An optical measurement system will be presented which allows the continuous recording of radiation induced optical loss and thermoluminescence signals during and after irradiation. The complete optical system can operate in the spectral range from 0.6 to 1.7 μm. This allows the detection of the following absorption and scattering processes: elec-tronic transitions, Rayleigh-scattering and vibrational modes. Measurements on typical fibers will be shown. The measurements are performed in order to examine the influence of lowest exposure levels and to evaluate the application in dosimetry systems.