Uncertainty analysis of absolute concentration measurement with continuous-wave cavity ringdown spectroscopy

To evaluate the uncertainty of concentration measurement using cavity ringd own spectroscopy, we analytically derived expressions for uncertainty for p arameters, such as temperature, laser frequency, and ringdown time deviatio n, from the model equation. The uncertainties that are due to systematic er rors in a practical cavity ringdown system were assessed through an experim ental study of the PQ(35) transition in an A band of molecular oxygen. We f ound that, except for the line strength that is regarded as a reference val ue independent of the measurement, the laser frequency jitter is the larges t uncertainty source in the system. Some practical requirements for minimiz ing the uncertainty in concentration measurements are discussed. We also de monstrated determination of the line strength of the PQ(35) transition line of oxygen to be 8.63(3) x 10(-27) cm(-1) with a relative uncertainty of le ss than 0.4%. (C) 2001 Optical Society of America.