Transmission and reflection type holograms may be formed utilizing a novel
polymer-dispersed liquid crystal (PDLC) material and its unique switching
characteristics to form optical elements. Applications for these
switchable holograms include communications switches and switchable
transmission, and reflection red, green, and blue lenses. The PDLC
material of the present invention offers all of the features of
holographic photopolymers with the added advantage that the hologram can
be switched on and off with the application of an electric field. The
material is a mixture of a polymerizable monomer and liquid crystal,
along with other ingredients, including a photoinitiator dye. Upon
irradiation, the liquid crystal separates as a distinct phase of
nanometer-size droplets aligned in periodic channels forming the
hologram. The material is called a holographic polymer-dispersed liquid
crystal (H-PDLC).