Abstract: An improved and lower cost color spectrophotometer, especially suitable for on-line color printer color control systems, incorporating a low cost commercial imaging chip, which normally only forms part of a three row, three color, document imaging bar used for imaging documents in scanners, digital copiers, or multifunction products, having multiple photo-sites with at least three different color filters in three rows. This multiple photo-sites chip may be modified to also provide unfiltered photo-sites. This spectrophotometer may have a substantially reduced number of different LED or other spectral illumination sources, one of which may be for white light, yet provide multiple spectral data outputs from the differently filtered photo-sites being simultaneous illuminated by the light reflected from a color test target area which is being sequentially illuminated by the respective limited number of LEDs, enabling broad spectrum information and color control.

Abstract: A method for detecting the presence of signal channels in a wavelength-multiplexed optical signal comprises the steps of providing an initial estimate of channels to obtain a coarse spectral match, performing a coarse nonlinear deconvolutional algorithm on the wavelength-multiplexed optical signal, and finding peak power levels of the signal in the initially estimated channels. The signal channels are selected from the initially estimated channels based upon the peak power levels. In an embodiment, power levels in the signal channels of the wavelength-multiplexed optical signal are determined with refined accuracy by performing a fine nonlinear deconvolutional algorithm. In a further embodiment, the coarse and fine nonlinear deconvolutional algorithms are performed by using Jansson's nonlinear iterative method. The method is applicable to the testing of wavelength-multiplexed optical signals generated by broadband dense wavelength division multiplexers (DWDMs) and other optical communications devices.

Abstract: An apparatus and system are provided for simultaneously analyzing a plurality of analytes anchored to microparticles. Microparticles each having a uniform population of a single kind of analyte attached are disposed as a substantially immobilized planar array inside of a flow chamber where steps of an analytical process are carried out by delivering a sequence of processing reagents to the microparticles by a fluidic system under microprocessor control. In response to such process steps, an optical signal is generated at the surface of each microparticle which is characteristic of the interaction between the analyte carried by the microparticle and the delivered processing reagent The plurality of analytes are simultaneously analyzed by collecting and recording images of the optical signals generated by all the microparticles in the planar array.

Abstract: Method and compositions are provided for the determination of telomere length and telomerase activity, as well as the ability to inhibit telomerase activity in the treatment of proliferative diseases. Particularly, primers are elongated under conditions which minimize interference from other genomic sequences, so as to obtain accurate determinations of telomeric length or telomerase activity. In addition, compositions are provided for intracellular inhibition of telomerase activity and means are shown for slowing the loss of telomeric repeats in aging cells.

Abstract: The invention concerns a device and a method for carrying out fluorescence immunoassays, wherein from at least one light source light is directed onto a surface at one end of a light waveguide and with the light coupled into the light waveguide by evanescent field excitation at the surface of the light waveguide fluorescence of at least one labelling substance bound to a chemical or biochemical partner of a general receptor-ligand system is excited. The solution according to the invention is here to provide a possible way of carrying out fluorescence immunoassays with high accuracy of measurement at low cost and within a short time. To achieve this object, the fluorescent light is decoupled from the light waveguide and directed via an optical system onto an optical detector with which the intensity of the fluorescent light is measured.

Abstract: A spectrophotometric instrument including a source of measurement light signals having measurement light wavelengths, and a probe having a tissue-engaging surface, a plurality of send fibers coupled to the measurement light signal source for transmitting the measurement light signals to the tissue-engaging surface, and a plurality of receive fibers for receiving light including the measurement light signals after the measurement light has been transmitted through the tissue.

Abstract: A spectrometer or multiple wavelength absorbance detection method and apparatus providing improved accuracy for an array of measurements at different wavelengths. The spectrometer utilizes a multiple wavelength illumination system with an array of independent detectors with different pathlength cells, where each cell is illuminated with predominately monochromatic light after separation by a light dispersing element. Each sample cell has an optical pathlength, optics and photodetection device that are optimized for its particular wavelength to accurately measure absorbance through an expected substance.

