A turbidimeter for measuring a turbidity of a liquid sample in a sample cuvette includes a cuvette receiving device configured to position the sample cuvette in a defined cuvette position, a light source configured to generate a parallel light beam in the sample cuvette, an annular 45° collecting mirror configured to surround the sample cuvette, a scattering body arranged concentric to the annular 45° collecting mirror, a scattering light detector arranged to receive light scattered by the scattering body, and an annular 45° concentration mirror arranged coaxially to the annular 45° collecting mirror and optically opposite to the annular 45° collecting mirror. The annular 45° collecting mirror is arranged concentric to the light beam. The annular 45° concentration mirror is configured to surround the scattering body.