PURPOSE: To enable a thin liq. crystalline polymer film to realize high contrast and different techniques to be employed in writing out and reading data by homeotropically orienting the film.

CONSTITUTION: This liq. crystalline polymer film is prepd. by applying a liq. crystalline polymer contg. a dichroic dye having mesogen groups represented by the formula [wherein R1 is a halogen, R2, OR2, C(O)R2, C(O)OR2, CN, or CF3; R2 is H or a 1-3C alkyl; R3 is the same as R1 but is selected independently; Q is a monomer residue linking a mesogen group to the polymer main chain; (m) and (n) are each 0 or 1; (y) is 0-3; (p) is 2-4; R4 is a 1-12C alkyl; X is 0-6; and Z is -C=N-, -N=C-, -C(O)-O-, -O-C(O)-, or -C=C-] to a substrate. The surface of the film is homeotropically oriented by treating with a surfactant, by applying electric field to a conductive layer to the liq. crystal layer, or by causing the film to pass through a heating roller.