JPS5726821A - Optical separator - Google Patents

Abstract

PURPOSE:To obtain a desired photometric distribution, by varying stepwise or continuously and area ratio of an effective reflection surface for forming a separated light beam of a relief type diffracted structure body, in the plane containing the relief type diffracted structure body. CONSTITUTION:An incident light beam 40 is reflected by a reflection film 41 and is totally reflected by the upper and lower borders of an optical separator, so that a separated light beam is led. In this case, the surface of a relief type diffracted grid which is turned toward a photodetector 34 side from the projection end facing to the photodetector 34 of the optical separator becomes an effective reflection surface. In the first execution example of this invention, it is attained to weight the photometric quantity on the photometric surface, by separating an area on which a relief type diffracted grid had been engraved, into plural areas, and discontinuously varying an area ratio of the effective reflection surface in each area, and also in other execution example, said purpose is attained by continuously varying the area ratio of the effective reflection surface extending over the whole area on which the grid has been engraved.