Compact, unit magnification, reflective imaging relay using freeform surfaces

Jose Sasian, Weichuan Gao

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


We present a design for a unit magnification imaging relay that is compact. The design uses two mirrors, and one is used by light twice for a three-reflection system. The mirrors are specified with freeform surfaces. There are several tradeoffs of performance depending on field of view, F / #, and wavelength range. One example provides a 30-mm circular field of view at F / 2.8, and another example provides a circular field of view of 40 mm in diameter at F / 4 for a length of 1/4400 mm. Adding a third nearly flat mirror allows a system to provide a 50-mm field of view at F / 4 for a length of 420 mm. A last example includes a beam splitter cube to allow accessing the full field of view. These systems are diffraction limited at 550 nm.

Original languageEnglish (US)
Article number095103
JournalOptical Engineering
Issue number9
StatePublished - Sep 1 2020


  • freeform surfaces
  • imaging relay
  • plane symmetry
  • reflective optics
  • unit magnification

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • General Engineering


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