errors of the primary, secondary, and tertiary mirrors are ≤λ/30. The wavefront error of each field of view of the system is in the range of λ/14-λ/8 at room temperature and in the range of λ/8-λ/7 at 100 K. According to the Rayleigh criterion, the wavefront is considered to be flawless. When λ = 632.8 nm, the modulation transfer function (MTF) of the system at a 50 lp/mm frequency is >0.7 at room temperature; at a low temperature, the MTF is >0.6. Meet the system at 50 lp/mm greater than 0.6 use requirements. The results indicate that the collimating optical system can output parallel light stably in a 100-K vacuum environment to meet the test requirements of low-temperature infrared equipment. In a material level test of fast radiation cooling, the temperature of the SiC mirror blank is stable at 130 K after 18 h. After 30 h, the mirror blank temperature stabilizes at 110 K. The experiment verifies the feasibility of fast radiation cooling of the SiC mirror.
    Q=-λAdTdx(1)

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    Rcd=LλA1(2)

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    Rjc=1KhA2(3)

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    (xi,yi,zi)T=(xi,yi,zi)T+C(dxi,dyi,dzi,θxi,θyi,θzi)T,(4)

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    E=i[(xi-xi')2+(yi-yi')2+(zi-zi')2](5)

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    Edxi=0,Edyi=0,Edzi=0Eθxi=0,Eθyi=0,Eθzi=0(6)

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    (xi'-a)2+(yi'-b)2+(zi'-c)2=R2(7)

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    αxi'+βyi'+γzi'+θ=-(xi'2+yi'2+zi'2)(8)

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    x1'y1'z1'1x2'y2'z2'1xn'yn'zn'1αβγθ=-x1'2+y1'2+z1'2x2'2+y2'2+z2'2xn'2+yn'2+zn'2(9)

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    Li=(xi'-a')2+(yi'-b')2(zi'-c')2(10)

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    L¯i=1ni=1nLi(11)

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    RMS=i=1n(Li-L¯i)2n(12)

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    PV=max(Li)-min(Li)(13)

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    Wenxiong LI, Junli SHEN, Xingxiang ZHANG, Zhenyu LU, Zhisheng LI, Hasiaoqier HAN, Qingwen WU. Design of low temperature infrared off-axis three-mirror collimation system[J]. Optics and Precision Engineering, 2023, 31(9): 1285
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