The Sendot optical oxygen sensor is based on the principle of fluorescence quenching. The sensitive coating has two components, one to measure temperature and one to measure oxygen. The temperature compensation of the oxygen measurement is thus uniquely and ideally embedded in the same coating. Because the coating does not use oxygen for the measurement this technology can be used in closed, nonstirred environments. The temperature compensation with an embedded component does not suffer from response time differences, making it possible to use the sensor in fast changing environments.