Abstract: An objective lens having a first surface and a second surface, includes a first face formed on the first surface, a second face formed on the second surface, and a third face formed on one of the first and second surfaces. The first, second, and third faces are adapted in such a way that the objective lens has at least two focal lengths.

Abstract: An optical pickup device using hologram optical elements, the pickup device including a laser diode and, a hologram glass plate diffracting a laser beam emitted from the laser diode and dividing and condensing the laser beam reflected by an optical disc. The hologram glass plate is arranged at the front of the laser source while being spaced apart from the laser diode by a predetermined distance and is provided with four holograms. A collimator is arranged at the front of the hologram glass plate and changes the laser beam emitted from the laser source as well as the laser beam reflected by the optical disc into a parallel beam. An objective lens focuses the parallel laser beam from the collimator on the optical disc. A pair of focusing photo detectors and a pair of tracking photo detectors are also provided at the front of the laser diode and detect the laser beams diffracted and condensed by the holograms of the hologram glass plate in the form of data reading signals.

Abstract: An optical pickup system capable of improving productivity by facilitating the arrangement and assembly of components thereof and preventing an error caused by wavelength variation of a laser beam includes a laser diode used as a light source, a grating for classifying a beam from the laser diode into three diffracted lights of zero, +first and -first orders, an objective lens placed the grating and an optical disc for focusing the three diffracted lights passed through the grating on the optical disc while receiving the lights reflected from the optical disc, a photodetector divided-by-five formed of five split areas partitioned in the longitudinal direction to be arranged side by side in the sequence of fourth, first, second, third and fifth split areas to receive the lights reflected from the optical disc focusing on the respective split areas for detecting a focus error and a tracking error and reading out information recorded on the optical disc, and a hologram element divided-by-two formed of a first ho

Abstract: An optical pickup system simply formed to improve readout speed and reduce manufacturing cost having a semiconductor laser light source, a polarizing beam splitter (PBS), a collimator lens for changing the laser beam into parallel beams, a reflection mirror, an objective lens, a photodetector divided-by-six for detecting tracking and focus errors, a hologram device, a bisectional photodetector, a Wollaston prism for separating a beam into P-wave and S-wave components from a mixed beam of P-wave and S-wave components from the PBS, and a focusing lens for focusing the P-wave and S-wave component beams separated by the Wollaston prism onto two sections of the bisectional photodetector.

Abstract: This invention relates to an optical pickup system which can detect focus errors and tracking errors without using diffraction grating. The optical pickup system comprises a laser diode for emitting laser beams, an objective lens for focusing the laser beam from the laser diode onto an optical disc, a two division hologram positioned between the laser diode and the objective lens for diffracting beams after separating a reflected beam reflected at the optical disc and passed through the objective lens into a first laser beam and a second laser beam along an tangential line to a track of the optical disc, and a four division photodetector for focusing the two laser beams diffracted by the two division hologram.

Abstract: An optical pickup system using a holographic optical element for achieving miniaturization and lightness. This optical pickup system comprises a semiconductor laser for generating a laser beam, an objective lens for focusing the laser beam emitted from the semiconductor laser on an optical disk, a quadrant hologram for diffracting and condensing the laser beam, reflected by the optical disc and transmitted through the objective lens, to a quadrant photo detector, and the quadrant photo detector detecting the laser beam, diffracted and condensed by the quadrant hologram, and reading data recorded on the optical disc. The quadrant hologram and the quadrant photo detector are arranged in such a manner that the optical paths of the first to fourth hologram members of the quadrant hologram pass through the centers of the first, third, second and fourth photo detecting members of the quadrant photo detector, respectively.

Abstract: An optical pick-up device capable of accurately detecting focus errors, tracking errors, magneto-optic signals and pit signals recorded on an optical disc by use of a dichotomous hologram and decreasing the number of optical elements used, thereby achieving a lightness and an improvement in reading rate.

Abstract: An optical pickup system for generating information signals recorded on a recording medium includes a semiconductor laser generating source for generating and emitting a laser beam, an object lens for condensing the generated laser beam for an optical disc and receiving the laser beam reflected by an optical disc, a beam separator for changing a forwarding direction of the laser beam reflected by an object lens reflected by the optical disc, a prism for directing a portion of the beam to a pair of photo detector units provided on the prism and for forwarding the remainder of said laser beam in the same direction it was travelling when first incident on the prism, a condensing lens for condensing the laser beam reflected by the prism, and a focusing error compensating means for compensating two signals to be zero by an actuator.

Abstract: An optical system for a laser beam scanner, is capable of reducing the manufacturing cost by substituting a holographic optical element for a toric lens, comprising a light source for generating a laser beam, a rotary polyhedron for collimating the laser beam from the light source and focusing and reflecting the laser beam; and a compensating lens array, including a concave lens for receiving the laser beam from the rotary polyhedron and a convex lens attached with a holographic optical element, for compensating the laser beam reflected from the rotary polyhedron and scanning the compensated laser beam to a drum.

Abstract: A displayer for use in a computer comprising a main body, a CRT mounted in the main body and generating an image in an electromagnetic beam, a pair of holograms for projecting the image from the CRT, the holograms mounted in the main body, and a screen for displaying the image projected by the holograms thereon, the screen mounted at a position at which the image is last projected by the holograms. The present invention provides a displayer which provides advantages in that the harmful electromagnetic waves generated from the CRT does not affect the operator by virtue of the holograms, and a screen of a desired large size is obtained at lower cost.

