Patent ID: 6370490
Filing Date: 2002-04-09
Classification: G01N,G06F

Abstract:
A method of determining an intrinsic spectrum f of radiation emitted by an object to be examined, which intrinsic spectrum f is represented by a set of N data points f1 . . . fN and is determined from a measured spectrum h which is represented by a set of M measuring points H1 . . . hM and is measured by means of an analysis apparatus having a given apparatus transfer function G in the form of an MÃ—N matrix, which method includes the following steps:a) forming an approximated intrinsic spectrum g of N data points g1 . . . gN; b) determining a measure of misfit &khgr;2 between the approximated intrinsic spectrum, convoluted with the apparatus transfer function G, and the measured spectrum; c) determining the value of a predetermined regularizing function S by inserting the approximated intrinsic spectrum in this function; d) forming a functional F=&khgr;2+&agr;S containing a regularizing constant &agr;; e) solving the regularizing constant &agr; from said functional, the N eigenvalues &lgr;1 . . . &lgr;N of an NÃ—N auxiliary matrix A formed from the apparatus transfer function and the approximated intrinsic spectrum being determined during said solution process; f) executing a minimizing process on the functional F with the last regularizing constant &agr; found, using the N data points of the intrinsic spectrum as variables, the N data points thus found constituting a next approximated intrinsic spectrum; g) repeating the steps b) to f), if necessary, until a predetermined convergence criterion has been satisfied; h) identifying the approximated intrinsic spectrum then valid as the intrinsic spectrum searched; characterized in that for the determination of the N eigenvalues &lgr;1 . . . &lgr;N N of the NÃ—N auxiliary matrix A, the auxiliary matrix is subdivided into a number of L partial auxiliary matrices Pj (j=1 . . . L) which are situated around the diagonal of the auxiliary matrix A, and that the eigenvalues of each partial auxiliary matrix Pj are determined separately, the set of eigenvalues &lgr;1 . . . &lgr;N of the NÃ—N auxiliary matrix A consisting of the set of all eigenvalues of the partial auxiliary matrices Pj.