Current Optics and Photonics

Optical Society of Korea (한국광학회)
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Wide-fan-angle Flat-top Linear Laser Beam Generated by Long-pitch Diffraction Gratings

  • Lee, Mu Hyeon (Department of Optical Engineering, Kongju National University) ;
  • Ryu, Taesu (Department of Optical Engineering, Kongju National University) ;
  • Kim, Young-Hoon (United Science Institute Co. Ltd.) ;
  • Yang, Jin-Kyu (Department of Optical Engineering, Kongju National University)
  • Received : 2021.06.10
  • Accepted : 2021.07.26
  • Published : 2021.10.25
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Abstract

We demonstrated a wide-fan-angle flat-top irradiance pattern with a very narrow linewidth by using an aspheric lens and a long-pitch reflective diffraction grating. First, we numerically designed a diffraction-based linear beam homogenizer. The structure of the Al diffraction grating with an isosceles triangular shape was optimized with 0.1-mm pitch, 35.5° slope angle, and 0.02-mm radius of the rounding top. According to the numerical results, the linear uniformity of the irradiance was more sensitive to the working distance than to the shape of the Al grating. The designed Al grating reflector was fabricated by using a conventional mold injection and an Al coating process. A uniform linear irradiance of 405-nm laser diode with a 100-mm flat-top length and 0.176-mm linewidth was experimentally demonstrated at 140-mm working distance. We believe that our proposed linear beam homogenizer can be used in various potential applications at a precise inspection system such as three-dimensional morphology scanner with line lasers.

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Acknowledgement

This work was supported by the Technology Development Program (S2719427) funded by the Ministry of SMEs and Startups (MSS, Korea).

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