Cavity Ring-Down Spectroscopy having Interleaved Data Acquisition for Interference Mitigation

A method of performing optical absorption spectroscopy, the method comprising:

• providing an optical absorption instrument having a tunable optical source;
• performing optical absorption measurements of one or more analytes in a sample with the optical absorption instrument in a time-sequential series of measurements having interleaved first measurements and second measurements, wherein each of the first and second measurements includes at least a time stamp, an optical source frequency, and an optical loss;
• wherein all of the first measurements are performed at a reference frequency fref of the optical source;
• wherein the second measurements include measurements performed at two or more optical source frequencies other than fref;
• determining an interference optical loss spectrum vs. time from the first measurements and from an interference spectral model;
• and
• correcting the second measurements using the interference optical loss spectrum vs. time to provide interference-corrected second measurements.