Radial tilt detection using one beam and its compensation in a high-density read only memory

Citation
Ty. Doh et al., Radial tilt detection using one beam and its compensation in a high-density read only memory, JPN J A P 1, 40(3B), 2001, pp. 1680-1683
Citations number
5
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Volume
40
Issue
3B
Year of publication
2001
Pages
1680 - 1683
Database
ISI
SICI code
0021-4922(200103)40:3B<1680:RTDUOB>2.0.ZU;2-U
Abstract
To increase the capacity of the optical disc, the shortening in the wavelen gth of the laser diode and the increase of the numerical aperture of the le ns have been attempted for several years. Unfortunately. the efforts have g enerated adverse effects of comatic aberration caused by disc tilt. To solv e this problem. a few detection and compensation methods of disc tilt have been proposed for random access memory (RAM) discs. However, no clear appro ach has been taken yet in the case of read only memory (ROM) disc. In this paper, we propose a method to detect the radial tilt in a high-density ROM disc using differential phase detection (DPD) signals generated by an 8 div ided photodetector. The developed radial tilt servo with a 3-axis lens actu ator compensates the detected radial tilt. Its effects on the tracking serv o which arise when the actuator rotates are introduced. Finally, the feasib ility of the proposed method is verified through experiments on a high-dens ity ROM.