FAST RESPONSE OPTICAL DEVICES BY DOUBLE LIQUID CRYSTAL CELLS STRUCTURE

摘要

A phase retarder comprises first and second π-cells or other tunable birefringent devices arranged optically in series. The phase retardation value of the phase retarder is a difference between the phase retardation values of the first and second π-cells. Driving circuitry drives the phase retarder to generate a target phase retardation value by: (1) prior to a relaxation period, biasing the π-cells to produce the target phase retardation value; (2) during the relaxation period, biasing the first π-cell at a constant bias value; and (3) during the relaxation period, lowering the bias value of the second π-cell continuously or stepwise to maintain the target phase retardation value for the phase retarder throughout the relaxation period. In some embodiments the operation (2) comprises applying zero bias to the first π-cell throughout the relaxation period. In some embodiments the operation (1) comprises applying a maximum operational bias to the second π-cell.

主权项

1. An apparatus comprising:
a phase retarder comprising a first tunable birefringent device and a second tunable birefringent device arranged optically in series wherein each of the first tunable birefringent device and the second tunable birefringent device has a maximum-bias phase retardation φmax—drive at steady state for a maximum bias value and a relaxed phase retardation φrelaxed at steady state for a minimum bias value; and driving circuitry configured to drive the phase retarder to generate a target phase retardation φtarget for the phase retarder over the relaxation period of a time frame comprising a transition period followed by a relaxation period by operations including:
(1) biasing the second tunable birefringent device at the maximum bias value during the transition period yielding the maximum-bias phase retardation φmax—drive for the second tunable birefringent device at the beginning of the relaxation period,(2) biasing the first tunable birefringent device during the transition period at a bias value determined based on the target phase retardation φtarget,(3) biasing the first tunable birefringent device at the minimum bias value during the relaxation period yielding the relaxed phase retardation φrelaxed for the first tunable birefringent device at the end of the relaxation period, and(4) biasing the second tunable birefringent device during the relaxation period at a bias value determined based on the target phase retardation φtarget,wherein the driving circuitry is configured to perform the biasing operations (2) and (4) at bias values between the minimum bias value and the maximum bias value.