Current Optics and Photonics

Optical Society of Korea (한국광학회)
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Novel Telecentric Collimator Design for Mobile Optical Inspection Instruments

  • Hojong Choi (Department of Electronic Engineering, Gachon University) ;
  • Seongil Cho (Department of Optical Engineering, Kumoh National Institute of Technology) ;
  • Jaemyung Ryu (Department of Optical Engineering, Kumoh National Institute of Technology)
  • Received : 2023.02.06
  • Accepted : 2023.04.26
  • Published : 2023.06.25
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Abstract

A collimator refers to an optical system that images a collimated beam at a desired point. A resolution target located at a near distance can be converted into a virtual image located at a long distance. To test the resolution for mobile cameras, a large target is placed at a long distance. If a collimator system is used, the target can be placed at a near distance. The space required for a resolution inspection can thus be drastically reduced. However, to inspect a mobile camera, the exit pupil of the collimator system and the entrance pupil of the mobile camera must match, and the stop of the collimator system must be located on the last surface. Because a collimator system cannot be symmetrical with respect to the stop, the distortion becomes extremely large, which can be corrected by combining the collimator symmetrically with respect to the object plane. A novel system was designed to inspect an optical lens on a mobile phone. After arranging the refractive power, lenses were added using the equivalent lens design method. The distortion was reduced to less than 1%. This optical system satisfies a half-field angle of 45° and an optical performance sufficient for inspection.

Keywords

Acknowledgement

The authors thank the American English editing services for scientific papers.

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