Multi-channel molecular gas analysis by laser-activated Raman light scattering

A device for the analysis of gases in a gas sample utilizing Raman light scattering, comprising:

• a light source for producing a beam of optical radiation along a longitudinal axis;
• a means for containing said gas sample at multiple locations along said longitudinal axis so that said beam of optical radiation is incident upon said gas sample at said multiple locations;
• and
• a plurality of optical detector channels for simultaneously acquiring a plurality of samples of the optical energy scattered out of said beam incident upon samples from said multiple locations along said longitudinal axis.

A device for analyzing a sample utilizing Raman spectroscopy comprising:

• a light source for producing optical energy;
• a collimator means for collimating said optical energy from said light source into a collimated beam of optical radiation propagating along an optical axis, said collimated beam of radiation comprising substantially parallel light rays along a region of said optical axis wherein said collimated beam interacts with said sample;
• a sample container for holding said sample to be analyzed in said interaction region;
• and
• multiple detector channels positioned at a plurality of locations within said interaction region of said optical axis for detecting light scattered out of said collimated beam by said sample at said plural locations.

A device for analyzing a sample utilizing Raman scattered light comprising:

• a light source;
• multiple optical elements for focusing a beam of light from said light source thus creating multiple regions of increased intensity along said beam wherein light rays entering said regions substantially converge at said regions and light rays exiting said regions substantially diverge, said multiple regions lying along an optical axis in the general direction of propagation of said beam;
• a sample container for hold said sample within said high intensity regions so that said light beam interacts with said sample;
• and
• multiple detectors for detecting light scattered out of said beam by said sample at said multiple high intensity regions.

A system for the simultaneous analysis and quantification of selected multiple polyatomic gases in a gas sample by Raman light scattering, comprising:

• a source of laser light capable of producing a polarized laser beam of a selected wavelength comprising a laser resonant cavity, said laser resonant cavity comprising a plasma tube and wherein one end of said laser resonant cavity contains an output coupler mirror and the other end contains a high reflectivity mirror which does not transmit light;
• gas sampling cell means defining a longitudinal gas constraining chamber having end optical means interconnected by a sidewall, said cell means being oriented relative to said laser cavity such that when said laser beam is activated, the laser beam is coincident with and traverses the axis of said longitudinal gas chamber, said optical end means being positioned to reflect or transmit a laser beam along the axis of the longitudinal gas chamber, said cell means also having opposing, aligned side windows in said sidewall parallel to and on either side of the axis of said longitudinal gas chamber;
• a series of optical filter-detection channels, the optical portions of said channels being longitudinally aligned on either side of said cell means positioned parallel to and in alignment with said side windows, each of said optical filter-detection channels comprising:
• an optical portion comprising a collection lens means positioned parallel to and in alignment with said laser beam and side windows outside said cell means to collect elastic laser scattered light and inelastic Stokes or anti-Stokes Raman scattered light passing through said side windows:
• a filter portion comprising an interference filter means adapted to receive signals of both inelastic Stokes or anti-Stokes Raman scattered light and elastic laser scattered light passing through each such optical portion and transmit a Single Stokes or anti-Stokes Raman line of a predetermined wavelength while rejecting scattered elastic laser light signals and all other signals of Stokes and anti-Stokes inelastic Raman scattered light;
• and
• a detection portion comprising detection and amplification means for receiving Stokes or anti-Stokes Raman signals passing through said filter portion and converting said signals to digital electrical pulses, currents or voltages;
• processing mean for interpreting said digital electrical pulses, currents or voltages from each channel and converting them to visual readouts indicative of the concentration of each of said selected polyatomic molecular gases in said sample;
• and
• power means to operate said laser means, each optics filter-detection channel, amplification means and processing means.

A method for the simultaneous and near instantaneous determination of the concentration of multiple polyatomic gas molecules in the gas sample, comprising:

• providing a laser means capable of producing a polarized laser beam of a selected wavelength comprising a laser resonant cavity, said laser resonant cavity comprising a plasma tube, and wherein one end of said laser resonant cavity comprises an output coupler mirror and the opposite end comprises a high reflectivity mirror;
• introducing said gas sample into a gas sampling cell means defining a longitudinal gas-constraining chamber having end optical means interconnected by a sidewall, said cell means being oriented relative to said laser cavity such that, when said laser beam is activated, the laser beam is coincident with and traverses the axis of said longitudinal gas chamber, said optical end means being positioned to reflect or transmit a laser beam along the axis of the longitudinal gas chamber, said cell means also having opposing, aligned side windows in said sidewall parallel to and on either side of the axis of said longitudinal gas chamber;
• subjecting said gas sample in said cell means to a laser beam of selected wavelength and polarization having sufficient intensity to produce detectable signals of inelastic Stokes or anti-Stokes raman scattered light;
• subjecting signals of either inelastic Stokes or anti-Stokes Raman scattered light and elastic laser scattered light to the optical portion of a series of optical filter-detection channels said optical portion of said channels being longitudinally aligned on either side of said cell means positioned parallel to and in alignment with said side windows and also having an optical axis which is substantially perpendicular to the axis to said laser beam;
• collecting signals of elastic laser scattered light and inelastic Stokes and anti-Stokes Raman scattered light by said optical portion of said channels;
• directing said signals of either inelastic Stokes or anti-Stokes Raman scattered light and elastic laser scattered light passing through such optical portion onto said filter portion of said channels, wherein a single Stokes or anti-Stokes Raman line of a predetermined wavelength is transmitted through said filter portion, and wherein scattered elastic laser light signals and all other signals of Stokes and anti-Stokes inelastic Raman scattered light are rejected;
• sensing each single Stokes or anti-Stokes Raman line signal passing through each filter system by said detection portion of said channels, wherein said signals are detected, amplified and converted into digital electrical pulses, current or voltage;
• and
• processing said digital electrical pulses from each optical filter-detection channel in processing means and converting them to visual readouts indicative of the concentration of each of said polyatomic molecules in said gas sample being determined.

A method of analyzing a gas sample comprising:

• producing a beam of optical radiation which propagates along a longitudinal axis;
• confining said gas sample in a region along said longitudinal axis so that said beam of radiation propagates through said sample;
• and
• collecting Raman scattered light which results from the interaction of said beam of radiation with said gas sample from multiple regions located along said longitudinal axis.