Thermometer for optical fibre.

摘要

A thermometer which efficiently determines the temperature of an optical fibre (3) includes a continuous source (1) of high power light, and an acousto-optical switch (2) providing an optical path between the continuous source (1) of light and an optical fibre (3) the temperature of which is to be determined. The acousto-optical switch (2) has a primary diffraction side input (2a), an output (2b) and a zero order optical terminal (2c). The primary diffraction side input receives light from the continuous source (1) and the output (2b) is connected to the optical fibre (3). The thermometer also includes a wavelength separating optical filter (4) having an input optically connected to the zero order optical terminal (2c), the zero order optical terminal allowing Raman scattered light from the optical fibre (3) to pass to the optical filter (4) where it is filtered, and a data processor (5) optically connected to an output of the optical filter (4) and arranged to determine the temperature of the optical filter by deriving the intensity ratio of the Stokes light to the anti-Stokes light of the Raman scattered light.