Optical Recording Media
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Organic cholesteric liquid crystals are the active medium of an optical recording disk. A one-micron-thick layer of a counterclockwise twisted, helical cholesteric-phase medium reflects about 100% of right circularly polarized light, and transmits left circularly polarized light, when the wavelength of light approximates the helical pitch. This property allows for either reflective or transmissive reading of a data track. The liquid crystal layer is written by the use of a laser beam. The beam's heat melts the liquid crystal. When the beam is turned off (i.e., the heat is removed), local cooling results in formation of the crystal's scattering phase.