摘要:
An objective lens that allows spherical aberration to be suppressed during the reproduction of a CD without sacrificing reproduction characteristics of a DVD, has a first numerical aperture comprising a refracting surface that is in rotatory symmetry about an optical axis. A part of the refracting surface is displaced along the optical axis as an annular concave (or convex) portion centered on the optical axis. The annular concave (or convex) portion has a certain inner diameter r.sub.1 and a certain outer diameter r.sub.2 that reduce RMS aberration V to a value close to a minimum value. The annular portion has a certain depth (or height).
摘要:
A pickup device includes an irradiation optical system including an object lens for focusing light flux on a track of a recording surface of an optical recording media having a plurality of recording layers stacked while a spacer layer is interposed between the recording layers to form a spot and a detection optical system including an photo detector having a plurality of light receiving parts for receiving returning light reflected from the spot through the object lens to perform photoelectric conversion. The pickup device controls a position of the object leans according to an electrical signal calculated from outputs of the light receiving parts. The pickup device further includes an astigmatic device for providing astigmatism to the returning light directed to the light receiving parts and a division device, having divisional regions divided by a division line extending in an astigmatic direction about an optical axis of the returning light, for dividing the returning light having the astigmatism into a plurality of partial light fluxes divided for the respective divisional regions along the optical axis of returning light. The neighboring divisional regions provide the partial light fluxes with an optical action so that interference between the corresponding partial light fluxes does not occur on the light receiving parts.
摘要:
A pickup device includes an irradiation optical system including an object lens for focusing light flux on a track of a recording surface of an optical recording media having a plurality of recording layers stacked while a spacer layer is interposed between the recording layers to form a spot and a detection optical system including an photo detector having a plurality of light receiving parts for receiving returning light reflected from the spot through the object lens to perform photoelectric conversion. The pickup device controls a position of the object leans according to an electrical signal calculated from outputs of the light receiving parts. The pickup device further includes an astigmatic device for providing astigmatism to the returning light directed to the light receiving parts and a division device, having divisional regions divided by a division line extending in an astigmatic direction about an optical axis of the returning light, for dividing the returning light having the astigmatism into a plurality of partial light fluxes divided for the respective divisional regions along the optical axis of returning light. The neighboring divisional regions provide the partial light fluxes with an optical action so that interference between the corresponding partial light fluxes does not occur on the light receiving parts.
摘要:
The present invention provides an optical pickup device requiring no position adjustment of a diffraction grating at the time of assembling the optical pickup device, and capable of suppressing fluctuations in a differential push-pull signal amplitude and cancelling a push-pull offset.An optical pickup device 200 of an embodiment of the present invention has a diffraction grating 230 of a special shape including predetermined grooves and two kinds of lattice grooves arranged at a pitch determined on the basis of a pitch of grooves formed in the surface of an optical disk 50, numerical aperture, wavelength of a light beam, and effective diameter of the light beam applied on the optical disk 50. To suppress push-pull signals generated in the ± first-order diffraction rays, reflection rays from the optical disk 50 of a zeroth-order diffraction ray and ± first-order diffraction rays are detected, and signals corresponding to light reception results are output to a reproduction unit 150, a control unit 130, and an actuator servo circuit 140.
摘要:
A pickup device which, focusing a ray bundle on a track of a recording surface of an optical recording medium to form a light spot, comprises a detection optical system including a photo detector to receive return light reflected from the light spot via an objective lens and perform photoelectric conversion. The photo detector has at least two photoreceptor sections positioned axis-symmetrical with respect to a detection-side division line extending through an optical axis of the return light and parallel to the track. A dividing element placed in an optical path between the photo detector and the objective lens includes at least two inner divided areas positioned axis-symmetrical with respect to a deflection-side division line extending through the optical axis of the return light and parallel to the track, and at least two outer divided areas positioned sandwiching the inner divided areas and axis-symmetrical with respect to the deflection-side division line. The inner divided areas are formed such that parts of a light beam from the other region than overlap regions, divided axis-symmetrically along the deflection-side division line, are exchanged in position across the detection-side division line and directed to the photoreceptor sections of the photo detector so as to be axis-symmetrical with respect to the detection-side division line.
