Electro-optical devices using dynamic reconfiguration of effective electrode structures
Variable liquid crystal devices for controlling the propagation of light through a liquid crystal layer use a frequency dependent material to dynamically reconfigure effective electrode structures in the device. The drive signal source uses pulse-width modulation to set a frequency and an amplitude of the drive signal.
1. A tunable optical device comprising:
at least one liquid crystal layer; and
an electrode structure having a planar electrode, a hole-patterned electrode and a weakly conductive material extending across an aperture of the hole-patterned electrode, said planar electrode and said hole-patterned electrode being arranged on opposite sides of said layer;
a signal generator comprising a pulse-width modulation circuit; wherein said circuit a voltage of a drive signal provided to said electrode structure; and
a controller connected to said pulse-width modulation circuit and configured to set an amplitude and a frequency of said drive signal as a function of a desired tunable optical property.
2. The device as claimed in claim 1 , wherein said pulse-width modulation circuit provides a plurality of amplitudes of a PWM waveform, and said amplitude is changed with a corresponding change in duty cycle to deliver substantially a same effective PWM voltage when a frequency content in said waveform contains too much energy away from a central frequency.
3. The device as claimed in claim 2 , wherein said device is a gradient index lens.
4. The device as claimed in claim 1 , wherein said controller is configured to avoid duty cycles that generate undesired frequencies in said drive signal, said controller being configured to vary both frequency and amplitude of said drive signal.
5. The device as claimed in claim 4 , wherein said device is a gradient index lens.
6. The device as claimed in claim 1 , wherein said device is a gradient index lens.
7. The device as claimed in claim 1 , wherein the device is a beam steering device.