Abstract: An optical recording medium, typically an optical disc, has a recording region of a laser medium extending thicknesswise thereof, and a reference region positioned radially inwardly of the recording region for emitting reference light. The recording region has pits and lands formed on a surface thereof as representing recorded information. The pits and lands having respective first surfaces parallel to corresponding second surfaces on an opposite surface of the recording region. The first and second surfaces provide different thicknesses of the recording region. When pumping light emitted from a semiconductor laser, for example, is applied to the recording region, the recording region operates as optical resonators between the first and second surfaces for emitting laser signal light of a variable frequency depending on the recorded information. The optical resonators have respective optical axes extending thicknesswise of the recording region.

Abstract: An end pumped solid-state laser is comprised of a resonator formed of a pair of mirrors and a laser rod disposed between the pair of mirrors, an exciting light source for generating a pumping light which excites the laser rod and a converging optical element for converging the pumping light from the exciting light source so that the converged pumping light is irradiated on an end face of the laser rod. The wavelength of the light generated from the exciting light source is widened in band and/or a converging optical element having a large wavelength dispersion is employed, whereby heat generation in the optical axis direction of the laser rod is uniformed so as to generate a laser beam of large power.

Abstract: A single focusing lens for an optical disc recording and/or reproducing apparatus, wherein the lens two aspherical surfaces, has a large numerical aperture of about 0.6, and a focal length and a thickness that satisfy following formulas0.25<.tau./f<0.350.3<r/t<0.4where f, t and .tau. represent the focal length and the thickness of the single focusing lens and the thickness of the optical disc substrate, respectively.

Abstract: A laser apparatus includes first and second laser rods disposed at both sides of a center point on an optical axis, respectively, first and second concave lenses, for compensating the first and second thermal lenses, disposed at positions which are both sides of the center point on the optical axis and inner sides of the first and second laser rods, respectively, first and second reflection mirrors disposed at positions which are both sides of the center point on the optical axis and outer sides of the first and second laser rods, respectively, a first supporting unit for supporting the first laser rod and the second concave lens such that a distance therebetween on the optical axis is kept to be a constant value, and a second supporting unit for supporting the second laser rod and the first concave lens such that a distance therebetween on the optical axis is kept to be a constant value, wherein the first and second supporting units are relatively movable on the optical axis.

Abstract: A plasma X-ray source comprises inner and outer cylindrical electrodes disposed coaxially and with a certain distance with respect to each other, an electrical insulator disposed between end portions of the inner and outer cylindrical electrodes, and a discharge vessel disposed to envelop the inner and outer cylindrical electrodes. A pulse voltage is applied between the inner and outer cylindrical electrodes to produce plasma in the discharge vessel. An electrically conductive spherical shield is disposed to envelop a space where the plasma is pinched, and the spherical shield is maintained at a potential equal to that applied to the outer cylindrical electrode.

Abstract: Focussing error detecting apparatus includes a composite lens formed of a single glass lens and a single plastic lens and a photodetector disposed behind the composite lens in opposed relation thereto. The glass lens has a uniform focal length, the plastic lens is formed of a pair of lens regions divided by a flat interface including an optical axis of light incident on the composite lens, and the pair of lens regions have back focal lengths different from each other and optical axes spaced apart from each other. The photodetector is placed so that its photodetecting face is at a middle point between converged points of light emitted from the pair of lens regions on the optical axis of the incident light when the light incident on the composite lens is focussed.

Abstract: A radiation detecting apparatus includes a pair of substrates disposed face to face in such a manner that a plurality of grooves provided in one of the facing surfaces at a predetermined interval face a plurality of grooves provided in the other of the facing surfaces at the predetermined interval. Radiation shielding plates are inserted at both ends thereof into a facing pair of grooves to be held by both of the substrates, scintillators are mounted on a corresponding one of the radiation shielding plates, and photodetectors are fixed to either one of the facing surfaces of the substrates between adjacent grooves so that a plurality of facing pairs of photodetectors are juxtaposed.

Abstract: In an optical reproducing apparatus a divergent beam from a semiconductor laser light source is collimated to form a parallel light beam that is converged by an objective lens and focussed on an optical record medium. The light beam is reflected by the optical record medium and introduced into a signal photodetector so as to provide a reproduced signal. A phase type diffraction grating between the semiconductor laser light source and a beam splitter separates the laser beam from the semiconductor laser light source into zero, plus first and minus first order diffracted beams. A pair of tracking photodetectors receive reflected beams of the plus first and minus first order diffracted beams reflected by the optical record medium and then by the beam splitter.

Abstract: An optical apparatus is provided which comprises: a semiconductor laser having first and second emitting points for light emitted in the junction plane and perpendicular thereto, respectively; a cap element covering the semiconductor laser and having an aperture therein; means to produce focused light; and at least one plane-parallel, light transmitting body arranged in the aperture of the cap element to cause the astigmatism of the optical apparatus to be substantially zero.

Abstract: An apparatus for detecting a position of an optical pickup is disclosed in which there are provided a lens having lens areas of four quadrants sectioned by two planes, each including an optical axis and being perpendicular to each other, focal lengths of the lens areas of first and third quadrants being selected equal with each other, focal lengths of the lens areas of second and fourth quadrants being selected equal to each other, the focal length of the lens areas in the first and third quadrants being selected different from that of the lens areas in the second and fourth quadrants, the respective lens areas having axial symmetry, the lens being located within the optical path of the reflected beam on an optical disc, and a photo detector having four divided detecting portions in correspondence with the respective lens areas for detecting the reflected beam passed through the lens.

Abstract: An apparatus for continuously measuring a gradient of a curved surface at a number of different points thereon is disclosed in which a laser beam reflected at the point to be measured on the surface makes a beam spot on a photo sensor. The photo sensor follows the beam spot while the center of the beam spot and the center of the photo sensor coincide. The displacement between the beam spot from the point subjected to measurement and the beam spot from a reference point on the surface of the photo sensor is proportional to the gradient at the point subjected to measurement. The photo sensor is, for example, a differential type which comprises four photo diodes. The numerical control table is used to determine the positional relationship of the point to be measured with respect to the laser beam and an X-Y recorder is used to follow the beam spot.

Abstract: A gas laser is disclosed, in which one end surface of a plasma tube of a gas laser envelope is worked to be perpendicular to the axis of the plasma tube, a cap covers a mirror and the end surface of the plasma tube so as to make the mirror abut against the worked end surface, the cap is fixed at its open end to the plasma tube by frit material, and a bore is formed through the plasma tube which is covered by the cap.