Patent ID: 6903817
Filing Date: 2005-06-07
Classification: G01N

Abstract:
1. A method for detecting chemical species present in a condensed medium comprising: determining characteristic wavelengths and intensity values of back-scattered electromagnetic emission signals due to fluorescence of chemical species excited in response to a multiplicity of electromagnetic excitations of distinct wavelengths of at least one chemical species that could be contained in said condensed medium; successively exciting a multiplicity of surface elements of a surface portion of said condensed medium with a laser beam having tunable wavelength capable of taking on at least one of value of said distinct wavelengths of said multiplicity of electromagnetic excitations; successively recording wavelengths and intensity values of the electromagnetic emission signals back-scattered by each of said surface elements in response to the electromagnetic excitations produced by said beam; comparing at least one excitation wavelength and at least one corresponding emission wavelength of the recorded intensity value of said electromagnetic signal back-scattered by each of said surface elements with said determined characteristic intensity value of said back-scattered electromagnetic signal of said chemical species that could be contained in said surface portion; and determining the presence of said chemical species in each of said surface elements when said recorded intensity value of said electromagnetic signal back-scattered by said surface element is greater than a threshold defined at least by said determined characteristic intensity value of said back-scattered electromagnetic signal of said chemical species.