A liquid crystal device, includes: (a) a liquid crystal cell includes a pair of base plates, and a ferroelectric smectic liquid crystal having a negative dielectric anisotropy, (b) a device for applying to the ferroelectric liquid crystal an alternating electric field capable of causing the crystal to...http://www.google.com.au/patents/US4902107?utm_source=gb-gplus-sharePatent US4902107 - Ferroelectric liquid crystal optical device having temperature compensation
