Characterization of a precise phase-reading, CO₂laser-based photoacoustic spectrometer

Abstract

Abstract. We present a simple resonant photoacoustic (PA) setup based on a modulated CW CO 2 laser and a synchronic detection system that acquires the signal and the reference through the sound card of a PC. The precise phase reading of this system allows detecting the delay of the signal coming from the excited CO 2 molecules immersed in air and, with an adequate processing, the environmental abundance of this gas, closely related to global warming, can be determined.

Photoacoustic Detection of Perfluorocarbon Tracers in Air for Application to Leak Detection in Oil-Filled Cables

“…The calculated concentrations of CO 2 are consistent with globally reported values [10] and those for H 2 O correspond to lower values than expected from the humidity (>5000 ppm), which is due to adsorption to the walls and condensation. CO 2 and H 2 O in environmental samples have been measured in our lab by the same system with satisfactory results in [5].…”

“…The microphone is attached at the walls in the center of the resonator. Synchronous detection is performed by a PC-based system developed in our lab [5]. Briefly, both the amplified microphone signal and a reference from a pyroelectric detector (Molectron J3-05), which samples the laser beam, are acquired through the line input channels of a PC sound card for further processing.…”

Photoacoustic Signals Processing for Determining Concentrations of Co2 and C2h4 in Air

“…Cabe destacar que se han obtenido con este método buenos resultados expuestos en trabajos previos 3,4 , aunque con ciertas limitaciones. En primer lugar, la ecuación utilizada parte de un modelo teórico, en el cual se hacen ciertas consideraciones para llegar a la aproximación lineal.…”