Abstract: A photon correlator comprises a plurality of sampling gates 11a-11e which are open during different periods of time; a plurality of memories 12a-12e each provided corresponding to each of the plurality of sampling gates 11a-11e for storing data corresponding to the number of photons; and a data processing control section for reading out the data stored in the memories 12a-12e, and performing a correlation calculation by means of software. The mechanism of the hardware comprising the sampling gates 11a-11e and memories 12a-12e enables high-speed writing of data in the memories and real-time read out of the data. In addition, the software performs correlation calculations in parallel with the above processing. Accordingly, the particle sizes and diffusion coefficient of particles in a fluid can be obtained at high speed under various conditions.

Abstract: A continuous wave laser excites a biological particle. Detection channels are created to detect light scattered by the biological particle, and to detect any auto-fluorescence emitted by the biological particle. Additional channels can also detect light emitted by auto-fluorescence of the biological particle when simultaneously excited by light at harmonics of the laser's fundamental wavelength. The biological particle is identified using Mie scattering and auto-fluorescence. Ratio-metric calculations generated by calculating ratios of detected peak heights or integrated pulse values in the channels provides additional information for identifying and classifying the biological particle. A warning or alert can be provided if the identified biological particle is a particle of interest.

Abstract: An apparatus and method permits measuring of near-direct forward scattering functions in water to enable acceptable underwater imaging for detection, classification, and identification of objects, such as mines. A source of light mounted on a housing member receiving ambient water emits a beam of light along an axis to a scattering detector assembly mounted on the base member. The detector assembly has a central active region disposed in the axis to receive portions of the light beam emitted along the axis and a plurality of concentric active regions are located radially outwardly from the central active region and the axis to receive scattered portions of the light beam. The central and concentric active regions provide signals representative of the magnitudes of the axial and scattered portions of the light beam for determination of the scattering function of the ambient water.

Abstract: A particle sizing method and apparatus of the PIDS type uses randomly polarized radiation to irradiate a particle sample. Portions of the resulting side scattering pattern are decomposed to simultaneously produce, for each decomposed portion, first and second linearly polarized beams of radiation in which the respective planes of polarization of the two beams are mutually perpendicular. Each of the polarized beams is focused onto a photodetector, and the respective photodetector outputs are differentiated to provide PIDS signals that are useful in calculating a particle size distribution for the sample.

Abstract: A method for determining optical properties of a target, using a plurality of transmitters for transmitting signals at the target, and a plurality of receivers for detecting reflected signals from the target, comprises the steps of: a) transmitting radiation signals with a plurality of wavelengths at the target; b) detecting trace reflected radiation signals from the target; c) modulating the plurality of transmitters with a waveform for generating transmitter modulation codes; d) mixing the transmitter modulation codes with the trace reflected radiation signals to generate total signals; e) transmitting the total signals at the target; f) detecting reflected total signals from the target; g) digitizing the reflected total signals with an analog-digital converter to generate digitized signals; h) integrating the digitized signals with decoding functions to extract individual signals from the total signals; and i) determining the optical properties of the target from the individual signals.

Abstract: The analytical method having both flow cytometery and cytodiagnosis functions comprises the steps of: preparing a sample containing particulate substances such as cells and viruses; injecting the sample into a plate-like sample container; centrifuging the sample container; and using the sample container in which a distribution of the particulate substances has been formed as a preparation for analysis. The preparation is scanned with a laser beam to obtain analytical data. An analytical device for this method is also provided.

Abstract: A device for determining the values of a parameter of particles, especially of water droplets, includes a measuring element having a measuring region that is intended to accommodate the particles. An illumination device illuminates the measuring region with a light beam, and an image acquisition device, having a camera, acquires an image of the measuring region illuminated by the illumination device. A processing device determines the values of the parameter from the image acquired by the camera. To determine the values of the parameter, the illumination device produces point illumination using a light beam whose light rays are focused on an objective optic of the image acquisition devices.

