摘要:
The optical disk apparatus of this invention is provided with a memory for memorizing a track offset signal corresponding to an angle of a galvanic mirror, or a photodetector having two pairs of photodetecting regions to detect different tracking error signals to each other, or two galvanic mirrors which are adjusted so as to prevent the track offset signal.
摘要:
An optical system of an optical disc apparatus is disclosed for converging and projecting a bundle of rays emitted from a light source onto an optical disc. The optical system includes a collimating lens which collimates the bundle of rays emitted from the light source, two anamorphic prisms for shaping the cross section of the collimated bundle of rays transmitted through the collimating lens, and an objective lens which converges the bundle of rays shaped by the anamorphic prisms onto the optical disc. At least one of the anamorphic prisms is detachably mounted to an immovable body portion of the optical system.
摘要:
A signal detecting apparatus in an optical disc apparatus having an objective lens which converges light emitted from a light source onto an optical disc and a condenser lens which converges light reflected by the optical disc and transmitted through the objective lens includes first and second light receiving elements, each having a light receiving surface located before or behind a convergence point on which the light reflected from the optical disc is converged when the objective lens is in a focal position. Each of the light receiving surfaces are split into at least four light receiving areas. The signal detecting apparatus also includes a means for calculating a sum of differences of outputs of the light receiving surfaces' inner light receiving areas, calculating a sum of differences of outputs of the light receiving surfaces' outer light receiving areas, and then calculating a difference of the sums of differences, so that a track error signal is output in accordance with the difference of sums of differences calculated by the calculating means.
摘要:
An optical disc apparatus includes a fixed portion having a light source portion and a movable portion that holds an objective lens and moves along a radial direction of an optical disc. The fixed portion includes the light source portion for selectively emitting short and long wavelength laser beams, and a collimator lens for collimating the laser beams. The objective lens includes a positive refractive lens and a diffractive lens structure formed on a surface of the refractive lens. The diffractive lens structure has wavelength dependence such that spherical aberration varies in the undercorrected direction as wavelength of incident light increases. The objective lens converges the short wavelength laser beam of a predetermined diffraction order onto an informatlon layer of a thin cover type optical disc, and converges the long wavelength laser beam of the identical diffraction order onto an information layer of a thick cover type optical disc.
摘要:
A signal sensing device is provided that includes an optical system having a first splitting function by which a beam reflected by a magneto-optic disk is split by a small amount, a second splitting function by which the beam is split into a P-polarized-component and an S-polarized-component, and a third splitting function by which the beam is split into a first optical path and a second optical path. The second splitting function is carried out by an optical element carrying out one of the first and third splitting functions. A first photo sensor is provided with a beam receiving area divided into four parts, and an undivided beam receiving area, and a second photo sensor is provided with a beam receiving area divided into two parts and an undivided beam receiving area. The beam receiving divided area of the first photo sensor receives the P-polarized-component and senses a focusing error signal, and the beam receiving divided area of the second photo sensor receives the S-polarized-component and senses a tracking error signal. The beam receiving undivided areas of the first and second photo sensors are provided for sensing an information record signal.
摘要:
An lens evaluating system for evaluating a dual-focus lens is disclosed. The lens evaluating system is provided with an interferometer to form an image of interference fringes and a masking system which masks a part of the image corresponding to a noise component.
摘要:
A reflected light beam from a magneto-optic disk is reflected by a first and second reflective element toward a signal detecting system. The first reflective element reflects the reflected light from the magneto-optic disk and gives a phase difference into the light beam. The second reflective element reflects the reflected light by the first reflective element toward the signal detecting system, and gives a phase difference which has the same amount as the phase difference caused by the first reflective element, but with the inverse sign thereof.
摘要:
An objective lens system used in an optical system of an optical disk device. The objective lens system includes at least one lens element and converges light emitted from a light source onto a reflecting layer of an optical disk. The lens element has an offense against the sine condition OSC, and the optical disk has a substrate thickness T and a refractive index n. A ray of light exits the lens element and intersects an optical axis of the lens element at an angle .alpha.. The values of OSC, .alpha., n and T satisfy the following relationship for light rays that are incident on the objective lens system at distances from the optical axis of the objective lens system which are least equal to a predetermined percentage of an effective height of an aperture of the objective lens: ##EQU1## Accordingly, a spherical aberration of the optical system is corrected. An offense against the sine condition of only the objective lens is substantially coincident with a spherical aberration of the objective lens such that a coma of only the objective lens is corrected.
摘要:
An optical head structure, employed in an optical device, in which light radiated from a predetermined light source is projected onto a predetermined recording medium through a light splitting member is disclosed. Part of the light is directed to the outside of the light splitting member and converged so as to be detected by a predetermined light detecting member. The light directed to the outside of the light splitting member is reflected at a predetermined angle by a predetermined light reflecting member. Thus, it becomes possible to make the whole volume of the optical device smaller. Also, the number of parts required in the optical head structure can be decreased.
摘要:
In an optical system comprising a light source section consisting of a semiconductor laser and a collimator lens, an objective lens for focusing a light beam on an optical disk, a beam splitter for separating part of the light beam reflected from the optical disk, a condenser lens, and a photosensor for detecting the separated light beam to produce a focusing and a tracking error signal, a plane parallel plate is provided between the light source section and the beam splitter. By rotating the plane parallel plate with an adjusting mechanism, the light beam undergoes a parallel shift, so that the intensity distribution of light being incident on the objective lens is varied and a tracking offset due to a deviation of the optical axis of the output light from the light source section can be compensated for. The plane parallel plate may be disposed between the beam splitter and the condenser lens.