Thermo Electron Scientific Instruments Corporation

Nicolet Instrument Corporation

James Ronald Hyatt

Francis Jerome Deck

James V Howard

Kevin K Kim

William E Drummond

George Douglas Jones

Dean A Stocker

Mark E Misenheimer

David R Fahrbach

William Joseph McCarthy

Louie Delaware

Todd R Clermont

Gabor John Kemeny

John R O'Keefe

Steven Ralph Lowry

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

A multifunctional infrared spectrometer system has an interferometer which receives the infrared beam from a source and provides a modulated output beam on beam paths to multiple spatially separated infrared detectors. A multi-position mirror element mounted at a junction position receives the beam on a main beam path and directs it on branch beam paths to sample positions, with the beam then being directed on the branch beam path to one of the detectors. One of the branch beam paths may include a sample holder at the sample position which can index between a position at which a sample is analyzed, to a reference material position, to a pass-through position for calibration purposes. The multi-position mirror element may also be indexed to direct the beam on a branch path to a fiber optic cable which has a probe at the end of it which may be inserted in a sample fluid or powder to be analyzed, with the reflected light from the probe being directed back on an optical fiber cable to a detector at the spectrometer. The multi-position mirror element may be moved to a position at which the beam is directed on a beam path to and through an integrating sphere to a solid sample, with the reflected light from the sample being directed by the surfaces of the integrating sphere to a detector. A detector may be mounted to detect the light transmitted through the sample to obtain measurements of both reflected and transmitted infrared light at the sample.

Multifunctional fourier transform infrared spectrometer system

A circuit for automatically matching the gain and offset of a time-shifted digitizing channel in a data acquisition circuit which includes a reference digitizing channel, having a fixed voltage reference, and at least one time-shifted digitizing channel having components that are adjustable for gain and offset. Feedback is provided by examining the dynamic range and average value of a known input signal which is digitized, sent through the time-shifted digitizing channel and stored in memory. A microprocessor reads the stored data and, by separately varying the gain and offset parameters, computes optimal values for each parameter. Digital-to-analog converters (DAC's) allow the microprocessor to communicate with one fixed-gain variable-offset amplifier in the front end and with one fixed-gain variable-offset amplifier and one analog-to-digital converter (ADC) in each time-shifted digitizing channel. By controlling the offset of the amplifiers and the reference level of the ADC, precise matching of the gain and offset of the time-shifted digitizing channel with the gain and offset of the reference digitizing channel may be performed easily and inexpensively. The circuit may be extended to an arbitrary number of additional time-shifted digitizing channels and provides a comparatively simple, inexpensive way to automatically match the gain and offset of each time-shifted digitizing channel.

Method and apparatus for automatically calibrating the gain and offset

Digital data acquisition apparatus for periodically sampling a waveform. Periodic data acquisition signals are provided at predetermined intervals with the waveform being sampled at the predetermined intervals in response to the data acquisition signals. The apparatus has at least a first operation mode wherein waveform sampling is initiated on the occurrence of a trigger event. In this operation mode, the apparatus includes an improvement for increasing its effective sample rate by providing a first data acquisition signal, following a trigger event, at an interval after the trigger event that is shorter than the interval between subsequent data acquisition signals. A second mode of operation may also be provided wherein sampling is manually initiated. In either operation mode, a phase locked loop may be employed to regulate, or tune, the interval between data acquisition signals.

Digital data acquisition apparatus

Growing community of inventors

Madison, WI, United States of America

James Ronald Hyatt