DIFFRACTIVE OPTICAL ELEMENT USING POLARIZATION ROTATION GRATING FOR IN-COUPLING
First Claim
1. An optical system, comprising:
- a substrate of optical material;
a first diffractive optical element (DOE) disposed on the substrate, the first DOE having an input surface and configured as an in-coupling grating to receive one or more optical beams as an input; and
a second DOE disposed on the substrate and configured for pupil expansion of the one or more optical beams along a first direction,wherein at least a portion of the first DOE is configured with a polarization rotating grating.
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Abstract
In an optical display system that includes a waveguide with multiple diffractive optical elements (DOEs), an in-coupling DOE couples light into the waveguide, an intermediate DOE provides exit pupil expansion in a first direction, and an out-coupling DOE provides exit pupil expansion in a second direction and couples light out of the waveguide. The in-coupling DOE is configured with two portions—a first portion includes a grating to rotate a polarization state of in-coupled light while a second portion couples light into the waveguide without modulation of the polarization state. The in-coupled light beams with different polarization states are combined in the waveguide after undergoing total internal reflection. However, as the difference in optical path lengths of the constituent light beams exceeds the coherence length, the combined light has random polarization (i.e., a degree of polarization equal to zero).
83 Citations
20 Claims
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1. An optical system, comprising:
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a substrate of optical material; a first diffractive optical element (DOE) disposed on the substrate, the first DOE having an input surface and configured as an in-coupling grating to receive one or more optical beams as an input; and a second DOE disposed on the substrate and configured for pupil expansion of the one or more optical beams along a first direction, wherein at least a portion of the first DOE is configured with a polarization rotating grating. - View Dependent Claims (2, 3, 4, 5)
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6. An electronic device, comprising:
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a data processing unit; an optical engine operatively connected to the data processing unit for receiving image data from the data processing unit; an imager operatively connected to the optical engine to form images based on the image data and to generate one or more input optical beams incorporating the images; and an exit pupil expander, responsive to the one or more input optical beams, comprising a structure on which multiple diffractive optical elements (DOEs) are disposed, in which the exit pupil expander is configured to provide one or more output optical beams, using one or more of the DOEs, as a near eye virtual display with an expanded exit pupil, and wherein at least one of the DOEs has at least one portion configured as a polarization rotating grating with a plurality of grating elements that are periodically arranged along first and second directions that are different from each other. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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receiving light at an in-coupling diffractive optical element (DOE) disposed in an exit pupil expander; expanding an exit pupil of the received light along a first coordinate axis in an intermediate DOE disposed in the exit pupil expander; expanding the exit pupil along a second coordinate axis in an out-coupling DOE disposed in the exit pupil expander; and outputting light with an expanded exit pupil relative to the received light at the in-coupling DOE along the first and second coordinate axes using the out-coupling DOE, in which the in-coupling DOE includes gratings configured to provide a periodic contoured surface having a first periodicity along a first direction and a second periodicity along a second direction so as to cause rotation of a polarization state of optical beams that are incident on the in-coupling DOE. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification