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Proceedings Paper

Scanning Techniques For Optical Data Storage
Author(s): David K. Towner
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Paper Abstract

It seems almost paradoxical that beams of light can be moved and steered at very high speeds using a variety of scanning methods, yet the optical disk drives now being designed and marketed for data storage applications have comparatively long access times. Knowing that optical data storage has unrealized potential is of interest, but of more immediate concern is the recognition that poor access performance is a serious design issue. Magnetic disk drives offer average seek times in the 15-25ms range, compared to about 80-500ms (or more, for CD ROMS) for current optical drives. This performance disparity exists, in part, because the relatively massive "optical heads" in use today cannot be transported across the radius of a disk as quickly as a stack of much lighter magnetic heads. Any potential distance advantage that the optical drive might have, due to its substantially higher track density, is offset by the magnetic drive's use of a multi-disk stack. As a result, the drive must achieve similar radial accelerations during seeks if it is to have similar average access times. The inability of current optical drives to approach the access speeds of comparable magnetic drives significantly reduces the competitiveness of optical products in major segments of the very large data storage market. This shortcoming is especially disturbing when we know that opto-mechanical scanners typically operate in the 1-10ms range and that non-mechanical scanning techniques can be substantially faster than that.

Paper Details

Date Published: 14 January 1987
PDF: 10 pages
Proc. SPIE 0695, Optical Mass Data Storage II, (14 January 1987); doi: 10.1117/12.936834
Show Author Affiliations
David K. Towner, Hewlett-Packard Co. (United States)

Published in SPIE Proceedings Vol. 0695:
Optical Mass Data Storage II
Robert P. Freese; Albert A. Jamberdino; Maarten R. de Haan, Editor(s)

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