Canon patent application (in Japan) 2017-227774 describes methods and technology to reduce light reflection on optical filters.
Patent application abstract (machine translated):
To provide an optical filter, a light quantity adjusting device, and an optical device having an excellent light reflection preventing effect.
A fine structure provided on the multilayered film, wherein the microstructure is provided with a plurality of light emitting elements arranged in a matrix so that incident light from the outermost surface of the fine structure A microstructure surface having a fine uneven structure equal to or smaller than a wavelength of reflected light at an interface between the multilayer film and the microstructure, and a plurality of interfaces of the multilayer film and a plurality of interfaces of the multilayer film and the transparent substrate The relationship between the phase of the reflected light at one interface with respect to the incident light from the interface between the fine structure and the multilayer film and the phase of the reflected light at the other interface between the interface and the interface And a light reflection preventing structure having an anti-phase relationship in which they cancel each other out.
If I got it right, light reflection is reduced by applying a multilayered film with an extreme fine structure on the filter glass, a structure that’s “equal to or smaller than a wavelength of reflected light”.
Other interesting Canon patent applications that might go into production:
- Patent application describing how to improve burst rate by compressing raw files
- Patent application describing a new way to review photos from a sequential shot
- Patent application that describes technology to improve wireless communication while reducing power consumption
- Patent application to spot and reduce moire artefacts in image data
Japanese patent applications can not be linked. To learn more about this or other Japanese patent applications use this site and the number of the patent application (e.g. 2017-227774)