Acta Optica Sinica, Volume. 45, Issue 7, 0722001(2025)
Design of Off-Axis Catadioptric Infrared Space Optical Systems with Long Image Surface and Low Distortion
Figures & Tables(16)
Fig. 1. Schematic diagram of imaging principle of traditional re-imaging infrared optical system. (a) Re-imaging principle; (b) the match principle between exit pupil and cold stop principle
Fig. 3. Structure diagram of coaxial catadioptric re-imaging image-side telecentric optical system
Fig. 4. Layout of off-axis catadioptric infrared space optical system with long image size. (a) Layout of whole optical system; (b) layout of relay optical system
Fig. 7. Relative illumination curves of optical system. (a) Field of view in X direction; (b) field of view in Y direction
Fig. 8. Inspection optical path design of the free-form surface with CGH compensator. (a) Optical path diagram; (b) main holographic phase
Fig. 9. Design and manufature of CGH compensator. (a) Overall design layout of CGH compensator; (b) physical CGH compensator
Fig. 10. Manufacture and inspection of free-form surface relay lens.
Table 1. Optical system design specification
View tableTable 1. Optical system design specification
Parameter Value Wavelength /μm 8‒10 Focal length /mm 1038 Field of view /[(°)×(°)] 8.84×1.10 Aperture /mm 435 F-number 2.386 MTF of design status ≥0.3@25 lp/mm MTF of tolerance included ≥0.26@25 lp/mm Relative distortion /% ≤0.3 Relative illumination /% ≥98 Detector pixel size /(μm×μm) 20×20
Table 2. Initial structure parameters of coaxial catadioptric optical system
View tableTable 2. Initial structure parameters of coaxial catadioptric optical system
Optical element Radius /mm Focal length /mm Distance /mm Conic coefficient Primary mirror -851.25 — 284.31 -0.9444 Secondary mirror -309.06 — 337.33 -1.4471 Tertiary mirror -674.66 — 251.04 -8.3391 Intermediate image — — 100.00 — Front lens — 100 200.00 — Back lens — 100 100.00 —
Table 3. XY polynomial coefficients of freeform surface
View tableTable 3. XY polynomial coefficients of freeform surface
No. XY polynomial term Coefficient No. XY polynomial term Coefficient 1 X0Y1 -0.3415 9 X4Y1 -0.0119 2 X2Y0 3.1443 10 X2Y3 -0.0221 3 X0Y2 3.1388 11 X0Y5 -0.0094 4 X2Y1 0.0562 12 X6Y0 0 5 X0Y3 0.0465 13 X4Y2 -0.0008 6 X4Y0 -1.8225 14 X2Y4 -0.0077 7 X2Y2 -3.6302 15 X0Y6 -0.0248 8 X0Y4 -1.7979
Table 4. Tolerance distribution of optical system
View tableTable 4. Tolerance distribution of optical system
Optical element Conic constant Surface error
RMS /λ（λ=632.8 nm）
Surface
decenter /mm
Thickness /
mm
Distance /
mm
Element decenter /mm Tilt /（″） Primary mirror 0.0005 0.100 — — 0.02 Base Base Secondary mirror 0.001 0.050 — — 0.02 0.02 10 Tertiary mirror 0.001 0.100 — — 0.02 0.02 7 Lens 1 —
—
0.067 0.01 0.02 0.02 0.01 25 0.067 Lens 2 — 0.040 0.008 0.01 0.01 0.01 25 0.001 0.040 Lens 3 — 0.050 0.01 0.01 0.01 0.008 25 — 0.050 Lens 4 — 0.050 0.01 0.01 0.01 0.008 15 — 0.050 Lens 5 — 0.050 0.01 0.012 0.01 0.01 20 — 0.050 Lens 6 — 0.067 0.01 0.015 0.02 0.01 25 — 0.067 Window — 0.100 0.02 0.02 — 0.02 30 — 0.100
Table 5. Results of Monte Carlo tolerance analysis
View tableTable 5. Results of Monte Carlo tolerance analysis
Sample probability /% Average MTF@25 lp/mm 90 0.2732 80 0.2816 50 0.2948
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Baohua Wang, Huilin Jiang, Xiaoyong Wang, Yunsong Nie, Hui Xing, Chao Yang, Yang Li, Gaojin Wen. Design of Off-Axis Catadioptric Infrared Space Optical Systems with Long Image Surface and Low Distortion[J]. Acta Optica Sinica, 2025, 45(7): 0722001
Paper Information
Category: Optical Design and Fabrication
Received: Dec. 30, 2024
Accepted: Feb. 27, 2025
Published Online: Apr. 27, 2025
The Author Email: Huilin Jiang (HLJiang@cust.edu.cn)
CSTR:32393.14.AOS241957
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