Nippon Telegraph and Telephone Corporation

Sumitomo Electric Industries, Limited

Tetsuro Yabuta

Shigeru Tanaka

Hiroaki Sano

Kinji Taguchi

Takeshi Tsujimura

Toshio Kurashima

Tsuneo Horiguchi

Nobuyuki Yoshizawa

Koushi Ishihara

Hidenobu Tada

A method of measuring a length of a conduit comprises the steps of: supplying air into a conduit to insert a filamentary body into the conduit by flow of the air; detecting arrival of a forward end of the filamentary body at an outlet of the conduit; and measuring the length of the conduit from the length of the filamentary body inserted into the conduit. An apparatus for measuring a length of a conduit, comprises an air supply device for supplying air into the conduit; a filamentary body including a wire and a plurality of elastic large-diameter members attached to the wire; and a device for detecting that a forward end of the filamentary body arrives at an outlet end of the conduit, where the length of the conduit is measured from the length of the filamentary body inserted into the conduit.

Method and apparatus for measuring length of conduit and for diagnosing

An optical cable has a center member, around which a plurality of coated optical fibers are tightly stranded. Each optical fiber is given uneven strains in its longitudinal direction. Adhesive resin is applied to surround each of the coated optical fibers and binds each of them to the center member to make an integral optical unit when cured.

Optical cable and its manufacturing method

Growing community of inventors

Ibaraki, Japan

Tetsuro Yabuta