Abstract: A dispersion compensating device for compensating dispersion of signal light. In an optical fiber communication system, distortion of optical pulse waveform caused by wavelength distortion is compensated. The signal light is inputted through an input port, propagating through a dispersion compensating fiber through a port of an optical circulator. The signal light is reflected by a totally internal highly reflective surface, again propagating through the dispersion compensating fiber reciprocally, thus being outputted through an output port of the optical circulator. Since the signal light propagates through the dispersion compensating fiber reciprocally, the dispersion compensating fiber is capable of compensating dispersion with one-half the length of the conventional example.

Abstract: An electrofusion joint includes an electrical heating wire embedded in its inner peripheral region. The electrofusion joint can be fitted to an end of a plastic pipe. By supplying electrical current to the electrical resistance heating wire the interface between the joint and the pipe are fusion bonded. In order to allow easy determination of the completion of fusion bonding, the electrofusion joint is provided with an annular groove in the outer peripheral surface extending to a region of the joint near the electrical resistance heating wire. A pin or bar-like core member is located at and extends upwardly from the center of the groove.

Abstract: This invention relates to an electrofusion joint, in which the electric power is supplied to a heating wire, which is buried in a resin, to melt the resin and thereby connect pipes together, and more particularly to an electrofusion joint, in which a member to be connected to a sensor-carrying connector is molded unitarily with the joint with a code member, which is to be detected by the sensor, molded unitarily with the member to be connected. A code displayed on the code member is read by the sensor and judged by a control unit as the quantity of power supplied to the heating wire through the connector and the member to be connected, or as the time during which the electric current is thus supplied to the heating wire, whereby an electric power of a predetermined magnitude is supplied thereto.

Abstract: Thermoplastic pipes held by a pair of clamp mechanisms are fusibly interconnected. A torque wrench moves one clamp mechanism toward the other clamp mechanism and provides a signal when the force applied is a given value. A locking mechanism is operated in response to this signal to lock the torque wrench in position. The apparatus is programmed to release the locking mechanism at the end of a predetermined time period. Changes in the programmed conditions are effected in response to changes in the size of one of the clamp mechanisms.

Abstract: An improved optical fiber cathode ray tube is provided which enables the recording of images on a recording medium with a high resolution even if the recording medium is disposed with an increased gap between the tube and the recording medium to prevent the mechanical contact therebetween. The tube is provided with a light transparent thin layer between the non-lens-like optical fiber face plate and the phosphor layer. The light transparent thin layer is a transparent plate and may include a spatial gap.