Abstract: A diffraction element for diffracting a particular wavelength of incident optical beam includes: a base section made from a first resin and provided with a predetermined diffraction pattern; and a cover section made from a second resin and covering the diffraction pattern, wherein a rate of change of refraction index of the first resin is substantially the same as a rate of change of refraction index of the second resin in a temperature range between a first temperature and a second temperature.

Abstract: The first and second materials of the diffraction element are selected such that the first material's refraction indexes n1(?1), n1(?2) and n1(?3) for the first, second and third wavelengths ?1, ?2 and ?3 and the second material's refraction indexes n2(?1), n2(?2) and n2(?3) for the first, second and third wavelengths ?1, ?2 and ?3 satisfy one of the conditions (1) or (2).

Abstract: The first and second materials of the diffraction element are selected such that the first material's refraction indexes n1(?1), n1(?2) and n1(?3) for the first, second and third wavelengths ?1, ?2 and ?3 and the second material's refraction indexes n2(?1), n2(?2) and n2(?3) for the first, second and third wavelengths ?1, ?2 and ?3 satisfy one of the conditions (1) or (2).

Abstract: An optical pickup includes: a light source that emits first, second and third wavelengths of optical beam; and an objective lens unit including a diffraction element whose one surface includes a first diffraction pattern where the first wavelength is diffracted while the second and third wavelengths pass through and whose other surface includes a second diffraction pattern where the second wavelength is diffracted while the first and third wavelengths pass through; and an objective lens that collects the optical beam from the diffraction element, wherein the second and third wavelengths traveling through the objective lens unit are on the optical axis of the objective lens unit while the first wavelength traveling through the objective lens unit have an angle with respect to the optical axis; and the first diffraction pattern is located at a position so as to minimize aberration of the first wavelength of optical beam.

Abstract: A diffraction element for diffracting a particular wavelength of incident optical beam includes: a base section made from a first resin and provided with a predetermined diffraction pattern; and a cover section made from a second resin and covering the diffraction pattern, wherein a rate of change of refraction index of the first resin is substantially the same as a rate of change of refraction index of the second resin in a temperature range between a first temperature and a second temperature.

Abstract: A diffraction element includes: an injection-molded transparent first member having two optical surfaces; and a second member firmly attached to one of the optical surfaces of the first member and provided with a first diffraction pattern on a surface, wherein the second member is a first ultraviolet curable resin having a refraction index in a range of ±0.013 with respect to a refraction index of the first member.

Abstract: A lens, a light irradiation apparatus and a laser pointer to which the lens is applied to are provided, in which eccentricity, discrepancy of light axes, uneven gap of lens surfaces and the like are reduced without performing positioning of respective lenses; and cost of manufacturing a lens having a plurality of functions can be reduced. A lens according to the present invention is the lens, in which a light diameter expanding element for expanding a diameter of incident light and a light collimating element for projecting approximately collimated light after receiving the incident light having the diameter thereof expanded by the light diameter expanding element are integrally formed in advance as a lens of one unit.

Abstract: A lens, a light irradiation apparatus and a laser pointer to which the lens is applied to are provided, in which eccentricity, discrepancy of light axes, uneven gap of lens surfaces and the like are reduced without performing positioning of respective lenses; and cost of manufacturing a lens having a plurality of functions can be reduced.

Abstract: A stationary head type magnetic recording/reproducing system which includes a magnetic head responsible for recording/reproduction of signal to and from a running magnetic tape, and a pair of guides positioned on both sides of the magnetic head, the magnetic head having a flat slide-contact plane which comes into contact with the magnetic tape, and beveled planes at ends thereof.

Abstract: The present invention discloses a stationary head type magnetic recording/reproducing system which comprises a magnetic head responsible for recording/reproduction of signal to and from a running magnetic tape; and a pair of guide means provided in a depth-wise direction and on both sides of the magnetic head. The magnetic head has a flat slide-contact plane which comes into contact with the magnetic tape, and performs recording/reproduction of signal while pressurizing the magnetic tape which runs as being guided by the guide means.

Abstract: A magnetic head includes a first magnetic core half having a coil winding groove coupled to a second magnetic core half having an auxiliary core element accommodated in the coil winding groove, such that a magnetic gap is defined between joining faces of the first and second core halves. Alternatively, a composite magnetic head includes a pair of magnetic heads that have magnetic gaps with different azimuth angles from each other and disposed closely in an opposing relationship to each other in a head feeding direction so as to define respective track widths and a track pitch. A thin conductor film is formed on at least one of a pair of opposing faces of the magnetic heads for intercepting leakage fluxes from the magnetic gap of the other magnetic head. The thin conductor film has a thickness and is located such that the track pitch formed by the magnetic heads is substantially independent of the thickness of the thin conductor film.

Abstract: A thin film type magnetic head that electromagnetic conversion efficiency is improved by making gradually magnetic resistance larger with approaching to a magnetic gap can be provided. There is disclosed a magnetic head including a pair of magnetic core half members having nonmagnetic substrates and magnetic metal films formed on the nonmagnetic substrates and a coil formed at a concave part by a thin film forming process, the pair of magnetic core half members being jointed to each other opposite to each other through a magnetic gap formed between the respective magnetic metal films, the concave part formed on the surface formed by joining at least one of the magnetic metal films and the other magnetic metal film, wherein assistant cores consisting of magnetic materials are joined on the side of the surface by joining a pair of nonmagnetic substrates and the magnetic metal films are formed connected with the assistant cores.

Abstract: A magnetic head reduces a slant of a magnetic head chip in comparison with a conventional case. The magnetic head is produced by a manufacturing method. A ridge on a back surface side of a magnetic chip is brought into contact with a chip attachment surface of a chip attachment base. A height of the magnetic head chip is adjusted by using the ridge as a fulcrum.