Patent ID: 7495832
Filing Date: 2009-02-24
Classification: G02B,H01S,H04B

Abstract:
1. A light dispersion filter comprising: three or more optically transparent layers each having a value equal to the value of a product of a refractive index and a thickness of said optically transparent layer, and transmitting light; a plurality of partially reflective layers having predetermined reflectivities, and arranged alternately with said optically transparent layers; and a reflective mirror for completely reflecting light, said reflective mirror being disposed at a location at which the value of a product of a distance to a light exit plane and the refractive index of a material between said exit plane and said reflective mirror is one-half of a product of the refractive index and thickness of said optically transparent layer, wherein the reflectivity is highest on a partially reflective layer disposed near the center of said light dispersion filter in a direction of thickness of said light dispersion filter, and the reflectivities of the respective partially reflective layers are gradually lower toward both end faces of said light dispersion filter.