Method and apparatus for bistable optical information storage for erasable optical disks
AssigneeSandia Corporation
InventorsCecil E. Land, Ira D. McKinney
Life of this patent
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Abstract
A method and an optical device for bistable storage of optical information, together with reading and erasure of the optical information, using a photoactivated shift in a field dependent phase transition between a metastable or a bias-stabilized ferroelectric (FE) phase and a stable antiferroelectric (AFE) phase in an lead lanthanum zirconate titanate (PLZT). An optical disk contains the PLZT. Writing and erasing of optical information can be accomplished by a light beam normal to the disk. Reading of optical information can be accomplished by a light beam at an incidence angle of 15 to 60 degrees to the normal of the disk.
Claims30
A method of bistable storage of optical information, which comprises:
- providing a material capable of shifting between stable first antiferroelectric and second ferroelectric phases by applying at least one of electric energy and illumination energy thereto,
- applying an electrical field across a surface of the material, so that the material shifts from the first phase to the second phase,
- illuminating parts of the material, thereby causing the illuminated parts to shift back to the first phase,
- removing the illumination and electrical field so that the illuminated parts remain in the first phase and the unilluminated parts remain in the second phase, and
- directing a read light beam onto the portion of the material and determining the first and second phase parts thereof.
Apparatus for bistable optical information storage comprising:
- optical disk means for storing binary information as a function of the ferroelectric/antiferroelectric phases at different locations on the disk surface;
- write-erase means for writing and erasing binary optical information on and from a surface of the optical disk means, said write-erase means comprising:
- electric means for applying an electric potential across said optical disk means;
- and
- light means for directing a write-erase light beam toward said disk surface to selectively alter said phases;
- and
- read means for reading binary optical information from said surface.
Dependencies are inferred from the claim text.