Gradient photochromic dimming device and optical assembly including the same

1. An optical dimming device, comprising:

a photochromic element including a photochromic composition,

wherein the photochromic composition includes a combination of a first photochromic material and a second photochromic material having different steady-state absorption profiles,

wherein each of the first photochromic material and the second photochromic material is distributed in the photochromic element from a top portion of the photochromic element to a bottom portion of the photochromic element, and

wherein, in a direction from the top portion to the bottom portion of the photochromic element, a concentration of the first photochromic material in the combination decreases and a concentration of the second photochromic material in the combination increases.

2. The optical dimming device of claim 1 , wherein the first photochromic material at a dark steady-state has a higher absorption for at least a visible light than the second photochromic material at the dark steady-state.

3. The optical dimming device of claim 1 , wherein the top portion and the bottom portion of the photochromic element are located at opposite ends of the photochromic element.

4. The optical dimming device of claim 1 , wherein the photochromic element includes a base substrate, and the photochromic composition is disposed in a form of a layer at a surface of the base substrate.

5. The optical dimming device of claim 1 , wherein the photochromic composition is at least partially integrally disposed in a main body of the photochromic element.

6. The optical dimming device of claim 1 , wherein the photochromic composition further comprises liquid crystals doped with the combination of the first photochromic material and the second photochromic material.

7. The optical dimming device of claim 1 , wherein at least one of the first photochromic material or the second photochromic material includes liquid crystals containing one or more photochromic moieties.

8. The optical dimming device of claim 1 , further comprising a first gradient ultraviolet filter disposed at a first surface of the photochromic element.

9. The optical dimming device of claim 8 , further comprising a second ultraviolet filter disposed at a second surface of the photochromic element, the second surface being opposite to the first surface where the first gradient ultraviolet filter is disposed.

10. An optical dimming device, comprising:

a photochromic element including a photochromic composition; and

a heating element coupled to the photochromic element and configured to realize a gradient temperature of the photochromic element,

wherein the heating element includes a plurality of heating units, and a distribution density of the heating units changes along a direction from a first portion to a second portion of the photochromic element in a gradient manner.

11. The optical dimming device of claim 10 , wherein the heating element includes a resistive heating element, and the heating units include resistive heating units.

12. The optical dimming device of claim 10 , wherein the photochromic element includes a base substrate, and the photochromic composition is disposed in a form of a layer at a surface of the base substrate.

13. The optical dimming device of claim 12 , wherein the heating element is disposed between the photochromic composition and the base substrate.

14. The optical dimming device of claim 10 , wherein the photochromic composition is at least partially integrally disposed in a main body of the photochromic element.

15. The optical dimming device of claim 10 , further comprising a first gradient ultraviolet filter disposed at a first surface of the photochromic element.

16. The optical dimming device of claim 15 , further comprising a second ultraviolet filter disposed at a second surface of the photochromic element, the second surface being opposite to the first surface where the first gradient ultraviolet filter is disposed.

17. An optical assembly, comprising:

an optical combiner including a first side facing a real world environment and an opposing second side facing an eye-box of the optical assembly; and

an optical dimming device disposed at the first side of the optical combiner and configured to provide a gradient dimming effect to a first light from the real world environment and output a second light to the optical combiner, the optical dimming device including:

a photochromic element including a combination of a first photochromic material and a second photochromic material having different steady-state absorption profiles for the first light,

wherein each of the first photochromic material and the second photochromic material is distributed in the photochromic element from a top portion of the photochromic element to a bottom portion of the photochromic element,

wherein in a direction from the top portion to the bottom portion of the photochromic element, a concentration of the first photochromic material in the combination decreases and a concentration of the second photochromic material in the combination increases, and

wherein the optical combiner is configured to combine a third light from a light source and the second light and output a combined light to the eye-box.

18. The optical assembly of claim 17 , wherein the first photochromic material at a dark steady-state has a higher absorption for at least a visible light than the second photochromic material at the dark steady-state.

19. The optical assembly of claim 17 , further comprising an optical switch disposed between the optical combiner and the optical dimming device.

20. The optical assembly of claim 17 , wherein the optical dimming device has a first side facing the real world environment and an opposing second side facing the eye-box of the optical assembly, and the optical assembly further includes a pixelated ultraviolet switch disposed at the first side of the optical dimming device.