Abstract: This optical coupler for coupling a plurality of visible light beams having different wavelengths includes: a substrate made of a material different from lithium niobate; and an optical coupling function layer formed on a main surface of the substrate. The optical coupling function layer includes: two multimode-interference-type optical coupling parts; optical-input-side waveguides and an optical-output-side waveguide connected to one multimode-interference-type optical coupling part, and optical-input-side waveguides and an optical-output-side waveguide connected to the other multimode-interference-type optical coupling part. The multimode-interference-type optical coupling parts, the optical-input-side waveguides, and the optical-output-side waveguides are made of a lithium niobate film.

Abstract: To provide an improved perpendicular magnetic recording medium suitable for high density magnetic recording. In a perpendicular magnetic recording medium comprising a perpendicular magnetic layer and protective layer provided on a non-magnetic substrate via a soft magnetic backlayer, a polycrystalline MgO film is inserted between the soft magnetic backlayer and perpendicular magnetic layer.

Abstract: To provide an improved perpendicular magnetic recording medium suitable for high density magnetic recording.

Abstract: To provide an improved perpendicular magnetic recording medium suitable for high density magnetic recording. In a perpendicular magnetic recording medium comprising a perpendicular magnetic layer and protective layer provided on a non-magnetic substrate via a soft magnetic backlayer, a polycrystalline MgO film is inserted between the soft magnetic backlayer and perpendicular magnetic layer.

Abstract: A recording disk has a surface provided with guide grooves for controlling the position of a recording head, and recording bits formed in the guide grooves for high-density recording. The recording bits have the shape of a tadpole in a plane. The width Ws of the recording bits is greater than the width Wg of the guide grooves. An AFM probe serving as a recording head travels along the guide grooves without running off the guide grooves. When a tip part of the AFM probe coincides with the recording bit, the tip part drops deep into the guide groove, whereby the recording bit is detected.

Abstract: A recording disk has a surface provided with guide grooves for controlling the position of a recording head, and recording bits formed in the guide grooves for high-density recording. The recording bits have the shape of a tadpole in a plane. The width Ws of the recording bits is greater than the width Wg of the guide grooves. An AFM probe serving as a recording head travels along the guide grooves without running off the guide grooves. When a tip part of the AFM probe coincides with the recording bit, the tip part drops deep into the guide groove, whereby the recording bit is detected.

Abstract: A recording and reproducing or observing apparatus based on a laser beam deflection detection method in which an object has a very small area for reflecting light. A laser beam emitted by a semiconductor laser diode passes through a collimator lens and a stop. The beam passes through the lens and stop and is reflected by a polarization beam splitter and focused by an objective lens onto a surface of a cantilever. Reflected light from the cantilever surface is focused by the lens before being received by a position sensor. Either the incident light or the reflected light passes through an optical path that is substantially 90 degrees relative to the optical axis of the other light.

Abstract: A recording-reproducing apparatus can remarkably relax the reproduction tracking accuracy by use of a head wider than the track width. The carrier signal frequency assigned to a recording track is designated to a synthesized signal generator. In compliance with this designation, the synthesized signal generator generates a signal of the designated frequency. This carrier signal is amplitude-modulated by the baseband signal to be recorded in a mixer. The unrequired frequency components are removed from this modulation signal by a bandpass filter, and the resulting signal is recorded in a recording medium by a head. The recording medium and the head are in relative motion. In read mode, a track is specified by the carrier signal.