Optical integrator
A method of manufacturing an optical integrator panel is provided. The method comprises the steps of: suspending a plurality of elongate particles in a liquid; applying an electric or magnetic field to the suspension to orientate the particles with parallel longitudinal axes; and solidifying the liquid to fix the orientation of the particles, thereby forming an optical integrator panel having a homogeneous distribution of elongate particles. An optical integrator panel is also provided. The optical integrator panel is adapted to reduce the angular dependence of contrast of a liquid crystal display. Specifically, the optical integrator panel is for placement in the path of reflected or transmitted light emitted by the liquid crystal display. The optical integrator panel comprises: a solid transparent panel; and a plurality of elongate particles homogeneously distributed in the panel, wherein the plurality of elongate particles are orientated with parallel longitudinal axes.
1. A method of manufacturing an optical integrator panel, the method comprising:
suspending a plurality of elongate particles in a liquid;
applying a electric or magnetic field to the suspension to orientate the particles with parallel longitudinal axes and random rotations about the respective parallel longitudinal axes; and
solidifying the liquid to fix the orientation of the particles, thereby forming an optical integrator panel having a homogeneous distribution of elongate particles.
2. The method of claim 1 , further comprising:
bringing the suspension between two parallel substrates prior to applying the electric or magnetic field.
3. The method of claim 2 , wherein the substrates are coated with electrically conductive electrodes, and wherein at least one of the substrates and its respective electrode are at least partially transparent to ultraviolet light.
4. The method of claim 1 , wherein ratio between thickness and length of the elongate particles is at least 1:10.
5. The method of claim 1 , wherein the elongate particles have reflective surfaces.
6. The method of claim 5 , wherein the elongate particles comprise multiple layer dielectric materials.
7. The method of claim 1 , wherein the thickness of the elongate particles is in the range 5 nm to 1 μm and the length of the elongate particles is in the range 1 μm to 50 μm.
8. The method of claim 1 , wherein the liquid becomes a flexible transparent solid after solidification.
9. The method of claim 1 , wherein the liquid comprises a polymerisable liquid, and solidifying the liquid comprises polymerising the liquid.
10. The method of claim 1 , wherein the liquid comprises an organic material having a solidifying temperature above 40° C., and wherein solidifying the liquid comprises cooling the liquid.
11. The method of claim 9 , wherein polymerising the liquid comprises initiating a polymerisation reaction by exposing the polymerisable liquid to ultraviolet light or heat.
12. The method of claim 11 , wherein the polymerisable liquid comprises a metha(acrylate) monomer, an epoxy, a vinylether monomer or a thiolene system.
13. The method of claim 1 , wherein the suspension has a concentration of elongate particles by weight of less than 1%.
14. The method of claim 2 , wherein the longitudinal axes of the elongate particles are orientated to be perpendicular to the substrates.
15. An optical integrator panel having a homogeneous distribution of elongate particles, the optical integrator panel being formed according to the method of claim 1 .