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EP-4024037-B1 - PARALLEL IMAGE SEGMENTATION AND SPECTRAL ACQUISITION

EP4024037B1EP 4024037 B1EP4024037 B1EP 4024037B1EP-4024037-B1

Inventors

  • KOCÁR, Darius

Dates

Publication Date
20260513
Application Date
20201230

Claims (17)

  1. A system configured for material analysis and mineralogy, comprising a scanning microscope system (100), the scanning microscope system (100) comprising a first detector (111) and a second detector (112), and further comprising a data-processing system (800), the data-processing system (800) comprising a data-storage component (810) and a segmentation component (820), wherein the data-storage component (810) is configured for providing at least one image of a sample based on first emissions from a plurality of first scan locations, wherein the first detector is configured for detecting the first emissions from the first scan locations, wherein the segmentation component (820) is configured for determining at least one or a plurality of second scan location(s) for at least one or a plurality of region(s) of the at least one image, wherein the second detector (112) is configured for detecting second emissions from at least one of the second scan locations of at least one of the regions, characterised in that the system is further configured for determining the second scan location(s) for the region(s) and detecting the second emissions from the at least one of the second scan locations of the at least one of the regions in parallel, wherein the data processing system (800), particularly the segmentation component (820), is configured for determining each second scan location for the duration time of a segmentation dwell period, and wherein the segmentation dwell period depends on image properties, such as the resolution and the magnification of the at least one image.
  2. The system according to the preceding claim, wherein the scanning microscope system (100) is configured for focusing a beam of charged particles (such as electrons) to a scan point on the sample and/or is configured for scanning the beam of charged particles over a plurality of scan locations in one or two dimensions, wherein the scan locations correspond to the first scan locations and/or the second scan locations.
  3. The system according to any of the preceding claims, wherein the scanning microscope system is configured for generating the first emissions (109) and the second emissions (110).
  4. The system according to any of the preceding claims, wherein the first detector (111), is configured for detecting the first emissions (109) for the duration time of a first dwell period at each first scan location, and/or the second detector (112) is configured for detecting the second emissions (110) for the duration time of a second dwell period at each second scan location.
  5. The system according to any of the preceding claims, wherein the data-processing system (800) is configured for generating the at least one image based on the first emissions (109) detected at each first scan location, and/or the at least one image corresponds to a backscattered electron image.
  6. The system according to any of the preceding claims, wherein the data-processing component (800) comprises a pre-processing component (830), wherein the pre-processing component (830) is configured for dividing the at least one image into at least two or a plurality of sub-images, wherein a sub-image of the at least one image is delimiting one region relating to a particle in the sample (108).
  7. The system according to any of the preceding claims, wherein the segmentation dwell period is shorter than or equal to the second dwell period.
  8. The system according to any of the preceding claims, wherein the data-processing system further comprises a post-processing component (840), wherein the post-processing component is configured for generating at least one spectrum based on the second emissions from the at least one of the second scan locations of the at least one of the regions, wherein the at least one spectrum corresponds to an X-ray spectrum.
  9. A method for determining properties of a sample, wherein the method comprises using a system according to any of the claims 1-8, the method comprising: • performing an image providing step, comprising providing at least one image of the sample based on first emissions from a plurality of first scan locations; • performing a segmentation step, comprising determining at least one or a plurality of second scan location(s) for at least one or a plurality of regions of the at least one image; • performing a detection step, comprising detecting second emissions from at least one of the second scan locations of at least one of the regions; characterised in that • performing the segmentation step and the detection step in parallel; • determining each second scan location for the duration time of a segmentation dwell period, wherein the segmentation dwell period depends on image properties, such as the resolution and the magnification of the at least one image.
  10. The method according to the preceding claim, wherein the method further comprises focusing a beam of charged particles (such as electrons) to a scan point on the sample and/or scanning the beam of charged particles over a plurality of scan locations in one or two dimensions, wherein the scan locations correspond to the first scan locations and/or the second scan locations.
  11. The method according to any of the two preceding claims, wherein the method further comprises generating the first emissions (109) and the second emissions (110).
  12. The method according to any of the claims 9-11, wherein the method further comprises detecting the first emissions for the duration time of a first dwell period at each first scan location, and/or the detection step comprises detecting the second emissions for the duration time of a second dwell period at each second scan location.
  13. The method according to any of the claims 9-12, wherein the method comprises generating the at least one image based on the first emissions (109) detected at each first scan location, and/or the at least one image corresponds to a backscattered electron image.
  14. The method according to any of the claims 9-13, wherein the method further comprises a pre-processing step, wherein the pre-processing step comprises dividing the at least one image into at least two or a plurality of sub-images, wherein a sub-image of the at least one image is delimiting one region relating to a particle in the sample (108).
  15. The method according to any of claims 9-14, wherein the segmentation step comprises determining each second scan location for the duration time of a segmentation dwell period, wherein the segmentation dwell period is shorter than or equal to the second dwell period.
  16. The method according to any of the claims 9-15, wherein the method further comprises a post-processing step, wherein the post-processing step comprises generating at least one spectrum based on the second emissions from the at least one of the second scan locations of the at least one of the regions, wherein the at least one spectrum corresponds to an X-ray spectrum.
  17. A computer program product comprising instructions which, when the program is executed by a data-processing system, cause the data processing system to perform the steps for which the data-processing system of the system according to any of the claims 1 - 8 is configured.