摘要:
An optical pickup device includes an irradiating optical system for converging a light beam to form a spot on a recording surface via a light-transmitting layer of an optical recording medium, and a photodetection optical system for converging return light reflected and returned from the spot on a photodetector. The device detects wave aberration and focal error of the light beam. A diffractive optical element is disposed on the optical axis of return light in the photodetection optical system and provided with an annulus. The diffractive optical element annularly extracts, from return light, ray components in the vicinity of a predetermined radius on a pupil on the emitting pupil surface of the irradiating optical system, which is affected by the wave aberration generated in the optical system. The photodetector contains first light receiving components for receiving the ray components transmitted and extracted by the annulus, and second light receiving components for receiving at least some of the ray components other than the ray components transmitted by the annulus. The device further includes a focal error detecting circuit connected to the first light receiving components and which detects the focal error of the light beam on the basis of a subsequent photoelectrically converted output. The device may include a wave aberration error detecting circuit connected to the second light receiving components and which detects the wave aberration of the light beam on the basis of a subsequent photoelectrically converted output.
摘要:
A focus error detecting apparatus and a focus error detecting method of an optical pickup in which the system is not easily influenced by track transversal noises and an optical disc thickness error and which can be used together with a 3-beam system or a DPD system. The return light from an optical disc is divided to a first optical path and a second optical path by a hologram device, a predetermined astigmatism is applied to the light on each divided optical path, the light is received and detected by a first detector and a second detector, and a focusing error signal is obtained by predetermined arithmetic operations. The return light from the optical disc is divided to the first optical path P1 and the second optical path P2 by a lens device constructed by combining eccentric cylindrical lenses, a predetermined astigmatism is applied to the light on each divided optical path, the light is received and detected by a first detector and a second detector each having photosensing portions divided into four portions by dividing lines having a lightning shape, and a focusing error signal is obtained by predetermined arithmetic operations.
摘要:
A pickup device comprising an irradiation optical system including an objective lens to focus a ray bundle on a track of a recording surface of an optical recording medium to form a light spot, and a detection optical system including a photo detector to receive return light reflected from the light spot via the objective lens and perform photoelectric conversion and controls said objective lens in position according to electrical signals produced through operations on outputs of said photo detector.
摘要:
An optical pickup apparatus reads an information signal recorded on a recording surface of an optical disk along a track by projecting a light beam. Said optical pickup apparatus has: an objective lens for converging said light beam onto said recording surface; an objective lens moving device for moving said objective lens in a radial direction of said optical disk; and a divisional photosensing device for receiving return light reflected by said optical disk, in a plurality of divided regions. Said divisional photosensing device has: a first divisional photosensing device for dividing a first region including both edge portions in said radial direction of said return light, in two divided areas in said radial direction; a second divisional photosensing device for receiving a second region including both edge portions in a direction which perpendicularly crosses said radial direction of said return light, in two divided areas in said radial direction; and a third divisional photosensing device for receiving a third region including an almost center portion of said return light, in two divided areas in said radial direction.
摘要:
An optical pickup apparatus reads an information signal recorded on a recording surface of an optical disk along a track by projecting a light beam. Said optical pickup apparatus has: an objective lens for converging said light beam onto said recording surface; an objective lens moving device for moving said objective lens in a radial direction of said optical disk; and a divisional photosensing device for receiving return light reflected by said optical disk, in a plurality of divided regions. Said divisional photosensing device has: a first divisional photosensing device for dividing a first region including both edge portions in said radial direction of said return light, in two divided areas in said radial direction; a second divisional photosensing device for receiving a second region including both edge portions in a direction which perpendicularly crosses said radial direction of said return light, in two divided areas in said radial direction; and a third divisional photosensing device for receiving a third region including an almost center portion of said return light, in two divided areas in said radial direction.