Patent ID: 6563119
Filing Date: 2003-05-13
Classification: G01N

Abstract:
A method for identifying at least one plastic material in a sample comprising said at least one plastic material by optical measurement, comprising the steps of:measuring said sample and providing a sample spectrum; providing reference spectra for a group of reference materials; determining at least one identification frequency range, said range comprised of a high absolute deviation ratio D and/or a high smoothed deviation ratio Dâ€², determining spectral distances between said sample spectrum and said reference spectra within said identification frequency range; identifying said plastic material by comparing the sample spectrum to the reference spectrum, providing a sample spectrum only in at least one identification frequency range in a number of levels, wherein said at least one identification frequency range in each level is different from the identification frequency range in the preceding level; providing reference spectra in respective identification frequency ranges for the possible materials in the respective levels; determining spectral distances between sample spectrum and reference spectra only in the respective identification frequency ranges; and associating the sample to at least two materials in the first level, to at least one material in all levels starting with the second level, and to only one material in a last level, having the reference spectrum or spectra with the smallest spectral distance to the sample spectrum.