Abstract: A method for processing a material for a die for molding an objective lens which is formed with a multilevel structure on the curved surface thereof, wherein the transfer surface of the objective lens is cut by a tool having a cutting face, the outline of which includes a linear first edge portion, a linear second edge portion extending in a direction which intersects the first edge portion at an acute angle thereto, and a third edge portion which joins the ends of the first and second edge portions, while the die material is rotated around the axis thereof, in a state in which at least the first edge portion and the second edge portion of the tool is inclined with respect to the axis and while the tool is moved only in the axial direction and in the direction which intersects the axis.

Abstract: In an eccentricity measuring method according to the present invention, a first position of a light source image formed by reflection at one optical surface is measured (S2), a predetermined second position related to another optical surface is measured (S3), and a relative eccentricity between both optical surfaces is calculated based on the first and second positions (S5). Therefore, the eccentricity measuring method enables measurement of eccentricity by a same measurement optical system regardless of a radius of curvature of an optical surface of an optical element.

Abstract: In an eccentricity measuring method according to the present invention, a first position of a light source image formed by reflection at one optical surface is measured (S2), a predetermined second position related to another optical surface is measured (S3), and a relative eccentricity between both optical surfaces is calculated based on the first and second positions (S5). Therefore, the eccentricity measuring method enables measurement of eccentricity by a same measurement optical system regardless of a radius of curvature of an optical surface of an optical element.

Abstract: A method for processing a material for a die for molding an objective lens which is formed with a multilevel structure on the curved surface thereof, wherein the transfer surface of the objective lens is cut by a tool having a cutting face, the outline of which includes a linear first edge portion, a linear second edge portion extending in a direction which intersects the first edge portion at an acute angle thereto, and a third edge portion which joins the ends of the first and second edge portions, while the die material is rotated around the axis thereof, in a state in which at least the first edge portion and the second edge portion of the tool is inclined with respect to the axis and while the tool is moved only in the axial direction and in the direction which intersects the axis.

Abstract: Provided are an optical pickup apparatus and an objective lens which can record and/or reproduce information for discs with different recording densities and can realize simplification of the structure of themselves and reducing cost. When the expression (1) is satisfied, step differences of a step structure can be further reduced than those in the case that d1=?1(n?1) holds, and fine grooves corresponding to a steps structure, formed on an optical-surface transfer surface of a mold for molding the objective lens become shallow, to be easily processed. In addition, the moldability is enhanced because the material of the objective lens easily enters the inner portion of the grooves. Further, a fluctuation of a diffraction efficiency caused when wavelength of a light flux changes or temperature changes is reduced so that information can be recorded and/or reduced stably.

Abstract: Provided are an optical pickup apparatus and an objective lens which can record and/or reproduce information for discs with different recording densities and can realize simplification of the structure of themselves and reducing cost. When the expression (1) is satisfied, step differences of a step structure can be further reduced than those in the case that d1=?1(n?1) holds, and fine grooves corresponding to a steps structure, formed on an optical-surface transfer surface of a mold for molding the objective lens become shallow, to be easily processed. In addition, the moldability is enhanced because the material of the objective lens easily enters the inner portion of the grooves. Further, a fluctuation of a diffraction efficiency caused when wavelength of a light flux changes or temperature changes is reduced so that information can be recorded and/or reduced stably.

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 polarization conversion optical system converts light having a nonuniform plane of polarization into light having a uniform plane of polarization. The system includes a multilayer dielectric film at the side upon which the target light is incident. The film exhibits the property that it reflects one polarized component of the light and transmits a second polarized component of the light at a first angle of incidence, but transmits the first component at a second angle of incidence. Incident target light that is transmitted through the film at the first angle of incidence passes through a quarter-wavelength plate and is reflected at the second angle, whereupon it is retransmitted through the quarter-wavelength plate to be converted from one plane of polarization to the other. It is then emitted from the dielectric film in the same plane of polarization as light reflected by the film.

Abstract: An objective lens system for optical pickups reading and/or writing information by condensing a luminous flux from a light source onto an optical information recording medium, consists of, a single lens having, from a light source side, a first surface convex to the light source side and a second surface convex to an image side. A medium of the single lens is a homogeneous medium. At least one of the two surfaces is aspherical. The system satisfies the predetermined conditions.

