Optical head and optical recording medium drive device

Abstract

The present invention is directed to an optical head adapted for performing recording or reproduction of information signals with respect to an optical disc (102), which controls light coupling efficiency with respect to light beams irradiated onto the optical disc (102) by light coupling efficiency adjustable element such as a liquid crystal element (214), etc. in accordance with type of the optical disc (102), recording surface of multi-layer optical disc and / or operation mode to change power of light beams irradiated onto the optical disc (102) to a large extent without excessively increasing change quantity of output power of a semiconductor laser element (212). A beam splitter (218) divides incident light beams of P-polarized light at a predetermined ratio to allow the light beams thus obtained to be incident on a light detector (219) for disc surface power monitor.

Description

technical field [0001] The present invention relates to an optical head and an optical recording medium drive apparatus suitable for recording various information on an optical recording medium such as an optical disc or performing reproduction of recorded information. Background technique [0002] Hitherto, optical discs have been widely used as optical recording media. As an optical disc, a reproduction-only optical disc in which an information signal has been prerecorded by a minute uneven pattern, and / or an optical disc in which a phase change material or a magneto-optical material is used for a recording layer to allow recording of an information signal is used. [0003] Among them, in an optical recording medium drive device such as an optical disc device using an optical disc in which information can be recorded and reproduced as a recording medium, a semiconductor having a relatively large maximum emitted light amount (optical output maximum rating) Lasers have gene...

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Problems solved by technology

[0007] The above-mentioned light source having a large maximum rating of light output has such a problem that not only its realization is difficult, but also the power consumption of the light source becomes large, etc.

In addition, when attempting to use such a light source in a state where the light output is as small as the condition of the reproduction time period, laser noise becomes large so that satisfactory reproduction characteristics cannot be obtained

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