An optical system employs an optical coating on a substrate positioned relative to an optical collection system. The thickness of the coating is tailored such that light perceived by the collection system over prescribed angles of acceptance has a spectral content that is unchanged, or changed in a prescribed manner, from that entering the system when the sensor is oriented in the "look ahead" direction. The thickness of the coating is varied so that the wavelengths transmitted or reflected correspond to those required by a specific application. The invention is adaptable to system requirements that are centered about a single wavelength, or that require multiple wavelengths. The optical coating can take any of a number of forms, including stacked dielectric layers and rugate filters.