Device for spatially resolved measurement of temperature, strain, or both by Brillouin scattering, with a laser light source (1) for generating a laser radiation, an optical fiber (5) used for the measurement, into which the laser radiation can be coupled in and from which Brillouin signals generated by Brillouin scattering can be coupled out, sensors for detecting the coupled-out Brillouin signals, evaluators for determining spatially resolved from the detected Brillouin signals the temperature, strain, or both of sections of the optical fiber (5), a polarization beam splitter (10, 11) capable of splitting the coupled-out Brillouin—signals into two components (12, 13) having mutually different polarizations, and an optical coupler (16, 17) for admixing a laser radiation to the Brillouin signal.