Patent attributes
A tunable illuminator includes a light source, at least one geometric phase liquid crystal element, and a driver. The light source is configured to emit an illumination beam. The geometric phase liquid crystal element is disposed on a path of the illumination beam and configured to be switched between a first state and a second state, wherein the first state is closer to a geometric phase than the second state is. The driver is configured to respectively apply a first voltage difference and a second voltage difference to the geometric phase liquid crystal element, wherein the geometric phase liquid crystal element is switched to the first state in response to the first voltage difference, the geometric phase liquid crystal element is switched to the second state in response to the second voltage difference, and the first voltage difference is less than the second voltage difference.
