Optical system for head-mounted display
A head-mounted display may include a display system and an optical system in a housing. The display system may have a pixel array that produces light associated with images. The display system may also have a linear polarizer through which light from the pixel array passes and a quarter wave plate through which the light passes after passing through the quarter wave plate. The optical system may be a catadioptric optical system having one or more lens elements. The lens elements may include a plano-convex lens and a plano-concave lens. A partially reflective mirror may be formed on a convex surface of the plano-convex lens. A reflective polarizer may be formed on the planar surface of the plano-convex lens or the concave surface of the plano-concave lens. An additional quarter wave plate may be located between the reflective polarizer and the partially reflective mirror.
1. A head-mounted display configured to display images viewable by a user, comprising:
an array of pixels configured to produce the images;
a linear polarizer through which light associated with the images passes;
a first planar quarter wave plate that receives the light from the linear polarizer;
a plano-convex lens element having a convex surface and an opposing planar surface;
a partially reflective mirror on the convex surface;
a reflective polarizer;
a second planar quarter wave plate, wherein the second planar quarter wave plate is between the reflective polarizer and the partially reflective mirror; and
a plano-concave lens element having a concave surface and an opposing planar surface, wherein the planar surface of the plano-concave lens element is interposed between the concave surface and the planar surface of the plano-convex lens element, and wherein the planar surface of the plano-convex lens element is interposed between the planar surface of the plano-concave lens element and the convex surface.
2. The head-mounted display defined in claim 1 further comprising an additional linear polarizer through which the light passes after passing through the reflective polarizer.
3. The head-mounted display defined in claim 1 wherein the second planar quarter wave plate is formed at the planar surface of the plano-convex lens element.
4. The head-mounted display defined in claim 1 wherein the planar surface of the plano-concave lens element is parallel to the planar surface of the plano-convex lens element.
5. The head-mounted display defined in claim 1 wherein the reflective polarizer is formed at the concave surface of the plano-concave lens element.
6. The head-mounted display defined in claim 5 further comprising an additional lens element, wherein the reflective polarizer is interposed between the additional lens element and the plano-concave lens element.
7. The head-mounted display defined in claim 6 further comprising an additional linear polarizer at a surface of the additional lens element, wherein the additional lens element is interposed between the additional linear polarizer and the reflective polarizer.
8. The head-mounted display defined in claim 1 further comprising:
control circuitry that is configured to supply image data to the array of pixels; and
input-output devices coupled to the control circuitry.
9. The head-mounted display defined in claim 8 wherein the input-output devices include a camera.
10. A head-mounted display configured to display images viewable by a user, comprising:
an array of pixels configured to produce the images;
a linear polarizer through which light associated with the images passes;
a first quarter wave plate that receives the light from the linear polarizer;
a first lens element having first and second opposing surfaces;
a second lens element having third and fourth opposing surfaces, wherein the third surface faces the second surface;
a third lens element having fifth and sixth opposing surfaces, wherein the fifth surface faces the fourth surface;
a partially reflective mirror on the first surface;
a second quarter wave plate, wherein the second quarter wave plate is between the second and third surfaces; and
a reflective polarizer between the fourth and fifth surfaces.
11. The head-mounted display defined in claim 10 further comprising an additional linear polarizer at the sixth surface through which the light passes after passing through the reflective polarizer.
12. The head-mounted display defined in claim 11 wherein the first surface is a convex surface and the second surface is a planar surface.
13. The head-mounted display defined in claim 12 wherein the third surface is a planar surface, the fourth surface is a concave surface, the fifth surface is a convex surface, and the sixth surface is a concave surface.
14. The head-mounted display defined in claim 11 wherein the second surface is a concave surface and the third surface is a convex surface.
15. The head-mounted display defined in claim 11 wherein the first surface is a convex surface, the second surface is a concave surface, the third surface is a convex surface, and the second and third surfaces have cylindrical shapes.
16. The head-mounted display defined in claim 10 wherein the fourth and fifth surfaces are dome-shaped surfaces.
17. A head-mounted device configured to present images to a user, comprising:
a support structure configured to be worn on a head of the user;
a display system supported by the support structure that produces light for the images; and
a catadioptric optical system supported by the support structure that focuses the light as the light passes to the user from the display system, wherein the catadioptric optical system includes a first lens element having a first surface that is convex and having an opposing second surface, a partially reflecting mirror on the first surface, a quarter wave plate at the second surface, a second lens element having a third surface at the quarter wave plate and an opposing fourth surface that is concave, a reflective polarizer at the fourth surface having a reflection axis and having a pass axis that is perpendicular to the reflection axis, and a third lens element having a fifth surface that is convex at the reflective polarizer and an opposing sixth surface that is concave.
18. The head-mounted device defined in claim 17 further comprising a linear polarizer on the sixth surface.
19. The head-mounted device defined in claim 18 wherein the second and third surfaces are planar and the quarter wave plate is planar.
20. The head-mounted device defined in claim 18 wherein the second and third surfaces have mating cylindrical shapes.
21. The head-mounted display defined in claim 1 , wherein the convex surface is interposed between the planar surface of the plano-convex lens and the array of pixels.