Chinese Journal of Lasers, Volume. 50, Issue 14, 1410003(2023)
Application Design of Dewar Window for Cold Optical Large-Aperture Long-Wave Infrared Detectors
Figures & Tables(14)
Fig. 2. NSR curves. (a) NSR of different temperatures of window under 300 K blackbody target; (b) NSR of 200 K window under different temperatures of blackbody target
Fig. 3. Effect of window temperature on Dewar temperature field and stray light. (a) Dewar liquid nitrogen temperature field at the window room temperature; (b) Dewar simulation temperature field at window temperature 200 K; (c) temperature of cold screen and detector versus window temperature; (d) irradiance of the cold screen to the detector versus window temperature
Fig. 5. Dewar window deformation caused by aerodynamic pressure effect. (a) Inner surface; (b) outer surface
Fig. 7. Dewar window deformation caused by aerodynamic pressure and temperature fields. (a) Inner surface; (b) outer surface
Fig. 8. Deformation curves of Dewar window with different radius. (a) 46 mm; (b) 50 mm; (c) 54mm; (d) 58 mm
Table 1. Material properties of optical window
View tableTable 1. Material properties of optical window
Material Elastic modulus /Pa Poisson’s
ratio
Thermal conductivity /
（W·m-1·℃-1）
Coefficient of thermal expansion /℃ Density /
（kg·m-3）
Refractive index at 10 μm Abbe number in band 8-12 μm Ge 10.3×1010 0.26 60.2 6.1×10-6 5323 4.0031 834 ZnSe 7.03×1010 0.28 18 7.1×10-6 5270 2.4064 57 ZnS 7.45×1010 0.29 16.7 7.6×10-6 4080 2.2002 23 GaAs 8.48×1010 0.31 48 5.7×10-6 5315 3.2770 107
Table 2. Material properties of shell
View tableTable 2. Material properties of shell
Material Yield strength /MPa Thermal conductivity /（W·m-1·K-1） TC4（Ti6Al4V） 870 8.37 4J29 343 16.53 304L 225.6 14.7
Table 3. First ten Zernike polynomial coefficients of inner and outer surface shapes under condition 3
View tableTable 3. First ten Zernike polynomial coefficients of inner and outer surface shapes under condition 3
Coefficient Value of outer surface Value of inner surface Z1 0.0002406 0.0002285 Z2 -2.297×10-6 -2.675×10-6 Z3 0.0001111 -0.0001059 Z4 3183×10-6 3.064×10-6 Z5 1.937×10-6 1.859×10-6 Z6 -2.852×10-7 -2.704×10-7 Z7 -2.128×10-9 -1.742×10-9 Z8 3.438×10-8 3.281×10-8 Z9 -8.153×10-9 -7.768×10-9 Z10 -1.1452×10-9 -8.751×10-10
Table 4. Variation of the system MTF of three fields at Nyquist frequency
View tableTable 4. Variation of the system MTF of three fields at Nyquist frequency
Condition MTF at 16.67 lp/mm Axial field of view 0.7 field of view Full field of view Meridian Sagittal Meridian Sagittal Meridian Sagittal Original 0.5010 0.5010 0.4890 0.4952 0.4893 0.4878 Condition 1 0.5002 0.5002 0.4893 0.4953 0.4885 0.4869 Condition 2 0.4996 0.4996 0.4891 0.4944 0.4881 0.4867 Condition 3 0.4985 0.4985 0.4840 0.4926 0.4933 0.4919
Table 5. Variation of wave aberration of primary wavelength based on deformation effect
View tableTable 5. Variation of wave aberration of primary wavelength based on deformation effect
Condition RMS of wavefront error /λ Axial field of view 0.7 field of view Full field of view Without deformation 0.0179 0.0444 0.0270 Condition 1 0.0185 0.0455 0.0286 Condition 2 0.0181 0.0437 0.0274 Condition 3 0.0189 0.0468 0.0291
Tools
Get Citation
Copy Citation Text
Haiyong Zhu, Zhijiang Zeng, Xue Li, Peng Ji, Junlin Chen, Qi Zhang, Shaobo Luo. Application Design of Dewar Window for Cold Optical Large-Aperture Long-Wave Infrared Detectors[J]. Chinese Journal of Lasers, 2023, 50(14): 1410003
Paper Information
Category: remote sensing and sensor
Received: Dec. 20, 2022
Accepted: Feb. 27, 2023
Published Online: Jul. 10, 2023
The Author Email: Zeng Zhijiang (jonzeng@mail.sitp.ac.cn)
© Copyright 2018-2021 | Chinese Laser Press.
All Rights Reserved 沪ICP备15018463号-20