Abstract: A biosensor comprises a waveguide into which light is coupled by a diffraction grating. The sample to be analyzed is placed on a reaction region in which a component of the immunological reaction is provided, for example antibodies or antigens. Fluorescence is excited on the surface of the waveguide because of the presence of a marker for example, a labelled antigen or antibody. Fluorescence is decoupled from the waveguide by the coupling diffraction grating or another diffraction grating. The waveguide is made of a material emitting light when it is excited by the marker excitation beam. This latter emission has a peak wavelength different from that of the emission radiation due to the marker used in the immunological reaction. Waveguide material fluorescence emission provides a reference during measurement.

Abstract: A method of calculating optical frequency spectrum for use in an optical-spectrum measuring apparatus for measuring optical spectrum characteristics of a light source. In the method, a bandwidth storage section stores a characteristic of a bandwidth of passed wavelengths with respect to a measuring wavelength of a spectrometer. A CPU obtains a bandwidth of wavelengths with respect to each measuring point in accordance with the stored bandwidth of wavelengths. Then, measured intensities of light at the measuring points are used to add measured values across the measured value in a required range of bandwidth of optical frequencies. Moreover, correction is performed in accordance with a ratio of the bandwidth of wavelengths at each of the measuring points and the intervals of wavelength at the measuring points. Thus, an intensity of light at each of the measuring points is obtained.

Abstract: A surface plasmon resonance apparatus for detecting a soluble analyte (e.g. a protein) or a particulate analyte (e.g. a cell), the apparatus comprising: (a) a sensor block adapted to receive a sensor, said sensor, for example a sensor slide, having a metallised sensor surface capable of binding the analyte; (b) a light source capable of generating an evanescent wave at the sensor surface of a sensor slide on the sensor block; (c) a first detector capable of detecting light from the light source which is internally reflected from the sensor surface; and (d) a second detector (e.g. a video camera) capable of detecting light scattered or emitted from an analyte bound thereto. Optionally the apparatus further comprises a second light source for increasing the intensity of the light scattered or emitted from an analyte bound to the sensor surface, preferably this is sited to such as to minimise the amount of light transmitted therefrom which is detected by the first detector.

Abstract: In order to analyze a medical sample while avoiding error contributions due to hemolysis, prior to the main reaction for a component present in the sample, a pre-reaction is produced and measured by which the degree of hemolysis in the sample is determined and the result of the sample to be determined that is subsequently obtained is corrected by this error contribution using the relationship (correlation) that has been found between the degree of hemolysis and the error contribution.

Abstract: Apparatus and methods for measuring light transmitted from a sample. The apparatus may include a stage, a light source, and a detector. The stage may be configured to hold a microplate having a plurality of sample wells. The apparatus may be configured to take frequency-domain time-resolved measurements of one or more of luminescence lifetimes and reorientational correlation times of a luminescent analyte in the sample.

Abstract: The present invention can accurately detect a wavelength of a light to be detected, which is output from a source of light to be detected, without an error even if there is a change in the characteristic of a spectroscope due to an individual difference among the spectroscopes or a change in the measuring environment. The device according to the invention emits at least two reference lights (Ln, La) having different wavelengths (&lgr;n, &lgr;a) as the reference lights by reference light source. And, actual characteristic value (D) of spectroscope is calculated on the basis of detection positions (Sn, Sa) of the at least two reference lights (Ln, La) on a sensor and the known wavelengths (&lgr;n, &lgr;a) of the at least two reference lights (Ln, La) (D=(&lgr;a−&lgr;n)/(Sa−Sn)).

Abstract: Described herein is an optical measurement instrument for a living body, comprising light incident means for simultaneously applying incident light of a wavelength in a visible-infrared region to a plurality of incident positions on the surface of a subject, light detection means for simultaneously detecting lights obtained by allowing the incident light to pass through the subject, at a plurality of detection positions on the surface of the subject, and imaging means for imaging information on the inside of the subject using detected signals outputted from the light detection means. The light incident means includes light modulation means for intensity-modulating the incident light applied to the plurality of incident positions with modulation frequencies respectively different every the respective incident positions.

Abstract: A readhead for a spectrometer for illuminating a target area and receiving light from said target area is provided with a housing adapted to be incorporated in a spectrometer, a light source mounted in a fixed position relative to the housing, a support mechanism adapted to support a biological sample to be illuminated by the light source, a light-shaping mechanism disposed between the light source and the support for increasing the diameter, intensity, and uniformity of the light beam, and a photodetector mounted in fixed position relative to the housing, the photodetector being adapted to detect light from a biological sample disposed in the target area illuminated light sources. The light sources may be in the form of a light-emitting diode that emits substantially monochromatic light having a first wavelength, and the readhead may also include a second light-emitting diode that is adapted to emit substantially monochromatic light of a second wavelength towards the target area.

