Patent ID: 8537466
Filing Date: 2013-09-17
Classification: G02B

Abstract:
1. A multi-holographic optical element (HOE) grating, comprising: a first volume phase grating having a first spatial frequency of “A” lines per mm; and a second volume phase grating having a second spatial frequency of “B” lines per mm; wherein the first volume phase grating and the second volume phase grating are positioned relative to each other such that radiation propagates through and is diffracted by the first volume phase grating and the second volume phase grating; wherein the first volume phase grating and the second volume phase grating are not tilted with respect to each other; and wherein the multi-HOE grating provides at least as much dispersion and has less polarization dependent loss (PDL) than a single grating having a spatial frequency of “A+B” lines per mm.