The expressions of the second harmonic（2f） signal are derived on the basis of absorption spectral and lock-in theories.A parametric study indicates that the phase shift between the intensity and wavelength modulatio...The expressions of the second harmonic（2f） signal are derived on the basis of absorption spectral and lock-in theories.A parametric study indicates that the phase shift between the intensity and wavelength modulation makes a great contribution to the 2f signal.A self-calibration wavelength modulation spectroscopy（WMS） method based on tunable diode laser absorption spectroscopy（TOLAS） is applied,combining the advantages of ambient pressure,temperature suppression,and phase-shift influences elimination.Species concentration is retrieved simultaneously from selected 2f signal pairs of measured and reference WMS-2f spectra.The absorption line of acetylene（C2H2） at 1530.36 nm near-infrared is selected to detect C2H2 concentrations in the range of 0-400 ppmv.System sensitivity,detection precision and limit are markedly improved,demonstrating that the self-calibration method has better detecting performance than the conventional WMS.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047,61502538,and 61501525)
文摘The expressions of the second harmonic（2f） signal are derived on the basis of absorption spectral and lock-in theories.A parametric study indicates that the phase shift between the intensity and wavelength modulation makes a great contribution to the 2f signal.A self-calibration wavelength modulation spectroscopy（WMS） method based on tunable diode laser absorption spectroscopy（TOLAS） is applied,combining the advantages of ambient pressure,temperature suppression,and phase-shift influences elimination.Species concentration is retrieved simultaneously from selected 2f signal pairs of measured and reference WMS-2f spectra.The absorption line of acetylene（C2H2） at 1530.36 nm near-infrared is selected to detect C2H2 concentrations in the range of 0-400 ppmv.System sensitivity,detection precision and limit are markedly improved,demonstrating that the self-calibration method has better detecting performance than the conventional WMS.
