Abstract: A method for monitoring changes in a gap which corresponds to changes in a particular environmental parameter using a tunable laser and interferometer at high frequency is disclosed. The laser light provided to the interferometer is swept through a small range of wavelengths. Light modulated by the interferometer is detected and a non-sinusoidal light intensity output curve is created, a reference point on the curve identified and subsequent sweep of the laser performed. The difference in time, wavelength, or frequency at the occurrence of the reference point between the two sweeps allows for measuring the relative changes in the gap and, as a result, the change in the environmental parameter.

Abstract: A signal conditioner to measure the length of an interferometric gap in a Fabry-Perot sensor (interferometer). The invention includes a light source, a Fabry-Perot interferometer capable of spanning a range of gaps in response to physical changes in the environment, a second interferometer that is placed in series with the Fabry-Perot interferometer which does not filter any particular wavelengths of light but acts as an optical cross-correlator, a detector for converting the correlated light signal into electronic signals, and an electronic processor which controls system elements and generates a signal indicative of the length of the gap spanned by the Fabry-Perot sensor.

Abstract: A method and apparatus for quantitatively measuring the distance of an unknown variable gap is disclosed. Light is provided to two Fabry-Perot interferometers arranged in a series, one spanning the unknown gap and the other spanning a controllably variable gap. Means for verifying the positioning of the Fabry-Perot interferometer having the controllably variable gap work in conjunction with a signal processor, a correlation burst signal detector and means for conveying the light to the various system elements to perform a comparison of detector signals from the two interferometers and quantitatively establish the gap distance. The invention may also be varied to function on a time basis, include more than one source of light, possess filter means to distinguish between light sources and/or include one or more reference interferometers.

Abstract: Linear variable reflector sensors can be used to measure the displacement of objects. These sensors are useful in that they can be very small, do not conduct electricity, and are resistant to electrical interference from EMI/EMP and lightning strikes. The present linear variable reflector system comprises a light source, a light transmitting member in optical communication with the light source, a sensor in optical communication with the light transmitting member. The sensor comprises a moveable transparent body, a reflective material deposited on the transparent body, and at least one film deposited over said reflective material, wherein said reflective material reflects light. Further, the linear variable reflector system comprises a detector coupled to the sensor to detect displacement of the moveable transparent body.

Abstract: A fiber optic monitor that utilizes optical phase interferometry to monitor a patient's vital signs such as respiration, cardiac activity, blood pressure and body's physical movement. The monitor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acousto-mechanical signals from the patient are coupled into the optical fiber. Responsive thereto, the interferometer generates a time-varying optical intensity resulting from the interference of optical signals, which are detected at a photo-detector. A signal processor coupled to the optical detector provides one or more processed output signals indicative of the vital functions. The monitor system has broad applicability, from routine monitoring of infants at home to detection of apnea, arrhythmia, blood pressure and trauma.

Abstract: A fiber optic monitor that utilizes optical phase interferometry to monitor a patient's vital signs such as respiration, cardiac activity, blood pressure and body's physical movement. The monitor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acousto-mechanical signals from the patient are coupled into the optical fiber. Responsive thereto, the interferometer generates a time-varying optical intensity resulting from the interference of optical signals, which are detected at a photo-detector. A signal processor coupled to the optical detector provides one or more processed output signals indicative of the vital functions. The monitor system has broad applicability, from routine monitoring of infants at home to detection of apnea, arrhythmia, blood pressure and trauma. The system can be implemented in embodiments ranging from a low cost in-home monitor for infants to a high end product for in hospital use.

Abstract: A fume sensor system that measures the concentration of fume particulate in a boiler and suppresses background noise.

Abstract: An apparatus and method for sensing temperature within a broad temperature range, includes a fiber optic having an etalon at one end for reflecting light supplied at an opposite end by a pair of light sources operating at different wavelengths. The light sources are either applied to the optical fiber at different times for discriminating between the wavelengths and producing a temperature signal based on the two wavelengths, or the light is simultaneously applied to the optical fiber from both sources and thereafter divided into its component wavelengths before reflected and reference light detectors detect light signals at the different wavelengths. Known etalon/optical fiber based temperature sensors having a usual maximum temperature range of 500° C. are thus modified to increase their range to as much as double this range.

Abstract: An apparatus and method for sensing temperature within a broad temperature range, includes a fiber optic having an etalon at one end for reflecting light supplied at an opposite end by a pair of light sources operating at different wavelengths. The light sources are either applied to the optical fiber at different times for discriminating between the wavelengths and producing a temperature signal based on the two wavelengths, or the light is simultaneously applied to the optical fiber from both sources and thereafter divided into its component wavelengths before reflected and reference light detectors detect light signals at the different wavelengths. Known etalon/optical fiber based temperature sensors having a usual maximum temperature range of 500.degree. C. are thus modified to increase their range to as much as double this range.

Abstract: A scintillating optical fiber sensitive to low energy radiation has a clear, solid, elongated core with a thin cladding layer surrounding substantially all of the core along substantially all the length of the core and a dye dopant dispersed within the thin cladding layer. When a low energy radiation particle contacts the thin cladding layer, energy from the particle is transferred to photons having a radiant energy frequency determined by the dye dopant color, and a fraction of the photons are transmitted through the fiber by total internal reflection. A detector using the scintillating optical fiber is also disclosed having a sensor for detecting and indicating the presence of photons operatively connected to an end of at least one optical fiber, such that when the fraction of photons are transmitted through the fiber by total internal reflection to the end, the sensor detects the photons and subsequently provides an indication that low energy radiation has been detected.

