Patent ID: 6137104
Filing Date: 2000-10-24
Classification: G01J,G01N

Abstract:
A method for treatment of spectra observed on the focal plane of an optical spectrometer wherein spectra are excited by inductively coupled plasma processes, comprising the steps of(a) forming a representation for expected features in a predetermined spectral interval,(b) locating at least one first selected wavelength corresponding to a position on said focal plane, whereby a wavelength reference is established over said predetermined spectral interval on said focal plane,(c) observing at least one predetermined spectral feature having a known concentration, whereby a scale of concentration is established,(d) representing each said spectral feature by the combination of a selected mathematical form dependent upon wavelength and the residuals realized by comparison of said form and said observed spectral feature whereby a model spectral component is obtained,(e) analyzing a sample,(f) recording the spectra of said sample at least within said spectral window and simultaneously therewith observing again said at least one first selected wavelength,(g) determining any shift in location on said focal plane for said first selected wavelength as obtained at step (b) compared to step (f) and incorporating any said shift in each said model spectral component by transforming said mathematical form and said residuals accordingly,(h) performing a linear least squares fit of said recorded spectra to said model spectral components whereby the intensity of spectral features corresponding to said model components is established together with the distribution of residuals resulting therefrom,(i) analyzing said residuals and determining whether said fit meets predetermined criteria for terminating said treatment, and in default thereof,(j) inspecting said distribution of residuals to determine whether a significant residual maximum is located therein and in response thereto,locating the wavelength corresponding to said residual maximum and defining another model component located at the wavelength of said residual maximum and repeating steps (h) and (i), or,where no significant residual maximum is located, displaying said intensity and terminating the treatment.