Abstract: A particle size distribution analysis apparatus comprising a sample measurement zone adapted to define a sample of particles, a light emitting means adapted to provide a source of light incident upon the sample measurement zone, and at least a first detection means adapted to measure light levels in the apparatus at particular scattering angles and output a signal to a computation means enabling the particle size distribution of particles contained within the sample to be determined, wherein the computation means is adapted, in use, to calculate a particle size distribution taking into account reflections by the measurement zone of light scattered off the particles.

Abstract: A method for determining absolute number densities of particles in a solution is disclosed based on a light scattering method. A light scattering photometer is calibrated to produce the Rayleigh ratio at each angle measured with respect to light scattered per unit incident intensity, per unit volume illuminated within the field of view of each detector per steradian subtended by said detector. In order that the numbers calculated be accurate, the illuminated particles should be effectively monodisperse. From the excess Rayleigh ratios measured at a plurality of angles with respect to the incident light beam illuminating said sample particles, an effective size is calculated which, in turn, is used to calculate the differential scattered intensity at each angle. The number of particles per unit volume element is then determined from the measured excess Rayleigh ratio divided by the corresponding differential scattered intensity.

Abstract: An improvement is provided for a system that identifies particles such as microorganisms in fluid by directing a laser beam (52) forwardly through a tiny detect zone (46) in the fluid and detecting the pattern of light scatter by a particle as it passes through the detect zone. The improvement includes a holographic optical element (60) positioned forward of the detect zone to intercept light scattered in multiple directions by the particle. The holographic optical element is divided into discrete areas, or sections, that each directs intercepted scattered light toward a selected photodetector (74, 90, 92) of a linear array (62) of photodetectors. A converging lens (106) reduces the required diffraction angles of the sections of the holographic optical element. This arrangement avoids the need to custom mount and connect numerous individual photocells, and enables simplified high speed readout of the photodetectors.

Abstract: This invention provides a particle size distribution measuring apparatus, which has a function of informing an operator of a procedure of validation work of the particle size distribution measuring apparatus. A storage medium which records validation data providing a procedure of validation work for the particle size distribution measuring apparatus and a control unit which has a validation help function which successively reads a validation procedure from the validation data and controls the particle size distribution measuring apparatus according to a measuring procedure without any operation by an operator in the validation procedure while teaching the operator a work procedure requiring an operation by the operator.

Abstract: The process is used for the screening of molecules from molecule libraries with regard to their individual binding behavior towards at least one given ligand. For this purpose the ligands labelled with a fluorescent dye are mixed with the molecule library which is in the form of a suspension. The mixture is plated out on a two-dimensional substrate (2) after the excess, unbound ligands have been washed out. Then the local fluorescence intensities on the substrate are electro-optically identified in a fluorescence microscope (5) and electronically discriminated in accordance with given selection criteria. The objects selected and localised in this way are then sequentially positioned exactly by a displacement, the coordinates of which are controlled by the image calculator, between the substrate (2) and a separation actuator (20, 21) and are spatially separated from the substrate (2) by the separation actuator (20, 21).

Abstract: An optical system for visualizing an object includes an object lens, an imaging lens disposed on an optical axis of the object lens, and a spatial filter disposed on the optical axis between the object lens and the imaging lens. The spatial filter includes a first portion away from the optical axis and a second portion adjacent to the optical axis, the first porting having a higher light transmittance than the second portion. The distance of the first portion from the optical axis is set to maximize the light from the object. This optical system is particularly useful for detecting an object in a light scattering medium. Movement of the optical system also allows a tomographic image to be generated.

Abstract: The present invention relates to an optical system for an apparatus for multi-part differential particle discrimination to facilitate analysis, classification, and sorting of various fluid components for presentation. The optical system is characterized by one or more of the following: a synchronized illumination beam and flow cell conduit, a flow cell arrangement to control back reflection, and light sensor arrangement to particularly gather a specific range of light scatter, such specific range of light scatter directly corresponding to at least one type of particle capable of being identified by the apparatus.

Abstract: Unique methods and apparatus are provided for rapidly identifying microscopic particles, such as protozoa and other microbes suspended in a fluid or gas.