Abstract: The present method of processing spectral data calculates the first to fourth derivative spectra of an original spectrum with respect to the wavenumber and creates a two-dimensional representation by plotting coordinates consisting of the derivative values of some order as their abscissas and the original spectral values or derivative values of another order different from that order as their ordinates. In this two-dimensional plotting, maximal points, minimal points, maximal slope points (inflection points) and the like are clearly represented, so that a great amount of accurate feature information about the analyzed object can be easily obtained.

Abstract: Confirming sufficient mixture uniformity between a reagent and liquid sample experiencing a kinetic reaction by comparing the amount of light absorbed within the mixture after the reaction begins with the amount of light absorbed within the solution at the completion of the reaction and requiring that the difference between measured amounts of absorbed light be less than a predetermined value.

Abstract: The present invention includes an apparatus configured for identification of a material, and methods of identifying a material. One embodiment of the invention provides an apparatus including a first region configured to receive a first sample, the first region being configured to output a first spectrum corresponding to the first sample and responsive to exposure of the first sample to radiation; a modulator configured to modulate the first spectrum according to a first frequency; a second region configured to receive a second sample, the second region being configured to output a second spectrum corresponding to the second sample and responsive to exposure of the second sample to the modulated first spectrum; and a detector configured to detect the second spectrum having a second frequency greater than the first frequency.

Abstract: One or both of two methods and systems are used to determine concentration of a known material in an unknown mixture on the basis of the measured interaction of electromagnetic waves upon the mixture. One technique is to utilize a multivariate analysis patch technique to develop a library of optimized patches of spectral signatures of known materials containing only those pixels most descriptive of the known materials by an evolutionary algorithm. Identity and concentration of the known materials within the unknown mixture is then determined by minimizing the residuals between the measurements from the library of optimized patches and the measurements from the same pixels from the unknown mixture. Another technique is to train a neural network by the genetic algorithm to determine the identity and concentration of known materials in the unknown mixture. The two techniques may be combined into an expert system providing cross checks for accuracy.

Abstract: Systems and methods for providing an ultra-stable measurement of the density of a fluid/gas species such as ozone in a mixture. The technique is based on information extracted from multi-wavelength light absorption, at which the species exhibits different absorption properties (coefficient values). The technique provides real-time compensation for short- and long-term instability in the light source and detector, and for detectable changes in the optical characteristics of the cell, thus improving the accuracy of the measurement while making frequent zeroing of the instrument unnecessary. In addition, the invention provides a high-performance technique for measuring ultra-high ozone densities using absorption at the Chappuis band.

Abstract: One or both of two methods and systems are used to determine concentration of a known material in an unknown mixture on the basis of the measured interaction of electromagnetic waves upon the mixture. One technique is to utilize a multivariate analysis patch technique to develop a library of optimized patches of spectral signatures of known materials containing only those pixels most descriptive of the known materials by an evolutionary algorithm. Identity and concentration of the known materials within the unknown mixture is then determined by minimizing the residuals between the measurements from the library of optimized patches and the measurements from the same pixels from the unknown mixture. Another technique is to train a neural network by the genetic algorithm to determine the identity and concentration of known materials in the unknown mixture. The two techniques may be combined into an expert system providing cross checks for accuracy.

Abstract: The concentration of the active ingredient in a rolling oil emulsion can be rapidly determined, and correction of the concentration of the active ingredient can be undertaken by measuring the measuring the amount of light reflected from the emulsion at the peak absorbing wavelength of the dye to obtain a first reflectance value and measuring the amount of light reflected from said emulsion at a wavelength other than the peak absorbing wavelength of the dye to obtain a second reflectance value for at least two different concentrations of the rolling oil in the rolling oil emulsion, establishing a calibration curve, and then monitoring the rolling oil emulsion in like manner. The results may be utilized to feed additional additive to the emulsion, or may be used to feed water into the emulsion system.

