Method and apparatus for bistable optical information storage for erasable optical disks
First Claim
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1. 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, anddirecting a read light beam onto the portion of the material and determining the first and second phase parts thereof.
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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.
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Citations
30 Claims
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1. A method of bistable storage of optical information, which comprises:
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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. - View Dependent Claims (2)
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3. Apparatus for bistable optical information storage comprising:
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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. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification