Patent ID: 6327086
Filing Date: 2001-12-04
Classification: G02B,G03F

Abstract:
An optical diffraction element comprising a plurality of stair-like constructions each having a plurality of steps, said plurality of stair-like constructions diffracting light and said plurality of steps being formed so that interference among light rays reflected from said plurality of steps causes an overall intensity of the reflected light rays to become substantially zero, wherein said plurality of steps comprises at least three steps, and wherein said plurality of steps are formed so that the following conditions are satisfied:L=1-k+.lambda./{(n.sub.s -n.sub.i)h},h=.lambda./(2pn.sub.i), and0<k.ltoreq.1where .lambda. is the wavelength of the reflected light rays, n.sub.s is the refractive index of each of said plurality of stair-like constructions, n.sub.i is the refractive index of a medium in contact with a light incident side of said plurality of stair-like constructions, L is the number of steps in each of said stair-like constructions, h is the height of each of said plurality of steps, and p is an integer equal to or greater than 2.