Properties of optical retardation plates by easily prepared birefringent bulk plastics

When a dc electric field is applied to molten polystyrene and α-methylstyrene, the molecules are aligned in the direction of the electric field. Since this state is maintained even in a solid state, birefringent bulk plastics are easily obtained. The merit of this technique is that the magnitude of birefringence is contained by controlling the dc electric field. Since there is no size limitation, λ/4 and λ/2 plates were obtained easily at low cost. Furthermore, these optical retardation plates can be used for a wide range of wavelengths. It was found that the temperature dependence of the optical properties does not cause problems at normal usage temperatures.