X-ray detector for electron microscope
AssigneeFEI Company
InventorsHanno Sebastian von Harrach, Bert Freitag, Pleun Dona
Life of this patent
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Abstract
Multiple detectors arranged in a ring within a specimen chamber provide a large solid angle of collection. The detectors preferably include a shutter and a cold shield that reduce ice formation on the detector. By providing detectors surrounding the sample, a large solid angle is provided for improved detection and x-rays are detected regardless of the direction of sample tilt.
Claims35
An x-ray detector assembly for an electron microscope, comprising:
- a mount configured for being supported within the lens of a transmission electron microscope;
- at least two x-ray detectors supported by the mount, the x-ray detectors arranged to receive x-rays from at least three different directions from a sample, each detector including;
- a cold shield at least partly surrounding the detector;
- and
- a heat source to maintain the detector at a higher temperature than the cold shield
A method of determining three-dimensional positional and compositional information about a microscopic specimen, comprising:
- scanning an electron beam across the sample;
- detecting x-rays characteristic of the material in the sample using multiple x-ray angularly spaced around the sample, the x-rays caused to be emitted from the sample by the impact of the electron beam;
- determining from the difference in the x-ray signals detected by the multiple detectors the position of the source of the x-rays along the beam direction;
- and
- improving the accuracy of compositional information by means of the difference in attenuation of the x-ray signal detected by the multiple detectors.
A transmission electron microscope or scanning transmission electron microscope, comprising:
- a source of electrons;
- a lens including an upper pole piece and a lower pole piece;
- a sample holder for positioning a sample between the upper and lower pole pieces;
- at least two x-ray detectors positioned circumferentially around the sample so that an x-ray signal is detectable regardless of which direction the sample is facing.
A transmission electron microscope or scanning transmission electron microscope, comprising:
- a source of electrons;
- a lens including an upper pole piece and a lower pole piece;
- a sample holder for positioning a sample between the upper and lower pole pieces;
- at least three x-ray detectors positioned circumferentially around the sample and supported by the lower pole piece or the upper pole piece.
A transmission electron microscope or scanning transmission electron microscope, comprising:
- a sample holder for positioning a sample between the upper and lower pole pieces;
- at least one x-ray detector positioned to receive x-rays form the sample;
- a cold shield positioned near the at least one x-ray detector to reduce condensation onto the x-ray detector, the cold shield being maintained at a temperature of at least 20 degrees cooler than the x-ray detector;
- a single cooling conduit for removing heat from the cold shield and from the x-ray detector, the single cooling conduit being connected to the cold shield, the cold shield being connected to the x-ray detector through a thermally resistive pathway.
The apparatus of claim 35 further comprising a heating element in thermal contact with the x-ray detector.
Dependencies are inferred from the claim text.