Image stabilization and shifting in a liquid crystal lens

Patent metadata

Field	Value
Publication number	US-9429799-B2
Application number	US-201514694386-A
Country	US
Kind code	B2
Filing date	Apr 23, 2015
Priority date	Dec 23, 2009
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

Variable liquid crystal devices for controlling the propagation of light through a liquid crystal layer use a frequency dependent material to dynamically reconfigure effective electrode structures in the device. The frequency of a drive signal that generates an electric field in the device can be varied, and the frequency dependent material has different charge mobilities for the different frequencies. At a low charge mobility, the frequency dependent material has little effect on the existing electrode structures. However, at a high charge mobility, the frequency dependent material appears as an extension of the fixed electrodes, and can be used to change the effective electrode structure and, thereby, the spatial profile of the electric field. This, in turn, changes the optical properties of the liquid crystal, thus allowing the optical device to be frequency controllable.

First claim

What is claimed is:

1. A tunable lens optical device for controlling the propagation of light passing through the device using a dynamically-configured effective electrode geometry, said optical device comprising:
a liquid crystal layer configured to pass said light therethrough, optical properties of the liquid crystal layer controlling said light propagation;
an electrode system arranged to generate an electric field acting on said liquid crystal layer the electrode system including a segmented ring electrode; and
an electrical signal generator for generating a drive signal at a plurality of different frequencies and applying the drive signal to the electrode system to generate said electric field, the electrical signal generator being further configured to apply a separate drive signal component of the drive signal to each electrode segment of the segmented ring electrode, each drive signal component having a corresponding frequency;
wherein:
said electrode system comprises a frequency dependent material interacting with the electric field, the frequency dependent material having a charge mobility therein that varies with a frequency of the drive signal such that a spectral content of said drive signal dynamically configures an effective electrode geometry of said electrode system whereby a spatial profile of the electric field varies as a function of said spectral content to alter the optical properties of the liquid crystal layer;
said signal generator is configured to apply a drive signal that prevents disclinations of liquid crystal in said liquid crystal layer; and
said electrode system is configured to controllably move an optical axis of the lens created in said liquid crystal layer by said electric field, driving said segmented ring electrode providing a parametric lens.

2. The device as claimed in claim 1 , wherein said signal generator controls said light propagation without substantive voltage variation of said drive signal.

3. The device as claimed in claim 1 , wherein said drive signal comprises a plurality of frequencies that combine to create said spatial profile.

4. The device as claimed in claim 1 , or ill wherein said signal generator changes an amplitude of said drive signal to adjust said light propagation.

5. The device as claimed in claim 1 , wherein said liquid crystal layer comprises a low angle pre-tilt alignment layer.

6. The device as claimed in claim 5 , wherein said generator is configured to provide a first drive signal at which said spatial profile is substantially uniform, with said liquid crystal being reoriented from a ground state defined by said alignment layer, with said optical properties of said liquid crystal layer being spatially uniform, and a second drive signal at which said spatial profile is not spatially uniform to achieve a desired control over light propagation.

7. The device as claimed in claim 1 , wherein said device is a lens, said liquid crystal layer comprises a low angle pre-tilt alignment layer, and said signal generator is operative to apply said drive signal that prevents liquid crystal in said liquid crystal layer from remaining close to a ground state defined by said alignment layer and thus reduce image aberration through improved response of said liquid crystal to said electric field.

8. The device as claimed in claim 1 , wherein said device comprises at least two liquid crystal layers having a different direction of liquid crystal orientation to reduce polarization sensitivity of said device.

9. The device as claimed in claim 8 , wherein said electrode system comprises a middle ring electrode positioned between at least one upper liquid crystal layer and at least one lower liquid crystal layer, an upper transparent electrode and a lower transparent electrode, said frequency dependent material comprises a layer of material located near said middle ring electrode, said spatial profile modulated by said frequency dependent material being thus the same for said at least one upper liquid crystal layer between the middle ring electrode and the upper transparent electrode and for said at least one lower liquid crystal layer between the middle ring electrode and the lower transparent electrode.

10. The device as claimed in claim 1 , wherein said liquid crystal layer is substantially planar.

11. The device as claimed in claim 1 , wherein said device is a gradient index lens (GRIN).

12. The device as claimed in claim 11 , wherein said lens has a tunable variable optical power, preferably over a range of more than 3 diopters.

13. The device as claimed in claim 1 , wherein said electrode system comprises a hole patterned ring electrode.

14. The device as claimed in claim 13 , wherein said frequency dependent material comprises a thin layer of material close to said hole patterned ring electrode of said electrode system.

15. The device as claimed in claim 1 , wherein said electrode system and said frequency dependent material provide a non-spatially uniform effective electrode geometry, said spatial modulation of said electric field being created by electrode geometry in addition to any spatial modulation of electrode voltage.

16. The device as claimed in claim 15 , wherein said electrode system comprises a curved electrode.

17. The device as claimed in claim 1 , wherein said frequency dependent material comprises an one of: impurity and dopant substance contained within liquid crystal of said liquid crystal layer.

18. The device as claimed in claim 1 , wherein said signal generator comprises a pulse-width modulation circuit.

19. The device as claimed in claim 18 , wherein said pulse-width modulation circuit provides a plurality of amplitudes of a PWM waveform, and said amplitude is changed with a corresponding change in duty cycle to deliver substantially a same effective PWM voltage when a frequency content in said waveform contains too much energy away from a central frequency.

20. The device as claimed in claim 1 , wherein said frequency dependent material comprises a semiconductor material.

21. The device as claimed in claim 1 , further comprising a controller for dynamically adjusting said electrical signal generator.

22. The device as claimed in claim 1 , each drive signal component further having a corresponding voltage, wherein different voltages are applied to different electrode segments, driving said segmented ring electrode providing a parametric lens.

Assignees

• Lensvector Inc

Inventors

• Galstian Tigran
• Presniakov Vladimir
• Asatryan Karen
• Zohrabyan Armen

Classifications

• G02F1/134309 Primary

  characterised by their geometrical arrangement · CPC title

• G02F2203/06

  Polarisation independent · CPC title

• G02F1/13439

  characterised by their electrical, optical, physical properties; materials therefor; method of making · CPC title

• G02F1/13471

  in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells (G02F1/13475 takes precedence) · CPC title

• G02F2001/294

  Physics · mapped topic