Accommodation bifocal optical assembly and optical system including same

1. A device, comprising:

an electronic display configured to emit a first image light and a second image light; and

an optical assembly configured to direct the first image light and the second image light to an eye-box of the device, the optical assembly comprising:

a first optical element portion configured to focus the first image light propagating through the first optical element portion to a first image plane; and

a second optical element portion configured to focus the second image light propagating through the second optical element portion to a second image plane different from the first image plane, the second optical element portion including a liquid crystal (“LC”) lens configured to provide an adjustable optical power,

wherein the second optical element portion is surrounded by and encapsulated in the first optical element portion, and

wherein a first focal length of the first optical element portion is greater than a second focal length of the second optical element portion.

2. The device of claim 1 , wherein the LC lens includes a segmented phase profile (“SPP”) LC lens.

3. The device of claim 2 , wherein the SPP LC lens has a Fresnel structure including a plurality of Fresnel resets that are concentric ring-shaped zones of increasing radii.

4. The device of claim 3 , wherein:

the SPP LC lens includes a plurality of ring electrodes corresponding to the plurality of Fresnel resets, the ring electrodes being concentric and having an identical area, and

a phase difference between adjacent Fresnel resets is substantially the same.

5. The device of claim 4 , wherein:

the ring electrodes are driving electrodes,

the SPP LC lens further includes a plurality of floating electrodes that are discrete and concentric ring electrodes, and are capacitively coupled to the driving electrodes through an insulating layer, and

each floating electrode covers an overlapping area between neighboring driving electrodes.

6. The device of claim 1 , wherein the LC lens includes a plurality of SPP LC lenses stacked together.

7. The device of claim 6 , wherein each SPP LC lens has a Fresnel structure including a plurality of Fresnel resets that are concentric ring-shaped zones of increasing radii.

8. The device of claim 7 , wherein the corresponding Fresnel resets of the plurality of SPP LC lenses are offset by a predetermined distance in a lens plane.

9. The device of claim 6 , wherein the plurality of SPP LC lenses include two stacked SPP LC lenses, with a same configuration and opposite alignment directions.

10. The device of claim 1 , further comprising a controller configured to:

determine a vergence distance of a virtual object represented by the second image light and viewed through the second optical element portion.

11. The device of claim 10 , wherein the controller is further configured to:

determine, based on the determined vergence distance, the optical power of the LC lens; and

control the LC lens to provide the determined optical power to adjust an image distance of the second image plane at which the second image light propagating through the second optical element portion is focused to correspond to the vergence distance.

12. The device of claim 10 , further comprising an eye-tracking device configured to obtain eye-tracking information and to provide the eye-tracking information to the controller.

13. A system, comprising:

an eye-tracking device configured to obtain eye-tracking information; and

an optical assembly comprising:

a first optical element portion configured to focus a first image light propagating through the first optical element portion to a first image plane; and

a second optical element portion configured to focus a second image light propagating through the second optical element portion to a second image plane, the second optical element portion including a liquid crystal (“LC”) lens configured to provide an adjustable optical power adjustable based on the eye-tracking information,

wherein the second optical element portion is surrounded by and encapsulated in the first optical element portion, and

wherein a first focal length of the first optical element portion is greater than a second focal length of the second optical element portion.

14. The system of claim 13 , wherein the LC lens includes a plurality of segmented phase profile (“SPP”) LC lenses stacked together.

15. The system of claim 14 , wherein at least one of the plurality of SPP LC lenses has a Fresnel structure including a plurality of Fresnel resets that are concentric ring-shaped zones of increasing radii.

16. The system of claim 15 , wherein the corresponding Fresnel resets of the plurality of SPP LC lenses are offset by a predetermined distance in a lens plane.

17. The system of claim 15 , wherein:

at least one of the plurality of SPP LC lenses includes a plurality of ring electrodes corresponding to the plurality of Fresnel resets, the ring electrodes being concentric and having an identical area, and

a phase difference between adjacent Fresnel resets is substantially the same.

18. The system of claim 17 , wherein:

the ring electrodes are driving electrodes,

at least one of the plurality of SPP LC lenses further includes a plurality of floating electrodes that are discrete and concentric ring electrodes, and are capacitively coupled to the driving electrodes through an insulating layer, and

at least one of the plurality of floating electrodes covers an overlapping area between neighboring driving electrodes.

19. The device of claim 1 , wherein:

the first image light represents a far virtual object displayed by a first portion of the electronic display, and

the second image light represents a near virtual object displayed by a second portion of the electronic display.