Patent ID: 8717677

Claim:
An optical device, comprising: a beam splitting device configured to split an incident light beam into at least a first order diffracted light and a second order diffracted light, wherein the first order diffracted light at a first wavelength spatially overlaps the second order diffracted light at a second wavelength different than the first wavelength; a substrate having a coating region and an adjacent non-coating region, wherein the coating region is located where the first and second order diffracted light spatially overlap; and a first film on the coating region, wherein the first film has a band edge structure extending from a portion of the first film having a uniform thickness to a portion of the non-coating region, and wherein an angle is formed between a surface of the band edge structure and a surface of the portion of the first film having uniform thickness to diminish the attenuation of the first and second order diffracted light, configured such that a transmittance of the portion of the first film having uniform thickness for the spatially overlapping first order diffracted light having the first wavelength and the second order diffracted light having the second wavelength is 70% to 100% and 0% to 1%, respectively.