The device for the detection of diffusely scattering impurities (18) in containers (10) that have a transparent wall (16) has a light source (12), which produces one or more light beams (14) for illuminating the wall (16), and an optical detecting device (22) for production of an image of the illuminated wall (16), with the light source (12) and the optical detecting device (22) arranged according to dark-field detection. The light source (12) is designed so that the light beam or beams (14) that it emits have an intensity distribution over their cross-section with an intensity contrast at one point at least within their cross-section.