Abstract: A laser radar includes: a projection optical system configured to project laser light emitted from a laser light source, to a target region; and a light-receiving optical system configured to condense reflected light that is the laser light reflected by an object existing in the target region, onto a photodetector. The projection optical system and the light-receiving optical system are disposed such that optical axes thereof are separated from each other. The photodetector includes a plurality of sensor portions aligned in a direction perpendicular to a separation direction of these optical axes. The plurality of sensor portions each have a shape that is long in the separation direction of the optical axes.

Abstract: A laser radar includes: a base member; a drive part configured to rotate the base member about a rotation axis; and a plurality of optical units arranged on the base member at a predetermined interval in a circumferential direction about the rotation axis and each configured to project laser light in a direction away from the rotation axis. Here, projection directions of the laser lights from the plurality of optical units are different from each other in a direction parallel to the rotation axis.

Abstract: An optical pickup apparatus comprising: a diffraction grating configured to diffract laser light from a laser diode so that signals recorded in first and second optical discs are selectively reproduced, thicknesses of protective layers between surfaces and signal recording surfaces of the first and second optical discs being different from each other; a polarization beam splitter configured to divide laser light from the diffraction grating into first and second laser lights whose light amounts are substantially the same; a first objective lens configured to focus the first laser light onto the signal recording surface of the first optical disc; a second objective lens configured to focus the second laser light onto the signal recording surface of the second optical disc; and a photodetector configured to be applied with return lights of the first and second laser lights reflected from the signal recording surfaces of the first and second optical discs.

Abstract: A semiconductor laser emits infrared laser light for CD and red laser light for DVD. A collimator lens and a CD/DVD objective lens have optical axes thereof aligned with an optical axis of the infrared laser light. The CD/DVD objective lens is mounted on a holder to be inclined in such a direction as to suppress inherent coma aberration of the CD/DVD objective lens, and to suppress astigmatism generated in the red laser light from a state in parallel to a reference plane of the holder.

Abstract: An optical-pickup apparatus comprising: a laser diode to emit laser light forward and backward; an objective lens to focus the laser light emitted forward from the laser diode onto a signal-recording layer of an optical disc; a spherical-aberration correction element that is arranged on an optical path between the laser diode and the objective lens, and is so movable in an optical-axis direction of the laser light as to correct spherical aberration; a movement-position detection unit to detect a movement position of the spherical-aberration correction element, and output a detection signal indicating the movement position of the spherical-aberration correction element; a photodetector to receive the laser light emitted backward from the laser diode, and output a monitor signal corresponding to a light-receiving level of the laser light; and a control unit to control intensity of the laser light emitted from the laser diode based on the monitor and detection signals.

Abstract: Provided is an optical pickup device capable to suppress an occurrence of an aberration on a recording medium and a decrease of power of laser beams while employing a diffraction grating as an optical axis correction element. The laser element emitting the laser beam for CD (780 nm in wavelength) is disposed between the laser element emitting the laser beam for next-generation DVD (405 nm in wavelength) and the laser element emitting the laser beam for DVD (650 nm in wavelength). Only the laser beam for DVD is aligned by a diffraction effect of the optical axis correction element (diffraction grating) with the optical axis of the laser beam for next generation DVD. It is possible that a decrease of laser power due to diffraction efficiency is suppressed as much as possible because only the optical axis of the laser beam for DVD is aligned with the optical axis of the laser beam for next-generation DVD.

Abstract: A quarter-wave plate and a polarization beam splitter are used as means for guiding a laser beam to first and second objective lenses. A half of the circularly-polarized laser beam incident to the polarization beam splitter is reflected in the form of an S-polarized light component by the polarization beam splitter and guided to a first objective lens, and the other half is transmitted through the polarization beam splitter in the form of a P-polarized light component and guided to a second objective lens. The whole of light quantity of the laser beam reflected from an optical disk through the first or second objective lens passes substantially through the polarization beam splitter. Therefore, the light quantity of the laser beam guided to a photodetector can be enhanced.

Abstract: Provided is an optical pickup device capable to suppress an occurrence of an aberration on a recording medium and a decrease of power of laser beams while employing a diffraction grating as an optical axis correction element. The laser element emitting the laser beam for CD (780 nm in wavelength) is disposed between the laser element emitting the laser beam for next-generation DVD (405 nm in wavelength) and the laser element emitting the laser beam for DVD (650 nm in wavelength). Only the laser beam for DVD is aligned by a diffraction effect of the optical axis correction element (diffraction grating) with the optical axis of the laser beam for next generation DVD. It is possible that a decrease of laser power due to diffraction efficiency is suppressed as much as possible because only the optical axis of the laser beam for DVD is aligned with the optical axis of the laser beam for next-generation DVD.