Method and system for large field of view display with scanning reflector
An image display system includes an optical subsystem configured to emit a first light beam and a second light beam, wherein the first light beam illuminates a first portion of a composite field of view and the second beam illuminates a second portion of the composite field of view. A scanning mirror is positioned to intercept and reflect the first light beam and the second light beam. The system also has a waveguide with at least one input coupling optical element for receiving the first light beam and the second light beam into the waveguide. The waveguide also has an output coupling optical element for projecting a plurality of output light beams derived from the first light beam and the second light beam from the waveguide to illuminate the composite field of view.
1. An image display system, comprising:
an optical subsystem configured to emit a first imagewise modulated light beam and a second imagewise modulated light beam, wherein the first imagewise modulated light beam illuminates a first portion of a composite field of view (FOV) and the second imagewise modulated light beam illuminates a second portion of the composite field of view, wherein the composite field of view comprises the first portion and the second portion to form a tiled image in an enlarged composite field of view;
a scanning mirror positioned to reflect the first imagewise modulated light beam at a first angle and the second imagewise modulated light beam at a second angle different from the first angle; and
a waveguide, having:
at least one diffractive input coupling optical element for diffracting the first imagewise modulated light beam and the second imagewise modulated light beam from the scanning mirror into the waveguide to propagate in the waveguide by total internal reflection (TIR); and
an output coupling optical element for projecting a plurality of output light beams derived from the first imagewise modulated light beam and the second imagewise modulated light beam from the waveguide to illuminate the tiled image in the enlarged composite field of view.
2. The image display system of claim 1 wherein:
the optical subsystem is disposed on an opposite side of the waveguide from the scanning mirror.
3. The image display system of claim 2 wherein:
the at least one diffractive input coupling optical element is positioned between the optical subsystem and the scanning mirror such that the first imagewise modulated light beam and the second imagewise modulated light beam emitted from the optical subsystem pass through the at least one diffractive input coupling optical element before reaching the scanning mirror.
4. The image display system of claim 3 further comprising a polarization control element positioned between the optical subsystem and the at least one diffractive input coupling optical element such that the first imagewise modulated light beam and the second imagewise modulated light beam pass through the polarization control element before reaching the at least one diffractive input coupling optical element.
5. The image display system of claim 4 wherein the at least one diffractive input coupling optical element is a polarization selective device.
6. The image display system of claim 5 wherein the optical subsystem is configured to produce the first imagewise modulated light beam and the second imagewise modulated light beam in a linearly polarized state and the polarization control element comprises a waveplate that is configured to convert the first imagewise modulated light beam and the second imagewise modulated light beam to at least one circularly polarized light state and the at least one diffractive input coupling optical element is polarization selective in that the at least one diffractive input coupling optical element is selective on the basis of handedness of circularly polarized light.
7. The image display system of claim 5 wherein the at least one diffractive input coupling optical element comprises a diffraction grating that includes a cholesteric liquid crystal.
8. The image display system of claim 7 wherein the at least one diffractive input coupling optical element further comprises an alignment layer that establishes a periodic lateral variation in an alignment direction of the cholesteric liquid crystal.
9. The image display system of claim 1 wherein the optical subsystem comprises:
a first three color channel modulated light source that is configured to produce the first imagewise modulated light beam; and
a second three color channel modulated light source that is configured to produce the second imagewise modulated light beam.
10. The image display system of claim 9 wherein:
the first three color channel modulated light source comprises a first red laser, a first green laser, and a first blue laser; and
the second three color channel modulated light source comprises a second red laser, a second green laser and a second blue laser.
11. The image display system of claim 10 wherein:
the first three color channel modulated light source comprises a first dichroic beam combiner optically coupled to the first red laser, the first green laser and the first blue laser; and
the second three color channel modulated light source comprises a second dichroic beam combiner optically coupled to the second red laser, the second green laser and the second blue laser.
12. The image display system of claim 1 wherein the optical subsystem is configured to emit the first imagewise modulated light beam at a first angle and to emit the second imagewise modulated light beam at a second angle, the second angle being different than the first angle.
13. The image display system of claim 12 wherein the optical subsystem is configured to emit the first imagewise modulated light beam along a first path and to emit the second imagewise modulated light beam along a second path that intersects the first path at the scanning mirror, the second path being different than the first path.
14. The image display system of claim 1 wherein the optical subsystem is configured to emit the first imagewise modulated light beam collinear with the second imagewise modulated light beam.
15. The image display system of claim 1 further comprising a polarizer and a wave plate wherein the optical subsystem and the scanning mirror are disposed on a common side of the waveguide along with the polarizer and the wave plate and wherein a first optical path segment from the optical subsystem to the scanning mirror extends from the optical subsystem to the polarizer and from the polarizer through the wave plate and a second optical path segment from the scanning mirror to the at least one diffractive input coupling optical element traverses the wave plate and the polarizer.
16. The image display system of claim 1 , wherein the at least one diffractive input coupling optical element comprises a first input coupling grating and a second input coupling grating, and wherein the output coupling optical element comprises an output coupling grating.
17. The image display system of claim 1 wherein the first portion of the composite field of view is interleaved with the second portion of the composite field of view.
18. A method for providing a composite field of view (FOV), comprising:
providing a collimated incoming light beam including a plurality of components;
providing a scanning mirror with a diffractive surface for receiving the collimated incoming light beam and for separating the plurality of components into a plurality of reflected light beams having different angles of diffraction, each of the plurality of reflected light beams configured to provide a portion of the composite field of view;
diffracting the plurality of reflected light beams into an eyepiece waveguide to propagate in the eyepiece waveguide by total internal reflection (TIR); and
outputting a plurality of output light beams from the eyepiece waveguide to form a projected image in the composite field of view, wherein the plurality of output light beams are derived from the plurality of reflected light beams.
19. The method of claim 18 , wherein the plurality of components comprises components that are differentiated by wavelength.
20. The method of claim 18 , wherein the plurality of components comprises components that are differentiated by polarization state.