Patent ID: 7744275

Claim:
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.