Waveguide including volume Bragg gratings
AssigneeFacebook Technologies, LLC
InventorsWanli Chi, Hee Yoon Lee, Pasi Saarikko
Life of this patent
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Abstract
A waveguide is provided for conveying image light. The waveguide includes an input port for receiving a first beam of image light carrying an image in a wavelength band. A first diffraction grating of the waveguide includes a plurality of volume Bragg gratings (VBGs) configured to expand the first beam along a first axis and to redirect the first beam towards a second diffraction grating of the waveguide. The second diffraction grating includes a plurality of VBGs configured to receive the first beam from the first diffraction grating and to out-couple different portions of the first wavelength band of the first beam along a second axis, thereby expanding the first beam along the second axis for observation of the image by a user.
Claims20
A waveguide for conveying image light, the waveguide comprising:
- a first input port for receiving a first beam of image light carrying a first color channel of an image in a first wavelength band;
- opposed first and second optical surfaces for propagating the first beam therebetween;
- and
- first and second diffraction gratings disposed in the waveguide between the first and second optical surfaces and offset laterally from each other;
- wherein the first diffraction grating comprises a plurality of volume Bragg gratings (VBGs) configured to expand the first beam along a first axis and to redirect the first beam towards the second diffraction grating;
- and
- wherein the second diffraction grating comprises a plurality of VBGs configured to receive the first beam from the first diffraction grating and to out-couple portions of the first beam at a plurality of locations along a second axis, thereby expanding the first beam along the second axis for observation of the image by a user.
Dependencies are inferred from the claim text.