Acta Photonica Sinica, Volume. 51, Issue 5, 0511002(2022)
Design of Compact Off-axis Three-mirror Afocal System Based on Freeform Surface
Figures & Tables(16)
Fig. 2. Diagram of the relationship between entrance pupil diameter D and envelope R
Fig. 3. Aperture off-axis three-mirror afocal system based on freeform surface
Fig. 4. Wave aberration of the aperture off-axis three-mirror optical system
Fig. 5. Strehl Ratio of the aperture off-axis three-mirror optical system
Fig. 6. Field of view off-axis three-mirror afocal system based on freeform surface
Fig. 7. Wave aberration of the field of view off-axis three-mirror optical system
Fig. 8. Strehl Ratio of the field of view off-axis three-mirror optical system
Table 1. Design parameters of optical system
View tableView in ArticleTable 1. Design parameters of optical system
Parameter Specification Entrance pupil diameter /mm 350 Wavelength/μm 3.7~4.8 7.7~10.5 Compression ratio 7
Table 2. Parameters of the aperture off-axis three-mirror optical system
View tableView in ArticleTable 2. Parameters of the aperture off-axis three-mirror optical system
Mirror Radius/mm Thickness/mm Conic Rotation angle/（°） Primary Mirror（PM） -1260 -484.655 -1 0 Secondary Mirror（SM） -300.145 490.237 -4.501 0 Tertiary Mirror（TM） -180 -300 -1 0
Table 3. Zernike polynomial coefficients of the aperture off-axis three-mirror optical system
View tableView in ArticleTable 3. Zernike polynomial coefficients of the aperture off-axis three-mirror optical system
Item Coefficient（PM） Coefficient（SM） Coefficient（TM） Z4 -2.154 0.093 4.036 Z5 2.241×103 2.745×10-3 1.829×10-4 Z8 -3.984×10-3 -3.613×10-3 -1.181×10-3 Z9 -4.471×10-4 -3.322×10-4 -2.722×10-5 Z11 -1.615×10-5 2.106×10-4 5.745×10-5 Z12 -4.593×10-4 -4.248×10-4 1.876×10-4 Z15 1.033×10-4 3.919×10-4 -1.054×10-4 Z16 -1.876×10-5 1.344×10-4 -1.414×10-5 Z17 5.123×10-5 -1.400×10-4 2.566×10-5 Z20 -8.191×10-5 1.116×10-4 2.684×10-5
Table 4. Parameters of the field of view off-axis three-mirror optical system
View tableView in ArticleTable 4. Parameters of the field of view off-axis three-mirror optical system
Mirror Radius/mm Thickness/mm Conic Rotation angle/（°） Primary Mirror（PM） -986.159 -410.063 -1 0 Secondary Mirror（SM） -268.288 342.656 -4.529 -14.4 Tertiary Mirror（TM） -374.606 -300 -1 -52.8
Table 5. Zernike polynomial coefficients of the field of view off-axis three-mirror optical system
View tableView in ArticleTable 5. Zernike polynomial coefficients of the field of view off-axis three-mirror optical system
Item Coefficient（PM） Coefficient（SM） Coefficient（TM） Z4 0.391 -0.313 -0.033 Z5 -0.527 0.280 0.366 Z8 -0.015 0.015 -0.029 Z9 -0.269 0.208 -0.189 Z11 0.05 -0.014 6.074×10-3 Z12 0.126 -0.098 -0.036 Z15 -0.152 -0.070 0.052 Z16 5.401×10-3 0.018 7.341×10-3 Z17 0.028 -0.033 0.026 Z20 -0.062 -0.089 -0.016
Table 6. Tolerance distribution of optical system
View tableView in ArticleTable 6. Tolerance distribution of optical system
Surface type/λ
（λ=632.8 nm）
Radius/mm Distance/mm Decenter/mm Tilt/（°） Primary Mirror（PM） 1/50 ±0.1 ±0.1 ±0.01 —— Secondary Mirror（SM） 1/50 ±0.1 ±0.1 ±0.01 ±0.01 Tertiary Mirror（TM） 1/50 ±0.1 —— ±0.02 ±0.01
Table 7. Monte Carlo analysis results of the aperture off-axis three-mirror optical system
View tableView in ArticleTable 7. Monte Carlo analysis results of the aperture off-axis three-mirror optical system
Value/λ Monte Carlo 90%：0.085 037 11 80%：0.074 126 10 50%：0.040 324 53 20%：0.018 510 26 10%：0.012 537 94
Table 8. Monte Carlo analysis results of the field of view off-axis three-mirror optical system
View tableView in ArticleTable 8. Monte Carlo analysis results of the field of view off-axis three-mirror optical system
Value/λ Monte Carlo 90%：0.077 603 30 80%：0.066 189 41 50%：0.037 371 87 20%：0.016 235 19 10%：0.012 912 49
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Junhua YAN, Zijia HU, Deyan ZHU, Yang CHEN, Yin ZHANG, Liqian YU. Design of Compact Off-axis Three-mirror Afocal System Based on Freeform Surface[J]. Acta Photonica Sinica, 2022, 51(5): 0511002
Paper Information
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Received: Nov. 9, 2021
Accepted: Dec. 22, 2021
Published Online: Jun. 27, 2022
The Author Email: YAN Junhua (yjh9758@126.com)
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