FLUID LENS WITH OUTPUT GRATING
In some examples, a device, such as an augmented reality or virtual reality device, may include one or more waveguide displays and one or more adjustable lenses, such as adjustable fluid lenses. In some examples, a device includes a waveguide display and a rear lens assembly that together provide a negative optical power for augmented reality light. A front lens assembly, the waveguide display, and the rear lens assembly may together provide an approximately zero optical power for real-world light. In some examples, an eye-side optical element having a negative optical power may defocus light from the waveguide display. Example devices may allow the adjustable lens (or lenses) to have a reduced mass and/or a faster response time.
1 . A device comprising an optical configuration, wherein the optical configuration comprises:
a front lens assembly comprising a front adjustable lens;
a waveguide display assembly configured to provide augmented reality light; and
a rear lens assembly comprising a rear adjustable lens, wherein:
the waveguide display assembly is located between the front lens assembly and the rear lens assembly,
a combination of the waveguide display assembly and the rear lens assembly provide a negative optical power for the augmented reality light, and
the device is configured to provide an augmented reality image formed using the augmented reality light within a real-world image.
2 . The device of claim 1 , wherein the real-world image is formed by real-world light received by the front lens assembly, the real-world light then passing through at least a portion of the waveguide display assembly and the rear lens assembly.
3 . The device of claim 1 , wherein the device is configured so that, when worn by a user:
the front lens assembly receives real-world light used to form the real-world image, and
the rear lens assembly is located proximate an eye of the user.
4 . The device of claim 1 , wherein the device is configured so that the negative optical power corrects for vergence-accommodation conflict (VAC) between the real-world image and the augmented reality image.
5 . The device of claim 1 , wherein the waveguide display assembly provides at least a portion of the negative optical power for the augmented reality light.
6 . The device of claim 1 , wherein the waveguide display assembly comprises a waveguide display and a negative lens.
7 . The device of claim 1 , wherein the waveguide display assembly has a negative optical power of between approximately −1.5 D and −2.5 D, where D represents diopters.
8 . The device of claim 1 , wherein the waveguide display assembly comprises a waveguide display and the waveguide display provides the at least a portion of the negative optical power.
9 . The device of claim 1 , wherein the waveguide display assembly comprises a grating.
10 . The device of claim 1 , wherein the front adjustable lens comprises a front adjustable fluid lens having a front substrate, a front membrane, and a front lens fluid located between the front substrate and the front membrane.
11 . The device of claim 1 , wherein the rear adjustable lens comprises a rear adjustable fluid lens having a rear substrate, a rear membrane, and a rear lens fluid located between the rear substrate and the rear membrane.
12 . The device of claim 1 , wherein the rear lens assembly provides at least some of the negative optical power.
13 . The device of claim 1 , wherein the front lens assembly has a positive optical power.
14 . The device of claim 13 , wherein the positive optical power and the negative optical power are approximately equal in magnitude.
15 . The device of claim 1 , wherein the rear lens assembly comprises the rear adjustable lens and a supplemental negative lens.
16 . The device of claim 1 , wherein:
the rear adjustable lens comprises a substrate; and
the substrate has a concave exterior surface.
17 . The device of claim 1 , wherein:
real-world light is received by the device through the front lens assembly and passes through the waveguide display assembly and the rear lens assembly to form the real-world image;
the augmented reality light is provided by the waveguide display assembly and passes through the rear lens assembly to form the augmented reality image; and
the negative optical power reduces vergence-accommodation conflict between the real-world image and the augmented reality image.
18 . The device of claim 1 , wherein the device is an augmented reality headset.
19 . A method comprising:
receiving real-world light through a front lens assembly and generating a real-world image by directing the real-world light through a waveguide display and a rear lens assembly; and
directing augmented reality light from the waveguide display through the rear lens assembly to form an augmented reality image, wherein:
the waveguide display and the rear lens assembly cooperatively provide a negative optical power for the augmented reality light, and
the front lens assembly, waveguide display, and the rear lens assembly cooperatively provide an approximately zero optical power for the real-world light.
20 . The method of claim 19 , wherein the waveguide display receives the augmented reality light from an augmented reality light source and directs the augmented reality light out of the waveguide display using a grating.