Patent ID: 6707608
Filing Date: 2004-03-16
Classification: G02B

Abstract:
A method for producing a diffractive optical element having multiple gratings formed from multiple optical materials, comprising:providing at least first and second optical materials; forming at least a first grating from the first optical material and a second grating from the second optical material, wherein each grating comprises a plurality of pixels, each pixel in an operating region of the grating having a substantially uniform depth and a phase retardation dependent on the depth, the substantially uniform pixel depths in at least one of the gratings are non-identical, and the gratings are aligned such that the pixels of the gratings are in substantially mutual registration so as to form a plurality of combined pixels, each of the combined pixels having an overall phase retardation resulting from the phase retardations of mutually registered pixels; and controlling wavelength dispersion by controlling the pixel depths so as to control a rate of change, with respect to wavelength, of differences among the overall phase retardations.