Patent ID: 6965476
Filing Date: 2005-11-15
Classification: G02B

Abstract:
1. A diffractive optical element comprising: a first diffractive optical part having a phase-type diffractive grating; and a second diffractive optical part having a phase-type diffractive grating formed of a material differing from that of said first diffractive optical part; said first diffractive optical part and said second diffractive optical part being disposed in proximity to each other with a space therebetween; each of said first diffractive optical part and said second diffractive optical part having a mark for aligning them, said mark being in the area where the diffractive grating is provided; the depth or height of said mark is 10% or less of the depth or height of the diffractive grating of each of said first diffractive optical part and said second diffractive optical part.