Development of linear astigmatism free—three mirror system (Laf-tms)

Woojin Park, Seunghyuk Chang, Jae Hyuk Lim, Sunwoo Lee, Hojae Ahn, Yunjong Kim, Sanghyuk Kim, Arvid Hammar, Byeongjoon Jeong, Geon Hee Kim, Hyoungkwon Lee, Dae Wook Kim, Soojong Pak

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We present the development of Linear Astigmatism Free—Three Mirror System (LAF-TMS). This is a prototype of an off-axis telescope that enables very wide field of view (FoV) infrared satellites that can observe Paschen-α emission, zodiacal light, integrated starlight, and other infrared sources. It has the entrance pupil diameter of 150 mm, the focal length of 500 mm, and the FoV of 5°.5 × 4°.1. LAF-TMS is an obscuration-free off-axis system with minimal out-of-field baffling and no optical support structure diffraction. This optical design is analytically optimized to remove linear astigmatism and to reduce high-order aberrations. Sensitivity analysis and Monte-Carlo simulation reveal that tilt errors are the most sensitive alignment parameters that allow ∼1′. Optomechanical structure accurately mounts aluminum mirrors, and withstands satellite-level vibration environments. LAF-TMS shows optical performance with 37 μm FWHM of the point source image satisfying Nyquist sampling requirements for typical 18 μm pixel Infrared array detectors. The surface figure errors of mirrors and scattered light from the tertiary mirror with 4.9 nm surface microroughness may affect the measured point-spread function. Optical tests successfully demonstrate constant optical performance over wide FoV, indicating that LAF-TMS suppresses linear astigmatism and high-order aberrations.

Original languageEnglish (US)
Article number044504
JournalPublications of the Astronomical Society of the Pacific
Issue number1010
StatePublished - Apr 2020


  • Instrumentation: high angular resolution
  • Instrumentation: miscellaneous
  • Instrumentation: photometers
  • Telescope

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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