Patent ID: 6057923
Filing Date: 2000-05-02
Classification: G01J,G01N

Abstract:
A system for detecting a substance comprising:an optical path switch for receiving radiation passing along a sample path of interest, said optical path switch dividing said radiation into a time series of alternating first polarized components and second polarized components orthogonal to said first polarized components, said optical path switch transmitting said first polarized components along a first optical path and said second polarized components along a second optical path;a first gasless optical filter train disposed in said first optical path for filtering said first polarized components to isolate at least a first wavelength band wherein first filtered radiation is generated;a second gasless optical filter train disposed in said second optical path for filtering said second polarized components to isolate at least a second wavelength band wherein second filtered radiation is generated, wherein said first wavelength band and said second wavelength band are unique and wherein spectral absorption of a substance of interest is different at said first wavelength band as compared to said second wavelength band;a beam combiner disposed to receive said first filtered radiation and said second filtered radiation for combining said first filtered radiation and said second filtered radiation to form a combined beam of radiation; anddetector means disposed to monitor magnitude of at least a portion of said combined beam alternately at said first wavelength band and said second wavelength band as an indication of the concentration of said substance in said sample path.