Hitachi Cable, Inc.

The Tokyo Electric Power Company, Incorporated

Toshio Fukahori

Hitoshi Morinaga

Hiroshi Kajioka

Noribumi Shiina

Hideyuki Takashima

Satoshi Yamamoto

Hiroyuki Kunugiyama

Nobuo Ando

Hiroshi Kawakami

Yasuo Ozawa

Keiichi Hashiba

Shigehiro Endoh

Kouichi Sugiyama

Akira Tokushima

Kaoru Yamazaki

Teruaki Tsutsui

A fiber optic distributed temperature sensor system outputs a temperature distribution along the longitudinal direction of a sensor optical fiber by measuring the temperature dependency of Raman scattered light intensity produced in an optical fiber by use of the OTDR technique. The system is characterized in that a light output from a light source is input to the sensor (optical fiber) via an optical wavelength division demultiplexer, that among the reflected light of back scattered light returning from the sensor optical fiber, light of a particular wavelength range is reflected or transmitted by at least one optical filter of the optical wavelength division demultiplexer to separate the light of the particular wavelength range and that signal of the light of the particular wavelength range is guided to a detector of an optical measuring system.

Fiber optic distributed temperature sensor system

A multi-port fiberoptic rotary joint comprising a trapezoid prism provided between a rotative member and a fixed member of the rotary joint so as to be rotatable relative to the rotative member and coaxial with said rotative member, a speed change gear mechanism for transmitting the rotation of the rotative member to the trapezoid prism so as to rotate the trapezoid prism at an angular velocity half the angular velocity of the rotative member, rhomboid prisms provided on the entrance side of the trapezoid prism so as to optically guide the light coming from a region outside an aperture of the trapezoid prism to the trapezoid prism as the light parallel to the axis of the trapezoid prism within the aperture thereof, and the rhomboid prisms provided on the exit side of the trapezoid prism so as to optically guide the light emanating from the trapezoid prism to a region outside the aperture of the trapezoid prism, a plurality of pairs of convergent lenses respectively provided to the rotative member and the fixed member, the convergent lenses of each pair optically facing each other via the rhomboid prisms, the trapezoid prism and the rhomboid prisms, and entrance and exit side optical fibers respectively connected to the entrance and exit surface side convergent lenses.

Multi-port fiberoptic rotary joint

A rotary joint for polarization plane maintaining optical fibers which can couple two polarization plane maintaining optical fibers to each other while maintaining the polarization plane maintaining property. The rotary joint comprises a rotary member, a fixed member, two optical fiber collimators and a 1/2 wavelength plate for coupling a polarization plane maintaining optical fiber connected to the rotary member with another polarization plane maintaining optical fiber connected to the fixed member, and gears for rotating the 1/2 wavelength plate at a speed equal to one half the rotational speed of the polarization plane maintaining optical fiber on the rotary member side.

Rotary joint for polarization plane maintaining optical fibers

Growing community of inventors

Hitachi, Japan

Toshio Fukahori