Description

Field The present invention relates to the field of spectroscopy and image analysis. The present invention further relates to determining properties of a sample, e.g. by means of a parallel implementation of spectral acquisition and image segmentation. Background Material studies that involve characterizing the properties (e.g., structure, topography and chemical composition) of probes in the micro- and nanoscopic regime, can be performed through the implementation of scanning microscope systems, such as scanning electron microscopes (SEMs). A SEM is configured to scan the surface of the sample with a primary beam (i.e., an electron beam) and acquire an image of the sample based on various types of emissions e.g., emissions of backscattered, transmitted or secondary electrons. These emissions result from the interaction of the electron beam with the particles of the sample (such as atoms). In case of mineral studies, the sample consists of many thousands of mineral grains in particles embedded in an epoxy matrix. Backscattered electrons (BSE) originate from the primary electron beam, which, as the name suggests, are reflected back (i.e., out of the sample) via elastic scattering on the sample atoms. The number of backscattered electrons at each scan location on the sample depends on the atomic number of the chemical elements (e.g., mineral elements) located in the corresponding scan location. Thus, the brightness variations (e.g., gray-level variations) within a BSE image are indicative of the compositional variations within the sample. Along with the emissions of backscattered electrons, emissions of X-rays can also emerge from the interaction of the primary beam with the sample. In particular, characteristic X-rays are emitted when primary electrons cause the ejection of an electron in an inner shell of a sample atom, creating an electron hole. This electron hole is then filled by another electron from an outer atomic shell through the emission of an X-ray photon. The energy of that X-ray photon corresponds to the energy difference between the outer and inner shell. Thus, the emitted X-rays have energies that are unique for the corresponding chemical elements and their detection can therefore reveal the chemical composition of the sample. For the detection of X-ray emissions, SEMs are equipped with X-ray spectrometers that are configured to measure the number of detected X-rays with respect to their energies (energy-dispersive spectrometers, EDS) or their wavelengths (wavelength-dispersive spectrometers, WDS). Material analysis (e.g., mineralogy classification) commonly involves coupling the backscattered electron imaging process with the application of X-ray spectroscopy. However, the X-ray acquisition takes a few milliseconds per scan location, while the BSE acquisition at each scan location can be three to four orders of magnitude faster. Thus, obtaining the compositional information of the entire sample based on the X-ray detection from tens or hundreds of thousands of scan locations can be highly time-consuming, lasting from several minutes to a few hours. For this reason, a common measurement mode for material studies (e.g., mineralogy classification) that has been disclosed in the EP patent 2 546 638 B1, is to reduce the number of scan locations for the X-ray detection. This is done by acquiring a high-resolution BSE image and processing (segmenting) the image in order to identify parts (e.g., mineral grains) of the same contrast and thus the same chemical composition (e.g., mineral composition). For each identified mineral grain only one scan location is determined. The primary beam is then positioned at the scan location of each identified grain in order to detect the corresponding X-ray emissions and obtain the respective X-ray spectrum. However, a reliable grain identification and the production of corresponding scan locations requires complex algorithms that take significant time to execute (in relation to the X-ray acquisition time). Typical BSE image segmentation time for the entire sample can be low tens of seconds, during which the SEM is completely idle. An example of a current solution is to apply a fast and simple algorithm that finishes the segmentation sooner. However, this can lead to a problem called over-segmentation, which involves determining more than one scan location for each mineral grain, creating that way misidentified mineral grains. As a result, this can cause additional post-processing overhead, during which the scan locations of each grain are merged into one scan location. Furthermore, the post-processing step may not be able to merge all misidentified grains. This in turn can result to an over-acquisition of misidentified grains during the X-ray acquisition phase, thus increasing the total acquisition time. Another current solution is to constantly scan the beam over the sample, during which X-rays are continuously collected from arbitrary locations. While that modali