| 摘要 |
<p>A guided optical wave chemical sensor system (10) is adapted to measure the concentration of a chemical species in the presence of thin film surface contaminants on the waveguide (17). The system (10) has a light source (11) which launches two different optical waves into the waveguide (17) to establish evanescent fields (24, 25) of different penetration depths. The detector (15), which includes a data store and an arithmetic unit, is pre-calibrated using a known concentration of the chemical species and the same two different optical waves but prior to the waveguide (17) having been exposed to surface contaminants. When surface contamination is present the detector (15) evaluates the thickness of the contaminant layer from the pre-calibration data and hence evaluates the (unknown) concentration of the chemical species according to a predetermined algorithm.</p> |
