High power handling polarization switches
View Patent ↗Liquid crystal devices are described that maintain performance of polarization/amplitude modulation under high irradiance conditions. Configurations that isolate polarizing elements under high thermal load are discussed which allow other elements, such as glass, which may be sensitive to stress birefringence to remain near optimum thermal conditions.
1. A polarization switch, comprising:
a first assembly operable to receive light, comprising:
a first end cap;
a first polarizer located to receive light from the first end cap;
a second end cap located to receive light from the first polarizer;
a second assembly located to receive light from the first assembly, comprising:
a third end cap;
a first cell located to receive light from the third end cap;
a second cell located to receive light from the first cell;
a fourth end cap located to receive light from the second cell;
wherein a thermal isolation structure separates the first assembly from the second assembly.
2. The polarization switch of claim 1 , wherein the first end cap is borofloat glass.
3. The polarization switch of claim 2 , wherein the first end cap comprises an anti-reflective coating.
4. The polarization switch of claim 1 , wherein the first polarizer is a dye polarizer.
5. The polarization switch of claim 1 , wherein the second assembly further comprises a second polarizer located to receive light from the third end cap, and wherein the first cell is further located to receive light from the second polarizer.
6. The polarization switch of claim 5 , wherein the second polarizer is an iodine polarizer.
7. The polarization switch of claim 1 , wherein the first cell and the second cell are liquid crystal cells.
8. The polarization switch of claim 1 , wherein the thickness of the first, second, third and fourth end caps are in the approximate range of 3-12 mm.
9. The polarization switch of claim 1 , wherein the second end cap is synthetic fused silica.
10. The polarization switch of claim 1 , wherein the second assembly further comprises a first compensator located to receive light from the first cell, a second compensator located to receive light from the first compensator, and a third compensator located to receive light from the second cell, wherein the second cell is further located to receive light from the second compensator, and wherein the fourth end cap is further located to receive light from the third compensator.
11. The polarization switch of claim 10 , wherein the first, second, and third compensators are -C compensators.
12. The polarization switch of claim 1 , wherein the thermal isolation structure is in the approximate range of 0.5-10 mm thick.
13. The polarization switch of claim 1 , wherein the thermal isolation structure is an air gap.
14. The polarization switch of claim 1 , wherein the thermal isolation structure includes at least one of an oil, a grease, or an adhesive.
15. A high power handling polarization system, comprising:
a first optical assembly operable to receive light, comprising:
a first substrate operable to receive light;
a first polarizer adjacent to the first substrate and operable to receive light from the first substrate;
a planarization layer adjacent to the first polarizer;
a second optical assembly operable to receive light from the first optical assembly, comprising:
a second substrate located to receive light from the planarization layer of the first optical assembly;
a first liquid crystal cell located subsequent in the light path to the second substrate;
a second liquid crystal cell located to receive light from the first liquid crystal cell;
a third substrate located subsequent in the light path to the second liquid crystal cell; and
a thermal isolation structure located between the first optical assembly and the second optical assembly.
16. The high power handling polarization system of claim 15 , wherein the first polarizer is an iodine polarizer.
17. The high power handling polarization system of claim 15 , wherein the first and second liquid crystal cells comprise pi-cells.
18. The high power handling polarization system of claim 15 , wherein the thickness of the thermal isolation structure is in the approximate range of 0.5-10 mm.
19. The high power handling polarization system of claim 15 , wherein the planarization layer is approximately index-matched to the first polarizer surface.
20. The high power handling polarization system of claim 15 , wherein the thermal isolation structure includes at least one of an oil, a grease, or an adhesive.