Patent ID: 9081178
Filing Date: 2015-07-14
Classification: G02B

Abstract:
1. A projection display, for displaying an image to a viewer, comprising: a first plate waveguide made of light transmissive material; an image-providing light source device arranged to inject image bearing light into the first plate waveguide; a transmission grating within the first plate waveguide; an input device within the first plate waveguide arranged to direct the image bearing light onto the transmission grating of the first plate waveguide; the transmission grating being arranged to direct said image bearing light internally along the first plate waveguide and to output the image bearing light from the first plate waveguide; and a second plate waveguide made of light transmissive and transparent material, said second plate waveguide includes a coupling grating arranged to receive the image bearing light from the first plate waveguide, said second plate waveguide further includes an exit grating arranged to diffract received image bearing light out of the second plate waveguide, wherein image bearing light is diffractively inputted into the first or second plate waveguide and diffractively outputted from the first or second plate waveguide and the diffractive input and diffractive output powers are substantially matched, and dispersion associated with the diffractive input is oppositely matched with dispersion associated with the diffractive output thereby causing the net chromatic dispersion to a roach or substantially equal zero.