Hasegawa Shinya

Bio: Hasegawa Shinya is an academic researcher from Fujitsu. The author has contributed to research in topics: Holography & Lens (optics). The author has an hindex of 13, co-authored 164 publications receiving 723 citations. Previous affiliations of Hasegawa Shinya include Toshiba.

Laser beam scanner and its fabricating method

Abstract: A high precision laser beam scanner is provided which is able to shape a beam generated by a laser, suppress the influence of jitter of a scanning beam due to mode hopping of a semiconductor laser, and reduce aberration of the scanning beam. A beam source generates a semiconductor laser beam, which is diffracted by a rotary hologram, forming a scanning beam on a surface to be scanned. An aberration correcting stationary hologram is disposed between the beam source and the rotary hologram. The stationary hologram is constructed with an object wave and a reference wave, which interfere on a stationary hologram substrate subject so that an aberration of the scanning beam on the surface to be scanned shall be corrected. The object wave is a spherical wave which has an aberration, a wave length shorter than that of the semiconductor laser beam, and an incident angle which is not vertical but is inclined with respect to the stationary hologram substrate. A method for fabricating the laser beam scanner is also provided.

Semiconductor light emitting device

Abstract: PURPOSE:To enhance the light utility efficiency of a laser beam wave surface converter associated with a semiconductor laser and a hologram lens by forming the hologram lens on he surface of a beam emitting window, thereby eliminating the necessity of regulating the position of the lens. CONSTITUTION:A window glass 17 is formed to contain a hologram lens 20 in the inside surface (which is the surface faced with a laser diode 1), and the outside surface is formed in a flat plate shape. The lens 20 is secured to the glass 17 with resin adhesive. The lens 20 is formed to match the wavelength of the laser diode 1 in such a manner that the position is determined in the stage of manufacturing to always generate a parallel beam. An elliptical beam is collimated in a laser assembly.

Method of constructing holograms

Abstract: A method for constructing a hologram by use of a master hologram which includes a predetermined pattern of interference fringes formed thereon by optical interference of a plurality of constructing coherent light beams incident at different angles. The method includes preparing a photosensitive medium, in which the hologram is to be formed, on the master hologram, and copying the master hologram onto the photo-sensitive medium by impinging copying light beams onto the master hologram at an incident angle different from the angles of the constructing beams.

Holographic recording apparatus and holographic optical element

Abstract: A holographic recording apparatus includes first and second light sources for respectively generating first and second light beams. A mask is located in front of a hologram recording material and has an aperture. Interference fringes are recorded in a hologram cell on the hologram recording material corresponding to the aperture. A movement mechanism supports the hologram recording material masked by the mask and relatively moves the hologram recording material with respect to the mask in predetermined directions so that an interference pattern is formed in an area on the hologram recording material. A spatial frequency changing mechanism changes incident angles of the first and second light beams with respect to the mask.

Optical beam scanner

Abstract: PURPOSE: To decrease the positional fluctuation of a beam on a scanning plane by forming a hologram disk into two-layered constitution in such a manner that the respective layers have diffraction directions of opposite tendencies and that the synthetic sum of the space frequencycies of the two-layered hologram have a max. point at the reconstruction point or near the same. CONSTITUTION: The hologram disk 10 having the two-layered construction is constituted by joining, via a spacer 15, the 1st disk 11 having the hologram 13 of which the interference fringes are made to a monotonic change space frequency by the interference of a spherical wave 17 diverged from one point A on the center line 16 of rotation and a plane wave 18 having the optical axis at the disk plane normal of the incident point of the reconstruction beam and the 2nd disk 12 having the hologram 14 of which the interference fringes are made to the monotonic change space frequency of the interference of the divergent spherical wave 19 diverged from the point (c) on the side outer than the reconstruction point with respect to the axis 16 of rotation and the plane wave 20 having the optical axis at the disk plane normal of the incident point of the reconstruction beam. The incident point of the reconstruction light moves merely near the max. point even if the disk 10 has eccentricity when part of the spherical wave 17 is made incident on the reconstruction point from the point A. COPYRIGHT: (C)1986,JPO&Japio

Heat Assisted Magnetic Recording

Abstract: Heat-assisted magnetic recording is a promising approach for enabling large increases in the storage density of hard disk drives. A laser is used to momentarily heat the recording area of the medium to reduce its coercivity below that of the applied magnetic field from the recording head. In such a system, the recording materials have a very high magnetic anisotropy, which is essential for the thermal stability of the magnetization of the extremely small grains in the medium. This technology involves new recording physics, new approaches to near field optics, a recording head that integrates optics and magnetics, new recording materials, lubricants that can withstand extremely high temperatures, and new approaches to the recording channel design. This paper surveys the challenges for this technology and the progress that has been made in addressing them.

Lithographic apparatus, and device manufacturing method

Abstract: A lithographic apparatus configured to project a patterned beam of radiation onto a target portion of a substrate is disclosed. The apparatus includes a first radiation dose detector and a second radiation dose detector, each detector comprising a secondary electron emission surface configured to receive a radiation flux and to emit secondary electrons due to the receipt of the radiation flux, the first radiation dose detector located upstream with respect to the second radiation dose detector viewed with respect to a direction of radiation transmission, and a meter, connected to each detector, to detect a current or voltage resulting from the secondary electron emission from the respective electron emission surface.

Optical scanner and image forming apparatus

Abstract: An optical scanner includes a light source, an optical coupler, an optical line image unit, a deflector, and an optical scanning unit. The optical scanning unit includes scanning lenses that guide the beams to a surface to be scanned. A surface on the deflector side of the scanning lens closest to a deflection reflecting surface has a negative power in a vertical scanning direction, and is a special toric surface in which a radius of curvature in a vertical scanning changes from an optical axis of the lens surface toward a periphery of the horizontal scanning direction. An F number of the beams toward the surface to be scanned of the scanning lens in the vertical scanning direction is larger in a peripheral part than in a central part in an effective scanning width.

Integral three-dimensional imaging with digital reconstruction

Abstract: A computer-based three-dimensional image reconstruction method and system are presented. An elemental image array of a three-dimensional object is formed by a micro-lens array, and recorded by a CCD camera. Three-dimensional images are reconstructed by extracting pixels periodically from the elemental image array using a computer. Images viewed from an arbitrary angle can be retrieved by shifting which pixels are to be extracted. Image processing methods can be used to enhance the reconstructed image. Further, the digitally reconstructed images can be sent via a network. A system for imaging a three-dimensional object includes a micro-lens array that generates an elemental image array. The elemental image array is detected by a CCD camera to generate digitized image information. A computer processes the digitized image information to reconstruct an image of the three-dimensional object. A two-dimensional display device may be connected directly or indirectly to the computer to display the image of the three-dimensional object. The computer may also be used to generate virtual image information of a virtual three-dimensional object. This can then be combined with the digitized image information to provide combined image information. The two-dimensional display device may be used to display a virtual image or a combined image.

Gallium nitride-based III-V group compound semiconductor device and method of producing the same

Abstract: A gallium nitride-based III-V Group compound semiconductor device has a gallium nitride-based III-V Group compound semiconductor layer provided over a substrate, and an ohmic electrode provided in contact with the semiconductor layer. The ohmic electrode is formed of a metallic material, and has been annealed.