Abstract: The present disclosure relates to an arrangement (100) for obtaining a quantity related to a temperature along a part of an optical fibre (110). The arrangement comprises a light emitter (120) arranged to emit light into the optical fibre (110). The optical fibre is at at least one location along said part of the optical fibre provided with a Fibre Bragg Gratings, FBGs (111, 112, 113), wherein the FBGs are arranged to reflect light within a predetermined wavelength range. The arrangement further comprises a detector (160) arranged to receive and detect the reflected light, a first optical shutter (130) arranged in the optical path after the light emitter. The first optical shutter is arranged to be opened and closed in order to let the emitted light through and into the optical fibre (110), a second optical shutter (150) arranged to be opened and closed in order to let the reflected light through, and an optical circulator (140) having a first, a second and a third port.

Abstract: The present disclosure relates to an arrangement (100) for obtaining a quantity related to a temperature along a part of an optical fibre (110). The arrangement comprises a light emitter (120) arranged to emit light into the optical fibre (110). The optical fibre is at at least one location along said part of the optical fibre provided with a Fibre Bragg Gratings, FBGs (111, 112, 113), wherein the FBGs are arranged to reflect light within a predetermined wavelength range. The arrangement further comprises a detector (160) arranged to receive and detect the reflected light, a first optical shutter (130) arranged in the optical path after the light emitter. The first optical shutter is arranged to be opened and closed in order to let the emitted light through and into the optical fibre (110), a second optical shutter (150) arranged to be opened and closed in order to let the reflected light through, and an optical circulator (140) having a first, a second and a third port.