Hybrid varifocal lens
A hybrid lens is disclosed including optically coupled varifocal lens and adaptive lens. The varifocal lens is configured for varying optical power of the hybrid lens, and an adaptive lens includes a voltage-controlled element for varying optical power of the adaptive lens in coordination with varying the optical power of the varifocal lens and responsive to variation of the optical power of the hybrid lens, for lessening an optical aberration of the hybrid lens. The hybrid lens may be used in head-mounted displays e.g. for lessening a vergence-accommodation conflict.
1. A method for adjusting optical power of a hybrid lens for collimating image light, the hybrid lens comprising a varifocal lens optically coupled to an adaptive lens, the method comprising:
varying optical power of the varifocal and adaptive lenses in coordination with one another based on a pre-determined mutual variation of optical power for lessening an off-axis aberration of the hybrid lens with respect to the image light for each sub-range of a pre-defined set of sub-ranges of optical powers of the hybrid lens with respect to the image light.
2. The method of claim 1 , further comprising increasing the optical power of the varifocal lens when increasing the optical power of the adaptive lens.
3. The method of claim 1 , further comprising decreasing the optical power of the varifocal lens when decreasing the optical power of the adaptive lens.
4. The method of claim 1 , wherein the varifocal lens comprises a liquid lens, and wherein varying the optical power of the varifocal lens comprises varying the optical power of the liquid lens.
5. The method of claim 1 , further comprising determining a gaze convergence angle of eyes of a user, wherein the optical power of the hybrid lens is adjusted responsive to the determined gaze convergence angle.
6. The method of claim 1 , wherein the adaptive lens comprises a multifocal lens, the method further comprising switching the optical power of the multifocal lens between optical power values when adjusting optical power of the hybrid lens within the pre-defined optical power sub-ranges.
7. The method of claim 6 , wherein each optical power value of the multifocal lens corresponds to a particular one of the pre-defined optical power sub-ranges of the hybrid lens.
8. The method of claim 6 , wherein the multifocal lens comprises at least one of: a Pancharatnam-Berry phase (PBP) lens; a polarization volume holographic liquid crystal (LC) lens; or an LC Fresnel lens, and wherein switching the optical power of the multifocal lens comprises switching the optical power of the at least one of PBP lens, the polarization volume holographic LC lens, or the LC Fresnel lens.
9. A hybrid lens for collimating image light, the hybrid lens comprising a varifocal lens and an adaptive lens optically coupled to the varifocal lens and comprising a voltage-controlled element for varying optical power of the adaptive lens in coordination with varying optical power of the varifocal lens based on a pre-determined mutual variation of the optical power for lessening an off-axis aberration of the hybrid lens with respect to the image light for each sub-range of a pre-defined set of sub-ranges of optical powers of the hybrid lens with respect to the image light.
10. The hybrid lens of claim 9 , wherein the adaptive lens is disposed in an optical path downstream of the varifocal lens.
11. The hybrid lens of claim 9 , wherein the varifocal lens comprises a liquid lens.
12. The hybrid lens of claim 9 , wherein the adaptive lens comprises at least one of: a Pancharatnam-Berry phase (PBP) lens; a polarization volume holographic liquid crystal (LC) lens; or an LC Fresnel lens; and wherein a substrate of the adaptive lens comprises at least one of: a glass substrate; a plastic substrate; or a sapphire substrate.
13. The hybrid lens of claim 12 , wherein the adaptive lens comprises the PBP lens comprising at least one of: a nano-patterned birefringent structure; or a polymer-embedded LC layer.
14. The hybrid lens of claim 12 , wherein the voltage-controlled element comprises a first active PBP lens.
15. The hybrid lens of claim 14 , wherein the adaptive lens further comprises a first switchable polarization rotator optically coupled to the first active PBP lens.
16. The hybrid lens of claim 15 , wherein the adaptive lens further comprises a second active PBP lens and a second switchable polarization rotator optically coupled to the second active PBP lens.
17. A hybrid lens apparatus comprising the hybrid lens of claim 9 and a controller operably coupled to the varifocal lens and the voltage-controlled element of the adaptive lens and configured to vary the optical power of the varifocal lens in coordination with varying voltage applied to the voltage-controlled element, thereby lessening the off-axis aberration of the hybrid lens as optical power of the hybrid lens is varied.
18. The hybrid lens apparatus of claim 17 , wherein the controller is configured to increase the optical power of the adaptive lens when increasing the optical power of the varifocal lens, and to decrease the optical power of the adaptive lens when decreasing the optical power of the varifocal lens.
19. The hybrid lens apparatus of claim 17 , wherein:
the varifocal lens comprises a liquid lens comprising a pair of immiscible fluids separated by a boundary having a voltage-variable radius of curvature for varying optical power of the liquid lens; and
the controller is configured to vary the radius of curvature of the boundary by varying a voltage applied to the liquid lens in coordination with varying a voltage applied to the voltage-controlled element of the adaptive lens, thereby lessening the off-axis aberration of the hybrid lens as the optical power of the liquid lens is varied.
20. The hybrid lens apparatus of claim 19 , wherein the adaptive lens comprises an LC PBP lens, and wherein the voltage-controlled element comprises a voltage-controlled polarization rotator.