EDS CALIBRATION

20250110070

18/898430

September 26, 2024

A method comprises providing reference data indicative of at least one reference energy-dispersive x-ray spectrum, providing measured data indicative of at least one measured energy-dispersive x-ray spectrum obtained from a sample, and determining a transformation based on a comparison of the measured data with the reference data. A system configured to determine a transformation based on a comparison of measured data with reference data is also described.

1. A method, comprising: providing reference data indicative of at least one reference energy-dispersive x-ray spectrum; providing measured data indicative of at least one measured energy-dispersive x-ray spectrum obtained from a sample; and determining a transformation based on a comparison of the measured data with the reference data; the method further comprising detecting on the measured data calibration peaks; and wherein determining a transformation comprises determining at least one piecewise transformation based on the calibration peaks and the reference data.

2. The method according to claim 1, wherein the measured data comprises measured spectrum peaks; wherein the calibration peaks are a subset of the measured spectrum peaks; and wherein detecting on the measured data calibration peaks comprises classifying at least some of the measured spectrum peaks as calibration peaks.

3. The method according to claim 2, wherein classifying at least some of the measured spectrum peaks as calibration peaks is based on an intensity of the measured spectrum peaks relative to a background radiation intensity.

4. The method according to claim 2, wherein a particular measured spectrum peak is classified as a calibration peak if it is unobstructed such that any other measured spectrum peak in the measured data, present in the same measured spectrum as the particular measured spectrum peak, has an energy difference from the particular measured spectrum peak that exceeds an obstruction threshold.

5. The method according to claim 2, wherein detecting on the measured data calibration peaks comprises (a) for each measured spectrum in the measured data: (a1) detecting all measured spectrum peaks in the measured spectrum; (a2) rejecting measured spectrum peaks in the measured spectrum that comprise a peak-to-background ratio smaller than an intensity ratio threshold, wherein the peak-to-background ratio is a ratio between an intensity of the measured spectrum peak and a background radiation intensity; (a3) rejecting measured spectrum peaks in the measured spectrum that overlap with other measured spectrum peaks in that measured spectrum, wherein two peaks in a measured spectrum overlap if they comprise an energy difference that is smaller than an obstruction threshold; (b) grouping all non-rejected measured spectrum peaks from (a) in groups according to the x-ray emission line that they are indicative of; and (c) from each of the groups, determining the non-rejected measured spectrum peak with the highest peak-to-background ratio as a calibration peak.

6. The method according to claim 1, wherein each one of the at least one piecewise transformation is determined based on a respective pair of consecutive calibration peaks, wherein two calibration peaks are consecutive if no other calibration peak of the measured data comprises an energy between the energy of the two consecutive calibration peaks.

7. The method according to claim 1, wherein each one of the at least one piecewise transformation is selectively applied to a respective piecewise energy region of the reference data encompassing energies between or equal to respective energies of the respective pair of calibration peaks.

8. The method according to claim 1, wherein each one of the at least one piecewise transformation is a linear transformation.

9. The method according to claim 1, wherein the method comprises computing reference peak-width parameters for a plurality of reference spectrum peaks, respectively, wherein each reference peak-width parameter is indicative of an energy range encompassed by the respective reference spectrum peak; computing measured peak-width parameters for a plurality of measured spectrum peaks, respectively, wherein each measured peak-width parameter is indicative of an energy range encompassed by the respective measured spectrum peak; and wherein determining a transformation comprises determining a peak-width transformation based on the reference peak-width parameters and on the measured peak-width parameters.

10. The method according to claim 1, wherein determining a transformation comprises determining an end-to-end transformation based on a first measured spectrum peak, a second measured spectrum peak and the reference data; wherein the first measured spectrum peak is a first unobstructed measured spectrum peak with the lowest energy in the measured data and the second measured spectrum is a second unobstructed measured spectrum peak with the highest energy in the measured data; and wherein a particular measured spectrum peak is unobstructed if any other spectrum peak in the measured data, present in the same measured spectrum as the particular measured spectrum peak has an energy difference from the particular measured spectrum peak that exceeds an obstruction threshold.

11. The method according to claim 10, further comprising applying the transformation to the reference data to generate calibrated reference data.

12. The method according to claim 11, wherein applying the transformation comprises applying the at least one piecewise transformation at energy regions encompassing energies between a minimum and maximum energy of the calibration peaks, inclusive; and applying the end-to-end transformation at energy regions encompassing energies smaller than the minimum energy of the calibration peaks and energies larger than the maximum energy of the calibration peaks.

13. The method according to claim 9, wherein applying the peak-width transformation comprises adjusting the reference peak-width parameter of at least one reference spectrum peak using the peak-width transformation.

14. The method according to claim 10, further comprising determining elements contained in the sample by comparing the measured data to the calibrated reference data.

15. A system comprising: a beam source for emitting a beam onto a sample; an x-ray detector for detecting x-rays emitted from the sample upon impact of the beam; a computer readable memory storing reference data indicative of at least one reference energy-dispersive x-ray spectrum and computer instructions for: obtaining measured data indicative of at least one measured energy-dispersive x-ray spectrum obtained from a sample; and determining a transformation based on a comparison of the measured data with the reference data.

16. The system according to claim 15, wherein the computer readable memory further stores computer instructions for applying the transformation to the reference data to generate calibrated reference data.

17. The system according to claim 16, wherein the computer readable memory further stores computer instructions for: comparing the measured data with the calibrated reference data to determine elements contained in the sample.

18. The system according to claim 15, further comprising a data processing system configured to receive the computer instructions from the computer readable memory and to execute the computer instructions.

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