Planar waveguide apparatus with diffraction element(s) and system employing same
A waveguide apparatus includes a planar waveguide and at least one optical diffraction element (DOE) that provides a plurality of optical paths between an exterior and interior of the planar waveguide. A phase profile of the DOE may combine a linear diffraction grating with a circular lens, to shape a wave front and produce beams with desired focus. Waveguide apparati may be assembled to create multiple focal planes. The DOE may have a low diffraction efficiency, and planar waveguides may be transparent when viewed normally, allowing passage of light from an ambient environment (e.g., real world) useful in AR systems. Light may be returned for temporally sequentially passes through the planar waveguide. The DOE(s) may be fixed or may have dynamically adjustable characteristics. An optical coupler system may couple images to the waveguide apparatus from a projector, for instance a biaxially scanning cantilevered optical fiber tip.
1. A waveguide array apparatus, comprising:
a plurality of planar waveguides, each planar waveguide in the plurality having at least a first end, a second end, a first face, and a second face, the second end opposed to the first end along a length of the planar waveguide, at least the first and the second faces forming an at least partially internally reflective optical path along at least a portion of the length of the planar waveguide, and
for each of at least two planar waveguides in the plurality, a respective diffractive optical element disposed between the first and the second ends at respective positions along at least a portion of the length of the respective planar waveguide to partially reflect a respective portion of a spherical wave front outwardly from the first face of the respective planar waveguide.
2. The waveguide array apparatus of claim 1 wherein the diffractive optical element is integral with respective ones of the planar waveguides.
3. The waveguide array apparatus of claim 1 wherein the diffractive optical element is disposed between the first face and the second face.
4. The waveguide array apparatus of claim 1 wherein the diffractive optical element is at one of the first face or the second face.
5. The waveguide array apparatus of claim 1 wherein the diffractive optical element is a Bragg grating.
6. The waveguide array apparatus of claim 1 wherein the diffractive optical element combines a linear diffraction function and a radially circular lens function.
7. The waveguide array apparatus of claim 1 wherein the diffractive optical element has a phase profile that is a combination of a linear diffraction grating and a radially symmetric lens.