Electro-Active Ophthalmic Lenses Comprising Low Viscosity Liquid Crystalline Mixtures
An electro-active ophthalmic lens is presented in which the lens includes a progressive addition region having an add power and an electro-active element. The electro-active element is in optical communication with the progressive addition region and has an activated state and a deactivated state. The electro-active element also includes a liquid crystalline material disposed in a cavity having a diffractive surface relief structure. The liquid crystalline material has a low rotational viscosity.
1 . A device comprising:
a lens comprising:
a progressive addition region having an add power; and
an electro-active element in optical communication with the progressive addition region and having an activated state and a deactivated state, the electro-active element comprising a liquid crystalline material disposed in a cavity having a diffractive surface relief structure,
wherein:
(i) the liquid crystalline material has a first average index of refraction when the electro-active element is in the activated state and a second average index of refraction, different from the first average index of refraction, when the electro-active element is in the deactivated state,
(ii) a depth of the diffractive surface relief structure is from 1 micron to 10 microns,
(iii) the diffractive surface relief structure has an average index of refraction from 1.5 to 2, and
(iv) the liquid crystalline material has a rotational viscosity of 50 mPa.s or less.
2 . The device of claim 1 , wherein the liquid crystalline material has a dielectric anisotropy of 10 or higher.
3 . The device of claim 1 , wherein the liquid crystalline material has a haze clearing time of 600 msec or less.
4 . The device of claim 1 , wherein the liquid crystalline material has a switching time of 5 msec or less.
5 . The device of claim 1 , wherein the liquid crystalline material switches at an applied voltage of 8 V or less.
6 . The device of claim 1 , wherein the liquid crystalline mixture has a static haze of 1.3% or less.
7 . The device of claim 1 , wherein the liquid crystalline material:
has a dielectric anisotropy of 10 or higher,
has a haze clearing time of 600 msec or less,
has a switching time of 5 msec or less,
switches at an applied voltage of 8 V or less, and
has a static haze of 1.3% or less.
8 . The device of claim 1 , wherein the second average index of refraction of the liquid crystalline material is substantially the same as the average index of refraction of the diffractive surface relief structure.
9 . The device of claim 1 , wherein the electro-active element further comprises:
a first substrate having the diffractive surface relief structure; and
a second substrate.
10 . The device of claim 9 , wherein at least the diffractive surface relief structure of the first substrate and the second substrate define a shape of the cavity.
11 . The device of claim 9 , wherein the electro-active element further comprises:
a first electrode disposed between the first substrate and the liquid crystalline material; and
a second electrode disposed between the second substrate and the liquid crystalline material.
12 . The device of claim 11 , wherein the electro-active element further comprises an insulation layer between the first and second electrodes.
13 . The device of claim 11 , wherein the electro-active element further comprises an alignment layer disposed on at least one of the first and second electrodes.
14 . The device of claim 1 , wherein the device is a pair of spectacles.
15 . The device of claim 1 , wherein the average index of refraction of the diffractive surface relief structure is from 1.5 to 1.8.