Optical systems for displays
An electronic device may include a display system for presenting images close to a user's eyes. The display system may include a display unit that directs light and an optical system that redirects the light from the display unit towards a user's eyes. The optical system may include an input coupler and an output coupler formed on a waveguide. The input coupler may redirect light from the display unit so that it propagates in the waveguide towards the output coupler. The output coupler may redirect the light from the input coupler so that it exits the waveguide towards the user's eyes. A light-redirecting element may be used to redirect edge light that would otherwise be outside of the user's field of view towards the user's eyes.
1. A display system, comprising:
a head-mounted support structure;
a display unit in the head-mounted support structure;
an optical system that receives light from the display unit and that redirects the light out of the optical system, wherein the optical system includes an input coupler, an output coupler, and a first waveguide that propagates the light along a first direction, wherein the input coupler couples the light into the first waveguide and the output coupler couples the light out of the first waveguide, and wherein the input coupler and the output coupler are located on the same side of the first waveguide; and
a light-redirecting element interposed between the display unit and the optical system, wherein the light-redirecting element includes a second waveguide that propagates the light along a second direction and includes an additional input coupler and an additional output coupler on the second waveguide, wherein the additional input coupler receives the light from the display unit and redirects the light towards the additional output coupler, wherein the additional output coupler receives the light from the additional input coupler and redirects the light towards the input coupler, and wherein the first direction is perpendicular to the second direction.
2. The display system defined in claim 1 wherein the input coupler and the output coupler each include a holographic optical element.
3. The display system defined in claim 1 wherein the input coupler receives the light from the light-redirecting element and redirects the light towards the output coupler.
4. The display system defined in claim 3 wherein the output coupler receives the light from the input coupler and redirects the light out of the optical system.
5. The display system defined in claim 1 wherein the additional input coupler and the additional output coupler each include a holographic optical element.
6. A display system, comprising:
a head-mounted support structure;
a display unit in the head-mounted support structure;
an optical system that receives light from the display unit and that redirects the light out of the optical system, wherein the optical system includes a first input coupler, a first output coupler, and a waveguide, and wherein the first input coupler and the first output coupler are located on the same side of the waveguide; and
a light-redirecting element interposed between the input coupler and the output coupler, wherein the light-redirecting element includes a second input coupler and a second output coupler on the waveguide, and wherein the second input coupler receives the light from the first input coupler and the first output coupler receives the light from the second output coupler.
7. The display system defined in claim 6 wherein the first and second input couplers and the first and second output couplers each comprise a holographic optical element.
8. The display system defined in claim 6 wherein the waveguide propagates light from the first input coupler to the second input coupler along a first direction and wherein the waveguide propagates light from the second input coupler to the second output coupler along a second direction.
9. The display system defined in claim 8 wherein the first direction is perpendicular to the second direction.
10. The display system defined in claim 6 wherein the first input coupler has smaller dimensions than the first output coupler.
11. A display system, comprising:
a head-mounted support structure;
a display unit in the head-mounted support structure; and
an optical system that receives light from the display unit and that redirects the light out of the optical system, wherein the optical system includes an input coupler, an output coupler, and a waveguide that propagates light from the input coupler to the output coupler, wherein the output coupler includes first and second non-parallel interference patterns, and wherein the input coupler and the output coupler are located on the same side of the waveguide.
12. The display system defined in claim 11 wherein a thickness of the input and output couplers is greater than a thickness of the waveguide.
13. The display system defined in claim 11 wherein the input and output couplers each comprise holographic optical elements.
14. The display system defined in claim 13 wherein the holographic optical elements are color multiplexed.
15. The display system defined in claim 11 wherein the first and second non-parallel interference patterns each have a modulated diffraction efficiency.
16. The display system defined in claim 11 wherein the second interference pattern is located in an upper portion of the output coupler and a lower portion of the output coupler.