Abstract: A gas sampling device includes an analysis block defining a first portion of a chamber and a dilution block defining a second portion of the chamber. The sampling device includes an exhaust gas orifice at the first portion for withdrawing gas from the chamber in response to an applied suction, a sample gas orifice at the second portion to modify passage of a sample gas entering the chamber in response to the suction, and a dilution gas orifice at the second portion to modify passage of a dilution gas entering the chamber in response to the suction.

Abstract: A gas sampling device includes an analysis block defining a first portion of a chamber and a dilution block defining a second portion of the chamber. The sampling device includes an exhaust gas orifice at the first portion for withdrawing gas from the chamber in response to an applied suction, a sample gas orifice at the second portion to modify passage of a sample gas entering the chamber in response to the suction, and a dilution gas orifice at the second portion to modify passage of a dilution gas entering the chamber in response to the suction.

Abstract: A gas sampling device includes an analysis block defining a first portion of a chamber and a dilution block defining a second portion of the chamber. The sampling device includes an exhaust gas orifice at the first portion for withdrawing gas from the chamber in response to an applied suction, a sample gas orifice at the second portion to modify passage of a sample gas entering the chamber in response to the suction, and a dilution gas orifice at the second portion to modify passage of a dilution gas entering the chamber in response to the suction.

Abstract: A gas sampling device includes an analysis block defining a first portion of a chamber and a dilution block defining a second portion of the chamber. The sampling device includes an exhaust gas orifice at the first portion for withdrawing gas from the chamber in response to an applied suction, a sample gas orifice at the second portion to modify passage of a sample gas entering the chamber in response to the suction, and a dilution gas orifice at the second portion to modify passage of a dilution gas entering the chamber in response to the suction.

Abstract: A method and apparatus for in situ measurement of the concentration of a gas with a frequency modulated tunable diode laser is disclosed. The sampling cell, which is mounted in the flow of gases to be measured, is a Herriott cell. Gas enters the sampling cell through sintered metal filters that prevent entrance of particulates. Signals from a sample detector and a null detector are compared to eliminate interference patterns from the laser optics. High accuracy dynamic calibration of the apparatus is also disclosed.

Abstract: An apparatus and method are disclosed for measuring the concentration of gases that are unstable or difficult contain in a sample cell. A frequency modulated laser is tuned to the frequency of a first spectral feature of a gas of interest and a laser beam is projected through a reference cell containing, at a selected pressure, a selected second gas that has a second spectral feature near the first spectral feature of the gas of interest. The laser is line-locked to an outer zero crossing of a third harmonic of the detected laser beam coincident with the first spectral feature. The concentration of the gas of interest is calculated from a second harmonic of a portion of the laser beam projected through a transmission medium containing the gas.