Abstract: One or more light sources emit light within first, second, and third wavelength ranges through exhaust gas. The first and second wavelength ranges are characterized by first and second different absorption wavelength ranges of a background gas. The third wavelength range is characterized by an absorption wavelength range of a gas-of-interest. At least some of the light within the first, second, and third wavelength ranges is absorbed by the exhaust gas thereby providing modified light characterized by the first, second, and third absorption wavelength ranges. One or more detectors receive the modified light. A processing subsystem determines a temperature of the exhaust gas based on the modified light characterized by the first and second absorption wavelength ranges and a concentration of the gas-of-interest based on the modified light characterized by the third absorption wavelength range and the temperature of the exhaust gas.

Abstract: A method for determining a multi-dimensional profile of at least one emission parameter corresponding to an exhaust emission of a combustion process is presented. The method includes emitting a laser beam in a plurality of directions through the exhaust emission. The laser beam includes a plurality of wavelengths and the exhaust emission is characterized by the plurality of emission parameters. The method further includes detecting a plurality of absorption spectrum signals for each of the plurality of directions and determining a plurality of single-dimensional profiles corresponding to the at least one emission parameter. Each of the plurality of single-dimensional profiles is determined based on the plurality of absorption spectrum signals corresponding to each respective direction of the plurality of directions. The method also includes generating the multi-dimensional profile corresponding to the at least one emission parameter based on the plurality of single-dimensional profiles.

Abstract: One or more light sources emit light within first, second, and third wavelength ranges through exhaust gas. The first and second wavelength ranges are characterized by first and second different absorption wavelength ranges of a background gas. The third wavelength range is characterized by an absorption wavelength range of a gas-of-interest. At least some of the light within the first, second, and third wavelength ranges is absorbed by the exhaust gas thereby providing modified light characterized by the first, second, and third absorption wavelength ranges. One or more detectors receive the modified light. A processing subsystem determines a temperature of the exhaust gas based on the modified light characterized by the first and second absorption wavelength ranges and a concentration of the gas-of-interest based on the modified light characterized by the third absorption wavelength range and the temperature of the exhaust gas.

Abstract: A method for correcting frequency offset in a dual comb spectroscopy system is provided. The method includes causing a first laser (L1) generator to transmit L1 pulses at a repetition rate of a first frequency and causing a second laser (L2) generator to transmit L2 pulses at a repetition rate of a second frequency. The method also includes interrogating a reference material using a combination of the L1 pulses and the L2 pulses and capturing reference cell pulses. The method further includes interrogating a material of interest using the L1 pulses and capturing material of interest pulses. The method includes determining a frequency jitter based on the captured reference cell pulses and the combination of the captured material of interest pulses and the L2 pulses.

Abstract: A method for determining a multi-dimensional profile of at least one emission parameter corresponding to an exhaust emission of a combustion process is presented. The method includes emitting a laser beam in a plurality of directions through the exhaust emission. The laser beam includes a plurality of wavelengths and the exhaust emission is characterized by the plurality of emission parameters. The method further includes detecting a plurality of absorption spectrum signals for each of the plurality of directions and determining a plurality of single-dimensional profiles corresponding to the at least one emission parameter. Each of the plurality of single-dimensional profiles is determined based on the plurality of absorption spectrum signals corresponding to each respective direction of the plurality of directions. The method also includes generating the multi-dimensional profile corresponding to the at least one emission parameter based on the plurality of single-dimensional profiles.

Abstract: A method for correcting frequency offset in a dual comb spectroscopy system is provided. The method includes causing a first laser (L1) generator to transmit L1 pulses at a repetition rate of a first frequency and causing a second laser (L2) generator to transmit L2 pulses at a repetition rate of a second frequency. The method also includes interrogating a reference material using a combination of the L1 pulses and the L2 pulses and capturing reference cell pulses. The method further includes interrogating a material of interest using the L1 pulses and capturing material of interest pulses. The method includes determining a frequency jitter based on the captured reference cell pulses and the combination of the captured material of interest pulses and the L2 pulses.