Temperature distribution measuring apparatus using an optical fiber

A method of measuring a temperature distribution along an optical fiber, comprising the steps of:

• heating a portion of the optical fiber to a predetermined temperature, the portion having a predetermined length;
• projecting a first light pulse into the optical fiber, the first light pulse having a pulse width, one half of which is longer than the predetermined length of said portion;
• receiving a first Raman spectrum in a first backscattered light from the optical fiber in response to said first light pulse and extracting a first anti-Stokes component and a first Stokes component of the first Raman spectrum in the first backscattered light;
• performing a deconvolution a number of times on the first Stokes component and the first anti-Stokes component using an inverse matrix of the projected first light pulse to obtain a first temperature signal based on a result of the deconvolution, the number of times of performing the deconvolution being determined such that an error between the first temperature signal and the predetermined temperature is minimized;
• projecting a second light pulse into the optical fiber, with said optical fiber placed in an area where a temperature distribution is to be measured;
• receiving a second Raman spectrum in a second backscattered light from the optical fiber in response to said second light pulse and extracting a second anti-Stokes component and a second Stokes component of the second Raman spectrum in the second backscattered light;
• and
• performing a deconvolution a number of times on the second Stokes component and the second anti-Stokes component using an inverse matrix of the projected second light pulse to obtain a second temperature signal based on a result of the deconvolution on the second Stokes and anti-Stokes components, the number of times of performing the deconvolution on the second Stokes and anti-Stokes components being equal to the number of times of performing the deconvolution on the first Stokes and anti-Stokes components, the second temperature signal corresponding to the temperature distribution along the optical fiber.