Fujikura Limited

Keiichi Horimoto

Akira Sakamoto

Yoshikiyo Noguchi

Satoshi Okude

Optical fiber thermometer includes one optical fiber that relays light from the light source to a measuring unit, two parallel optical fibers that relay light from a mirror at the measuring unit to two light-receiving units, and an arithmetic processing circuit that calculates the temperature of the measuring unit from the ratio of electrical signals from the two light-receiving units; end surfaces of three optical fibers facing the reflecting face being fixed at an angle &#x3b8; between the longitudinal direction of the optical fibers and the normal to the reflecting face that is not zero, the angle between the optical fibers for reception and projection being symmetrical based on the normal to the reflecting face. Each of the optical fibers is a single-mode fiber at the wavelength being used.

Optical fiber thermometer and temperature-compensated optical fiber sensor

An optical sensor includes a light source, a sensing unit, a first optical fiber transmitting light from the light source to the sensing unit, second and third optical fibers transmitting the light from a reflecting surface of the sensing unit to light-receiving portions, and a calculation unit calculating physical quantities from electrical signals from the light-receiving portions. End surfaces of these fibers opposed to the reflecting surface are fixed so that the longitudinal direction thereof and the normal line of the reflecting surface form an angle &#x3b8;, the second and third optical fibers are parallel to each other, and the fixing angles of the first optical fiber and the second and third optical fibers are symmetric about the normal line. These optical fibers have a single mode in the wavelength of which the optical fibers are used. A depolarizer is interposed between the light source and the first optical fiber.

Optical sensor

One embodiment of the present invention provides an optical detection sensor configured so as to irradiate exit light emitted from a light source onto an object to be measured, the object being disposed a relative distance away from an end face of a first optical fiber, and receive the reflection light therefrom with a second and a third optical fiber, thereby computing a displacement amount of the object. In this sensor, the first optical fiber is disposed so that an angle between a longitudinal direction thereof and a normal line to an incident surface of the object becomes &#x3b8;; the second and the third optical fiber are disposed so as to be mutually parallel and so that an angle between a longitudinal direction of the second and the third optical fiber and the normal line becomes &#x3b8;; the first optical fiber is disposed symmetrically with the second and the third optical fiber with respect to the normal line; and the first to the third optical fiber have a dNA/d&#x3bb; of 4&#xd7;10or less with respect to a wavelength of the light source.

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Sakura, Japan

Keiichi Horimoto