A new design of TMn-film grating optical low-pass filter and its fabrication

Cheng Chung Lee, Sheng Hui Chen

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations


When sampling a periodic image that includes high spatial frequencies with a digital image device, alias distortion is always produced. To reduce the distortion, an optical low-pass spatial filter (OLFF), which cuts off the high spatial frequency, can be applied. In this study thin-film phase grating optical low-pass filter (GOLF) with two-phase and threephase of have been analyzed. By matching the period of the grating to the thickness of the thin film of two-phase GOLF, the cut-off bandwidth was twice of the pass bandwidth. By using the same technique, the cut-off bandwidth of threephase GOLF was five times of the pass bandwidth. Two-phase GOLF was fabricated by using physical vapor deposition technology with a metal mesh as mask and showed advantages of being simple, cheap and good for mass-production as compared with the conventional methods. The surface profiles of the thin-film phase GOLF was measured by a white light interferometer. The optical property, the modulation transfer function (MTF) was measured by a MTF measurement system. Both results showed good agreement with the theoretical calculation. The image of a digital image device also showed the Moire pattern was suppressed successfully by the thin-film phase GOLF.

Original languageEnglish
Title of host publicationAdvances in Thin-Film Coatings for Optical Applications III
StatePublished - 2006
EventAdvances in Thin-Film Coatings for Optical Applications III - San Diego, CA, United States
Duration: 13 Aug 200614 Aug 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


ConferenceAdvances in Thin-Film Coatings for Optical Applications III
Country/TerritoryUnited States
CitySan Diego, CA


  • Aliasing distortion
  • Grating optical low-pass filter
  • MTF
  • Thin film


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