Abstract: A wide range particle counter has sections which separately detect coarse and fine particles in an aerosol. The coarse particles are counted and sized in an optical particle counter. The fine particles are classified with a differential mobility analyzer to determine size and then passed through a vaporizer and condenser and also counted. Using the different sections permits counting and measuring a wide range of particle size in a single instrument with high accuracy and reliability.

Abstract: An apparatus for identifying microscopic particles in a fluid, includes a laser beam (16) that passes though a narrow detect zone (22), and photodetectors (30) that detect light scattered by microscopic particles that pass through the detect zone. The laser beam has a horizontal width (W) that is a plurality of times as great as its average vertical thickness (T), to increase the number of particles passing through the zone while minimizing the time of each particle in the zone. A quadrant detector (48) that is used to detect deviation of the laser beam from a predetermined path, is oriented about 45° from the usual direction. The laser beam is generated by a diode laser (82) whose output passes through two appropriately-positioned cylindrical lenses (84, 86) to produce the desired the ratio of width (W) to thickness (T).

Abstract: Apparatus (10) for simultaneous light scattering includes a plurality of chambers and/or sub-chambers (41) in which light scattering can occur; a light source (20) or light sources for providing light to be scattered to the sub-chambers; light detectors (55, 62) optically coupled to the sub-chambers (41) for detecting scattered light; transmitters (31, 32) for transmitting information from the light detectors to a computer (30) for analysis. A method of performing simultaneous light scattering includes: providing a plurality of sub-chambers (41) in which light scattering can occur; providing light (22) to be scattered to the sub-chambers (41); detecting light scattered in the sub-chambers (41) with light detectors (55, 62); transmitting information from the light detectors (55, 62) to a computer (30) for analysis. Preferably, the information is transmitted to a single computer.

Abstract: The high numerical aperture flow cytometer of the present invention includes a flow cell and a laser input. The laser input emits a beam of light that is oriented substantially orthogonally to the flow of blood cells through the flow cell such that laser light impinges upon the blood cells as they pass through the flow cell. A portion of the beam from the laser input that impinges upon the blood cells in the flow cell is scattered at a substantially right angle to the beam of laser input (“right angle scatter”). A second portion of the beam from the laser input that impinges upon the cells in the flow cell is scattered at a much lower angle than 90°.

Abstract: A fibre detector assembly comprising: (i) a scattering chamber body; (ii) means for drawing airborne particles through said body chamber, said means being adapted such the the particles tend to travel in single file with the longitudinal axis of particles with elongate shape substantially aligned with the direction of the air flow; (iii) means for illuminating the particle stream within the chamber body; (iv) an optical detector adapted to intercept and collect a portion of the light scattered by particles passing through the illuminating beam; (v) data processing means adapted to capture and process the signals from the optical detector; characterised in that the optical detector comprises a photodiode array consisting of a central opaque area surrounded by two or more annular rings of detector elements.

Abstract: A system for identifying microorganisms and other microscopic particles in a fluid, includes a laser that directs a laser beam (14) through a detect zone (20) and a plurality of photodetectors (30) that detect light scattered in different directions from a particle at the detect zone, and includes a carrier (110) that confines fluid to movement along a narrow path. The carrier includes a glass sphere (112) with a passage (116) for carrying the fluid. The spherical surface allows light scattered at a large angle from the direction of the laser beam, to pass through the glass sphere to its outside for detection there.

Abstract: A radiation sensing method and device that is used to measure physical properties of materials over a wide dynamic range. The sensor (20) comprises multiple radiation sources and multiple detectors at multiple separation distances. The detected signals from the different sources are separated and then combined mathematically in a manner such that the combination is self-compensated for both component drift and changes in radiation coupling efficiency between the source or detector and the material of interest. In a preferred embodiment, the biomass in a liquid cell culture (54) is measured with high accuracy over a wide dynamic range using optical wavelength radiation. The measurement can be made with the sensor external to the liquid culture container in a manner that is compensated for the thickness of the container window (50).

