Patent ID: 7821900
Filing Date: 2010-10-26
Classification: G02B

Abstract:
1. A reflective diffractive optical element, comprising: a light-reflective substrate having a top surface, the top surface being etched into a pattern, the pattern including a periodic surface pattern of grooves each having a width W, wherein the pattern has a continuous depth profile h(x), x being a coordinate in a width direction that varies across the width W, wherein the pattern is formed such that when an incoming light beam having a wavelength λ is shone onto the top surface of the light-reflective substrate, the incoming light beam will reflect and be split into a plurality of diffracted light beams, wherein the plurality of diffracted light beams includes a plurality of primary diffracted order beams and a plurality of secondary diffracted order beams, wherein the primary diffracted order beams have a primary aggregate efficiency above ninety percent, where the primary aggregate efficiency is the total power of the primary diffracted order beams divided by the incoming beam power, wherein the plurality of secondary diffracted order beams have a secondary aggregate efficiency of lower than ten percent, where the secondary aggregate efficiency is the total power of the secondary diffracted order beams divided by the incoming beam power, and wherein a maximum power of the primary diffracted order beams and a minimum power of the primary diffracted order beams differ by at least ten percent of an average power of the primary diffracted order beams.