Abstract: An optical pickup apparatus has a semiconductor laser source which emits a laser beam in a wavelength band of 405 nm having an elliptic light intensity distribution; a beam shaping element which shapes the light intensity distribution of the laser beam; a polarizing beam splitter having a polarized light separation film in contact with the air and reflecting the laser beam shaped by the beam shaping element on the polarized light separation film; and an objective lens which focuses the laser beam reflected on the polarized light separation film onto an optical information recording medium.

Abstract: An optical pickup apparatus includes a diffractive optical element, and an objective lens that focuses a light beam of a first wavelength ?1, a light beam of a second wavelength ?2 and a light beam of a third wavelength ?3 on a first recording medium, a second recording medium, and a third recording medium, respectively, the wavelengths ?1, ?2, and ?3 being different from each other.

Abstract: In a beam shaping device for converting the laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, the light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in the minor-axis direction of the cross section of the elliptic beam. Of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface. The beam shaping device fulfills prescribed conditions with respect to the center thickness, surface shapes, and/or other features.

Abstract: A lens optical system is provided with a cemented lens element formed by cementing two constituent lens elements made of different optical materials together, with a diffractive optical surface formed at the cementing interface between the two constituent lens elements. The two constituent lens elements have at their respective interfaces with air a radius of curvature different from the radius of curvature that they have at the cementing interface.

Abstract: In a beam shaping device for converting the laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, the light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in the major-axis direction of the cross section of the elliptic beam. Of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface.

Abstract: A thin and light optical device satisfactorily separates light components having different properties. A blazed grating is formed on a surface of a flat-plate-shaped transparent substrate, and a separation coating that reflects or transmits incident light according to the properties of the incident light is provided on the blazed grating. The thus obtained optical device offers a function of separating light into reflected light and transmitted light, and also has a function of diffracting or refracting the thus separated light. As the separation coating, a polarization separation film, dichroic film, angle separation film, or chiral nematic liquid crystal layer is used to separate linearly polarized light components having different polarization planes, light components having different wavelengths, light components incident at different angles of incidence, or circularly polarized light components having different rotation directions.

Abstract: In a beam shaping device for converting the laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, the light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in the minor-axis direction of the cross section of the elliptic beam. Of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface. The beam shaping device fulfills prescribed conditions with respect to the center thickness, surface shapes, and/or other features.

Abstract: In a beam shaping device for converting the laser light emitted from a semiconductor laser light source from an elliptic beam to a circular beam, the light-entrance-side and light-exit-side surfaces of the beam shaping device both have a curvature only in the major-axis direction of the cross section of the elliptic beam. Of the light-entrance-side and light-exit-side surfaces, one is a circular-arc cylindrical surface and the other is a non-circular-arc cylindrical surface.

Abstract: A thin and light optical device satisfactorily separates light components having different properties. A blazed grating is formed on a surface of a flat-plate-shaped transparent substrate, and a separation coating that reflects or transmits incident light according to the properties of the incident light is provided on the blazed grating. The thus obtained optical device offers a function of separating light into reflected light and transmitted light, and also has a function of diffracting or refracting the thus separated light. As the separation coating, a polarization separation film, dichroic film, angle separation film, or chiral nematic liquid crystal layer is used to separate linearly polarized light components having different polarization planes, light components having different wavelengths, light components incident at different angles of incidence, or circularly polarized light components having different rotation directions.

Abstract: An optical pickup apparatus has a semiconductor laser source which emits a laser beam in a wavelength band of 405 nm having an elliptic light intensity distribution; a beam shaping element which shapes the light intensity distribution of the laser beam; a polarizing beam splitter having a polarized light separation film in contact with the air and reflecting the laser beam shaped by the beam shaping element on the polarized light separation film; and an objective lens which focuses the laser beam reflected on the polarized light separation film onto an optical information recording medium.

Abstract: An optical pickup apparatus detects optical information by making a laser beam in a 405 nm wavelength band emitted from a semiconductor laser light source incident on an optical information recording medium and then making the laser beam reflected from the optical information recording medium incident on a photodetector. The optical pickup apparatus has a polarizing beam splitter including a polarizing beam splitting film that forms an optical path from the semiconductor laser light source to the optical information recording medium by reflecting the s-polarized component of the laser beam and that forms an optical path from the optical information recording medium to the photodetector by transmitting the p-polarized component of the laser beam; and a monitoring sensor that receives the laser beam to monitor the laser output intensity of the semiconductor laser light source.

