Systems, devices, and methods for inputting light from a scanning laser projector into a waveguide
A laser projection system utilizes a waveguide having a narrow incoupler for double-bounce mitigation and form factor reduction. An optical scanner includes an optical relay positioned in between two scan mirrors. The first scan mirror scans laser light into the optical relay in a first dimension, and the optical relay and converges the scanned laser light towards a second scan mirror. The second scan mirror scans laser light along a second dimension substantially perpendicular to a path over which the laser light is scanned across the second scan mirror, and the convergence introduced by the optical relay causes the laser light to be scanned as a line or arc path of an exit pupil plane that is coincident with the incoupler. The optical relay may include one or more lenses or may be a monolithic molded structure, which may be an Offner-style relay or a molded reflective relay.
1. A laser projection system comprising:
a first scan mirror configured to scan laser light along a first scanning dimension;
an optical relay configured to receive the laser light from the first scan mirror and to relay the laser light, wherein an entrance pupil of the optical relay is coincident with the first scan mirror;
a second scan mirror configured to reflect the relayed laser light from the optical relay and to scan the relayed laser light along a second scanning dimension that is different than the first scanning dimension, wherein the first scan mirror is substantially coplanar with and disposed on a common surface with the second scan mirror; and
a waveguide comprising an incoupler, wherein the second scan mirror is further configured to scan the relayed laser light along a path of an exit pupil plane at the incoupler.
2. The laser projection system claim 1 , wherein the optical relay comprises:
a first lens configured to receive the laser light from the first scan mirror; and
a second lens configured to receive the laser light from the first lens and to relay the laser light to converge to the exit pupil plane that is coincident with the incoupler after the laser light exits the optical relay, wherein at least one of the first lens or the second lens is configured to reshape a cross-section of the laser light by magnifying the laser light in one or both of a first direction and a second direction, and wherein the first direction is substantially orthogonal to the second direction.
3. The laser projection system of claim 1 , wherein the optical relay comprises a monolithic molded structure.
4. The laser projection system of claim 3 , wherein the monolithic molded structure is an Offner-style relay that comprises:
a first spherical mirror; and
a second spherical mirror that is concentric with the first spherical mirror.
5. The laser projection system of claim 4 , wherein the Offner-style relay further comprises:
a first fold mirror configured to receive the laser light from the first scan mirror and to reflect the laser light toward a first portion of the first spherical mirror;
a second fold mirror; and
wherein the first portion of the first spherical mirror is configured to relay the laser light toward the second spherical mirror, the second spherical mirror is configured to relay the laser light toward a second portion of the first spherical mirror, the second portion of the first spherical mirror is configured to relay the laser light toward the second fold mirror, the second fold mirror is configured to reflect the laser light out of the optical relay toward the second scan mirror, and the second portion of the first spherical mirror is configured to relay the laser light to converge to the exit pupil plane that is coincident with the incoupler after the laser light exits the optical relay.
6. The laser projection system of claim 3 , wherein the monolithic molded structure is a molded reflective relay that comprises:
a first curved mirror configured to receive the laser light from the first scan mirror and to relay and reflect the laser light; and
a second curved mirror configured to receive the laser light from the first curved mirror and to relay and reflect the laser light out of the optical relay toward the second scan mirror.
7. The laser projection system of claim 6 , wherein the first curved mirror is configured to cause the laser light to converge to an intermediate image plane disposed between the first curved mirror and the second curved mirror, and wherein the second curved mirror is configured to relay the laser light to converge to the exit pupil plane that is coincident with the incoupler after the laser light exits the optical relay.
8. The laser projection system of claim 7 , wherein the molded reflective relay further comprises:
a first fold mirror disposed in an optical path between the first curved mirror and the second curved mirror following the intermediate image plane, wherein the first fold mirror is configured to receive the laser light output from the intermediate image plane and to reflect the laser light toward the second curved mirror.
9. The laser projection system of claim 8 , wherein the molded reflective relay further comprises:
a second fold mirror disposed in an optical path between the first curved mirror and the first fold mirror, prior to the intermediate image plane, wherein the second fold mirror is configured to receive the laser light from the first curved mirror and to reflect the laser light toward the first fold mirror via the intermediate image plane.
10. The laser projection system of claim 1 , further comprising:
an optical engine comprising a plurality of laser light sources, each configured to output a respectively different wavelength of laser light;
a plurality of primary lenses comprising a respective primary lens for each of the wavelengths of laser light output by the optical engine; and
a beam combiner configured to receive the wavelengths of laser light from the optical engine via the primary lenses and to combine the wavelengths of laser light to produce the laser light that the first scan mirror is configured to receive.
11. The laser projection system of claim 10 , wherein the waveguide further comprises:
an exit pupil expander comprising a diffraction grating configured to receive the relayed laser light from the incoupler, wherein the incoupler is configured to redirect the relayed laser light toward the exit pupil expander in a first direction that is substantially perpendicular to the path across which the relayed laser light is scanned across the incoupler; and
an outcoupler that is configured to receive the laser light from the diffraction grating of the exit pupil expander and to redirect the relayed laser light out of the waveguide, wherein the diffraction grating of the exit pupil expander is configured to redirect the laser light toward the outcoupler in a second direction that is substantially perpendicular to the first direction.