Optical data storage apparatus and method
First Claim
1. An optical data storage apparatus for storing and retrieving digital information, comprisingan optical data disc having a substrate whose surface defines a plurality of data-storage positions,a stable-resonator laser having a resonator cavity, for use in producing a coherent output light beam,means for focusing said output beam onto the surface of said disc,at each data-storage position on the surface of said substrate, reflecting means effective to reflect the focused coherent beam, when said beam is directed against said position, from a selected one of 2N submicron displacement distances normal to the surface of the substrate, where N is an integer greater than 2, corresponding to a selected one of 2N bits of information, back into the laser cavity,means for moving the focused output beam relative to the disc surface to selected data-storage positions thereon, at successive, known times,means for measuring the power of said output beam, as the focused primary beam is moved to such selected sites, andmeans operatively connected to said moving means and said measuring means for converting time-dependent changes in the measured power of said output beam to position-dependent displacement distances at the selected data-storage sites, for determining the selected one of the 2N bits stored at each such site.
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Accused Products
Abstract
An optical data storage apparatus and disc in which information is stored in the form of multiple submicron depths at information-storage sites on the disc surface. The depth information is read by directing a focused laser beam onto the storage sites, back reflecting a portion of the reflected beam into the laser cavity, and converting power fluctuations in the laser beam to submicron distance measurements.
58 Citations
11 Claims
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1. An optical data storage apparatus for storing and retrieving digital information, comprising
an optical data disc having a substrate whose surface defines a plurality of data-storage positions, a stable-resonator laser having a resonator cavity, for use in producing a coherent output light beam, means for focusing said output beam onto the surface of said disc, at each data-storage position on the surface of said substrate, reflecting means effective to reflect the focused coherent beam, when said beam is directed against said position, from a selected one of 2N submicron displacement distances normal to the surface of the substrate, where N is an integer greater than 2, corresponding to a selected one of 2N bits of information, back into the laser cavity, means for moving the focused output beam relative to the disc surface to selected data-storage positions thereon, at successive, known times, means for measuring the power of said output beam, as the focused primary beam is moved to such selected sites, and means operatively connected to said moving means and said measuring means for converting time-dependent changes in the measured power of said output beam to position-dependent displacement distances at the selected data-storage sites, for determining the selected one of the 2N bits stored at each such site.
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8. An optical data storage disc comprising
a substrate having a surface defining a plurality of data-storage positions, and at each data-storage position, reflecting means effective to reflect a focused coherent beam, when said beam is directed against said position, from a selected one of 2N submicron displacement distances normal to the surface of the substrate, corresponding to a selected one of 2N information bits, where N> - 2,
wherein said substrate has a transparent outer layer which defines said plurality of data-storage positions, and a depth which encompasses said 2N submicron distances normal to the surface of the substrate, and said reflecting means includes means at each data-storage position for reflecting said focused light beam from a selected one of the 2N depths in said layer. - View Dependent Claims (9, 10)
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11. A method of retrieving digital information, comprising
directing a focused laser beam onto the surface of an optical data disc whose surface defines (i) a plurality of data-storage positions, and (ii) at each such position, one of 2N submicron displacement distances normal to the surface of the substrate, where N is an integer greater than 2, corresponding to a selected one of 2N bits of information, moving the focused beam relative to the disc to a selected data-storage positions on the disc, at each such position, back reflecting at least a portion of the laser beam reflected from such positions, measuring the power of said output beam, as the focused primary beam is moved to each such selected position, and converting the measured power of said output beam at the selected data-storage positions to one of 2N bits of information at that position.
Specification