Optical filters for suppressing unwanted reflections

Abstract From the Canadian patent

An optical filter is provided for suppressing unwanted reflections of background light when used with a display device such as a cathode ray tube or an electroluminescent screen or in optical communication or surveillance. The filter has multiple thin layers including a first series of layers for suppressing reflections from its outer surface and a second series of layers constituting a bandpass interference filter. The first series of layers is arranged to suppress reflections over a broad wavelength band while the second series of layers allows transmittance over a relatively narrow wavelength passband within the broad wavelength band resulting in improved contrast when the display is …