Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Patent
1996-12-19
1999-07-27
Hindi, Nabil
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
369 4423, 369109, 369112, G11B 700
Patent
active
059302208
ABSTRACT:
In an optical head, light from a semiconductor laser is directed through a condensing optical system with a condensing lens onto an optical information recording medium through a transparent substrate in the form of a light spot. A unit for producing a light spot position control signal and a unit able to move the light spot, which supports the objective lens for movement, position the light spot on an information track. Light reflected from the optical information recording medium is directed through a polarized light branching element to a photo detector. Also mounted for movement with the objective lens are a polarization conversion element, arranged between the optical information recording medium and the polarized light branching element in order to change the polarization state of light incident to the optical information recording medium and reflected therefrom and a polarization diffraction grating, the diffraction efficiency of which changes depending on the change in the polarization state of the incident light and the reflected light caused by the polarization conversion element. The light spot control signal is detected from both reflected light diffracted through the polarization diffraction grating and non-diffracted reflected light contained in the light which passes through the polarized light branching element.
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National Technical Report, vol. 40, No. 6 (1994), pp. 771-778.
Arimoto Akira
Inoue Masayuki
Nakao Takeshi
Ohnishi Kunikazu
Shimano Takeshi
Hindi Nabil
Hitachi , Ltd.
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