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Proceedings Paper

Focus Error Detection In Optical Data Storage Systems
Author(s): Richard V. Johnson
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Paper Abstract

One of the most distinctive features of the optical disk mass storage technology which has been under development at Xerox Electro-Optical Systems is the extremely high numerical aperture (NA) of the objective lenses used for writing and playback. A disk system with a 0.90 NA lens has over five times the data capacity of a comparable disk system with a 0.40 NA lens. This increased data capacity comes at the price of a reduced depth of focus and significantly increased sensitivity to aberrations. The subject of this paper is the performance of the "skew beam" and the "Foucault knife-edge" techniques for sensing focus errors. Specific topics include: (1) An analysis for optimizing the sensitivity of the skew beam configuration, (2) An observation of the close similarity between the skew beam and the Foucault knife-edge techniques, and (3) A partial list of sources of aberrations unique to high numerical aperture optics, and their impact upon the performance of the focus error sensing detector.

Paper Details

Date Published: 12 February 1980
PDF: 6 pages
Proc. SPIE 0200, Laser Recording and Information Handling, (12 February 1980); doi: 10.1117/12.958070
Show Author Affiliations
Richard V. Johnson, Xerox Electro-Optical Systems (United States)

Published in SPIE Proceedings Vol. 0200:
Laser Recording and Information Handling
Albert A. Jamberdino, Editor(s)

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