Abstract: The stranded optical cable 10 includes a plurality of stranded multicore optical cables 12 and a cable sheath 16 covering the multicore optical cables 12, each multicore optical cable 12 including at least two of optical units 13 as a pair and a unit sheath 14 covering the optical units 13, each optical unit 13 being formed by bundling a plurality of optical fibers. And, parts of the cable sheath corresponding to both ends of the stranded optical cable 10 are removed to expose the multicore optical cables 12 certain lengths so that the optical connectors 21 are connected to the multicore optical cables 12, respectively.

Abstract: In a safety structure for an automatic opening/closing umbrella, a completely locked-in condition is provided for determining whether or not the umbrella is closed and stored to prevent an accident caused a partially locked-in condition of the umbrella, such as a sudden pop-out of a handle part of the umbrella that hits any part of a user's body. The safety structure alleviates impacts and includes a mark and the handle part is made of an elastic material. When the rod is pushed into the handle part to enter an entry portion of the umbrella and reach a completely locked-in condition, the mark is labeled noticeably on the rod, and at least one distal portion of the handle part is made of a suitable elastic material such as polyurethane.

Abstract: The present invention relates to a multi-mode optical fiber having a structure to reduce the numerical aperture at the emission end of the multi-mode optical fiber having a length for which practical use is assumed. The multi-mode optical fiber comprises a core portion, a trench portion, and a cladding portion. The multi-mode optical fiber is designed such that the numerical aperture at the emission end thereof is reduced as the fiber length increases, and moreover such that the numerical aperture of the multi-mode optical fiber having a length for which practical use is assumed satisfies a specific condition. By this means, the numerical aperture at the emission end of the multi-mode optical fiber can be kept small, and coupling efficiency of the multi-mode optical fiber with other optical components is drastically improved.

Abstract: The stranded optical cable 10 includes a plurality of stranded multicore optical cables 12 and a cable sheath 16 covering the multicore optical cables 12, each multicore optical cable 12 including at least two of optical units 13 as a pair and a unit sheath 14 covering the optical units 13, each optical unit 13 being formed by bundling a plurality of optical fibers. And, parts of the cable sheath corresponding to both ends of the stranded optical cable 10 are removed to expose the multicore optical cables 12 certain lengths so that the optical connectors 21 are connected to the multicore optical cables 12, respectively.

Abstract: In a safety structure for an automatic opening/closing umbrella, a completely locked-in condition is provided for determining whether or not the umbrella is closed and stored to prevent an accident caused a partially locked-in condition of the umbrella, such as a sudden pop-out of a handle part of the umbrella that hits any part of a user's body. The safety structure alleviates impacts and includes a mark and the handle part is made of an elastic material. When the rod is pushed into the handle part to enter an entry portion of the umbrella and reach a completely locked-in condition, the mark is labeled noticeably on the rod, and at least one distal portion of the handle part is made of a suitable elastic material such as polyurethane.

Abstract: Based on an intermediate 20A in which a cladding portion 22 is formed on the outer periphery of a core portion 21, a pair of holes 23 and 24 are provided parallel to the z axis on both sides of the core portion 21 within the cladding portion 22, and an intermediate 20 is thereby fabricated. In this intermediate 20, a width Ry in the y-axis direction is made smaller than a width Rx in the x-axis direction. Moreover, a cylindrical stress applying part 33 is inserted into a hole 23 of the intermediate 20, and a cylindrical stress applying part 34 is inserted into a hole 24 thereof. Thus, a preform 40 is formed. These materials are drawn and integrated together, and a polarization maintaining optical fiber is thereby manufactured.

Abstract: The present invention relates to a method of making a glass tube. In the method, a diameter expanding member is inserted through a hole in a tubular glass blank so as to expand the diameter of the hole while the temperature of the glass blank is controlled to be more than or equal to the softening point. The tubular glass blank may be a purchased product or a self-made product. In the above-mentioned method of making a glass tube, the diameter of the hole in the glass blank may be expanded while at least the rear end of the diameter expanding member is supported. The diameter of the hole in the glass blank may be expanded while both ends of the diameter-expanding member are supported. The present invention also relates to an apparatus for manufacturing a glass tube.

Abstract: Based on an intermediate 20A in which a cladding portion 22 is formed on the outer periphery of a core portion 21, a pair of holes 23 and 24 are provided parallel to the z axis on both sides of the core portion 21 within the cladding portion 22, and an intermediate 20 is thereby fabricated. In this intermediate 20, a width Ry in the y-axis direction is made smaller than a width Rx in the x-axis direction. Moreover, a cylindrical stress applying part 33 is inserted into a hole 23 of the intermediate 20, and a cylindrical stress applying part 34 is inserted into a hole 24 thereof. Thus, a preform 40 is formed. These materials are drawn and integrated together, and a polarization maintaining optical fiber is thereby manufactured.