Optical pickup apparatus

Abstract

The present invention provides a kind of optical pick-up device, has: the 1st light source; Converging optical system, comprise objective lens, also have the main light beam that emits the diffracted light as predetermined diffraction order and the diffraction as the order of diffraction other than the predetermined diffraction order The optical surface of the diffraction structure of the sub-beam of light; the first optical element with the first and second optical regions; the second optical element with the third and fourth optical regions; between the first optical element and the second optical element A condensing element that condenses the main beam; a polarized light branching optical member that separates the main beam and the sub-beam that have passed through the first and second optical elements; and a photodetector that receives the main beam and passes through the first and fourth optical elements. The polarization direction of the main beam of the optical region and the main beam passing through the second and third optical regions is the first direction, and the main beam passing through the first and third optical regions and the secondary beam passing through the second and fourth optical regions The polarization direction of the light beam is a second direction different from the above-mentioned first direction.

Description

technical field [0001] The present invention relates to an optical pickup device for recording and / or reproducing information using diffracted light. Background technique [0002] In recent years, in the optical pick-up device, the short wavelength of the laser light source used as the light source for reproducing the information recorded on the optical disc or recording the information on the optical disc has been improved, and various blue-violet laser light sources are being realized. Practical. If these blue-violet semiconductor lasers are used, when using the same numerical aperture (NA) objective lens as DVD (Digital Versatile Disc), information recording of 15 to 20 GB can be carried out for an optical disc with a diameter of 12 cm. When the NA is as high as 0.85, about 25 GB of information can be recorded on an optical disc with a diameter of 12 cm. Hereinafter, in this specification, an optical disc and a magneto-optical disc using a blue-violet laser light source...

AI Technical Summary

Problems solved by technology

Especially when making the information recording light incident of CD use to diffractive structure, in addition to the diffracted light of the predetermined number of times used for the recording / reproducing of information, the unnecessary diffracted light of times other than this sometimes occurs, and there are some Unwanted diffracted light incident on the photodetector poses a risk of impediment to correct signal reading

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