Enhanced response time of tunable optical electrowetting elements with shaped input voltage functions

1. An improved tunable optical electrowetting device comprising:

a tunable optical electrowetting element having a liquid-liquid interface shape controlled by an applied voltage;

circuitry for applying a voltage to the electrowetting element, the circuitry configured to apply a shaped voltage signal by combining a first fast-rising voltage signal and a second, distinct, fast-rising voltage signal;

wherein each fast-rising signal rises fast enough that it would cause an under-damped response in the electrowetting element on its own; and

wherein the second signal is selected to reduce the ringing caused by the first signal by more than three times.

2. The device of claim 1 wherein the second signal is offset in time from the first signal.

3. The device of claim 1 wherein one of the signals is faster-rising than the other signal.

4. The device of claim 1 wherein one of the signals is a nonlinear signal.

5. The device of claim 4 wherein one of the signals is an exponential signal.

6. The device of claim 4 wherein both of the signals are nonlinear signals.

7. The device of claim 6 wherein both of the signals are exponential signals.

8. The device of claim 7 wherein the signals are offset in time.

9. The device of claim 7 wherein the response time is improved by at least 29% over using a single signal comprising an exponential signal having the same rise time as the first fast-rising signal.

10. The device of claim 1 wherein the electrowetting element is an EWOD lens.

11. The device of claim 1 wherein the electrowetting element is an EWOD prism.

12. The device of claim 1 wherein the circuitry for applying a voltage is further configured to apply an AC carrier frequency to the shaped voltage signal, and wherein the AC carrier frequency is too high to cause ringing in the liquid-liquid interface of 75% or more of the desired final value.

13. The method of tuning an optical electrowetting device comprising the steps of:

applying a shaped voltage signal to the optical electrowetting device to tune the device by changing the shape of a liquid-liquid interface in the device;

generating the shaped voltage signal by combining a first fast-rising voltage signal and a second, distinct, fast-rising voltage signal;

wherein each fast-rising signal rises fast enough that it would cause an under-damped response in the electrowetting element on its own; and

selecting the second signal such that it reduces the ringing cause by the first signal by more than three times.

14. The method of claim 13 further including the step of temporally offsetting the first signal and the second signal.

15. The method of claim 13 wherein one of the signals is a nonlinear signal.

16. The method of claim 13 wherein one of the signals is an exponential signal.

17. The method of claim 16 wherein both of the signals are nonlinear signals.

18. The method of claim 17 wherein both of the signals are exponential signals.

19. The method of claim 18 wherein the response time achieved by the method is improved over a method where the generating step uses a single exponential signal having the same rise time as the first fast-rising signal by at least 29%.

20. The method of claim 19 wherein the response time achieved by the method is improved over a method where the generating step uses a single exponential signal having the same rise time as the first fast-rising signal by at least 41%.

21. The method of claim 18 wherein the response time achieved by the method is improved over a method where the generating step uses a single exponential signal having a rise time of 15 ms by at least 29%.

22. The method of claim 19 wherein the response time achieved by the method is improved over a method where the generating step uses a single exponential signal having a rise time of 2 ms by at least 41%.