Optical pickup optics system and apparatus, optical disc reproducing and/or recording apparatus and relay lens

Abstract

An optical system is used in an optical pickup apparatus which conducts reproducing and / or recording information for a first optical disk having a thinner protective substrate t 1 [mm] and a second optical disk having a thicker protective substrate t 2 [mm]. The optical system comprises a relay lens group comprising at least one movable lens group. The movable lens group moves so that for the first optical disk, a parallel or substantial parallel light flux emitted from the relay lens group enters the objective lens while a divergent light flux emitted from the relay lens group enters the objective. The movable lens group satisfies the following formu

Description

technical field [0001] The present invention relates to an optical pick-up optical system, an optical pick-up device, an optical disc recording and reproducing device, and a relay lens, and in particular relates to at least one of information recording and reproducing operations interchangeable for different types of optical information recording media. An optical pickup optical system, a drive device for an optical disc, and a relay lens. Background technique [0002] In recent years, with the practical use of short-wavelength red semiconductor lasers, DVD (Digital Versatile Disc) as a high-density optical disc has been commercialized. Compact Disc) the same size, and can record a large amount of information. [0003] Recently, next-generation optical discs capable of recording larger-capacity information are being developed. However, in order to realize high-density recording signals and reproduction of high-density recording signals, the light-collecting optical system o...

AI Technical Summary

Problems solved by technology

For this reason, when the object optical system of the above-mentioned document 1 is applied as it is, in BD and HD, since the wavelength of the light source is the same, it is difficult to correct the spherical aberration caused by the thickness of the protective layer by the action of diffraction.

[0011] On the other hand, when the object optical system described in the above document 2 is applied as it is, in BD and HD in which the object optical system has a high numerical aperture, the amount of spherical aberration due to the difference in the thickness of the protective layer is large. , causing the problem that it is difficult to correct the spherical aberration to a practically usable level

[0012] In addition, in the case where the recording operation of information is performed interchangeably with BD and HD, since the numerical apertures of BD and HD are different, as a technique for controlling the numerical aperture of the object optical system according to the wavelength of the light source, even if a known The technology using the wavelength dependence of the diffraction effect or the technology using the wavelength selection filter having the wavelength dependence of the transmittance also has a problem that it is difficult to apply to BD and HD with the same wavelength of the light source.

Images