Hybrid lens for head mount display
A lens assembly, related methods and constituent optical elements are described. The assembly may be used to direct and focus light for various applications. In one instance, the lens assembly is used in conjunction with one or more sources of light such as projected images or video as part of a virtual reality system. The lens assembly includes two or more optical elements arranged to receive light or direct light through different spatial regions of the assembly at different focal powers corresponding to a first user viewing zone and a second user viewing zone. In one instance, the first user viewing zone is a peripheral viewing zone and the second viewing zone is a primary or non-peripheral viewing zone (or vice versa).
1. An apparatus for viewing a stereoscopic image, the apparatus comprising:
a headset comprising a display and a housing, the housing comprising a first lens configured to be positioned substantially over a first eye of a user of the headset and a second lens configured to be positioned substantially over a second eye of the user of the headset;
wherein the first lens and the second lens respectively comprise a central portion and a peripheral portion surrounding at least part of the central portion, the central portion comprising an aspheric lens and the peripheral portion comprising a Fresnel lens, and
wherein:
the central portion comprises a peripheral portion-receiving cavity, the peripheral portion-receiving cavity defining a part of the central portion configured to receive the peripheral portion, or
the peripheral portion comprises a central portion-receiving cavity, the central portion-receiving cavity defining a part of the peripheral portion configured to receive the central portion.
2. The apparatus of claim 1 , wherein the display is a curved display, and wherein the first lens and the second lens are configured to project onto the curved display.
3. The apparatus of claim 2 , wherein a curvature of the curved display varies.
4. The apparatus of claim 1 , wherein the Fresnel lens is formed from a stack of one or more Fresnel elements.
5. The apparatus of claim 1 , wherein the Fresnel lens has a curvature configured to provide an increased peripheral field of view on opposed lateral sides of the headset and to conform to a shape of a head of the user of the headset.
6. The apparatus of claim 1 , wherein the Fresnel lens and the aspheric lens are unitary.
7. The apparatus of claim 1 , wherein the aspheric lens is positioned substantially in a center of the Fresnel lens.
8. The apparatus of claim 1 , wherein the aspheric lens is positioned offset from a center of the Fresnel lens such that the aspheric lens of the first lens and the aspheric lens of the second lens are located closer to a midline of headset.
9. The apparatus of claim 1 , wherein a position of the central portion and a position of the peripheral portion in the first lens mirrors a position of the central portion and a position of the peripheral portion in the second lens.
10. The apparatus of claim 1 , wherein the aspheric lens includes an antireflective coating.
11. A lens assembly, comprising:
a central lens portion comprising an aspheric lens; and
a peripheral lens portion comprising a Fresnel lens,
wherein the peripheral lens portion surrounds at least part of the central lens portion,
wherein the peripheral lens portion comprises a central portion-receiving cavity defining a part of the peripheral lens portion configured to receive the central lens portion, or
wherein the central lens portion comprises a peripheral portion-receiving cavity, the peripheral portion-receiving cavity defining a part of the central lens portion configured to receive the peripheral lens portion.
12. The lens assembly of claim 11 , wherein the Fresnel lens has a curvature that provides an increased peripheral field of view relative to a lateral side of the lens assembly.
13. The lens assembly of claim 11 , wherein the central portion-receiving cavity defined by the peripheral lens portion is positioned substantially in a center of the peripheral lens portion such that the central lens portion is positioned substantially in the center of the peripheral lens portion.
14. The lens assembly of claim 11 , wherein the central portion-receiving cavity defined by the peripheral lens portion is positioned offset from a center of the peripheral lens portion such that the central lens portion is positioned substantially offset from the center of the peripheral lens portion.
15. The lens assembly of claim 11 , wherein the Fresnel lens comprises an optically transmissive material, the optically transmissive material comprising a first Fresnel surface, wherein the first Fresnel surface defines a plurality of grooves.
16. The lens assembly of claim 15 , wherein the plurality of grooves respectively have a cross-sectional profile that includes at least one of a triangular profile, an arcuate profile, or a saw tooth profile.
17. The apparatus of claim 1 , wherein the central portion comprising the aspheric lens is attached to the peripheral portion comprising the Fresnel lens using an optical glue.
18. The apparatus of claim 1 , wherein a center of the central portion is offset from a center of the peripheral portion.
19. The lens assembly of claim 15 , wherein the plurality of grooves comprise a constant groove depth profile.
20. The lens assembly of claim 15 , wherein the plurality of grooves comprise a groove depth profile that varies from a center of the Fresnel lens to a periphery of the Fresnel lens.