Optical head and optical disk device

Abstract

An interference type optical head and an optical disk device that can easily adjust an optical path length difference of a couple of lights, ensure higher signal amplification effect, and are suitable for reduction in size are provided in order to improve a regeneration signal quality with amplification of signal in the case where reflectivity of each layer must be lowered and relative noise for the signal increases because read speed is high in a multilayer optical disk. In view of essentially improving an S / N ratio of the regeneration signal in high-speed rotation of a multilayer disk, a plurality of interference phases are generated and an optical system for differential calculation has been reduced in size with an angular selective polarization conversion element in the optical disk device for amplifying the signal with interference of the light not radiated to the disk with the reflected light from the disk. Moreover, adjustment of reflection mirror angle of the reference light is no longer required by using a corner cube prism as the reference light reflection mirror and highly accurate signal detection can also be realized with a simplified structure.

Description

technical field [0001] The present invention relates to an optical head capable of handling a high S / N ratio of a reproduced signal, and an optical disc device equipped with the optical head. Background technique [0002] The optical disc as an optical recording medium has reached the commercialization of the Blu-ray disc using a blue laser diode and an objective lens that can handle high NA. The resolution of the optical system has almost reached the limit, and the recording layer of the optical disc is facing further increase in capacity. The multilayering of is arguably the most promising. In this multi-layer optical disc, the detection light power from each layer is required to be almost equal, and the emissivity of irradiation light from a specific layer has to be reduced. However, it is necessary to increase the reproduction speed of video and the like while increasing the capacity of the optical disk, and the transmission speed is also continuously increased, so it i...

AI Technical Summary

Problems solved by technology

However, it is necessary to increase the speed of reproduction of video and the like while increasing the capacity of the optical disk, and the speed of transmission is also increasing, so it is difficult to ensure the S / N ratio of the reproduced signal sufficiently.

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