20130021515 | ADVANCED INFRARED CUT-OFF OPTICAL FILTERS - An infrared cut-off optical filter includes a substrate and a film structure. The substrate has a thickness and allows incoming lights to enter the optical filter at an incidence angle. The film structure is formed on the substrate to reduce an angle dependence of the optical filter with respect to the incoming lights. Further, the film structure contains a plurality of first type thin films with a first refractive index and a plurality of second type thin films with a second refractive index; the first type thin films and the second type thin films are arranged alternately; and thickness of individual films of the first type thin films and the second type thin films are controlled individually such that a substantial number of the first type thin films and the second type thin films have different thickness. | 01-24-2013 |