Abstract: A magneto-optical disc recording apparatus is constituted by a pre-output detection circuit, a post-output detecting circuit, a pre-output pulsing circuit, a post-output pulsing circuit, a logical operation circuit, a recording data memory circuit and a comparison operation circuit. An optical head is configured by arranging photodetectors in an array so that the light returned from the areas in the medium on which the laser beam is irradiated can be separately detected at two or more positions along the direction of advance of the laser beam.

Abstract: An apparatus for optical master disk exposure for exposing guide grooves and pre-pits with laser beams has a reference signal generator which generates a reference signal for being supplied to a groove reference voltage generator that generates a groove reference voltage according to the reference signal. A pre-pit designation signal generator generates a pre-pit designation signal designating formation of the pre-pits. A pre-pit region voltage generator generates a pre-pit region voltage with a power of level of 70 to 75% of the groove reference voltage according to the pre-pit designation signal. A bias voltage generator generates a bias voltage with a power level of 80 to 90 of the groove reference voltage when no pre-pit is formed according to the pre-pit designation signal.

Abstract: A laser beam type distance measuring device comprises a laser beam emitter; a returning laser beam detector; a polygon mirror rotated about a first axis for reflecting a going laser beam from the laser beam emitter toward a remote object and reflecting a returning laser beam from the object toward a given optical track along which the returning laser beam travels to the returning laser beam detector; and a nodding mechanism for pivoting the polygon mirror about a second axis which is perpendicular to the first axis. These parts are housed in a case which has a window opening through which the going and returning laser beams pass. An outwardly swelled transparent cover covers the window opening in such a manner that a depressed inner surface thereof faces toward the polygon mirror in the case. A shielding plate is installed in the case near the polygon mirror to prevent the going laser beam from entering the given optical track.

Abstract: A distance measuring device of laser beam using type has a laser diode for producing laser beams. A scanning mechanism projects the laser beams against an object and includes a polygon mirror to and by which the laser beams are directed and reflected. A receiver mechanism receives the laser beams reflected by the object. A control unit measures the period required for the laser beams to make the trip around the object. The polygon mirror is so arranged as to be rotated about a first axis and swung about a second axis.

Abstract: A tension adjusting apparatus comprising a coupling device for movably coupling both ends of an elongated member disposed in the shape of a loop in a direction in which both ends approach and/or move apart from each other along the longitudinal direction of the elongated member, and an urging member retained by the coupling device and for urging the elongated member via the coupling device in a direction in which both ends of the elongated member approach to each other in order to apply tension to the elongated member. The smooth movement of the elongated member transmitting motive power and the tension of the elongated member at a predetermined value are thereby maintained without impeding the durability of the elongated member.