Abstract: The present invention provides a method for manufacturing an optical fiber comprising the steps of forming a glass body containing a core, preparing a glass tube which will form a cladding portion, inserting the glass body into the glass tube, and collapsing the glass tube with the glass body by heating, wherein the method comprises a step of processing the glass tube such that it has at least one end tapered to which a pull is to be applied. The method may further comprise the steps of cleaning the outer surface of the glass tube, choosing the outer diameter of the glass body and the inner diameter of the glass tube such that the difference between the two diameters is not lower than 1.0 mm but not higher than 10.

Abstract: A method of manufacturing an optical fiber, characterized by comprising the steps of forming a glass body having a core, forming a glass tube constituting a clad portion, inserting the glass body into the glass tube, forming the glass body integrally with the glass tube, finishing at least the extraction side end part of the glass tube in a tapered shape and washing the outer surface of the glass tube, characterized in that a difference between the outer diameter of the glass body and the inner diameter of the glass tube is 1.0 to 10.0 mm, and the inner diameter of a support tube fitted to one end of the glass tube is increased more than that of the glass tube or the extraction side end part of the glass tube is sealed with a tapered part provided at least on the inner surface thereof and a spacer is installed so that a clearance between the outer diameter of the glass body and the inner diameter of the glass tube becomes generally constant in the longitudinal direction.

Abstract: An optical communication link that has an optical transmission line constructed by combining a positive dispersion optical fiber having a positive dispersion value with a negative dispersion optical fiber having a negative dispersion value, in a wavelength region to be used: wherein a dispersion value of the positive dispersion optical fiber is 5 ps/nm/km or more and 15 ps/nm/km or less; and wherein DPS values of both the positive dispersion optical fiber and the negative dispersion optical fiber are 250 nm or more, the DPS values being obtained by dividing dispersion values of the respective fibers at a wavelength of 1550 nm by a dispersion gradient.

Abstract: An optical fiber having a good signal-to-noise ratio (SNR) and high Raman efficiency in an optical signal transmission system using Raman amplification, the optical fiber having a refractive index profile, including at least one annular region between a center core and a cladding layer, a Rayleigh scattering coefficient not more than 1 &mgr;m4·dB/km, a relative refractive index difference of the center core with respect to the cladding layer of a positive value not more than 0.9%, a relative refractive index difference of an annular region adjoining the center core with respect to the cladding layer from −0.7% to −0.

Abstract: The optical fiber which enables the optical fiber transmission stabilized in the wavelength range of the pump light also, which is not used conventionally, and suppresses the non-linear effect on the occasion of WDM transmission is offered. The optical fiber for WDM transmission has at least three or more layers wherein the first core doped with germanium is located at the center and surrounded by the second core having a refractive index lower than the first core, and cladding having a refractive index lower than the first core and higher than second core surrounds the second or last core layer.

Abstract: An optical communication link that has an optical transmission line constructed by combining a positive dispersion optical fiber having a positive dispersion value with a negative dispersion optical fiber having a negative dispersion value, in a wavelength region to be used:

Abstract: An optical fiber having a good signal-to-noise ratio (SNR) and high Raman efficiency in an optical signal transmission system using Raman amplification, the optical fiber having a refractive index profile, including at least one annular region between a center core and a cladding layer, a Rayleigh scattering coefficient not more than 1 &mgr;m4·dB/km, a relative refractive index difference of the center core with respect to the cladding layer of a positive value not more than 0.9%, a relative refractive index difference of an annular region adjoining the center core with respect to the cladding layer from −0.7% to —0.

Abstract: The present invention relates to a dispersion shifted optical fiber having zero dispersion at a wavelength band of 1.5 &mgr;m, which suppresses an increase of transmission loss and an increase of polarization mode dispersion when carrying out fiber drawing. An optical fiber according the invention is provided with the first core (refractive index n1.), the second core (refractive index n2), the first clad (refractive index n3) and second clad (refractive index n4) in this order from the center to outside, wherein the abovementioned refractive indexes are in a relationship of n1>n4>n2>n3, Ge which is at a ratio of 0.4 to 1.0% for the value of relative refractive index difference with respect to the second clad is doped on the first core, which is at a ratio of 0.1 to 0.5% for the value of relative refractive index difference with respect to the second clad is doped on the second core as in the above, and the second clad is SiO2, which has a thickness from 1 &mgr;m or more to 40 &mgr;m or less.

