Multichannel exhaust gas analyzer

Claim 2

A multichannel exhaust gas analyzer for monitoring the time variant concentrations of a multicomponent mixture of gases by measuring the absorption by the mixture at selected optical wavelengths comprising, a radiation source, a detector, means establishing a radiation path between said source and said detector, a plurality of absorption cells of different lengths located in said radiation path, means for communicating said mixture serially through said plurality of absorption cells, a reference cell containing a reference gas located adjacent the first of said absorption cells, a span cell containing a calibration gas located adjacent the last of said absorption cells, a rotatable chopper wheel interposed between said source and said detector and containing a plurality of spectral filters arranged to be sequentially positioned in said radiation path during rotation of said chopper wheel, each of said filters sequentially passing radiation of a particular optical wavelength through each of said cells, and means for rotating said chopper wheel.

Claim 3

A multichanneled exhaust gas analyzer for monitoring the time variant concentrations of a multicomponent mixture of gases by measuring the absorption by the mixture at selected optical wavelengths comprising, an electrically heated radiation source, a quantum detector, a pair of parabolic mirrors for collimating radiation from said source to said detector, a plurality of absorption cells of different lengths located in said radiation path, means for communicating said mixture serially through said plurality of cells, a reference cell containing a reference gas located adjacent the first of said absorption cells, a span cell containing a calibration span gas located adjacent the last of said plurality of absorption cells, a rotatable chopper wheel interposed between said source in said detector and containing a plurality of spectral filters arranged to be sequentially positioned in said radiation path during rotation of said chopper wheel, each of said filters sequentially passing radiation of a particular wavelength through each of said cells, an indexing light source, an indexing detector, an index slot formed in said wheel for communicating the light from said indexing light source through said indexing detector, means for rotating said chopper wheel, and electronic signal processing means responsive to the output of said quantum detector and said indexing detector for determining saiD concentrations.

Claim 4

A multichanneled exhaust gas analyzer for monitoring the time variant concentrations of a multicomponent mixture of gases by measuring the absorption by the mixture at selected optical wavelengths comprising, an electrically heated radiation source, a quantum detector, a pair of parabolic mirrors for collimating radiation from said source to said detector, a plurality of absorption cells of different lengths located in said radiation path, means for communicating said mixture serially through said plurality of cells, a reference cell containing a reference gas located adjacent the first of said absorption cells, a span cell containing a calibration span gas located adjacent the last of said plurality of absorption cells, a rotatable chopper wheel interposed between said source in said detector and containing a plurality of spectral filters arranged to be sequentially positioned in said radiation path during rotation of said chopper wheel, each of said filters sequentially passing radiation of a particular wavelength through each of said cells, an indexing light source, an indexing detector, an index slot formed in said wheel for communicating the light from said indexing light source through said indexing detector, means for rotating said chopper wheel, and electronic signal processing means responsive to the output of said quantum detector and said indexing detector for determining saiD concentrations.