Thermo Electron Scientific Instruments Corporation

Tom Jacobs

James V Howard

David B Rohde

Mark E Misenheimer

Bruce R Weber

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.

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Madison, WI, United States of America

Tom Jacobs