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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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 µm 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.

Original languageEnglish (US)
Title of host publicationElectro-Optical and Infrared Systems
Subtitle of host publicationTechnology and Applications XVII
EditorsDuncan L. Hickman, Helge Bursing
PublisherSPIE
ISBN (Electronic)9781510638877
DOIs
StatePublished - 2020
EventElectro-Optical and Infrared Systems: Technology and Applications XVII 2020 - Virtual, Online, United Kingdom
Duration: Sep 21 2020Sep 25 2020

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume11537
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceElectro-Optical and Infrared Systems: Technology and Applications XVII 2020
Country/TerritoryUnited Kingdom
CityVirtual, Online
Period9/21/209/25/20

Keywords

  • Dual-band
  • Freeform mirror
  • Infrared
  • Linear astigmatism
  • Monte-Carlo simulation
  • Off-axis
  • Telescope
  • Tolerance analysis

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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