| abstract |
A method and apparatus for background correction in photoluminescent analysis of a selected photoluminescent target substance with a relatively narrow emission spectrum in the presence of ambient substances with a combined photoluminescent spectrum which is relatively broad. The photoluminescence of the target substance is sampled and measured in a narrow wavelength band corresponding to the principal emission spectrum of the target. A second sample of photoluminescence is measured in one or more wavelength bands adjacent to the first wavelength band, but excluding substantially all of the photoluminescence of the target substance, and transmitting only ambient photoluminescence. The second measurement is converted into an amount which would occur if ambient photoluminescence had been sampled in the first wavelength band and then the converted amount is subtracted from the first measured amount, thereby correcting the first measured amount for photoluminescence derived from ambient substances. |