Abstract: In an analysis system including as light sources an incandescent lamp and a blue light emitting diode, the light of the two sources is combined and directed through filters and a test tube with material to be examined to a photodiode array spectrometer. The filters are so selected that they counteract the intensity drop of the incandescent lamp and the sensitivity decrease of the photodiode array of the spectrometer at short wave lengths.

Abstract: A method of superficial laser induced fluorescence for measuring film cooling performance within a fluid tunnel apparatus includes the step of introducing a test fluid uniformly dyed with a fluorescent dye into the fluid tunnel apparatus so as to surround a cooling model having a test geometry. The cooling model is positioned adjacent to a laser sheet. A background fluorescent image of the test fluid about the cooling model is recorded. The test fluid is then flushed from the tunnel apparatus. Next, a cooling simulation fluid flow and a hot gas simulation flow are introduced within the fluid tunnel apparatus. The cooling simulation fluid contains the same fluorescent dye concentration as the test fluid and the hot gas simulation fluid contains no fluorescent dye. A data image of the cooling simulation fluid flow is recorded about the cooling model as the cooling simulation fluid flow passes through the cooling model and into the hot gas simulation fluid flow.

Abstract: There is disclosed fiber optic sensor which detects a sample in contact with the sensor by surface plasmon resonance (SPR) measurements, as well as methods and apparatus relating thereto. The fiber optic SPR sensor of this invention employs a limited range of incident angles and uses incident light having multiple wavelengths. In preferred embodiments, both an in-line transmission-based fiber optic SPR sensor and a terminated reflection-based fiber optic SPR sensor are disclosed. The fiber optic SPR sensor includes a surface plasmon supporting metal layer in contact with an exposed portion of the optical fiber core, and may optionally contain one or more additional layers deposited on the surface plasmon supporting metal layer.

Abstract: A system and method for optical interrogation and measurement of a hydrocarbon fuel gas includes a light source generating light at near-visible wavelengths. A cell containing the gas is optically coupled to the light source which is in turn partially transmitted by the sample. A spectrometer disperses the transmitted light and captures an image thereof. The image is captured by a low-cost silicon-based two-dimensional CCD array. The captured spectral image is processed by electronics for determining energy or BTU content and composition of the gas. The innovative optical approach provides a relatively inexpensive, durable, maintenance-free sensor and method which is reliable in the field and relatively simple to calibrate. In view of the above, accurate monitoring is possible at a plurality of locations along the distribution chain leading to more efficient distribution.

Abstract: A technique for making precise spectrophotometric measurements illuminates a sample with two or more modulated light sources at two or more, typically closely spaced, wavelengths. Light from the sources is combined, homogenized, and directed to the sample, and the light from the sample is collected and detected by a photodetector. The optical output powers of two sources are modulated with the same periodicity and with a reversed amplitude. Variations in the concentrations of species in the sample affect the modulation amplitude representing the sum of the optical powers from two sources in such a way as to produce an output signal. That output signal, based on an electrical component varying with a periodicity at the fundamental frequency, provides a measure of the difference in the transmissions (or other optical properties) of the sample at the two wavelengths. Feedback methods, such as null-point detection, provide stable, sensitive measurements.

Abstract: A carousel receives a plurality of removable reagent containers, a turntable receives a plurality of sample fluid containers and a rotatable cuvette assembly holds an annular array of reaction and test cuvettes. A robotic arm carrying a fluid transfer needle coupled to a pair of syringes picks up one or more reagents and sample fluid for deposit into a cuvette. As the arm moves the needle tip exterior is washed and contaminants sent to a waste collector. At the end of a test cycle, the needle core is flushed and cleaned. A colorimetry photometric test is performed on the reacted fluids in each cuvette by a system employing ten interference filters, corresponding diode detectors and amplifiers employing two identical multiplexers providing identical filtered signals for logarithmic calculation of absorbance.

Abstract: A waveguide sensing element has a substrate having an input opening adapted to house an input optical fiber and an output opening adapted to house an output optical fiber. The input optical fiber transmits electromagnetic radiation, and the output optical fiber emits the electromagnetic radiation. The waveguide sensing element also has a guiding layer disposed adjacent the substrate. The guiding layer has a beveled end face. The angle of the bevel is chosen so that the guiding layer selects only those modes within a given range--i.e., high order modes. This increases the spectral absorption measurement sensitivity as compared to a waveguide sensing element which uses the complete mode spectrum. Such a highly sensitive waveguide sensing element has been found to be particularly useful as an internal reflection spectroscopic sensing element.

