Miniaturized nonresonant photoacoustic gas analyzer for CO2 detection

In this letter, a portable trace carbon dioxide (CO2) measurement instrument based on photoacoustic spectroscopy (PAS) was proposed and designed. The nonresonance PA cell (PAC) including a cooper tube with 251.2 mu l was designed. Two condenser microphones were used to measure the PA signal simultaneously. The center wavelength of the distributed feedback laser was chosen to 2004 nm. Within 1 s integral time, the detection limit for CO2 reached 12.7 ppm. The normalized noise-equivalent absorption coefficient was calculated to be 4.8468 x 10(-9) cm(-1)W/Hz(1/2). With Allan-Werle deviation analysis, the measurement detection limit for CO2 improved to 4 ppm with 30 s integration time. As a result, the trace CO2 instrument based on PAS shows a good performance in long-term detection.