Method and device for measuring a temperature and/or a strain in an optical fiber

A device for measuring a temperature and/or a strain in an optical fiber, comprising:

• means for calibrating the optical fiber comprising means for measuring a signal sensitive to an intensity and a phase of a Rayleigh backscattering signal of the optical fiber at a known state of temperature and a known state of strain, for various conditions of frequencies or wavelengths or wavenumbers of the backscattered signal and/or of known states of temperature and/or known states of strain, and for at least one longitudinal position inside the fiber,
• means for measuring the signal sensitive to an intensity and a phase of a Rayleigh backscattering signal of the optical fiber at an unknown state of temperature and/or an unknown state of strain, for various frequencies or wavelengths or wavenumbers of the backscattered signal and for at least one longitudinal position inside the fiber,
• determination means arranged to and/or configured to and/or programmed to determine the absolute value of the unknown state of temperature and/or the unknown state of strain, for at least one longitudinal position inside the optical fiber, based on a shift of frequency or temporal period or wavelength or wavenumber or a correlation between:
• the signal sensitive to the intensity and the phase of a Rayleigh backscattering signal of the optical fiber at a known state of temperature and a known state of strain, for various conditions of frequencies or wavelengths or wavenumbers of the backscattered signal and/or of known states of temperature and/or known states of strain, and
• the signal sensitive to the intensity and the phase of a Rayleigh backscattering signal of the optical fiber at an unknown state of temperature and/or an unknown state of strain.