Patent ID: 6529321
Filing Date: 2003-03-04
Classification: C23C,G02B,G03F,H01S

Abstract:
An overcoat protected diffraction grating having a large number of parallel grooves, each groove having a reflective face, said grating comprising:A. a rigid substrate; B. an aluminum grating layer comprising a very large number of parallel grooves; spaced apart by about 11.7966 microns; C. an adhesive layer affixing said aluminum grating layer to said rigid substrate; D. a thin album overcoat layer overcoating said aluminum grating layer, said aluminum overcoat layer having a thickness of less than 200 nm on said reflective faces; D. a protective layer comprised of one or more layers of dielectric material, overcoating said aluminum overcoat layer; wherein said protective layer or layers have a thickness or thicknesses chosen to increase normal reflectivity of said reflecting face of each groove.