摘要:
A method for separating light coming from an illuminated multilayer medium having a plurality of reflective surfaces to reach a light receiver through a focusing lens includes the steps of splitting the light traveling toward the light receiver through the focusing lens into at least two portions along the optical axis thereof and separating a light component coming from a particular position of the illuminated medium from each of the split portions of the light by removing a light component focused at a position closer to the focusing lens than the focal position of the light component coming from the particular position between the two focal positions and/or removing a light component focused at a position closer to the light receiver than the focal position of the light component coming from the particular position between the two focal positions.
摘要:
An optical reproducing apparatus according to the present invention includes a land/groove switching circuit for alternately switching reproduction of a record mark on a groove portion and a land portion. This allows a tracking operation to be carried out continuously at a connection point to a subsequent track in the recording direction without a laser beam from an optical pickup passing through an end of a spiral track. A recording medium according to the present invention includes a recording track formed of a groove portion and a land portion, and a record mark used for switching a tracking operation so that a light beam emitted from the optical pickup should be irradiated alternately on the groove portion and the land portion. When the record mark is detected, a track jump operation is carried out, and information is reproduced from the groove portion and the land portion alternately.
摘要:
A disc recording and/or reproducing apparatus includes a holding device for holding a disc cartridge which is a cartridge main body and a disc housed in the cartridge main body, a rotating and driving device for rotationally driving the disc housed within the holding device, and a positioning device provided within the rotating and driving device for positioning the disc cartridge housed within the holding device. The recording disc may be positioned highly accurately within the disc cartridge in such a manner that resonant vibrations may be prevented from being produced on the chassis.
摘要:
A laser irradiation device includes: a laser light source; a mirror that reflects a part of light output from the laser light source and allows the remainder to pass; an optical detector that detects reflection light reflected by the mirror; and a feedback control circuit that receives a signal output from the optical detector and controls the output of the laser light source to keep a signal intensity constant, wherein a thickness of the mirror is set such that a distance between a beam spot of the reflection light reflected by a front surface of the mirror on the detector and a beam spot of reflection light reflected by a back surface of the mirror on the detector is equal to or more than a predetermined value.
摘要:
A variable focal length lens includes: a lens portion including a pair of light transmissive members, at least one of which is deformable, and a light transmissive liquid medium sealed between the pair of light transmissive members; and a liquid medium container including a chamber that communicates with the lens portion and is filled with the liquid medium, the liquid medium container causing the shape of the surface of the deformable light transmissive member or members to be changed by changing the volume of the chamber to adjust the amount of liquid medium with which the lens portion is filled.
摘要:
A variable focal length lens includes: a lens portion including a pair of light transmissive members, at least one of which is deformable, and a light transmissive liquid medium sealed between the pair of light transmissive members; and a liquid medium container including a chamber that communicates with the lens portion and is filled with the liquid medium, the liquid medium container causing the shape of the surface of the deformable light transmissive member or members to be changed by changing the volume of the chamber to adjust the amount of liquid medium with which the lens portion is filled.
摘要:
The present invention can simplify the configuration of a polarization adjustment plate. According to the present invention, the crystal axis of the polarization adjustment wavelength plate 32 is so arranged as to be turned up from the X-Y plane being an orthogonal plane with respect to the optical axis 40a, and the wavelength dependence which the crystal material is originally provided with is largely expressed, and further the thickness “ta” with respect to the optical axis 40a is set up such that the phase difference Δ to be brought about at the beam center becomes low from 360°+180°=540° being a desired design value to irradiate the optical beam as the P-polarization by a predetermined difference value or 60°.
摘要:
An optical disc device performs tracking control using a light amount difference at two overlapping areas. The optical disc device includes a splitter, objective lens, detection-signal generator, tracking-signal generator, and driver. The splitter splits the light beam from a light source into a main beam and sub-beams. The objective lens converges the split beams and illuminates a signal-recording-layer track. The detection-signal generator receives reflected light beams and generates a detection signal according to the reflected-light-beam light amounts. The tracking-signal generator generates a tracking error signal on the basis of the detection signal. The driver drives the objective lens in a tracking direction on the basis of the tracking error signal. The splitter causes the light amounts of the overlapping areas at sub-reflected-light beams to be less than a light amount of an area other than the overlapping areas.
摘要:
In an optical pickup apparatus, including a laser source arranged along an optical axis, a polarization beam splitter and an objective lens, wherein light emitted from the laser source is emitted on a recording plane of an optical-magnetical recording media as a converged beam, light beams reflected from the recording media of the optical-magnetical recording media are separated by said polarization beam splitter to obtain a predetermined polarized light component, a phase change means, which changes a phase of light passing through one side of said optical axis and a phase of light passing through another side of said optical axis by a predetermined angle, such as 1/2 wavelength plate, a phase retardation type prism and a combination optical rotation plate, is provided between the polarization beam splitter and the objective lens, and, an optical detection element, which detects the light polarized by the polarization beam splitter, is provided at a side intersecting the phase change means of the polarization beam splitter.
摘要:
A disc recording and/or reproducing apparatus including a signal recording/reproducing section for recording and/or reproducing information signals on a disc 64 mm in diameter housed in a cartridge main body to form a disc cartridge, a loading mechanism for loading or unloading the disc cartridge on or from the signal recording/reproducing section and a control circuit controlling the recording/reproducing operation of the recording/reproducing section. The disc has a signal recording part divided into plural signal recording zones of substantially equal line recording density across the inner and the outer peripheries of the disc. The signal recording/reproducing section, the loading mechanism and the control circuit are housed in a casing which is 70 mm or less in width, 100 mm or less in length and 24.5 mm or less in height and which is provided with a disc inserting opening. The apparatus may be reduced in size without decreasing the recording capacity.