Abstract: An optical pickup apparatus includes a diffractive optical element, and an objective lens that focuses a light beam of a first wavelength ?1, a light beam of a second wavelength ?2 and a light beam of a third wavelength ?3 on a first recording medium, a second recording medium, and a third recording medium, respectively, the wavelengths ?1, ?2, and ?3 being different from each other.

Abstract: A method for fabricating a prism that comprises a first and a second substrate, both translucent, bonded together with an optical thin film interposed at the interface in between and that is used with the interface inclined relative to the optical axis of incident laser light of a wavelength of 420 nm or shorter includes the step of bonding together the first and second substrates of which the difference ?N1 in refractive index at the wavelength of the laser light fulfills the condition: ?N1?|1/(0.3×104×NA×t)|, where t represents the thickness of the first and second substrates cemented together as measured along the optical axis of the laser light, and NA represents the numerical aperture of the incident laser light.

Abstract: A thin and light optical device satisfactorily separates light components having different properties. A blazed grating is formed on a surface of a flat-plate-shaped transparent substrate, and a separation coating that reflects or transmits incident light according to the properties of the incident light is provided on the blazed grating. The thus obtained optical device offers a function of separating light into reflected light and transmitted light, and also has a function of diffracting or refracting the thus separated light. As the separation coating, a polarization separation film, dichroic film, angle separation film, or chiral nematic liquid crystal layer is used to separate linearly polarized light components having different polarization planes, light components having different wavelengths, light components incident at different angles of incidence, or circularly polarized light components having different rotation directions.

Abstract: A light source device has a semiconductor laser for emitting an elliptical divergent beam having a light intensity distribution in an elliptical form; and a beam shaping element for converting an elliptical divergent beam from said semiconductor laser into an approximately circular divergent beam having a light intensity distribution in an approximately circular form; wherein the beam shaping element has a first surface formed of a cylindrical surface and a second surface formed of an anamorphic surface, in order from said semiconductor laser side, and satisfies the predetermined conditional expressions.

Abstract: An optical pickup apparatus has a diffractive optical element and an objective lens that focuses light beams of different wavelengths, namely a first wavelength &lgr;1, a second wavelength &lgr;2, and a third wavelength &lgr;3, on an information recording surface formed on different types of recording medium, namely a first recording medium, a second recording medium, and a third recording medium, respectively. The diffractive optical element has a first diffractive surface that does not diffract the light beams of the first and third wavelengths &lgr;1 and &lgr;3 but that diffracts the light beam of the second wavelength &lgr;2 and a second diffractive surface that does not diffract the light beams of the first and second wavelengths &lgr;1 and &lgr;2 but that diffracts the light beam of the third wavelength &lgr;3.

Abstract: A method for fabricating a prism that comprises a first and a second substrate, both translucent, bonded together with an optical thin film interposed at the interface in between and that is used with the interface inclined relative to the optical axis of incident laser light of a wavelength of 420 nm or shorter includes the step of bonding together the first and second substrates of which the difference &Dgr;N1 in refractive index at the wavelength of the laser light fulfills the condition: &Dgr;N1≦|1/(0.3×104×NA×t)|, where t represents the thickness of the first and second substrates cemented together as measured along the optical axis of the laser light, and NA represents the numerical aperture of the incident laser light.

Abstract: A lens optical system is provided with a cemented lens element formed by cementing two constituent lens elements made of different optical materials together, with a diffractive optical surface formed at the cementing interface between the two constituent lens elements. The two constituent lens elements have at their respective interfaces with air a radius of curvature different from the radius of curvature that they have at the cementing interface.

Abstract: A laser irradiation optical system includes a dividing means for dividing a first entering laser beam once, and producing a plurality of second laser beams having beam widths equal to the beam which of the first laser beam and advancing in mutually different directions, a condensing means for condensing for condensing each second laser beam to mutually advance in near the same direction; and a shaping means for converting the intensity distribution of a cross section perpendicular to the optical path of each second laser beam in the optical paths of the mutually separated second laser beams.

Abstract: A method for fabricating a prism that comprises a first and a second substrate, both translucent, bonded together with an optical thin film interposed at the interface in between and that is used with the interface inclined relative to the optical axis of incident laser light of a wavelength of 420 nm or shorter includes the step of bonding together the first and second substrates of which the difference ?N1 in refractive index at the wavelength of the laser light fulfills the condition: ?N1?|1/(0.3×104×NA×t)|, where t represents the thickness of the first and second substrates cemented together as measured along the optical axis of the laser light, and NA represents the numerical aperture of the incident laser light.