Vol. 46, Issue 3, pp. 353-363

Abstract

A tunable diode laser absorption spectrometer was developed for trace acetylene gas analysis, the system performance was evaluated by combing an appropriate digital signal processing methods, i.e., Savitzky–Golay smoothing and differentiation algorithm. The calculation of the derivative spectra by this method is accompanied by simultaneous data smoothing. Based on the 2nd derivative spectra detection method, the Allan variance technique indicates a C₂H₂ detection limit of 1.7 ppm for 1-s averaging time, and a minimum noise level of 62 ppb (parts per billion), at the optimum integration time of ~60 s. The calculated 2nd derivative spectra with better resolution, lower detection limits, save signal processing time, and improve the ability to distinguish unresolved spectral signals.