Abstract: An electrical circuit provides a variety of stable and reliable bias voltages to accommodate the bias requirements of various sensor types. The electrical circuit comprises a programmable analog circuit capable of maintaining a plurality of programmable threshold voltages and producing a plurality of intermediary voltages. Such voltages act as an input to a differential amplifier that outputs a bias voltage within a range consistent with said programmable threshold voltages. The bias voltage is further conditioned by a conditioning amplifier that further stabilizes the bias voltage to an attached sensor.

Abstract: A Fourier-transform (FT) infrared (IR) spectrometer includes a Michelson interferometer without an IR beam compensator. An input IR beam is directed through a substrate and a beamsplitter attached to the substrate for support, with the input IR beam divided by the beamsplitter into a first beam portion incident upon a fixed retroreflector and a second beam portion incident upon a movable retroreflector. The first and second beam portions are then recombined to provide an uncompensated output IR beam with an interference pattern which is directed onto a sample to provide an uncompensated interferogram. The uncompensated interferogram is converted from a time domain to a frequency domain via a Fourier-transform to provide a complex intermediate spectrum, followed by a calculation of a corrected phase angle in terms of wavenumber arising from the substrate's optical thickness. The complex intermediate spectrum is then rotated by a negative of the corrected phase angle.

Abstract: A thermal gravimetric analyzer includes a reaction tube disposed within a heating element and including a sample container disposed therein. A reaction gas is introduced at a first end of the reaction tube and allowed to react with the sample, while a purge gas is introduced at a second, opposed end of the reaction tube to isolate a beam system, from which the sample and sample container are suspended, from the reaction gas. A Fourier transform infrared (FTIR) spectrometer as well as a mass spectrometer coupled to the reaction tube may be used to analyze the off-gas products of the reaction of the sample with the reaction gas. Sniffer tubes are used to provide off-gas samples to the two spectrometers, with each sniffer tube having a first inlet end disposed immediately adjacent the sample container and a second outlet end coupled to a sample inlet port of a respective spectrometer.