Polarizing-alignment layers for twisted nematic cells

We describe polarizing films formed from the lyotropic liquid crystalline p hases of dyes dissolved in water. The dye polarizers possess a high dichroi c ratio close to that of conventional polarizers. Tn addition, the dried dy e films provide a uniform homogeneous orientation for thermotropic nematic materials. Therefore, thin dye films can simultaneously serve as internal p olarizers and as alignment agents. These properties make them especially su itable for twisted nematic devices based on low cost birefringent plastic s ubstrates.