Abstract: The invention relates to fiber optic methods and devices for sensing physical parameters, like temperature or force, by converting a fraction of the intensity of the interrogating light into a positive signal with wavelengths and/or light propagation modes different from those of the interrogating light. Preferred embodiments make use of the redistribution of the intensity of the interrogating light between the core and a secong light-guiding region of an optical fiber probe, and the processing of the light carried by said second light-guiding region into a positive signal separable from the interrogating light.

Abstract: A device is provided which passes light of preselected wavelengths through a fluid, gas or vapor to be tested. The light is detected after it has passed through the fluid, gas or vapor. Upon detection, a voltage is created which is proportional in amplitude to the detected light strength for each wavelength of light. These voltages are compared to produce a ratio which represents the condition of the fluid, gas or vapor which is tested or the presence of an analyte of interest. When the ratio is outside of preselected boundaries, control signals are generated which may trigger alarms or otherwise respond to the condition. In a preferred embodiment of the invention, the presence of carbon gases such as carbon monoxide and carbon dioxide is detected in gases or vapors.

Abstract: Method of assay of enzymatic activity, comprising projecting excitation light to a sample containing an enzyme, a substrate which forms a product by action of the enzyme, and a reference substance which is insensitive to the action of the enzyme but emits fluorescence; obtaining a first measured value of fluorescence intensity of the sample at a first wavelength region which includes fluorescence emitted by the substrate or the product at least, obtaining a second measured value of fluorescence intensity at a second wavelength region which is different from the first wavelength region for the first measured value and includes fluorescence emitted by the reference substance; and assaying the enzymatic activity from the ratio of the first measured value to the second measured value and apparatus for performing the method. The method assures high accuracy and high sensitivity of measurement in enzyme labeled immunoassay and enzyme labeled DNA hybridization.

Abstract: A visual inspection apparatus (18) is disclosed for viewing welds between pipe sections (26, 28). The apparatus (18) can be part of a combination plug clamp and inspection apparatus (12) or used independently of the plug clamp (12). The TV camera (20) is aimed along the center line axis (52) of the apparatus and pipeline and a mirror (76) reflects the image of a portion of the weld into the lens of the camera. The mirror can be rotated to allow the entire circumference of the weld to be inspected. A weighted ring (102) provides a reference relative to the vertical independent of the orientation of the apparatus within the pipeline.

Abstract: There is disclosed fiber optic sensor which detects a sample in contact with the sensor by surface plasmon resonance (SPR) measurements, as well as methods and apparatus relating thereto. The fiber optic SPR sensor of this invention employs a limited range of incident angles and uses incident light having multiple wavelengths. In preferred embodiments, both an in-line transmission-based fiber optic SPR sensor and a terminated reflection-based fiber optic SPR sensor are disclosed. The fiber optic SPR sensor includes a surface plasmon supporting metal layer in contact with an exposed portion of the optical fiber core, and may optionally contain one or more additional layers deposited on the surface plasmon supporting metal layer.

Abstract: A differential spectrometry system detects very narrow-band spectral features, while providing much higher optical transmittance and signal-to-noise ratios than prior optical-filter-based spectrometer systems. A plurality of light detectors (10a, 10b) detect light that falls within respective wide wavebands. The wide wavebands have overlapping and non-overlapping portions, one of which is the desired narrow waveband. The detector outputs are operated upon to produce an output signal (22) which includes substantially only the desired narrow waveband. In the preferred embodiment, the light detectors (10a, 10b) are implemented with a pair of optical detectors (30a, 30b) and respective optical interference filters (24a, 24b). The filters have substantially identical cut-off wavelengths (.lambda..sub.2) and cut-on wavelengths that are shifted by .DELTA..lambda. with respect to each other (.lambda..sub.1 and (.lambda..sub.1 +.DELTA..lambda.), respectively).

