Abstract: A laser absorption spectroscopy exhaust gas sensor includes an optical cell with porous walls having pores with a mean diameter in the range of 0.1 nm to 1 mm; gold mirrors within the optical cell positioned to support a multi-pass optical path within the optical cell; an active heating element adapted to heat the optical cell to prevent condensation; a laser adapted to generate a laser beam; an optical detector adapted to detect a returning laser beam; and a processor for controlling the laser and the active heating element and for analyzing signals from the optical detector to identify a gas in the optical cell.

Abstract: A laser absorption spectroscopy exhaust gas sensor includes an optical cell with porous walls having pores with a mean diameter in the range of 0.1 nm to 1 mm; gold mirrors within the optical cell positioned to support a multi-pass optical path within the optical cell; an active heating element adapted to heat the optical cell to prevent condensation; a laser adapted to generate a laser beam; an optical detector adapted to detect a returning laser beam; and a processor for controlling the laser and the active heating element and for analyzing signals from the optical detector to identify a gas in the optical cell.

Abstract: A method of calibration-free scanned-wavelength modulation spectroscopy (WMS) absorption sensing is provided by obtaining absorption lineshape measurements of a gas sample on a sensor using 1f-normalized WMS-2f where an injection current to an injection current-tunable diode laser (TDL) is modulated at a frequency f, where a wavelength modulation and an intensity modulation of the TDL are simultaneously generated, extracting using a numerical lock-in program and a low-pass filter appropriate band-width WMS-nf (n=1, 2, . . .

Abstract: A method of calibration-free scanned-wavelength modulation spectroscopy (WMS) absorption sensing is provided by obtaining absorption lineshape measurements of a gas sample on a sensor using 1/-normalized WMS-2/j where an injection current to an injection current-tunable diode laser (TDL) is modulated at a frequency ? where a wavelength modulation and an intensity modulation of the TDL are simultaneously generated, extracting using a numerical lock-in program and a low-pass filter appropriate band-width WMS-<</ (n=1, 2, . . .