Optical assembly with holographic optics for folded optical path
An optical device for a head-mounted display device includes a first partial reflector and a second partial reflector positioned relative to the first partial reflector so that the second partial reflector receives first light transmitted through the first partial reflector and reflects at least a portion of the first light toward the first partial reflector as second light. At least a portion of the second light is reflected by the first partial reflector as third light, and at least a portion of the third light is transmitted through the second partial reflector. At least one of the first partial reflector or the second partial reflector includes a reflective holographic element.
1. An optical system, comprising:
an optical device including:
a first partial reflector; and
a second partial reflector positioned relative to the first partial reflector so that the second partial reflector receives first light transmitted through the first partial reflector and reflects at least a portion of the first light toward the first partial reflector as second light, wherein:
at least a portion of the second light is reflected by the first partial reflector as third light, and at least a portion of the third light is transmitted through the second partial reflector, and
at least one of the first partial reflector or the second partial reflector comprises a reflective holographic element,
the first partial reflector receives light emitted from a display panel of the display device, the emitted light having a limited emission cone, and
the emission cone varies spatially over the display panel; and
a display device.
2. The optical system of claim 1 , wherein the display device is coupled with a substantially coherent light source.
3. The optical system of claim 2 , wherein the substantially coherent light source includes a laser.
4. The optical system of claim 2 , further comprising a de-speckler.
5. The optical system of claim 4 , wherein the de-speckler is positioned to de-speckle light emitted from the substantially coherent light source.
6. The optical system of claim 4 , wherein the de-speckler is positioned to de-speckle light emitted from the display device.
7. The optical system of claim 4 , wherein the de-speckler includes an electroactive polymer configured to provide a time-varying diffusion pattern.
8. The optical system of claim 1 , wherein the display panel is configured to provide, at a first location on the display panel, light having a first emission cone characterized by a first emission cone angle and provide, at a second location on the display panel that is distinct from the first location, light having a second emission cone characterized by a second emission cone angle that is distinct from the first emission cone angle.
9. The optical system of claim 1 , wherein central rays of emission cones from the display panel intersect a common point in front of or behind the display panel.
10. The optical system of claim 1 , wherein emission cones substantially correspond to light that enters an eyebox of a user of the optical system.
11. The optical system of claim 1 , wherein the display device includes a directional backlight.
12. The optical system of claim 11 , wherein the directional backlight includes a volume hologram.
13. The optical system of claim 11 , wherein the directional backlight includes a non-directional light source and an angle limiting plate.
14. The optical system of claim 11 , wherein the directional backlight includes a diffuser.
15. The optical system of claim 1 , wherein the display device is positioned in proximity to the first partial reflector.
16. The optical system of claim 1 , wherein the optical system is configured to change a size of the air gap between the optical device and the display device.
17. The optical system of claim 1 , wherein the display device includes a liquid crystal display (LCD) panel or a liquid crystal on silicon (LCOS) panel.
18. An optical device for a head-mounted display device, the optical device comprising:
a first partial reflector; and
a second partial reflector positioned relative to the first partial reflector so that the second partial reflector receives first light transmitted through the first partial reflector and reflects at least a portion of the first light toward the first partial reflector as second light, wherein:
at least a portion of the second light is reflected by the first partial reflector as third light, and at least a portion of the third light is transmitted through the second partial reflector,
at least one of the first partial reflector or the second partial reflector comprises a metasurface or a multi-order diffractive element,
the first partial reflector receives light emitted from a display panel of the display device, the emitted light having a limited emission cone, and
the emission cone varies spatially over the display panel.