Tolerance analysis of wide field of view confocal off-axis telescope system using freeform mirrors for common optics MWIR/LWIR sensors onboard UAVs: linear astigmatism free three mirror system D70F1.4

Jimin Han; Woojin Park; Seunghyuk Chang; Sunwoo Lee; Hojae Ahn; Dae Wook Kim; Geon Hee Kim; Dae-Hee Lee; Hanshin Lee; Soojong Pak

doi:10.1117/12.2573698

20 September 2020 Tolerance analysis of wide field of view confocal off-axis telescope system using freeform mirrors for common optics MWIR/LWIR sensors onboard UAVs: linear astigmatism free three mirror system D70F1.4

Jimin Han, Woojin Park, Seunghyuk Chang, Sunwoo Lee, Hojae Ahn, Dae Wook Kim, Geon Hee Kim, Dae-Hee Lee, Hanshin Lee, Soojong Pak

Author Affiliations +

Proceedings Volume 11537, Electro-Optical and Infrared Systems: Technology and Applications XVII; 115370R (2020) https://doi.org/10.1117/12.2573698
Event: SPIE Security + Defence, 2020, Online Only

Conference Poster

Abstract

Linear Astigmatism Free - Three Mirror System (LAF-TMS) is a confocal off-axis system that eliminates linear astigmatism, which is the most critical aberration especially in the large field angle, and therefore, enables the telescope to have a wide field of view. Based on our experience with the telescope, we optimized the LAF-TMS for wavelength ranges of mid-wavelength infrared (3-5 µm) and long-wavelength infrared (8-12 µm) sensors onboard Unmanned Aerial Vehicles (UAVs). It has an entrance pupil diameter of 70 mm, a focal ratio of 1.4, and a wide field of view (FoV) of 6.20° × 4.68°, matching 10.9 mm × 8.2 mm sensor with 17 µ m sized pixels (LAF-TMS D70F1.4). The freeform mirrors of LAF- TMS D70F1.4 are optimized to eliminate the high order aberration. As a result, LAF-TMS D70F1.4 can achieve high- quality optical performance over a wide FoV without any additional correcting lenses. We performed the sensitivity analysis and the Monte-Carlo simulations as the feasibility study. During the sensitivity analysis and the Monte-Carlo simulation, decenter, tilt, despace, and surface RMS errors of three mirrors were analyzed. From the sensitivity analysis, we investigated 80% Energy Encircled Diameter by single factor perturbations. The system tolerance limits were calculated using the Monte-Carlo method with a normal distribution of errors. According to the results, we confirmed that the LAF-TMS D70F1.4 was feasible considering general fabrication and alignment tolerances.

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Jimin Han, Woojin Park, Seunghyuk Chang, Sunwoo Lee, Hojae Ahn, Dae Wook Kim, Geon Hee Kim, Dae-Hee Lee, Hanshin Lee, and Soojong Pak "Tolerance analysis of wide field of view confocal off-axis telescope system using freeform mirrors for common optics MWIR/LWIR sensors onboard UAVs: linear astigmatism free three mirror system D70F1.4", Proc. SPIE 11537, Electro-Optical and Infrared Systems: Technology and Applications XVII, 115370R (20 September 2020); https://doi.org/10.1117/12.2573698

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