Focus error detecting method and optical head using the same

Details Focus error detecting method and optical head using the same Focus error detecting method and optical head using the same

1991-05-24

1996-04-23

Hindi, Nabil Z.

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

369 4412, 369112, G11B 700

Patent

active

055110509

ABSTRACT:
A focus error detecting method and an optical head using it. In the focus error detecting method, a light beam is emitted from a light source, the beam is given positive and negative astigmatism by a diffraction grating or an acoustooptic element in a focusing optical system, beams thus formed are focused on an information recording surface, the beams reflected from the information recording surface are received by photo-detecting elements in separated optics, the reflected beams with positive and negative astigmatism are compared with each other to take a difference in a focus error detecting circuit, and a focus error detecting signal is obtained on the basis of the difference. The focus for the optical head can be adjusted using the focus error detecting signal.

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Webster's Ninth New Collegiate Dictionary by Merriam-Webster, 1986 p. 111.

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