Optical analysis device

An optical analysis device (100) for analyzing a medium in the measurement volume, comprising

• a housing (10) having an opening (21);
• a flange (10, 10′) for holding the housing (108) in a reception opening of the measurement volume;
• and
• an optical analysis unit in the housing (108) for the optical analysis of a medium in the measurement volume through the opening (21),
• further comprising
• a fastening stub (20) provided at the housing and including the opening (21) for fastening the housing (108) in the flange (10, 10′), with the fastening stub (20) having an outer geometry which is matched to the inner geometry of the flange (10, 10′) such that it can be displaced in the flange (10, 10′) in the direction of the measurement volume and away from it;
• and
• a clip (30) with which the flange (10, 10′) and the fastening stub (20) can be connected to one another in shape-matched and/or force-transmitting manner in different positions of the fastening stub (20) in the flange (10, 10′).