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Enhanced Reflectivity Rings for Optical Recording Track Servoing

IP.com Disclosure Number: IPCOM000049627D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Wieder, H: AUTHOR

Abstract

An improved system for track servoing for optical recording is describedd in which the WRITE laser is used to write servo tracks on the optical recording media by crystallization of the amorphous recording film.

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Enhanced Reflectivity Rings for Optical Recording Track Servoing

An improved system for track servoing for optical recording is describedd in which the WRITE laser is used to write servo tracks on the optical recording media by crystallization of the amorphous recording film.

The recording film may comprise, for example, a tellurium based alloy containing germanium, the crystallization temperature of which can be varied from about 100 degrees C to 250 degrees C, thereby providing an ample range of choice of an optimum temperature. In this system, the track following information is produced by heating the appropriate servo track areas of the film to the chosen temperature with the write beam laser. The resultant crystallization of the heated areas results in a reflectivity about 40 percent higher than the same material in the amorphous state, and this reflectivity change provides more than adequate signal for servoing purposes. In systems in which the less reflective (amorphous) region is used to write data, a displaced beam for servoing is provided which permits the write beam to remain on the low reflectivity regions. Alternatively, servoing can be done from the low reflectivity region.

This servoing scheme has an advantage over pregrooved servo tracks, since any subbing layer provided to smooth media defects can be any desired thickness.

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