Canon patent for ND filter with antireflection coating

Canon patent for an ND (Neutral Density) filter with antireflection coating. This patent may lead to a high performing ND filter with minimal image quality degradation.

• Patent Publication No. 2015-200805
  • Published 2015.11.12
  • Filing date 2014.4.9
• Canon patents
  • On the surface of the transparent substrate made of synthetic resin, deposited the inorganic hard film of fine uneven periodic structure
  • The refractive index changes toward the surface layer side from the transparent substrate side

[via Egami]