Optical pickup and optical storage device

Abstract

An optical pickup for an optical storage device includes a stem, a substrate mounted on the stem, and a laser diode mounted on the substrate. The substrate is integrally formed with an optical signal detector and an error signal detector for focusing error detection and tracking error detection. A cap is mounted on the stem so as to accommodate the substrate and the laser diode. A beam splitter unit including a polarization beam splitter and a beam splitting element is mounted on the cap. A hologram for diffracting a reflected beam toward the error signal detector is interposed between the cap and the beam splitter unit. The substrate is biased at a given potential, and has an insulating film opposed to the stem.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an optical pickup (optical head) for an optical device such as an optical disk drive, optical card drive, optical scanner, and microscope unit. [0003] 2. Description of the Related Art [0004] An optical disk inclusive of a magneto-optical disk has received attention as a memory medium that becomes a core in the recent rapid development of multimedia, and it is usually accommodated in a cartridge case to be provided as an optical disk cartridge for practical use. The optical disk cartridge is loaded into an optical disk drive to perform reading / writing of data from / to the optical disk by means of an optical pickup. [0005] The optical pickup in a recent optical disk drive intended to realize size reduction is composed of a fixed optical assembly and a movable optical assembly, wherein the fixed optical assembly includes a laser diode, a beam splitter for reflecting and transmitting a l...

AI Technical Summary

Benefits of technology

The design enhances signal detection quality by reducing stray light interference and crosstalk, resulting in improved regenerative and servo signals, achieving stable and high-quality signal output.

Problems solved by technology

Further, these recording media have warpage or undulation due to strain in forming the media, resulting in the tendency of eccentricity or inclination of the recording media.

Thus, the first, second, and third photodiodes are mounted on the stem in the optical pickup described in the above U.S. patent, so that there is a problem of insufficient integration of the photodiodes.

Such high-frequency variations in potential occur especially in writing data, and have adverse effects on a photodiode for detection of a focusing error signal, a photodiode for detection of a tracking error signal, and a photodiode for monitoring an output from the laser diode, thus causing instability in detecting signals output from these photodiodes.

This electrical charge has an influence on signal currents generated in the photodiode regions, causing a problem that high-quality signal currents cannot be obtained.

This is due to the fact that all of the light quantities of the laser beam output from the laser diode cannot be transmitted or reflected by each optical component, but a part of the laser beam remains in the optical unit to become stray light.

This stray light may enter the photodiode for detection of a magneto-optical signal, the photodiode for detection of a focusing error signal, the photodiode for detection of a tracking error signal, and a photodiode for automatic power control (APC), causing adverse effects on signal currents.

However, reflected light from the optical components is further reflected by the metal film to result in an increase in stray light.

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