Abstract: An optical disc having a transition linear velocity of 8-11 m/s when irradiating continuous light with 11±1 mW and a wavelength of 660±10 nm using a pickup head with a numerical aperture (NA) of 0.65, and satisfying the following condition: ?R=|Rb—Ra|?3% where Rb is a reflectance of an unrecorded area, and Ra is a reflectance of the top of an eye pattern after ten cycles of recording. In one recording mode therefor, the disc is rotated at a constant angular velocity so as to have a linear velocity of 3–4 m/s on an innermost track and a linear velocity of 8–9 m/s on an outermost track. In another mode, the disc is rotated at a constant angular velocity so as to have a linear velocity of 5–6 m/s on an innermost track and a linear velocity of 13–14 m/s on an outermost track.

Abstract: An optical fiber collimator including a microlens array and single mode optical fibers. Microlens elements are formed in two surfaces of the transparent substrate. Two opposing microlens elements each function as a collimator lens. The single mode optical fiber is optically coupled to the collimator lens.

Abstract: According to the present invention, there is provided a method of designing a collimator array device which enables reduction of the insertion loss because of the variation of the optical length. When the beam waist is positioned at the intermediate position between the emitting side planar microlens and the receiving side planar microlens (d1=L/2), the distance d0 between the emitting side fiber array and the emitting side planar microlens can be used as the distance between the receiving side fiber array and the receiving side planar microlens, and thereby the design of the collimator array device can be simplified. The distance d0 for satisfying d1=L/2 is calculated and two values d0-2 and d0-4 are obtained. By selecting the smaller value d0-2, it is possible to reduce the insertion loss because of the shift at the time of coupling.

Abstract: A method for making a filed-effect semiconductor device includes the steps of forming a gate electrode on a semiconductor layer composed of a gallium nitride-based compound semiconductor represented by the formula AlxInyGa1?x?yN, wherein x+y=1, 0?x?1, and 0?y?1; and forming a source electrode and a drain electrode by self-alignment using the gate electrode as a mask. A field-effect semiconductor device fabricated by the method is also disclosed.

Abstract: An optical fiber collimator including a microlens array and single mode optical fibers. Microlens elements are formed in two surfaces of the transparent substrate. Two opposing microlens elements each function as a collimator lens. The single mode optical fiber is optically coupled to the collimator lens.

Abstract: A method for making a filed-effect semiconductor device includes the steps of forming a gate electrode on a semiconductor layer composed of a gallium nitride-based compound semiconductor represented by the formula AlxInyGa1-x-yN, wherein x+y=1, 0?x?1, and 0?y?1; and forming a source electrode and a drain electrode by self-alignment using the gate electrode as a mask. A field-effect semiconductor device fabricated by the method is also disclosed.

Abstract: An initialization method in which a phase change optical recording medium is initialized with a laser beam having a power density of from 15 to 22 mW/&mgr;M2 at a linear velocity of from 8 to 12 m/s. The phase change optical recording medium is formed of a transparent substrate having a guide groove on the surface thereof, a first protective layer, a recording layer, a second protective layer and a reflective layer. The recording layer material may be represented by the following composition formula: Ag&agr;X&bgr;Sb&dgr;Te&egr;Ge&ggr;, wherein X is at least one of Ga, In, Tl, Pb, Sn, Bi, Cd, Hg, Mn, Dy, Cu and Au, and &agr;, &bgr;, &dgr;, &egr;, and &ggr; have units of atomic % and satisfy particular relationships.

Abstract: A method for making a filed-effect semiconductor device includes the steps of forming a gate electrode on a semiconductor layer composed of a gallium nitride-based compound semiconductor represented by the formula AlxInyGa1-x-yN, wherein x+y=1, 0≦x≦1, and 0≦y≦1; and forming a source electrode and a drain electrode by self-alignment using the gate electrode as a mask. A field-effect semiconductor device fabricated by the method is also disclosed.

Abstract: A compact gradient index rod lens that can be manufactured without decreasing the amount of incident light. The gradient index rod lens includes a lens body radially distributing refractive indexes. The lens body has a cross sectional outline formed by removing at least part of a peripheral portion of an original lens body.

Abstract: An optical disc having a transition linear velocity of 8-11 m/s when irradiating continuous light with 11±1 mW and a wavelength of 660±10 nm using a pickup head with a numerical aperture (NA) of 0.

