# US 7,744,275 B2 · Optical fiber temperature sensing device

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- Number: US 7,744,275 B2
- Document ID: US7744275B2
- Status: Granted
- Kind: B2
- Application number: 11/806,230
- Filed: 2007-05-30
- Published: 2007-12-06
- Granted: 2010-06-29
- Earliest claimed: 2006-05-31
- Assignees: Hitachi Cable, Ltd.
- Inventors: Hidetaka Kawauchi; Masaki Ogura; Juhyun Yu; Akihiro Hiruta
- Web page: https://patentgrep.com/patent/US7744275B2

## CPC

- G01J 5/60: using determination of colour temperature
- G01J 5/08: Optical arrangements
- G01J 5/0821: Optical fibres
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

An optical fiber temperature sensing device has a sensor body; a light source housed in the sensor body; a temperature measuring optical fiber disposed outside the sensor body and extended to a temperature measurement site, wherein, when a light is emitted from the light source into the temperature measuring optical fiber, Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the temperature measuring optical fiber are detected to determine a temperature at the temperature measurement site; a reference temperature optical fiber disposed inside the sensor body; and a controller that is operable to control an output of the light source by monitoring Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber.

## Claims

### Claim 1

An optical fiber temperature sensing device, comprising:
a sensor body;
a light source housed in the sensor body;
a temperature measuring optical fiber disposed outside the sensor body and extended to a temperature measurement site, wherein, when a light is emitted from the light source into the temperature measuring optical fiber, Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the temperature measuring optical fiber are detected to determine a temperature at the temperature measurement site;
a reference temperature optical fiber disposed inside the sensor body; and
a controller that is operable to control an output of the light source by monitoring Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber,
wherein:
the controller is operable to previously determine reference calculated values from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber at least at two arbitrary temperatures, to determine an approximation formula representing a relationship between the reference calculated values and the two arbitrary temperatures, to store the approximation formula in a memory device, to determine a first calculated value from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber at an other temperature, to determine a second calculated value at the other temperature by using the approximation formula, and to control a bias electrical current applied to the light source to make the first calculated value equal to the second calculated value.

### Claim 2 (depends on 1)

The optical fiber temperature sensing device according to claim 1, wherein:
the controller is operable to detect a malfunction of the device.

### Claim 3 (depends on 1)

The optical fiber temperature sensing device according to claim 1, wherein:
the controller is operable to detect a malfunction of the light source.

### Claim 4

An optical fiber temperature sensing device, comprising:
a sensor body;
a light source housed in the sensor body;
a temperature measuring optical fiber disposed outside the sensor body and extended to a temperature measurement site, wherein, when a light is emitted from the light source into the temperature measuring optical fiber, Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the temperature measuring optical fiber are detected to determine a temperature at the temperature measurement site;
a reference temperature optical fiber disposed inside the sensor body; and
a controller that is operable to control an output of the light source by monitoring Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber,
wherein:
the controller is operable to previously determine reference calculated values from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber at plural temperatures, to store the reference calculated values into a memory device, to determine a first calculated value from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber at an arbitrary temperature, to output a second calculated value at the arbitrary temperature from the reference calculated values, and to control a bias electrical current applied to the light source to make the first calculated value equal to the second calculated value.

### Claim 5 (depends on 4)

The optical fiber temperature sensing device according to claim 4, wherein:
the controller is operable to detect a malfunction of the device.

### Claim 6 (depends on 4)

The optical fiber temperature sensing device according to claim 4, wherein:
the controller is operable to detect a malfunction of the light source.

### Claim 7

An optical fiber temperature sensing device, comprising:
a sensor body;
a light source housed in the sensor body;
an optical fiber disposed from an inside of the sensor body to a temperature measurement site, to measure a temperature at the temperature measurement site by detecting Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the optical fiber when a light is emitted from the light source into the optical fiber; and
a controller to control an output of the light source by monitoring Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the optical fiber,
wherein:
the controller is operable to previously determine reference calculated values from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in a reference temperature optical fiber at least at two arbitrary temperatures, to determine an approximation formula representing a relationship between the reference calculated values and the two arbitrary temperatures, to store the approximation formula in a memory device, to determine a first calculated value from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber at an other temperature, to determine a second calculated value at the other temperature by using the approximation formula, and to control a bias electrical current applied to the light source to make the first calculated value equal to the second calculated value.

### Claim 8 (depends on 7)

The optical fiber temperature sensing device according to claim 7, wherein:
the controller is operable to detect a malfunction of the device.

### Claim 9 (depends on 7)

The optical fiber temperature sensing device according to claim 7, wherein:
the controller is operable to detect a malfunction of the light source.

### Claim 10

Optical fiber temperature sensing, comprising:
a sensor body;
a light source housed in the sensor body;
an optical fiber disposed from an inside of the sensor body to a temperature measurement site, to measure a temperature at the temperature measurement site by detecting Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the optical fiber when a light is emitted from the light source into the optical fiber; and
a controller to control an output of the light source by monitoring Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the optical fiber,
wherein:
the controller is operable to previously determine reference calculated values from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in a reference temperature optical fiber at plural temperatures, to store the reference calculated values into a memory device, to determine a first calculated value from Stokes light intensity and anti-Stokes light intensity of backscattered light generated in the reference temperature optical fiber at an arbitrary temperature, to output a second calculated value at the arbitrary temperature from the reference calculated values, and to control a bias electrical current applied to the light source to make the first calculated value equal to the second calculated value.

### Claim 11 (depends on 10)

The optical fiber temperature sensing device according to claim 10, wherein:
the controller is operable to detect a malfunction of the device.

### Claim 12 (depends on 10)

The optical fiber temperature sensing device according to claim 10, wherein:
the controller is operable to detect a malfunction of the light source.