Abstract: Each fiber-optic gyroscope unit is shaped like a tetragonal cone. A square plate (51) is used as a base which holds a light source module (52), a light receiving unit (detector) (53) and an optical fiber coil (54). Directional couplers (56a), (56b) are also mounted on the base (51). A phase modulator (55) which includes a piezoelectric element is disposed inside the optical fiber coil (54). A signal processing circuit board (58) which has pedestals (59) stands on the base (51) such that it positions above the optical fiber coil (54). A polarizer (510) is wound around the optical fiber coil (54). A reinforcement member (511) is also provided. All these components are so arranged as not to extend out of the tetragonal cone (OABCO*) which defines its own unit region. Three identical fiber-optic gyroscope units are combined by connecting members (512, 513, 514) to form a single fiber-optic gyroscope to detect rotational angular velocities about three orthogonal axes.

Abstract: A method of manufacturing a metal pipe clad cable having a fiber with an excess length housed therein, comprises the steps of preparing a metal pipe clad cable comprising a metal pipe and a fiber housed in the metal pipe, and passing said metal pipe clad cable through a plurality of sets of bending rolls. The metal pipe is repeatedly bent when passing through the plural sets of said bending rolls so as to generate a plastic deformation within the metal pipe and, thus, to impart an excess length to the fiber within the metal pipe.

Abstract: Metal pipes containing optical fibers are connected to each other directly or indirectly by use of a sleeve. In case of using the sleeve, the sleeve is connected at one end to one of the metal pipes, after the optical fibers are connected. Then, the sleeve is elongated by a predetermined length, so that the sleeve is connected at the other end to the other metal pipe. Consequently, no tensile stress resides in the connected optical fibers in the connected structure. When the metal pipes are connected directly to each other, one or both of the metal pipes are elongated, after the optical fibers are connected. Then, the metal pipes are connected by use of the elongated portions. Consequently, the same result is obtained as using the sleeve.

Abstract: Metal pipes containing optical fibers are connected to each other directly or indirectly by use of a sleeve. In case of using the sleeve, the sleeve is connected at one end to one of the metal pipes, after the optical fibers are connected. Then, the sleeve is elongated by a predetermined length, so that the sleeve is connected at the other end to the other metal pipe. Consequently, no tensile stress resides in the connected optical fibers in the connected structure. When the metal pipes are connected directly to each other, one or both of the metal pipes are elongated, after the optical fibers are connected. Then, the metal pipes are connected by used of the elongated portions. Consequently, the same result is obtained as using the sleeve.

Abstract: An optical fiber joint and a method of forming such optical fiber joint being reinforced by a reinforcement material, having a prescribed coefficient of thermal expansion, integrally molded thereon by applying heat so as to obtain a predetermined thermal gradient in the reinforcing material, whereby bends in the optical fiber core wire joints are suppressed and the transmission loss of the optical fiber is reduced.