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, comprising:
an array of pixels configured to produce light;
a first linear polarizer through which the light passes;
a first quarter wave plate that receives the light from the first linear polarizer;
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 second quarter wave plate at the second surface;
a second lens element having a third surface at the second quarter wave plate and an opposing fourth surface that is concave;
a reflective polarizer at the fourth surface;
a third lens element having a fifth surface and opposing sixth surface, wherein the second lens element is interposed between the first and third lens elements; and
a second linear polarizer that is interposed between the second and third lens elements.
2. The head-mounted display defined in claim 1 , wherein the third lens element is a dome lens.
3. The head-mounted display defined in claim 1 , wherein the second linear polarizer and the reflective polarizer have parallel pass axes.
4. The head-mounted display defined in claim 1 , wherein the reflective polarizer has a reflection axis and a pass axis that is orthogonal to the reflection axis.
5. The head-mounted display defined in claim 1 , wherein the first linear polarizer has a pass axis and wherein the first quarter wave plate has a fast axis that is at a 45 degree angle relative to the pass axis.
6. The head-mounted display defined in claim 1 , wherein the reflective polarizer has a pass axis and wherein the second quarter wave plate has a fast axis that is at a 45 degree angle relative to the pass axis.
7. The head-mounted display defined in claim 1 , wherein the second surface is cylindrically concave and wherein the third surface is cylindrically convex.
8. The head-mounted display defined in claim 1 , wherein the second and third surfaces are mating cylindrical surfaces.
9. The head-mounted display defined in claim 1 , wherein at least one of the fifth surface and the sixth surface is an aspheric surface.
10. A head-mounted display, comprising:
an array of pixels configured to produce light;
a first linear polarizer through which the light passes;
a first quarter wave plate that receives the light from the first linear polarizer;
a first lens element having a first surface that is convex and having an opposing second surface that is concave;
a partially reflecting mirror on the first surface;
a second quarter wave plate at the second surface;
a second lens element having a third surface that is convex and having an opposing fourth surface that is concave;
a reflective polarizer that is interposed between the first lens element and the second lens element; and
a second linear polarizer that is interposed between the first lens element and the second lens element.
11. The head-mounted display defined in claim 10 , wherein the second linear polarizer and the reflective polarizer have parallel pass axes.
12. The head-mounted display defined in claim 10 , wherein the reflective polarizer has a reflection axis and a pass axis that is orthogonal to the reflection axis.
13. The head-mounted display defined in claim 10 , wherein the first linear polarizer has a pass axis and wherein the first quarter wave plate has a fast axis that is at a 45 degree angle relative to the pass axis.
14. The head-mounted display defined in claim 10 , wherein the reflective polarizer has a pass axis and wherein the second quarter wave plate has a fast axis that is at a 45 degree angle relative to the pass axis.
15. The head-mounted display defined in claim 10 , wherein the second lens element is a dome lens.
16. A head-mounted display, comprising:
an array of pixels configured to produce light;
a first linear polarizer through which the light passes;
a first quarter wave plate that receives the light from the first linear polarizer;
a lens element having a first surface that is convex and having an opposing second surface that is concave;
a partially reflecting mirror on the first surface;
a second quarter wave plate at the second surface;
a reflective polarizer, wherein the second quarter wave plate is interposed between the reflective polarizer and the lens element; and
a second linear polarizer, wherein the reflective polarizer is interposed between the second linear polarizer and the second quarter wave plate.
17. The head-mounted display defined in claim 16 , wherein the second linear polarizer and the reflective polarizer have parallel pass axes.
18. The head-mounted display defined in claim 16 , wherein the reflective polarizer has a reflection axis and a pass axis that is orthogonal to the reflection axis.
19. The head-mounted display defined in claim 16 , wherein the first linear polarizer has a pass axis and wherein the first quarter wave plate has a fast axis that is at a 45 degree angle relative to the pass axis.
20. The head-mounted display defined in claim 16 , wherein the reflective polarizer has a pass axis and wherein the second quarter wave plate has a fast axis that is at a 45 degree angle relative to the pass axis.
21. An electronic device, comprising:
an array of pixels configured to produce light;
a first linear polarizer through which the light passes;
a first quarter wave plate that receives the light from the first linear polarizer;
a lens element having a first surface that is convex and having an opposing second surface that is concave;
a partially reflecting mirror on the first surface;
a second quarter wave plate at the second surface;
a reflective polarizer, wherein the second quarter wave plate is interposed between the reflective polarizer and the lens element; and
a second linear polarizer, wherein the reflective polarizer is interposed between the second linear polarizer and the second quarter wave plate.