Optical head and disk reproducing apparatus
An optical head and replay technology, which is applied in the direction of optical recording head, light beam guiding device, recording/reproducing by optical method, etc., can solve the problems such as the deviation of the phase change of the light spot, and achieve uniform phase change and good recording repeatability. put, to achieve the effect of miniaturization
Inactive Publication Date: 2006-08-02
SHARP KK
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Problems solved by technology
Once the refractive index is different for the light near the optical axis and the light around the light spot far from the optical axis, when the diffuse light enters the liquid crystal element using a coupling lens, even when recording and reproducing the MD, and at Hi When recording and reproducing the MD, the optimal phase compensation amount is given to the center of the light spot, and the actual phase change amount in the peripheral part of the light spot will also become a value different from the optimal phase compensation amount, so that there is The problem of deviation in the amount of phase change within the light spot
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[0055] The specific implementation manners of the present invention will be described in detail below with reference to the accompanying drawings.
[0056] FIG. 1 is a cross-sectional view schematically showing the configuration of an optical head 21 according to a first embodiment of the present invention. The optical head 21 includes a semiconductor laser element 22 , an objective lens 24 , a photodetector 25 , an optical system 26 , a liquid crystal element 27 , a voltage applying unit 28 , and a control unit 29 . The semiconductor laser element 22 is a light source for emitting light. The objective lens 24 condenses the light emitted from the semiconductor laser element 22 onto the optical recording medium 23 . The photodetector 25 receives the light reflected by the optical recording medium 23, and converts the received light into an electrical signal. The optical system 26 guides the light emitted from the semiconductor laser element 22 to the objective lens 24 and gui...
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An optical head includes a semiconductor laser element, an objective lens, and a liquid crystal element, a voltage applying section and a control section. The liquid crystal element is provided on an optical path of diffuse light between the semiconductor laser element and the objective lens is divided into a plurality of divisions. The voltage applying section applies a voltage to the plurality of divisions of the liquid crystal element to change the refractive index of the divisions. The control section controls the operation of the voltage applying section which applies a voltage to the divisions of the liquid crystal element to adjust the amount of phase compensation imparted to light incident on each of the divisions of the liquid crystal element such that a spot formed by light transmitted by the liquid crystal element undergoes a phase change that is uniform in the spot.
Description
technical field [0001] The present invention relates to an optical head and an optical disc playback device. Background technique [0002] Some optical disc playback devices are capable of recording and / or reproducing various types of magneto-optical recording media having different physical formats, such as MD (Mini Disc: registered trademark) and Hi-MD (registered trademark). In the optical head of the optical disc playback device that performs recording and playback of the various magneto-optical recording media, it includes: a light source that emits laser light; an objective lens; an optical system for separating laser light, which is return light reflected by the information recording surface of the magneto-optical recording medium; and a signal conversion unit for converting the laser light separated by the optical system into an electrical signal. [0003] On magneto-optical recording media such as MD and Hi-MD, guide grooves called grooves are provided on the infor...
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IPC IPC(8): G11B7/135
CPCG11B11/10597G11B7/1369G11B11/10532
Inventor 古屋贵昭
Owner SHARP KK