Sub-pixel analysis and display of fine grained mineral samples

Patent metadata

Field	Value
Publication number	US-9714908-B2
Application number	US-201314073523-A
Country	US
Kind code	B2
Filing date	Nov 6, 2013
Priority date	Nov 6, 2013
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

Method and apparatus for analysis and display of fine grained mineral samples. A portion of the sample is illuminated with a charged particle beam. Emitted radiation is detected, and a sample emission spectrum is generated and fit with a plurality of standard emission spectra of minerals in a candidate mineral composition. A mineral composition whose emission spectrum best fits the sample emission spectrum is selected from a plurality of candidate mineral compositions. An assigned color is received for each mineral in the selected mineral composition, and the assigned colors are blended according to the proportion of each mineral in the selected mineral composition. An image pixel corresponding to the portion of the sample is rendered for display.

First claim

We claim as follows:

1. A computer implemented method for displaying a mineral composition of a sample, comprising:
illuminating a portion of the sample with a charged particle beam;
generating, via one or more processors, a sample emission spectrum from detected emissions from the sample;
fitting the sample emission spectrum with a plurality of candidate emission spectra, wherein each candidate emission spectrum comprises a combination of the emission spectra from a plurality of minerals in proportions that are determined by the fit to the sample emission spectrum;
identifying an emission spectrum from among the plurality of candidate emission spectra based on a quality of fit to the sample emission spectrum, wherein the identified emission spectrum comprises a plurality of identified minerals in a respective plurality of identified proportions;
assigning a plurality of colors respectively corresponding to the plurality of identified minerals; and
rendering an image pixel corresponding to the illuminated portion of the sample by assigning the image pixel a definite color based on the plurality of identified minerals by blending the plurality of colors respectively corresponding to the plurality of identified minerals according to the respective plurality of identified proportions.

2. The method of claim 1 , wherein the charged particle beam is at least one of an electron beam, a proton beam or an ion beam.

3. The method of claim 1 , wherein generating the sample emission spectrum from detected emissions from the sample comprises generating a sample x-ray emission spectrum from detected x-ray emissions from the sample.

4. The method of claim 1 , wherein fitting the sample emission spectrum with a plurality of candidate emission spectra comprises using a curve fitting minimization technique to fit the sample emission spectrum with the plurality of candidate emission spectra.

5. The method of claim 1 , wherein generating the sample emission spectrum from detected emissions from the sample further comprises sub-sampling the emission spectrum as a function of energy.

6. The method of claim 1 , wherein fitting the sample emission spectrum with a plurality of candidate emission spectra further comprises using a weighted curve fitting minimization technique to fit the sample emission spectrum with the plurality of candidate emission spectra.

7. A computer implemented method for displaying a mineral composition of a sample, comprising:
illuminating a portion of the sample with a charged particle beam;
generating, via one or more processors, a sample emission spectrum from detected emissions from the sample;
receiving a plurality of candidate mineral compositions from a list of candidate mineral compositions, wherein each candidate mineral composition includes a plurality of minerals;
determining, for each of the plurality of candidate mineral compositions, a proportion for each of the plurality of minerals in the candidate mineral composition by fitting the sample emission spectrum with a candidate emission spectrum formed from a combination of emission spectra from the plurality of minerals in the candidate mineral composition;
identifying a candidate mineral composition whose candidate emission spectrum is a best fit to the sample emission spectrum;
assigning a plurality of colors respectively corresponding to the plurality of minerals in the identified candidate mineral composition; and
rendering an image pixel corresponding to the illuminated portion of the sample by assigning the image pixel a definite color based on the plurality of identified minerals through blending the plurality of colors respectively corresponding to the plurality of minerals in the identified candidate mineral composition according to the determined proportion for each of the plurality of minerals.

8. The method of claim 7 , wherein the charged particle beam is at least one of an electron beam, a proton beam or an ion beam.

9. The method of claim 7 , wherein generating the sample emission spectrum from detected emissions from the sample comprises generating a sample x-ray emission spectrum from detected x-ray emissions from the sample.

10. The method of claim 7 , wherein generating the sample emission spectrum from detected emissions from the sample further comprises sub-sampling the sample emission spectrum as a function of energy.

11. The method of claim 7 , wherein fitting the sample emission spectrum with a plurality of candidate emission spectra further comprising using a weighted least squares algorithm to fit the sample emission spectrum with the plurality of candidate emission spectra.

12. An apparatus for determining and displaying a mineral composition of a sample, comprising:
a charged particle beam source for illuminating a portion of the sample;
a detector for detecting radiation emitted from the illuminated portion of the sample; and
one or more processors configured to:
generate a sample emission spectrum from the detected radiation emitted from the illuminated portion of the sample;
fit the sample emission spectrum with a plurality of candidate emission spectra, wherein each candidate emission spectrum comprises a combination of the emission spectra from a plurality of minerals in proportions that are determined by the fit to the sample emission spectrum;
identify an emission spectrum from among the plurality of candidate emission spectra based on a quality of fit to the sample emission spectrum, wherein the identified emission spectrum comprises a plurality of identified minerals in a respective plurality of identified proportions;
assign a plurality of colors respectively corresponding to the plurality of identified minerals; and
render an image pixel corresponding to the illuminated portion of the sample by assigning the image pixel a definite color based on the plurality of identified minerals by blending the plurality of colors respectively corresponding to the plurality of identified minerals according to the respective plurality of identified proportions.

13. The apparatus of claim 12 , wherein the charged particle beam source is at least one of an electron beam source, a proton beam source or an ion beam source.

14. The apparatus of claim 12 , wherein the one or more processors generate the sample emission spectrum from the detected radiation emitted from the illuminated portion of the sample by generating a sample x-ray emission spectrum from detected x-ray emissions from the sample.

15. The apparatus of claim 12 , the one or more processors fit the sample emission spectrum with a plurality of candidate emission spectra using a least squares analysis.

16. An apparatus for determining and displaying a mineral composition of a sample, comprising:
a charged particle beam source for illuminating a portion of the sample;
a detector for detecting radiation emitted from the illuminated portion of the sample; and
one or more processors configured to:
generate a sample emission spectrum from the detected radiation emitted from the illuminated portion of the sample;
receive a plurality of candidate mineral compositions from a list of candidate mineral compositions, wherein each candidate mineral composition includes a plurality of minerals;
determine, for each of the plurality of candidate mineral compositions, a proportion for each of the plurality of minerals in the candidate mineral composition by fitting the sample emission spectrum with a candidate emission spectrum formed from a combination of emission spectra from the plurality of minerals in the candidate mineral composition;
id

Assignees

• Fei Co

Inventors

• Owen Michael James
• Howell Garth
• Donaldson Ashley

Classifications

• H01J2237/225

  Displaying image using synthesised colours · CPC title

• H01J2237/2442

  Energy-dispersive (Si-Li type) spectrometer · CPC title

• G01N23/225 Primary

  using electron or ion · CPC title

• G01N2223/402

  mapping distribution of elements · CPC title

• G01N2223/616

  earth materials · CPC title