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;
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;
a first substrate having the diffractive surface relief structure; and
a second substrate;
wherein:
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;
a depth of the diffractive surface relief structure is from 1 micron to 10 microns;
the diffractive surface relief structure has an average index of refraction from 1.5 to 2;
the liquid crystalline material has a rotational viscosity of 50 mPa·s or less;
the liquid crystalline material has a dielectric anisotropy of 10 or higher;
the liquid crystalline material has a haze clearing time of 600 msec or less;
the liquid crystalline material has a switching time of 5 msec or less;
the liquid crystalline material switches at an applied voltage of 8 V or less;
the liquid crystalline mixture has a static haze of 1.3% or less;
at least the diffractive surface relief structure of the first substrate and the second substrate define a shape of the cavity;
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;
the average index of refraction of the diffractive surface relief structure is from 1.5 to 1.8;
the device is a pair of spectacles; and
the electro-active element further comprises:
a first electrode disposed between the first substrate and the liquid crystalline material;
a second electrode disposed between the second substrate and the liquid crystalline material;
an insulation layer between the first and second electrodes; and
an alignment layer disposed on at least one of the first and second electrodes.