Abstract: A direct fuel injection-type spark-ignition internal combustion engine is disclosed. The engine comprises a fuel injector for injecting fuel as a spray in nearly the shape of a fan having a relative small thickness, a spark plug and a cavity formed on the top surface of a piston. The cavity has a long and narrow groove-like shape. The spray is injected by the fuel injector such that the spray is almost parallel with the center axis of the piston, and impinges in the cavity. The spark plug is arranged in the upper portion of the cylinder to face the cavity.

Abstract: A piezoelectric element is mounted to a clinch lever for detecting stress-strain generated therein when cutting and clinching leads of an electronic component that has been inserted in corresponding holes formed in a circuit board substrate. A detected voltage d is compared to a threshold voltage s selected from a plurality of threshold voltages preset in the device. When the detected voltage d exceeds the threshold voltage s, the insertion detecting section outputs a signal indicating that the insertion of the leads in the holes has been performed normally.

Abstract: A method for making a filed-effect semiconductor device includes the steps of forming a gate electrode on a semiconductor layer composed of a gallium nitride-based compound semiconductor represented by the formula AlxInyGa1-x-yN, wherein x+y=1, 0≦x≦1, and 0≦y≦1; and forming a source electrode and a drain electrode by self-alignment using the gate electrode as a mask. A field-effect semiconductor device fabricated by the method is also disclosed.

Abstract: A nitride based III-V compound semiconductor doped with a p-type impurity is formed on a substrate made from sapphire. The substrate is then placed between a pair of RF electrodes, and a radio frequency field is applied between the RF electrodes. With this operation, electrons present in the compound semiconductor attack the bonding between the p-type impurity and hydrogen, to cut the bonding. The hydrogen atoms thus dissociated are released from the compound semiconductor, to thereby activate the p-type impurity. In this case, it is not required to heat the compound semiconductor by a heater or the like.

Abstract: A large number of microscopic recess portions are formed on a surface of a glass substrate in a single dimension or two dimensions by conducting a wet etching through a mask. The large number of microscopic recess portions are aligned densely by again conducting the wet etching but not through the mask. A separating agent is applied upon the surface of the glass substrate and a light-curable or heat-curable resin material of high refractive index is applied thereon. The high refractive index resin material is cured, after piling a first glass substrate upon the high refractive index resin material so as to extend the high refractive index resin material thereon. The high refractive index resin material which is cured and the first glass substrate are separated from the glass substrate, and a low refractive index resin material is applied on the high refractive index resin material which is cured on the first glass substrate.

Abstract: A compact refractive index distribution lens that can be manufactured without decreasing the amount of incident light. The refractive index distribution lens includes a lens body radially distributing refractive indexes. The lens body has a cross sectional outline formed by removing at least part of a peripheral portion of an original lens body.

Abstract: By fitting a planar microlens array provided with one or more marks with a liquid crystal panel provided with one or more corresponding marks, it is possible to align the position of both exactly. The marks according to the present invention may comprise rod shapes, cross shapes, ring shapes, or square shapes, among others.

Abstract: A direct fuel injection-type spark-ignition internal combustion engine is disclosed. The engine comprises a fuel injector for injecting fuel as a spray in nearly the shape of a fan having a relative small thickness, a spark plug and a cavity formed on the top surface of a piston. The cavity has a long and narrow groove-like shape. The spray is injected by the fuel injector such that the spray is almost parallel with the center axis of the piston, and impinges in the cavity. The spark plug is arranged in the upper portion of the cylinder to face the cavity.

Abstract: A nitride based III-V compound semiconductor doped with a p-type impurity is formed on a substrate made from sapphire. The substrate is then placed between a pair of RF electrodes, and a radio frequency field is applied between the RF electrodes. With this operation, electrons present in the compound semiconductor attack the bonding between the p-type impurity and hydrogen, to cut the bonding. The hydrogen atoms thus dissociated are released from the compound semiconductor, to thereby activate the p-type impurity. In this case, it is not required to heat the compound semiconductor by a heater or the like.

Abstract: According to the present invention, there is provided a method of designing a collimator array device which enables reduction of the insertion loss because of the variation of the optical length. When the beam waist is positioned at the intermediate position between the emitting side planar microlens and the receiving side planar microlens (d1=L/2), the distance d0 between the emitting side fiber array and the emitting side planar microlens can be used as the distance between the receiving side fiber array and the receiving side planar microlens, and thereby the design of the collimator array device can be simplified. The distance d0 for satisfying d1=L/2 is calculated and two values d0-2 and d0-4 are obtained. By selecting the smaller value d0-2, it is possible to reduce the insertion loss because of the shift at the time of coupling.