Browse Prior Art Database

Remote Temperature Sensor

IP.com Disclosure Number: IPCOM000089342D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Blotekjaer, K: AUTHOR [+2]

Abstract

This article describes a sensor for detecting a localized temperature increase at any point over a long path or in areas that are normally inaccessible, such as a high power transmission line. The sensor consists of a fiber-optic light guide that is coated with a thermochromic material that changes its absorption when its temperature exceeds a certain value. An example of this type of material is a mixture containing 20 parts m-terphenyl and 1 part tetracyanoethylene (TCNE). This mixture is transparent in the 800-900 nm spectral range at temperatures below 66 Degrees C. At temperatures above 66 Degrees C, the mixture absorbs light. This transition has a sharp threshold of about 0.5 Degrees C, and it is reversible.

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Remote Temperature Sensor

This article describes a sensor for detecting a localized temperature increase at any point over a long path or in areas that are normally inaccessible, such as a high power transmission line. The sensor consists of a fiber-optic light guide that is coated with a thermochromic material that changes its absorption when its temperature exceeds a certain value. An example of this type of material is a mixture containing 20 parts m-terphenyl and 1 part tetracyanoethylene (TCNE). This mixture is transparent in the 800-900 nm spectral range at temperatures below 66 Degrees C. At temperatures above 66 Degrees C, the mixture absorbs light. This transition has a sharp threshold of about 0.5 Degrees C, and it is reversible.

A specific embodiment would involve combining this mixture with a transparent polymer (polystyrene) in a suitable solvent (benzene) and drawing the optical fiber through the solution to yield a coating film on the fiber. The coated optical fiber is placed in the desired place, for example, in the same sheath as a power transmission line. Infrared or visible radiation is coupled into one end of the fiber and detected at the other end with a photodetector. When a local increase in temperature occurs anywhere along the length of the fiber, an increase in the absorption occurs due to a change in the coating. The resultant decrease in light output is shown by the photodetector.

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