Flexible liquid crystal cells and lenses
A flexible optical element adopting liquid crystals (LCs) as the materials for realizing electrically tunable optics is foldable. A method for manufacturing the flexible element includes patterned photo-polymerization. The LC optics can include a pair of LC layers with orthogonally aligned LC directors for polarizer-free properties, flexible polymeric alignment layers, flexible substrates, and a module for controlling the electric field. The lens power of the LC optics can be changed by controlling the distribution of electric field across the optical zone.
1. A flexible electrically tunable liquid crystal lens, comprising:
a liquid crystal cell having a cell gap thickness X prior to bending the liquid crystal lens, and a cell gap thickness Y after returning to shape after the bending of the liquid crystal lens, wherein Y=X±10% X,
wherein the liquid crystal cell comprises elastic posts effective in limiting changes in the cell gap thickness to maintain Y=X±10%,
wherein the liquid crystal cell includes first and second alignment layers and a layer of liquid crystal between the first and second alignment layers, and
wherein the first and second alignment layers comprise a flexible polymeric material, and wherein at least one of the first and second alignment layers has liquid crystal moieties with distributed directors which induce passive lens power.
2. The flexible electrically tunable liquid crystal lens of claim 1 , wherein the liquid crystal cell comprises elastic polymer posts effective in limiting changes in the cell gap thickness to maintain Y=X±10% X.
3. The flexible electrically tunable liquid crystal lens of claim 1 , including a polymer lens body encasing the liquid crystal cell.
4. The flexible electrically tunable liquid crystal lens of claim 1 , wherein the elastic posts form an array of polymer posts extending through the layer of liquid crystal, and are bonded to the first and second alignment layers.
5. The flexible electrically tunable liquid crystal lens of claim 1 , wherein said bending includes folding the cell on a radius of 1 to 9 mm.
6. The flexible electrically tunable liquid crystal lens of claim 1 ,
wherein the liquid crystal cell includes:
first, second and third alignment layers;
a first layer of liquid crystal between the first and second alignment layers; and
a second layer of liquid crystal between the second and third alignment layers, wherein the second alignment layer includes a combination of liquid crystal and polymer material.
7. The flexible electrically tunable liquid crystal lens of claim 6 , wherein at least one of the first and third alignment layers has liquid crystal moieties with distributed directors which induce passive lens power.
8. The flexible electrically tunable liquid crystal lens of claim 1 , wherein the liquid crystal cell includes:
a first alignment layer and a second alignment layer with a gap between them;
an array of elastic polymer posts in the gap between the first alignment layer and the second alignment layer;
liquid crystal confined in the gap between the first and second alignment layers around the array of elastic polymer posts; and
one or more electrodes arranged to induce an electric field in the liquid crystal to control lens power of the lens.
9. The flexible electrically tunable liquid crystal lens of claim 1 , wherein at least a portion of the distributed directors are orthogonal to an optical path.
10. The flexible electrically tunable liquid crystal lens of claim 1 , further comprising:
first and second alignment layers,
wherein the liquid crystal cell is between the first and second alignment layers, and
wherein the cell gap thickness of the liquid crystal cell is measured as the thickness of the liquid crystal cell as located between the first and second alignment layers.
11. The flexible electrically tunable liquid crystal lens of claim 1 , wherein the elastic posts are formed within the cell through photo-polymerization of a polymer precursor according to a pattern.
12. The flexible electrically tunable liquid crystal lens of claim 11 , wherein the elastic posts are elastic polymer posts.