Abstract: An optical pickup apparatus comprises an orbicular zone forming lens group 14 for forming the section of the laser beam, which is irradiated to an optical disc DK having plural recording layers, into an annular shape, a condenser lens 35 that converges the reflected beam from the optical disc DK, and a pinhole plate 36 having formed thereto a pinhole 36a with a size corresponding to a flux diameter of the reflected beam converged by the condenser lens 35. The orbicular zone forming lens group 14 refracts the laser beam irradiated to the optical disc DK so as to form the section of the laser beam into an annular shape in order that the internal diameter of the annular converged flux formed on the pinhole plate 36a by the reflected beam from the recording layers other than the recording layer having an optical spot formed thereon becomes greater than the diameter of the pinhole 36a.

Abstract: The BCA recording and reproducing apparatus performs recording of data onto an optical disc placed on a recording turntable, reproduction of data recorded on an optical disc placed on a reproducing turntable and ejection of an optical disc placed on an exchanging table and placement of a new optical disc on the exchanging table in parallel. A processing time is thereby shortened compared with the case of performing data recording, reproduction and exchange in series.

Abstract: An optical pickup apparatus comprises an orbicular zone forming lens group 14 for forming the section of the laser beam, which is irradiated to an optical disc DK having plural recording layers, into an annular shape, a condenser lens 35 that converges the reflected beam from the optical disc DK, and a pinhole plate 36 having formed thereto a pinhole 36a with a size corresponding to a flux diameter of the reflected beam converged by the condenser lens 35. The orbicular zone forming lens group 14 refracts the laser beam irradiated to the optical disc DK so as to form the section of the laser beam into an annular shape in order that the internal diameter of the annular converged flux formed on the pinhole plate 36a by the reflected beam from the recording layers other than the recording layer having an optical spot formed thereon becomes greater than the diameter of the pinhole 36a.

Abstract: A media ID recording apparatus has an optical pickup 20 for forming an elongated optical spot on a recording surface of an optical disk DK; and a support table 32 for fixedly supporting the optical pickup 20. The optical pickup 20 is fixed to the support table 32 via a wedge-like spacer 33 as tilted toward the radial direction of the optical disk DK. The focal position of the elongated optical spot at the rear side in the moving direction is matched to the recording surface of the optical disk DK and the focal position of the optical spot at the front side in the moving direction is shifted from the recording surface of the optical disk DK, whereby the light intensity of the optical spot at the front side in the moving direction becomes smaller than the light intensity of the optical spot at the rear side in the moving direction. A media ID is recorded on the optical disk DK by using the optical spot thus set.

Abstract: The interferometer has a diffraction grating 21, a condenser lens 22, a transparent substrate 23, a field lens 24 and an imaging device 25 arranged in this order. The transparent substrate 23 is arranged at the position in the optical axis direction where both focal spots of a zeroth-order diffracted light L21 and a first-order diffracted light L22 are formed. Formed on the transparent substrate 23 is a circular opaque zone 23a whose central position is the central position of the focal spot of the first-order diffracted light L22. Formed at the center of the opaque zone 23a is a pinhole 23b whose central position is the central position of the focal spot of the first-order diffracted light L22. The contrast of the interference fringes observed on the image device 25 is enhanced by the optical interference between the first-order diffracted light L22 passing through the pinhole 23b and the zeroth-order diffracted light L21 passing through the transparent substrate 23.

Abstract: There is provided an optical pickup head which can accurately detect a focusing error even when the wavelength of light emitted from a light source varies. A holographic element diffracts a light beam reflected by an optical disk to obtain .+-.1st-order diffracted light beams, and has a diffracting area formed using a Fresnel zone plate, and a light-shading area for shading the reflected light beam. A photo-detector has four-elements light-receiving areas. The photo-detector detects the .+-.1st-order diffracted light beams diffracted by the diffracting area and focused by a convex lens, and converts these light beams into electrical signals. The photo-detector is disposed at substantially the middle point between the focal points of the -1st-order diffracted light beams formed by the convex lens. Since the middle point does not move even when the lasing wavelength of a semiconductor laser diode varies, the photo-detector can obtain stable signals.