Abstract: When tracking a dual-layer optical disc by a differential push-pull method, the adverse effect of the reflected light from an adjacent layer, which produces stray light, on a tracking control signal is prevented. A split wavelength plate 20 is inserted in the optical path of the reflected light from the optical disc including the stray light from the adjacent layer so as to detect a region having no interference with the stray light with a four-quadrant detector, and then a push-pull signal by a sub-beam is formed.

Abstract: The adverse influence of reflected light from adjacent layers as stray light on a control signal or data signal is reduced when tracking a multilayered optical disc using differential push-pull method. The reflected light from the optical disc including stray light from an adjacent layer is once condensed with a condenser lens having little aberration and is then reflected by a reflecting mirror having a partial reflecting region. The resultant reflected light, which has the influence of stray light reduced, passes through a polarization beam splitter and becomes incident on a four-quadrant detector (for main beam) and a split detector (for sub beam) via a condenser lens having astigmatic aberration.

Abstract: The amount of reflected light from an adjacent layer in a multilayer optical disc is reduced by means of a combination of half-wave plates having different optical axes and a flat mirror. The polarization direction of the reflected light from a target layer is changed without changing the polarization direction of reflected light from the adjacent layer so as to detect a signal from the target layer alone. Because no stray light is introduced into the tracking error signal or focus signal, the laser light irradiated position can be controlled with high accuracy. This makes it possible to accurately determine the laser irradiated position during reading and writing, thereby enhancing signal quality. Because no reflected light from the adjacent layer is introduced into the data signal, a data signal with reduced error can be obtained.

Abstract: When recording/reproducing an optical disc having a recording layer of multi-layer structure, an unwanted optical beam reflected from a recording layer other than a target layer for recording/reproduction is incident on a photodetector to cause an unwanted disturbance component to leak to a detection signal, giving rise to a degradation in the quality of a tracking control signal. In an optical pickup apparatus, for suppression of the degradation, an optical element is mounted having a diffraction area for diffracting part of the optical beam and light receiving planes for sub-optical beams are provided each of which has a light shielding zone or dead zone of a predetermined width on its central sectioning line.

Abstract: The three-dimensional information reading/recording method of this invention enhances the recording capacity as well as performs high-speed reading/recording of information three-dimensionally. The method includes: forming three-dimensional lattices in a three-dimensional optical disk, disposing to wobble the lattices in a plane perpendicular to the traveling direction of light spots, generating signals for controlling the light spots, and scanning at least one light spot between the lattices three-dimensionally to thereby read out and record the information.

Abstract: A method of mounting an optical device having a step on the surface opposing to a mounting substrate favorably by face-down bonding which enables a decrease in the number of components or integrate additional components on one identical substrate and, accordingly, is useful for reducing the size and the thickness of an optical head using a light source, the method includes the step of making the volume of a solder pattern to the area ratio of each electrode different for every wiring electrode portions upon mounting the electrodes on the substrate for mounting the optical device, in which the optical device having the step can be mounted favorably to the substrate by the control for the height of solder upon melting.

Abstract: This invention is provided to reduce wavefront aberrations caused by the filling of a transparent resin intended to prevent degradation of a diode laser in a hermetically sealed package. A parallel-plane plate is arranged between a diode laser and an objective lens, and a transparent resin is filled into a space formed between the diode laser and the parallel-plane plate. With this invention, degradations of the diode lasers can be prevented and the wavefront aberrations can be reduced.

Abstract: A method of mounting an optical device having a step on the surface opposing to a mounting substrate favorably by face-down bonding which enables a decrease in the number of components or integrate additional components on one identical substrate and, accordingly, is useful for reducing the size and the thickness of an optical head using a light source, the method typically includes the step of making the area ratio of each electrode to a solder pattern different for every wiring electrode portions upon mounting the electrodes on the substrate for mounting the optical device, in which the optical device having the step can be mounted favorably to the substrate by the control for the height of solder upon melting, and the volume of the solder is previously controlled depending on the wettability of a region of the substrate covered by the solder.