Abstract: A dispersion compensating optical fiber is connected to an optical fiber having chromatic dispersion at a transmission wavelength to cancel the chromatic dispersion out, thereby making the chromatic dispersion of an entire transmission system at the transmission wavelength substantially zero or making the chromatic dispersion close to zero. The dispersion compensating optical fiber comprises a core consisting of a quartz-based glass and a cladding formed on the surface of the core and consisting of a quartz-based glass, and a coating layer formed on the surface of the cladding and consisting of a resin, and the dispersion compensating optical fiber has an outer diameter of less than 250 .mu.m. The coating layer has a thickness of 20 .mu.m or more and a two-layer structure consisting of at least two layers including an inner layer and an outer layer having a Young's modulus higher than that of the inner layer.

Abstract: A balancing apparatus for suppressing engine vibrations is disclosed. The balancer apparatus includes a helical drive gear that is rotatable together with the crank shaft. A first driven helical gear for is driven by the drive gear and a second driven helical gear is driven by the first driven gear. Support shafts are provided to carry each of the driven gears and a weight associated therewith. A case is provided about the driven gears and carries the support shafts.

Abstract: A method of fabricating an optical fiber base material which comprises the steps of sequentially accumulating glass made of doped quartz on the inner peripheral surface of a quartz tube to form glass layers, and then forming by heating means the interior of the tube in a solid state, temporarily thermally shrinking the tube when the accumulating step of the glass layers approaches the final period, then again accumulating glass on the inner periphery of the resultant glass layer and then forming the interior of the tube in a solid state. Thus, this method can reduce the center-dip without loss of the controllability of a refractive index distribution.

Abstract: An apparatus for fabricating an optical fiber preform having a support for rotatably holding a reaction tube, a raw material supply unit for supplying a glass raw material from one end of the reaction tube to the interior of the reaction tube and a heater for heating the reaction tube by reciprocating in the axial direction of the reaction tube which comprises a pressure measuring unit at the other end of the reaction tube, a gas pressure control chamber having a gas inlet and an exhaust port, and a blower capable of controlling the introduced gas pressure according to the measured value of the pressure memasuring unit in the gas inlet. Thus, the apparatus can accurately control the internal pressure of a reaction tube in good responsiveness.

Abstract: A self-contained type automatic belt tensioner adjusts a tension of an engine timing belt for automobiles. The tensioner comprises a body, a plunger slidably mounted in the body, a reservoir chamber located in the plunger, a pressure chamber disposed between the plunger and a closed wall of the body, a rod member fixed to the plunger, a bellows shaped elastic diaphragm located in the reservoir chamber with one end thereof being fixed to the rod member and the other end being fixed to the body, a check valve allowing a fluid flow only from the reservoir chamber to the pressure chamber, and a return spring interposed between the plunger and the closed wall of the body so as to bias said plunger in the direction of the rod member.

Abstract: A process for fabricating an optical fiber by inner-lining a quartz tube with synthetic glass having a refractive index higher than the quartz tube and collapsing it while wire-drawing it via a wire-drawing furnace, comprising the steps of inner-lining the synthetic glass in the quartz tube so that the value of the inner diameter/the outer diameter of the quartz tube is 0.85 or less, sealing one end of the quartz tube to form a sealed end, then holding the quartz tube in a wire-drawing furnace, and wire-drawing it from the sealed end while holding the internal pressure of the quartz tube in negative pressure. Thus, the process prevents moisture from the exterior from mixing and allows the wire-drawing and collapsing steps to be performed stably and reliably.

Abstract: A pneumatic system consisting of an air pump, air-passage switching means, operating components and air pipes connecting those together. This pneumatic system features improvements in a pressure smoothing means for smoothing a surge pressure discharged from an air pump in the pneumatic system, which pressure smoothing means is built in the pneumatic system between the air pump and the air-passage switching means. The pressure smoothing means includes an air chamber having an air inlet and an air outlet, and means for increasing and decreasing the volume of the air passage defined between the aforesaid air inlet and outlet, commensurate to the surging discharge pressure from the air pump, i.e., in response to the surge pressure of the air being admitted in the air chamber. This pressure smoothing means is provided with a pressure receiving plate which is displaced under the air pressure being introduced into the air chamber, whereby the volume of the air passage defined within the air chamber may be adjusted.