
Assembly and alignment method for optimized spatial resolution of off-axis three-mirror fore optics of hyperspectral imager
Author(s) -
Youngsoo Kim,
Jinsuk Hong,
Byeong-Doo Choi,
Jong-Ung Lee,
Yeonsoo Kim,
HyunSook Kim
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.020817
Subject(s) - optics , coma (optics) , hyperspectral imaging , spectrometer , physics , primary mirror , optical axis , image resolution , field of view , secondary mirror , optical aberration , wavefront , adaptive optics , curved mirror , computer science , telescope , artificial intelligence , lens (geology)
A fore optics for the hyperspectral spectrometer is designed, manufactured, assembled, and aligned. The optics has a telecentric off-axis three-mirror configuration with a field of view wider than 14 degrees and an f-number as small as 2.3. The primary mirror (M1) and the secondary mirror (M2) are axially symmetric aspheric surfaces to minimize the sensitivity. The tertiary mirror (M3) is a decentered aspheric surface to minimize the coma and astigmatism aberration. The M2 also has a hole for the slit to maintain the optical performance while maximizing the telecentricity. To ensure the spatial resolution performance of the optical system, an alignment procedure is established to assemble and align the entrance slit of the spectrometer to the rear end of the fore optics. It has a great advantage to confirm and maintain the alignment integrity of the fore optics module throughout the alignment procedure. To perform the alignment procedure successfully, the precision movement control requirements are calculated and applied. As a result, the alignment goal of the RMS wave front error (WFE) to be smaller than 90 nm at all fields is achieved.