Abstract: A combine thresher has a multiple plate impedance cell grain moisture analyzer assembly with two of the plates being outside mounted ground plates to reduce EMI and RFI interference and provide more accurate moisture measurements. The assembly is ex-situ mounted to bypass a part of the grain flowing from the grain floor of the harvester to the grain accumulation bin to measure the moisture thereof and to exhaust same back into the mentioned grain flow. The analyzer has a bin full sensor to activate the bypass only when the analyzer is full for accurate moisture measurement.

Abstract: Lignin concentrations from wood pulp samples are measured by applying an excitation light at a selected wavelength to the samples in order to cause the lignin to emit fluorescence. A spectral distribution of the fluorescence emission is then determined. The lignin concentration is then calculated based on the spectral distribution signal. The spectral distribution is quantified by either a wavelength centroid method or a band ratio method.

Abstract: A method and apparatus of analyzing a burner flame comprises accumulating raw data such as radiate energy from the burner flame. A power spectrum and mutual information curve are generated from the raw data. A multi-dimensional attractor is also generated using the raw data which is analyzed in comparison to random data to determine whether the raw data is chaotic in nature. If the raw data is chaotic in nature, a Lyapunov exponent, Kolmogorov entropy or cross section of a chaotic attractor can be utilized as a measure of the quality of the flame and further used to control one or more parameters of the burner to adjust the flame.

Abstract: The displacement of a valve stem (16) is measured during diagnostic testing by temporarily mounting a laser head (112) on the valve body (18) or yoke (20), for generating a source laser beam (118) that reflects from a target (120) that moves with the stem. The timing of the reflected beam (132) returning to the head (112) relative to the projection of the source beam, gives an indication of the displacement of the stem.

Abstract: A fiber optic apparatus and method for monitoring color balance of a product that can consist of a complex two dimensional color pattern. This system employs at least one illuminating optical fiber (18) and at least two pick-up optical fibers (16). Filters (36) associated with each of the pick-up fibers (16) separate the reflected light into different color components. Photodetectors (38) convert the light intensity from each fiber (16) into analog electrical signals which are routed to a microprocessor based signal processing module (10) for conversion to digital output and subsequent analysis for monitoring color balance. If there is a change in color balance, a visual and/or acoustic alarm (62) is automatically activated.

Abstract: A method and appartus for measuring lignin concentration in an undiluted sample of wood pulp or black liquor comprises a light emitting arrangement for emitting an excitation light through optical fiber bundles into a probe which has a sensing end facing the sample. The excitation light causes the lignin concentration to produce fluorescent emission light which is then conveyed through the probe to analyzing equipment which measures the intensity of the emission light. Measures are taken to maximize the emission light intensity which is due to lignin concentration and distinguish it from background and interfering light. The fluorescent light intensity is found to drop off in a predictable manner with increased lignin concentration.

Abstract: A method and apparatus for measuring lignin concentration in a sample of wood pulp or black liquor comprises a light emitting arrangement for emitting an excitation light through optical fiber bundles into a probe which has an undiluted sensing end facing the sample. The excitation light causes the lignin concentration to produce fluorescent emission light which is then conveyed through the probe to analyzing equipment which measures the intensity of the emission light. Measures aThis invention was made with Government support under Contract Number DOE: DE-FC05-90CE40905 awarded by the Department of Energy (DOE). The Government has certain rights in this invention.

Abstract: A valve arrangement for use in measuring a wide range of gas flow rates, comprises a valve housing including one inlet for a gas flow and two outlets, one for a low flow rate and the other for high flow rate. A plug is vertically moveable in the housing and includes a large diameter lower end engageable against a seat for closing a large port in the housing, and a small diameter upper end for engagement against an upper small diameter seat in the housing. The large and small seats communicate with the high and low flow rate outlets. Ferromagnetic material forms at least part of each seat with the plug being magnetic for retaining either its upper or lower position depending on the inlet flow rate. With a high inlet flow rate, the plug is lifted from its lower seat to close its low flow rate outlet and open its high flow rate inlet. At low flow rate, gravity causes the plug to drop. This permits the passage of the low flow rate gas through the low flow rate outlet.

Abstract: A monitor for measuring the temperature distribution of a product (12) including a plurality of ball lenses (14) lying in a lenticular array (18) across the product (12). A signal processor (22) is connected to a photodiode array (20). Each photodiode in the array (20) is connected by a separate optical fiber (16) to one of the ball lenses (14).

Abstract: A method and apparatus for monitoring and measuring the level of ion exchange resin fragments in very pure water employs a laser light source to illuminate a water sample causing the resin fragments to fluoresce. This light of fluorescence is focused, filtered, and detected by a photodetector, whose electrical signal output is amplified and processed to provide an output related to the concentration of ion exchange resin fragments in the water. Separate calculations or a computer within the apparatus itself produce a measure of the concentration of the resin fragments in the sample. The apparatus and method are useful for maintaining purity of water in boilers employing condensate polisher systems, for example.