Curved retarder-based optical filters
View Patent ↗Curved polarization filters and methods of manufacturing such filters are described in the present disclosure. An exemplary method includes laminating a planar polarization layer to a planar retarder layer at a predetermined orientation and bending the laminate to create a curved filter. The strain on the retarder layer results in stress-induced birefringence, and the predetermined orientation of the retarder substantially compensates for the stress-induced birefringence. In some embodiments, the predetermination is based on mathematical models. In some other embodiment, the predetermination is based on experimental data.
1. A method for manufacturing a curved optical filter, the method comprising:
providing a drum having a curved surface;
feeding a first optical film onto the drum at a first rate;
feeding a second optical film onto an outer surface of the first optical film at a second rate;
coating the outer surface of the first optical film or an inner surface of the second optical film with an adhesive;
rotating the drum as the first and second optical films are being fed; and
laminating the first and second optical films together using a press roller, whereby the laminated first and second optical films have a curvature.
2. The method of claim 1 , wherein the first optical film is fed onto the curved surface of the drum.
3. The method of claim 1 , wherein the first and second optical films are fed into the drum at different angles with respect to a tangent of the curved surface of the drum.
4. The method of claim 1 , wherein the drum and an inner surface of the curved filter have the same curvature.
5. The method of claim 1 , wherein the first optical film is a polarizer.
6. The method of claim 1 , wherein the first optical film is a retarder.
7. The method of claim 5 , wherein the second optical film is a retarder.
8. The method of claim 1 , wherein the adhesive is a pressure-sensitive adhesive.
9. The method of claim 1 , wherein the second rate is faster than the first rate.