Compensation of Field-Angle-Dependent Illumination Variations in Imaging and Illuminating Optical Systems
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
Light transmission through an optical system varies as a function of the field angle, and the light spectrum is operated on so as to produce a variety of throughput versus angle functions. As the angle from the radiating element to the illuminated surface, both Lambertian surfaces, increases, more light is passed to the surface to compensate for the increase of the angle. This compensates for the cosine4 effect. A document 1, which is disposed in a plane perpendicular to the drawing, has light supplied thereto from a lamp 2 via a short-wave reflecting mirror/concentrator 3. The mirror/concentrator 3, which is a "dichroic" filter, reflects most light in the light spectrum below a specific wavelength.