Abstract: A holographic laser beam scanning apparatus capable of removing astigmatism created by a hologram disc of the apparatus due to discordance of wave fronts of the laser beams, thereby allowing precise scanning to be effected. The apparatus includes a focusing lens for focusing a laser beam generated by a laser generator, and a hologram for converting the focused beam into a parallel beam, both the lens and hologram being disposed between the laser generator for generating the laser beam and the hologram disc for irradiating the parallel beam as a diffracted beam.

Abstract: A multi-functional laser printer capable of executing both the printing operation and the manuscript readout operation with one unit. The laser printer comprises a printing unit for splitting a laser beam generated from a laser into a picture forming beam and a manuscript reading-out beam by a beam splitter, and a manuscript readout unit for reading out the content of the manuscript by scanning the manuscript reading-out beam on the manuscript. The printing unit and the manuscript readout unit commony have a double-structured hologram disk for diffracting and scanning the splitted beams. The double-structured hologram disk comprises picture forming holograms formed on the outer peripheral surface thereof and manuscript reading-out holograms formed on the interior thereof.

Abstract: An optical apparatus for a fingerprint recognition system utilizes a light source for emitting a spherical beam. A collimating hologram produces a plane beam upon receiving the emitted spherical beam from the light source. A diffuser generates a scattered beam by scattering the plane beam. A prism absorbs the light at ridges of a subject fingerprint and reflects the light at valleys of the subject fingerprint. An image producing hologram then processes the reflected spherical beam from the prism corresponding to the valleys and condenses the spherical beam upon an area CCD. The area CCD converts the produced fingerprint image into an electric signal. The fingerprint image producing hologram and a cutoff/absorption plate for cutting off and absorbing the beam are, respectively, mounted on a vertical surface of the prism.

Abstract: A compositive functional laser printer which is made not only to form a picture on a photo-sensitive drum but also to read out a manuscript by scanning laser beam by using a hologram disk. The laser printer comprises a laser beam generator, a beam splitting unit, a beam diffractive scanning unit, a picture forming signal control unit, a manuscript reading signal control unit, and a signal detecting and storing unit, so that a picture is formed on the photo-sensitive drum, as well as the content of manuscript can be read. According to the invention, since printing function as well as manuscript reading function can be carried out, functions of duplicator, facsimile and laser printer can be carried out by one instrument, therefore the low cost of optical unit can be obtained and the product can be miniaturized.

Abstract: A fingerprint recognition device is disclosed which is capable of making a more definite fingerprint recognition by using a hologram. The device includes a laser for emitting light, a collimator for making the light travel in parallel, and a tetragonal prism for forming a fingerprint image on it all of which are arranged along the first optical axis. A hologram is provided for shifting the position of the fingerprint image to a second optical axis, an image-forming lens for forming the fingerprint image, and an area CCD for converting the fingerprint image to electrical signals are arranged along the second optical axis. The area CCD is connected to a circuit which amplifies and analyzes the electrical signals. Accordingly, a virtual image of a fingerprint is shifted onto the optical axis of the image-forming lens by the hologram so as to be formed as a virtual image, the virtual image is formed on the area CCD by the image-forming lens to generate electrical signals according to the fingerprint image.

Abstract: A bar code reader includes a hologram disk having an arcuate circular shaped hologram disk disposed on a disk where the laser beam from a laser beam generator is applied. A laser controller is used for controlling the generating of the laser beam, and included are a signal analyzing unit having pre-amplifiers, a lock-in amplifier, a level shifter, an envelope detector, a waveform shaper, a decoding logic and a signal analyzer, a pair of photodetectors for detecting laser beams from the hologram disk, and a focusing lens, and a mirror member for forming a scanning pattern with a laser beam diffracted by the hologram disk.

Abstract: An optical scanning system of a bar code reader utilizing a hologram scanner in which a laser beam from a laser beam generator is divided into three parallel paths by three beam splitters. The beams pass through three focusing lenses and first reflectors. Each of the beams are focused into three holes in second reflectors before being directed in a perpendicular to a hologram disk. The hologram disk deflects the laser beams outwardly before being reflected again by third reflectors. These beams from the third reflectors are used for scanning an article having a bar code with star-shaped pattern beam through a window formed in a housing. The beams are reflected and contain bar code information. The reflected beams are passed back through the window and are reflected by the third reflectors respectively before passing through a hologram disk and being focused and reflected again at the second reflectors. The beams then pass through three pin holes, so that they are detected by photo-detectors.

Abstract: An apparatus for determining concentrations of mineral elements comprising an improved spectrometer wherein the spectrometer functions to diffract the light to be measured by means of a rotary grating and to determine the strength of light by using a single PM tube and further detects the wavelength of the diffracted light, by using a laser beam generator, reflective mirrors, photo diodes so as to analyze the composition and the concentration of mineral elements.

Abstract: A laser scanning system includes a read light emitting member, a green light emitting member, a blue emitting member, a scanning light member, and a controller. The red, green and blue emitting light members include an optical-frequency modulator and a liquid crystal plate placed between polarized light plates. The polarized light plates are disposed at an angle equal in the polarized light direction. This enables the viewer to use polarized glasses to view a three-dimensional color image on screen produced by the laser scanning system.