The invention relates to a measuring arrangement for detecting an absolute reflection spectrum of a sample in a process for producing the sample. It comprises a light source for generating measurement light, a homogenizer for generating a uniform spatial illuminance distribution of the measurement light; a movable reflector and a receiver for collecting the measurement light reflected from the sample and/or the reflector. According to the invention, the reflector both for a reference measurement and for a sample measurement is positioned in an observation beam path and arranged on the same side of the sample as the light source in order to feed the reflected measurement light to the receiver.