Abstract: A compact laser diode monitor for measuring concentrations of individual atomic and molecular species in both gaseous and semitransparent fluids, includes a first diode laser having an output for resonantly exciting a first selected electronic transition of a specific atomic or molecular species of a sample, and a second diode laser having an output for resonantly exciting a second selected electronic transition of said specific atomic or molecular species of said sample. A difference between said first and second frequency outputs is equal to a vibrational energy level difference of the specific atomic or molecular species. Further said first and second frequency outputs are simultaneously directed into said sample, with selected momentum vectors in order to cause the selected atomic or molecular species to emit a coherent photon signal in a selected direction having a frequency equal to twice the first frequency output minus the second frequency output.

Abstract: A method for analyzing the structures of chemical organic compounds, polymers, polynucleotides and peptides is disclosed. The method uses the integrated intensity of spectral light absorption in wide or narrow regions of the ultraviolet and/or visible spectrum and relates these parameters additively to the structural characteristics of the analyzed chemical compound. For the analysis of polymers, nucleotides and/or peptides the integrated intensities of spectral absorption are used sequentially in narrow regions of the ultraviolet light which enables the determination of the molecular weight and the complete amino acid composition of the analyzed compound. All these procedures are interconnected in an automatic spectrophotometric structural analyzer.

Abstract: A method and apparatus are provided for selecting and analyzing a subpopulation of cells or cell objects for a certain parameter such as DNA using image analysis means. The cells are first stained with an alkaline phosphatase technique including a monoclonal antibody specific to a protein in at least one of the cell's cytoplasm or on a cell membrane, thereby marking any cells including the protein as to type. A second staining of the DNA in the nucleus is accomplished by a Feulgen technique that destroys the cell cytoplasm. After the staining and marking, the cells may then be gated using the image analysis means on the visual parameter such as colored DNA or colored antigen into a subpopulation that is to be measured. The selected cells may then be examined by digital image processing and measured for a parameter such as a true actual measurement of DNA in picograms. A quantitation of the measured parameter may be generated and provided.

Abstract: A method for directly measuring the concentration of biocides in aqueous systems comprising directly determining an absorbance or emission spectrum of the aqueous system in a wavelength range of from 200 to 2500 nm and applying chemometrics algorithms to the spectrum to determine the concentration of the biocides.

Abstract: Methods and devices for sensing temperature changes at a plurality of locations use a light-transmitting optical fiber system along a path including said locations, said optical fiber system having a first end and a second end and a sensing element of said locations, each sensing element being so characterized that, when exposed to the temperature changes to be sensed and transmitting interrogating light of suitable wavelength or wavelengths .lambda..sub.v and an intensity P.sub.o, it converts a fraction .alpha.P.sub.o of the intensity of said interrogating light into a light separable from the interrogating light, at least part of the intensity of which is emitted from at least one of said two ends of the probe at wavelengths .lambda..sub.f different from .lambda..sub.v, where .alpha. is a temperature-dependent fraction smaller than unity, the value of which increases with increasing temperature within a temperature range, the intensity of said light of wavelengths .lambda..sub.

Abstract: A spectrometer comprises a tunable interferometer for producing a monochromatic continuous image at an image plane and including two mirrors having substantially parallel surfaces and an adjustable spacing therebetween, a radiation detector located at the image plane for recording the image, a filter arrangement for allowing at least one predetermined range of wavelengths to pass to the detector, and a lens arrangement for collecting radiation and limiting radiation incident on the interferometer to an angle which is substantially perpendicular to the substantially parallel surfaces of the two mirrors.

Abstract: Methods and apparatus for determining in a biological material one or more unknown values of at least one known characteristic (e.g. the concentration of an analyte such as glucose in blood or the concentration of one or more blood gas parameters) with a model based on a set of samples with known values of the known characteristics and a multivariate algorithm using several wavelength subsets. The method includes selecting multiple wavelength subsets, from the electromagnetic spectral region appropriate for determining the known characteristic, for use by an algorithm wherein the selection of wavelength subsets improves the model's fitness of the determination for the unknown values of the known characteristic. The selection process utilizes multivariate search methods that select both predictive and synergistic wavelengths within the range of wavelengths utilized. The fitness of the wavelength subsets is determined by the fitness function F=.function.(cost, performance).

