Ferroelectric liquid crystal optical device having temperature compensation

A liquid crystal optical device, comprising:

• (a) a liquid crystal cell comprising a matrix electrode structure composed of a first group of electrodes and a second group of electrodes intersecting the first group of electrodes with a ferroelectric smectic liquid crystal having a negative dielectric anisotropy disposed between the first and second groups of electrodes;
• (b) means for applying a scanning selection signal to at least one electrode of the first group of electrodes and a scanning nonselection signal to at least one of the other of the first group of electrodes;
• (c) means for applying information signals in parallel to the second group of electrodes, said information signals being repeated alternating electric fields:
• such that repeated alternating electric fields are applied to at least some intersections of the first group of electrodes and the second group of electrodes so as to place the ferroelectric smectic liquid crystal in a bistable memory orientation state with an increased tilt angle;
• (d) means for raising the frequency of the alternating electric field in accordance with a temperature increase in said liquid crystal cell;
• and
• (e) means for detecting an optical difference between light rays which have passed through the ferroelectric smectic liquid crystal oriented to a plurality of different orientation states.