Patent ID: 6614948
Filing Date: 2003-09-02
Classification: G02F,H04J,H04Q

Abstract:
An electrically switchable optical element using a dither-operated feedback loop, comprising:an electrically switchable optical element controlled by a dither-modulated driver that switches the focal length or deflection of the electrically switchable optical element, wherein the driver is modulated by a dither signal which causes the focal length or deflection of the electrically switchable optical element to oscillate about a nominal value; an optical source for illuminating the electrically switchable optical element with light which is focused or deflected to an output as determined by the nominal position of the electrically switchable optical element; a photodetector samples the output of the electrically switchable optical element to produce an electrical output signal which is dithered by the dither signal; a dither-operated feedback loop, responsive to the electrical output signal of the photodetector, for generating a feedback control signal to control the drive for the electrically switchable optical element to control the nominal position of the electrically switchable optical element so that the focus or deflection is optimized.