Abstract: There is provided a collimator lens which turns light emitted from a laser device, which is used in a laser display device, into parallel beams. The collimator lens is configured such that the wavelength of the light from the laser device is equal to or longer than 375 nm and equal to or shorter than 750 nm, the numerical aperture is equal to or larger than 0.2 and equal to or smaller than 0.75, and both conditions of “D/f>0.85 assuming that the lens thickness is D and the focal distance is f” and “?d>57 assuming that the Abbe number is ?d” are satisfied.

Abstract: An optical element includes a transparent substrate, a first light-blocking film attached to at least one surface of the transparent substrate and having a first circular opening, and a first lens portion disposed on the at least one surface of the transparent substrate, the first lens portion being composed of ultraviolet curable resin and having a first lens-functioning surface. The first lens portion is disposed such that the first lens-functioning surface covers the first opening and overlaps an area of the first light-blocking film that surrounds the first opening.

Abstract: An optical element includes a transparent substrate, a first light-blocking film attached to at least one surface of the transparent substrate and having a first circular opening, and a first lens portion disposed on the at least one surface of the transparent substrate, the first lens portion being composed of ultraviolet curable resin and having a first lens-functioning surface. The first lens portion is disposed such that the first lens-functioning surface covers the first opening and overlaps an area of the first light-blocking film that surrounds the first opening.

Abstract: A compound optical unit includes a housing mounted on an optical pickup apparatus, the housing has a semiconductor laser device, a light receiving device, and a compound optical device, fixed to the housing. The semiconductor laser device includes a laser diode for emitting shorter wavelength laser beams for a DVD and another laser diode for emitting longer wavelength laser beams for a CD. The compound optical device includes an incidence surface and an emission surface for receiving and emitting, respectively, the light beams emitted by the semiconductor laser device, a diffraction lattice provided on the emission surface for diffracting light beams reflected and returned from an optical disk, and a reflective surface for reflecting the light beams diffracted by the diffraction lattice toward the light receiving device. The reflective surface is provided with a correction element for focusing the light beams of different wavelengths on one light receiving position of the light receiving device.

Abstract: A disk drive includes a DVD optical head and a CD optical head. An objective lens in the CD optical head moves along a reference radial line passing through the center of rotation of an optical disk. An objective lens in the DVD optical head moves along a transfer line parallel to the reference radial line, and is disposed so that an expression R0<(Rmin+Rmax)/2 is satisfied, where Rmin and Rmax represent distances along the reference radial line between the center of rotation and the positions of the objective lens when it is disposed on the innermost and outermost tracks of the optical disk, respectively, and R0 represents a distance along the reference radial line between the center of rotation and the position of the objective lens when its tracking correction direction is towards the center of rotation of the optical disk.

Abstract: A compound optical unit includes a housing mounted to an optical pickup. A semiconductor laser, a light receiving member, and a composite optical member are integrally fixed to the housing. The semiconductor laser has a laser diode that emits a laser beam for a DVD. The composite optical member is provided with an incidence surface that admits light emitted from the semiconductor laser, an emission surface emits the light, a diffraction grating provided on the emission surface diffracts light reflected by an optical disk D, a reflecting surface that reflects light diffracted by the diffraction grating, and another emission surface that emits light reflected by the reflecting surface toward the light receiving member.

Abstract: In an optical transmitting and receiving module, a transmitting light beam having a wavelength &lgr;1 emitted from an light-emitting device passes through an optical demultiplexing filter and enters an optical fiber, and a receiving light beam emitted from an end face of the optical fiber is reflected from the optical demultiplexing filter and is incident on a light-receiving device. A cover for covering the front space of the optical demultiplexing filter is placed on a casing block, and a tongue piece serving as a returning-light preventing unit is formed on the cover. When a transmitting light beam emitted from the light-emitting device is reflected from the optical demultiplexing filter, the direction in which the reflected light advances is changed by the tongue piece so that the reflected light is not incident on the light-receiving device.

Abstract: The optical pickup includes a two-wavelength laser diode having two light sources that emit a laser beam for the DVD and a laser beam for the CD, a light-receiving member, and a beam splitter. The beam splitter is provided with a wavelength-separating layer composed of a first and a second interfaces and an optical thin plate between the interfaces, having a specific refractive index n2. The first and second interfaces each have a first and a second wavelength selecting films coated thereon, which reflect or permeate the laser beams each by the specific rates, bring the optical axes of the laser beams after having reflected on the first and second interfaces into coincidence, permit the laser beams to go out of the beam splitter, and make the return beams from the optical disks permeate through the wavelength-separating layer to guide them toward the light-receiving member.

Abstract: An optical transmission/reception module in which an LD, a lens holder, which supports a lens, a partial wave filter, a lens holder, which supports a lens, and an optical fiber are all mounted to a housing block, coaxially along a first axis. A reflecting mirror, a lens holder, which supports a lens, and a PD are also mounted to the housing block, coaxially along a second axis which is parallel to the first axis. Cutouts are formed in the housing block for providing large openings forwardly of and perpendicular to a mounting surface for mounting the partial wave filter thereon and a mounting surface for mounting the reflecting mirror thereon. In such an optical transmission/reception module, it is possible to maintain the precision with which a partial wave filter, which passes a transmission light therethrough, and a reflecting member, which reflects a reception light, are mounted to a desired mounting angle at a high level, and to reduce assembly costs.

Abstract: Light emitted from a light emitting device is reflected by a first reflection curved face so that the travel direction of the light is almost perpendicularly diffused, the light is reflected by a reflection face circumferentially formed on an end face of a rotor in the direction parallel to an axial line, and after that, the light is supplied to a stator side along a cylindrical part on the outer periphery of the rotor. In a stator, light is condensed again in the axial direction by a reflection face and, after that, the light is reflected by a second reflection curved face and is received by a photo sensing device. In this instance, since the light passed through whole slits on the end face of the rotor and whole slits in the peripheral part of the stator is converged and then detected by an FG, the signal level upon detection is increased, the detection accuracy is improved at low cost.

Abstract: A dielectric multilayer film which has a bandpass characteristic in which a light beam having a wavelength .lambda.2 passes and a light beam having any of the other wavelengths is blocked is formed on the emergent-side surface of a lens provided near a light-receiving device which receives a light beam having the wavelength .lambda.2. A dielectric multilayer film which has a bandpass characteristic in which a light beam having a wavelength .lambda.1 passes and a light beam having any of the other wavelengths is blocked is formed on the emergent-side surface of a lens provided near another light-receiving device which receives a light beam having the wavelength .lambda.1.

Abstract: An optical coupler including optical fibers having gaps between first coverings and second coverings corresponding thereto. Each cladding of the two optical fibers is formed into a proper shape, with a taper of a proper thickness. The two optical fibers are then joined together, forming a joined portion which engages an engaging groove in a pair of blocks and the pair of blocks are affixed together by welding. Thereafter, the second coverings are affixed to cutouts in a retainer member. Lastly, the retainer, fitted to the blocks, is affixed thereto. Such an optical coupler is highly practical, does not allow deterioration of light dividing properties caused by changes in the length of the cladding joined portion as a result of an external stress, and prevents breakage of the joined portion.