Abstract: This invention is provided to reduce wavefront aberrations caused by the filling of a transparent resin intended to prevent degradation of a diode laser in a hermetically sealed package. A parallel-plane plate is arranged between a diode laser and an objective lens, and a transparent resin is filled into a space formed between the diode laser and the parallel-plane plate. With this invention, degradations of the diode lasers can be prevented and the wavefront aberrations can be reduced.

Abstract: A photo semiconductor integrated circuit device has a photodiode portion and amplifier portion, each portion having a buried layer. The impurity concentration and/or depth of the buried layer for the photodiode portion is lower than that of the buried layer for the amplifier portion. As a result, the frequency band width is widened.

Abstract: To reduce an effect of reflected light from a layer (or layers) other than a layer to be read upon focus position control when reading a multilayer optical disk in an optical disk drive. In an optical system where a focus error signal is generated by the knife edge method, a photodetector 53 that is divided into four parts is used. Each of two pairs of light detecting elements on the right or left side are formed by division of a detection plane of the photodetector such that the reflected light from a neighboring layer falls half-and-half on that pair of the light detecting elements. Signals from the photodetector are given with alternating polarities in such a way that any adjacent light detecting elements have mutually different polarities and are added up together to form the focus error signal.

Abstract: Disclosed is an optical information processor having high-speed reading property by improving responsivity and extension of the frequency band width of a photodiode prepared on one identical substrate together with other semiconductor integrated circuit device. To extend the frequency band width, a buried layer of a photodiode portion is deeply implanted or the impurity concentration of the buried layer is lowered. To improve the responsivity, the thickness of the oxide layer of the SOI substrate is selected such that the reflected light is maximized.

Abstract: To reduce an effect of reflected light from a layer (or layers) other than a layer to be read upon focus position control when reading a multilayer optical disk in an optical disk drive. In an optical system where a focus error signal is generated by the knife edge method, a photodetector 53 that is divided into four parts is used. Each of two pairs of light detecting elements on the right or left side are formed by division of a detection plane of the photodetector such that the reflected light from a neighboring layer falls half-and-half on that pair of the light detecting elements. Signals from the photodetector are given with alternating polarities in such a way that any adjacent light detecting elements have mutually different polarities and are added up together to form the focus error signal.

Abstract: An apparatus for and a method of measuring a boundary surface of a sample are disclosed in which a ratio of the light quantity of a part of reflected light from a sample which travels in the vicinity of the optical axis of the reflected light, to the light quantity of another part of the reflected light which is directed to a position deviating from the optical axis by a predetermined distance is used to accurately measure a boundary surface of a sample. Since the accuracy of measurement is increased by using the above ratio, light capable of passing through the sample can be used as incident light. Thus, a deep hole in the surface of the sample and a void such as an air bubble in a living being sample, which cannot be measured by the prior art, can be measured very accurately.

Abstract: A confocal scanning laser microscope according to the present invention employs an aperture which is provided at a predetermined position within a plane of a photomask including rectilinear pattern edges orthogonal to each other formed on a transparent substrate. The aperture is moved in such a way that coordinate positions at which a laser beam traverses the respective rectilinear pattern edges orthogonal to each other are found using output signals from an optical detector, and it is consequently brought into agreement with a focused position of the laser beam.

Abstract: A pattern defect inspection apparatus detects presence or absence of a defect in a pattern formed on a semiconductor wafer by scanning the pattern normally to the surface thereof by a coherent light beam of a predetermined spot size, detecting reflected diffraction lights generated thereby and processing the detected lights. It comprises an abnormal direction signal detector including photo-detectors having wide light receiving areas arranged in a plurality of spatial areas which the reflected diffraction lights from a normal pattern do not normally reach, a normal pattern detector including photo-detectors having large light receiving areas arranged in a plurality of spatial areas which the reflected diffraction lights from the normal pattern reach, and a defect discriminator for determining if the abnormal direction signals are due to a true defect or not in accordance with the signals from the abnormal direction signal detector and the normal pattern detector.