Patent ID: 7557923

Claim:
A system for determining in situ the presence and concentration of an analyte of interest on a target surface of an object, comprising: a light emitting source, the light emitting source being capable of emitting modulated light having a plurality of different wavelengths of collimated light toward a target surface to be tested for an analyte of interest, the different modulations of the plurality of wavelengths being both uncorrelated to the each of the other modulated wavelengths so as to substantially eliminate covariance between light of differing wavelengths, and varying in the amount of light energy per unit time emitted toward the target surface; a wide band light detector for detecting light scattered back from the target surface, the light detector receiving light scattered from the target surface without intervening focusing optics; and a processor for calculating the covariance of the scattered light received by the light detector and predetermined spectral emission values, using said calculation to generate a signal representative of the presence or absence of the analyte of interest and, if the analyte of interest is present, using the light detected by the light detector over a multiple of wavelengths to generate a signal representative of the analyte concentration.