Thermo Electron Scientific Instruments Corporation

Thermo Noran, Inc.

David B Rohde

Patrick Paul Camus

James V Howard

Mark E Misenheimer

Gregory S Fritz

Tom Jacobs

Bruce R Weber

An X-ray spectroscope collects an energy-dispersive spectrum from a sample under analysis, and generates a list of candidate elements that may be present in the sample. A wavelength dispersive spectral collector is then tuned to obtain X-ray intensity measurements at the energies/wavelengths of some or all of the candidate elements, thereby verifying whether or not these candidate elements are in fact present in the sample. Additionally, the alignment of the wavelength dispersive spectral collector versus the sample can be optimized by tuning the wavelength dispersive spectral collector to the energy/wavelength of a selected one of the candidate elements&#x2014;preferably one whose presence in the sample has been verified, or one which has a high likelihood of being present in the sample&#x2014;and then varying the alignment of the wavelength dispersive spectral collector versus the sample until the wavelength dispersive spectral collector returns the maximum intensity reading for the selected candidate element. Intensity readings for the other candidate elements can then be collected at this optimized alignment.

Synergistic energy-dispersive and wavelength-dispersive X-ray spectrometry

A system for performing spectral microanalysis delivers analysis results during the course of data collection. As spectra are collected from pixels on a specimen, the system periodically analyzes the spectra to statistically derive underlying spectra representing proposed specimen components, wherein the derived spectra combine in varying proportions to result (at least approximately) in the measured spectra at each pixel. Those pixels having the same dominant proposed component, and/or which contain at least approximately the same proportions of the proposed components, may then have their measured spectra combined (i.e., added or averaged). These spectra may then be cross-referenced via reference libraries to identify the components actually present. During the foregoing analysis, the measured spectra are preferably condensed, as by reducing the number of energy channels/intervals making up the measured spectra and/or by combining the measured spectra of adjacent pixels, to reduce the size of the data cube and expedite analysis results.

Automatic material labeling during spectral image data acquisition

In an analytical instrument having a radiation detector, such as an electron microscope with an X-ray detector, a thermoelectric element (such as one or more Peltier junctions) is driven by a cooling power supply to cool the detector and thereby decrease measurement noise. Oil condensates and ice can then form on the detector owing to residual water vapor and vacuum pump oil in the analysis chamber, and these contaminants can interfere with measurement accuracy. To assist in reducing this problem, the thermoelectric element can be powered in the reverse of its cooling mode, thereby heating the detector and evaporating the contaminants. After the detector is cleared of contaminants, it may again be cooled and measurements may resume. Preferably, the thermoelectric element is heated by a power supply separate from the one that provides the cooling power, though it can also be possible to utilize a single power supply to provide both heating and cooling modes.

Deicing of radiation detectors in analytical instruments

A system and method for correcting automatically the distortions in electron background diffration (EBSD) patterns which result from magnetic fields produced by some scanning electron microscopes (SEMs) used for collecting such patterns from polycrystalline sample materials. The method may be implemented as a software program running on a computer which is part of a conventional system for obtaining and analyzing EBSD patterns to obtain crystallographic information about the sample material. The method includes a calibration procedure and a correction procedure. In the calibration procedure, a distorted EBSD pattern obtained from a calibration sample is displayed on an operator display and user interface. Using an input device, an operator defines segment endpoints along a Kikuchi band in the distorted EBSD pattern image. From the user defined segment endpoints, correction parameters are calculated based on a mathematical curve (e.g., cubic spline) fitting the endpoints. The correction parameters may also be corrected automatically, without user intervention. The correction parameters are saved and may be used to correct magnetic field distortions in all subsequent EBSD patterns obtained using the SEM geometry for which the calibration procedure is run. In the correction procedure, the correction parameters are employed to shift lines of pixels in the distorted EBSD pattern image by an amount defined by the correction parameters to correct the distortion in the EBSD pattern image. Thus corrected EBSD pattern images may be displayed to a operator of the system and saved for subsequent EBSD pattern analysis using conventional EBSD pattern analysis techniques.

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Madison, WI, United States of America

David B Rohde