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: On a waveguide 34 formed on a substrate 33, a plurality of comblike shaped electrodes 37, 38 that generate surface acoustic waves 37a, 38a from different directions are provided. And a periodic refractive indices portion 40 is formed, where the refractive indices are periodically distributed in accordance with the wavelengths of the surface acoustic waves 37a, 38a generated by applying a voltage to the comblike shaped electrodes 37, 38. And by changing a frequency of the applying voltage for sequentially changing the wavelengths of the surface acoustic waves 37a, 38a, the exiting direction of the light exiting from the periodic refractive indices portion 40 is scanned. This makes it possible to provide an optical functional device and an optical scanning apparatus that perform light scanning less costly but at a high speed, and that can secure a wide scanning angle.

Abstract: A diffractive optical element has a diffraction grating formed by periodic depressions and projections on the surface of a substrate and a dielectric multilayer film on the diffraction grating. The materials of the respective layers of the film are chosen such that the depth of the depressions is an integral multiple of the sum of the thickness of the layers in one period of the film. As a result, individual layers of the film are continuous across multiple depressions and projections, to provide improved first-order reflectance.

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: An optical device for making light converge produces a convergent light beam with a satisfactorily great numerical aperture and acceptably small aberrations. The optical device has a plurality of diffraction gratings that each make light converge. The light shone into the optical device is passed through one after another of those diffraction gratings in such a way that the light is made to converge to a higher degree every time it passes through one of the diffraction gratings. The diffraction gratings may be all transmissive, all reflective, or a combination of both. The diffraction gratings are formed on a surface of or at an interface inside the optical device, and two diffraction gratings may be formed on a single surface. The light is made to eventually converge on the exit surface of the optical device so that the optical device functions as a solid immersion device.

Abstract: An optical scanner having a simple structure in which the light quantities of a plurality of light beams are not varied by differences in polarization direction among the light beams. The optical scanner scans a surface by means of a plurality of light beams in which the polarization direction of at least one of the light beams is different from the polarization directions of the other light beams. An optical element having a surface with a reflectance for s-polarized light and a reflectance for p-polarized light that are substantially the same at a given incident angle is provided in the optical paths of the light beams.

Abstract: A photonic crystal device including a method of forming the photonic crystal device is provided wherein the photonic crystal device comprises a first medium having a thickness and periodically defining a plurality of periodically spaced concave portions. The concave portions having a depth less than the thickness of the first medium. A second medium fills the concave portions. One layer of the device, including both the first and second medium, acts as an optical waveguide layer, or photonic crystal. Another layer is at least partially formed from the first medium, such that the first and second layers share a common medium. A method of forming the photonic crystal device including the steps of applying a resist layer to a first medium, removing portions of the resist layer and corresponding portions of the first medium to form vacancies, and filling the vacancies with a second medium.

Abstract: An objective lens system for optical pickups reading and/or writing information by condensing a luminous flux from a light source onto an optical information recording medium, consists of, a single lens having, from a light source side, a first surface convex to the light source side and a second surface convex to an image side. A medium of the single lens is a homogeneous medium. At least one of the two surfaces is aspherical. The system satisfies the predetermined conditions.

Abstract: A multi-beam optical scanner includes shaping optics (42) by which a plurality of light beams issued from light emitting portions (411, 412) are shaped to be substantially parallel in a primary scanning direction, a deflector having reflecting faces (45) that reflect and deflect the plurality of light beams and scanning optics (46) by which the plurality of light beams reflected and deflected by the reflecting faces (45) are scanned across a plane (48) to be scanned as a plurality of adjacent beam spots, wherein the distance from the rear principal plane of the shaping optics (42) to the front principal plane of the scanning optics 46 is expressed by f1+f2, where f1 and f2 are the focal lengths of the shaping optics (42) and the scanning optics (46), respectively, in the primary scanning direction.

Abstract: An objective lens system for optical pickups performing at least one of reading and writing of information by condensing a luminous flux from a light source on an information recording medium, has the following two lens elements from a light source side: a first lens element having a first surface convex to the light source side and a second surface convex to the light source side; and a second lens element having a third surface convex to the light source side and a plane fourth surface, wherein the first surface is an aspherical surface.

Abstract: An objective lens system for optical pickups performing at least one of reading and writing of information by condensing a luminous flux from a light source on an information recording medium, has the following two lens elements from a light source side: a first lens element having a first surface convex to the light source side and a second surface convex to the light source side; and a second lens element having a third surface convex to the light source side and a plane fourth surface, wherein the first surface is an aspherical surface.