Thermo Electron Scientific Instruments Corporation

Noran Instruments, Inc.

James V Howard

Kevin K Kim

Mark E Misenheimer

Damian W Ashmead

William E Drummond

Dean A Stocker

Andrew Martin Braasch

David R Fahrbach

Jon J McCarthy

David B Rohde

James Ronald Hyatt

Tom Jacobs

Bruce R Weber

An embodiment of a path length calibration system is described that comprises a swing arm coupled to a first surface; a base coupled to a second surface configured to receive the sample; a position sensor system comprising a first component coupled to the swing arm and a second component coupled to the base, wherein the position sensor system is configured to provide an output voltage when the swing arm is in a down position; and a processor configured to calibrate a zero path length using the output voltage.

Path length calibration system and method

An apparatus includes a first pedestal surface coupled to i) a swing arm and to ii) a light source. The apparatus further includes a magnet, a base plate, a mechanical stop coupled to the base plate, and a second pedestal surface mechanically coupled to said base plate and configured to receive a liquid sample, said second pedestal surface being coupled to a spectrometer. The apparatus further includes a magnetic flux sensor located between north and south magnetic flux fields of the magnet such that the magnetic flux reaching the sensor while the mechanical stop is in physical contact with the swing arm provides a linear range of output of the magnetic flux sensor, and a processor adapted to calibrate the point for minimum optical path length using a threshold magnetic flux field emitted from the magnet and detected by the magnetic flux sensor.

An X-ray detector using a semiconductor detector, most preferably a Silicon Drift Detector, utilizes a field effect transistor or other voltage-controlled resistance to generate an output voltage proportional to its input charge (which is generated by the X-ray photons incident on the semiconductor detector). To keep the charge (and thus the output voltage) to an acceptable range&#x2014;one wherein the relationship between output voltage and input charge is substantially proportional&#x2014;a feedback circuit is provided between the output and input terminals, wherein the charge on the input terminal is depleted when the output voltage begins leaving the desired range. Preferably, this is done by a comparator which monitors the output voltage, and provides a reset signal to the input terminal when it begins moving out of range. Alternatively or additionally, the reset signal may be a pulse supplied to the input terminal from a pulse generator activated by the comparator.

Feedback circuit for output control in a semiconductor X-ray detector

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

An x-ray collimator for wavelength dispersive spectroscopy and the like includes a grazing incidence mirror optic having a polycapillary x-ray optic nested therein. The polycapillary x-ray optic is mounted in a hollow bore of the grazing incidence mirror optic so as not to interfere with operation of the grazing incidence mirror. The polycapillary x-ray optic extends the range of the grazing incidence mirror optic to higher energy ranges. The x-ray collimator of the present invention may be employed in a wavelength dispersive x-ray spectrometer including a diffracting element positioned to receive x-rays collimated by the x-ray collimator, and an x-ray detector positioned to receive the x-rays defracted by the diffracting element. A wavelength dispersive x-ray spectrometer in accordance with the present invention may be used in combination with an energy beam microscope, such as an electron microscope, to analyze x-rays emanating from a sample specimen.

Growing community of inventors

Madison, WI, United States of America

James V Howard