Abstract

Laser spectroscopy with wavelength modulation and second harmonic detection is used as a sensitive and highly selective technique for trace gas monitoring. Usually, the unknown concentration is derived by comparing with a certified reference mixture. We here present algorithms which will enable the quantitative analysis of the second harmonic signal to within ±10% without reference to a calibration gas. The algorithms are validated by measurements with an extended cavity diode laser on pure CO₂, and with a DFB laser on atmospheric CO₂.

© 1999 Optical Society of America