Abstract: A method of photometric in vitro determination of the content of an analyte in a sample is disclosed. The sample is located in a measuring chamber which has a radiation path length and has at least one at least partially transparent wall part. The measuring chamber is in optical communication with an optical system adapted for the analyte which includes a radiation source and a radiation detector. The measuring chamber is adjustable in shape which enables the radiation path length across the measuring chamber to be changed. In a first measuring step an unknown first radiation path length across the measuring chamber is set and radiation at at least two wavelengths is transmitted from the radiation source through the measuring chamber and to the radiation detector. In a second step, the measuring chamber is adjusted in shape thereby setting a second unknown path length across the measuring chamber.

Abstract: A new method for accurately and sequentially growing monolayers and creating new superlattice structures employing a MBE thermal source control technique employing a quasi-double beam atomic absorption background correction measurements with the beam blocked and with the beam unblocked and by calculating the concentration based on the: ##EQU1## and applying corrections for non-linear absorption curves because of comparable spectral bandwidth of the molecular beam.

Abstract: The invention relates to methods and devices for measuring physical parameters by converting a fraction of the intensity of the interrogating light into a positive optical signal with wavelengths and/or light propagation modes different from those of the interrogating light, and having at least one characteristic which is a known function of the physical parameter being measured. The invention is adapted to the measurement of distributed forces and/or temperatures along a continuous length of optical fiber, and to the non-invasive coupling of information into an optical fiber from the side at any point or a multiplicity of points. The optical fiber is so designed that information signals coupled into it simultaneously at different points are separable at one end of the fiber and measurable without interference from each other.

Abstract: There is disclosed fiber optic sensor which detects a sample in contact with the sensor by surface plasmon resonance (SPR) measurements, as well as methods and apparatus relating thereto. The fiber optic SPR sensor of this invention employs a limited range of incident angles and uses incident light having multiple wavelengths. In preferred embodiments, both an in-line transmission-based fiber optic SPR sensor and a terminated reflection-based fiber optic SPR sensor are disclosed. The fiber optic SPR sensor includes a surface plasmon supporting metal layer in contact with an exposed portion of the optical fiber core, and may optionally contain one or more additional layers deposited on the surface plasmon supporting metal layer.

Abstract: A glucose monitor, and related method, determines the concentration of glucose in a sample by monitoring fluorescent light produced directly by any glucose present in the sample. The glucose monitor illuminates the sample with ultraviolet excitation light that induces any glucose present in the sample to fluoresce, with the fluorescent light being monitored and processed to determine the concentration of glucose in the sample. A sensor monitors the return light, which includes fluorescent light produced by any glucose in the sample, and generates first and second electrical signals indicative of the intensity of light in two wavelength bands. One wavelength band includes a characteristic spectral peak of glucose fluorescence, and the other wavelength band is a reference band having known spectral characteristics. A processor then processes the first and second electrical signals to determine the concentration of glucose in the sample.

Abstract: A dual wavelength optical sensor for measuring chemical properties of a particular quantity, the optical sensor including a sensor probe having a thin sensing film whose optical characteristics are responsive to the chemical properties of the measured quantityThe United States Government has certain rights in this invention pursuant to Contract No. ITA87-02 between the U.S. Department of Commerce and Iowa State University.

Abstract: Methods and apparatus for accurately determining the volume of a pipette using a photometer. A reagent system for use with the photometer includes a first container holding a reference solution and at least one second container holding a sample solution. A container holding the reference solution having maximum absorbance at a first wavelength is positioned in the photometer. The absorbances of the container at the first wavelength and at a second wavelength are measured. Then the optical pathlength of the container at the second wavelength is calculated from the measured absorbances at the first and second wavelengths. An aliquot of the sample solution is introduced into the container with a pipette to be calibrated. The sample solution has maximum absorbance at the second wavelength. The sample solution is mixed with the reference solution to form a mixture. Then the absorbance of the mixture in the container is measured at the second wavelength.

Abstract: A device is provided which passes light of preselected wavelengths through a fluid or vapor to be tested. The light is detected after it has passed through the fluid or vapor. Upon detection, a voltage is created which is proportional in amplitude to the detected light strength for each wavelength of light. These voltages are compared to produce a ratio which represents the condition of the fluid or vapor which is tested. When the ratio is outside of preselected boundaries, control signals are generated which may trigger alarms or otherwise respond to the condition.