Abstract: An automatic fluid sampler works in conjunction with a conventional oil well test system. The sampler utilizes a rotating platter which aligns the mouth of a sampling container with a conduit for delivery of a composite sample which is provided in incremental volumes over the duration of a well test event. Upon completion of the well test, a fresh container is rotated to be in position to receive a composite sample for a new well test event.

Abstract: Systems and methods for determining olefin concentrations in olefin-containing fuels (e.g., gasoline) are described. Generally, a Raman spectrum from a linear-calibration reference sample (e.g., a pure hydrocarbon, such as toluene) and Raman spectra from multiple simulated fuel samples having known olefin concentrations are obtained. An area ratio for each simulated fuel sample is created by dividing the area in the olefin region of each fuel sample by the area in the chemical spectral region of the linear-calibration reference sample. The area ratio and the known olefin concentration for each simulated sample are used to create a linear olefin calibration. The olefin concentration of a fuel sample with an unknown olefin concentration is calculated by determining the area ratio between the olefin spectral region in the unknown sample and the chemical spectral region in a concentration-calculation reference sample (e.g., toluene) and placing the new area ratio into the linear olefin calibration.

Abstract: An optical fiber multiplexer having a fixed plate and a rotating plate. A plurality of fiber-optic channels are coupled to the fixed plate in a circumferential arrangement. One fiber-optic channel is coupled to the rotating plate. Each fiber-optic channel may include one or more separate optical fibers. A servo motor rotates the rotating plate. Switching between channels occurs by rotating the rotating plate and aligning the optical fibers on the fixed plate and the rotating plate. Lens-to-lens coupling is used to transmit optical signals between the rotating and fixed plates. An adjustment device, such as a gimbal mount, may be used to adjust the horizontal and vertical axial alignment of the optical fibers coupled to the fixed plate so that optimum light signal transmission can occur. A control unit controls the operation of the servo motor.

Abstract: One aspect of the present invention relates to a digitally controlled resistance standard, comprising a control system, a resistor element, hermetically sealed within an element assembly, a temperature/frequency measuring circuit for measuring the temperature of the resistor element and the frequency of an input signal, a heating/cooling assembly for raising and lowering the temperature of the resistor element a temperature controller for controlling the heating/cooling assembly, and a control system having a CPU. The control system is operable to execute computer instructions for storing the baseline characteristics of the resistor element, retrieve the temperature of the resistor element from the temperature/frequency measuring circuit, determine the actual resistance value of the resistor element, and adjust the actual resistance value of the resistor element to match a target resistance value using the temperature controller. A method for improving the accuracy of a resistance standard is also given.

Abstract: Raman spectrometer for analyzing the chemical composition of sample streams using an external cavity laser light source is disclosed. The laser provides an effective light source useful in continuously analyzing a sample stream containing petroleum products, aqueous or biological fluids, or solid slurries. The light is introduced into a bundle of optical fibers connected to a Raman sample cell. The Raman sample cell is configured to allow continuous sample flow therethrough. Scattered light from the sample cell preferably exits the optical fibers as a linear optical signal. A Raman spectrometer passes the optical signal through an excitation wavelength filter, an optical slit, and a volume holographic transmission grating with an aberration correction device before transmitting the optical signal to a charge coupled device array which converts the optical signal into a electronic signal.

Abstract: A spectrograph for analyzing the chemical composition of a sample is disclosed. Scattered light from a sample cell is collected by one or more optical fibers and is introduced into a collimating lens as a linear optical signal. The collimating lens directs the optical signal to a reflective diffraction grating which reflects the signal into a focusing lens. The focusing lens focuses the optical signal onto a charge coupled device array which converts the optical signal into a electronic signal. Aberration correction is provided by the collimating and focussing lenses. The electronic signal is analyzed and converted by computer into a representation of the chemical analysis of the sample stream.

Abstract: Apparatus and methods for analyzing the chemical composition of fluid streams using Raman spectroscopy are disclosed. The invention is particularly useful in continuously analyzing a fluid stream containing petroleum products, aqueous or biological fluids. The apparatus includes a laser source for producing light having an excitation wavelength. The light is introduced into a bundle of optical fibers connected to a tubular Raman enhancement cell. A transparent optical element (lens and/or window) acts as a barrier element to isolate the flowing sample stream from the optical components. The Raman enhancement cell is configured to allow continuous sample fluid flow therethrough, and it is preferably lined with a material having an index of refraction less than the index of refraction of the fluid stream. Scattered light from the enhancement cell preferably exits the optical fibers as a linear optical signal.