Erasable optical memory material from a ferroelectric polymer

A method for electro-optically writing, storing, reading and erasing comprising:

• providing a one-tenth to one hundred micron thick transparent film of polyvinylidene-fluoride copolymer having a Curie temperature less than its melting temperature;
• beaming optical energy pulses at discrete spots on the film, the energy of the pulses being sufficient to heat selective ones of the spots;
• impressing an electric field across the film while the optical energy pulses are being beamed onto the spots, the electric field being less than the coercive field of the film at ambient temperature;
• rotating the dipoles in the heated spots in the film as the heated spots are influenced by the electric field to write recorded information therein;
• illuminating the rotated-dipole heated spots with polarized light having a magnitude less than that needed to raise the film above its Curie temperature;
• compensating for the induced phase retardation caused by the inherent birefringence of the film;
• polarizing the polarized light that passes through the film and the rotated dipole heated spots to blank the polarized light that passes only through the film;
• detecting the polarized light that passes through the rotated dipole heated spots to read the recorded information therefrom.

An apparatus for optically writing, storing, reading and erasing digital information comprising:

• a film of at least partially transparent ferroelectric polymer having a Curie temperature below its melting temperature;
• means oriented to beam pulses of light onto the film for optically heating spots on the film;
• means for impressing an electric field across the film having a magnitude less than the coercive field of the film at ambient temperature but of sufficient magnitude to rotate dipoles in the heated spots and thereby change the polarity of the heated spots to effect an optical writing therein;
• means disposed for illuminating the polarity changed heated spots with polarized reading light, the illuminating means having a magnitude insufficient to heat the polarity changed spots above the film's Curie temperature, the polarized reading light having its polarization rotated where it passes through polarity changed heated spots;
• means receiving the polarized reading light passing through the film for passing only the polarization rotated portions that traverse the polarity changed heated spots;
• and
• means responsive to the passed polarization rotated portions for generating signals representative of digital information.