Abstract: A system for identifying microorganisms and other microscopic particles in a fluid, includes a laser that directs a laser beam (14) through a detect zone (20) and a plurality of photodetectors (30) that detect light scattered in different directions from a particle at the detect zone. The system includes a glass carrier (110) that confines fluid to movement along a narrow passage (116) in the carrier. The front surface (130) of the passage is flat, to facilitate prediction of the scatter light paths, and to enable the passage to have a small cross-sectional area.

Abstract: A concentration measuring apparatus for an absorption component in a scattering medium includes a light source (2) for generating at least two light rays having predetermined wavelengths, the light rays having different transport scattering coefficients for a scattering medium (20) as an object to be measured, and a known ratio of the transport scattering coefficients; light incidence means (6) for making the light rays incident from a light incident position into the scattering medium (20); photodetection means (12), (13) for detecting the light ray which has propagated inside the scattering medium (20) at at least one photodetection position different from the light incident position to acquire at least one photodetection signal; parameter detection means (15) for detecting, on the basis of the photodetection signal, a light intensity and a mean flight pathlength at the light detection position for each of the at least two light rays having predetermined wavelengths; and arithmetic processing means (16) for

Abstract: A turbidity sensor for measuring a full range of particulate content in a turbid environment, including a method thereof. The turbidity sensor includes a laser light source for emitting laser light through the particulate content. The turbidity sensor additionally includes at least one light-sensitive detector located proximate to the laser light source for the detection of light scattered from particles of the particulate content that come into contact with laser light emitted from the laser light source, thereby permitting the accurate measurement of the turbidity of the turbid environment. A plurality of light-sensitive detectors may be employed, including a back scatter detector, a side scatter detector, a forward scatter detector, and a direct transmission detector. The light-sensitive detectors may be arranged in a geometric configuration of light-sensitive detectors with respect to the laser light source.

Abstract: A fluid quality sensor system comprising a light source, a first light sensitive element disposed at a distance from the light source, forming a gap having dimensions suitable for permitting a fluid to flow therebetween, and aligned with the light source to receive light transmitted by the light source through the fluid, a second light sensitive element disposed perpendicular to a midpoint of a light path between the light source and the first light sensitive element, and a third light sensitive element disposed so as to form an acute angle at the midpoint with the light source.

Abstract: Apparatus and method are provided for measuring a dimension of an airborne fiber. The apparatus includes a flow channel for providing a laminar flow to at least a portion of the fibers in air sample and a light source for projecting a light beam along a selected beam path to impinge upon a first fiber in the sample to create scattered light. A portion of the scattered light is measured by a light detector to produce an electrical output which is related to the fiber's dimension.

Abstract: A surface inspection system and method is provided which detects defects such as particles or pits on the surface of a workpiece, such as a silicon wafer, and also distinguishes between pit defects and particle defects. The surface inspection system comprises an inspection station for receiving a workpiece and a scanner positioned and arranged to scan a surface of the workpiece at the inspection station. The scanner includes a light source arranged to project a beam of P-polarized light and a scanner positioned to scan the P-polarized light beam across the surface of the workpiece. The system further provides for detecting differences in the angular distribution of the light scattered from the workpiece and for distinguishing particle defects from pit defects based upon these differences.

Abstract: Method and device for simultaneous in-situ determination of particle size and mass concentration of fluid-borne particles, wherein the device includes a sensor unit comprising a sending unit and a receiver, a laser coupled to the sensor unit, a detector coupled to the sensor unit, and a microprocessor coupled to the sensor unit, wherein the sensor unit is at least one of adjustable in cross section and variable in diameter and wherein the sensor unit is arranged to one of protrude into the fluid-borne particles and wrap around the fluid-borne particles. The method includes placing the sensor unit adjacent a pipe having a gas flow and simultaneously determining a particle size and a mass concentration of the fluid-borne particles in the gas flow.

Abstract: Unique methods and apparatus are provided for rapidly identifying microscopic particles, such as protozoa and other microbes suspended in a fluid or gas.

Abstract: Scattered light obtained by irradiating parallel laser beam to particles to be measured is condensed by a condenser lens in a wide angle area from 0° to over 40°, and an intensity distribution of the light is spatially continuously measured by an optical sensor positioned at a focal point of the condenser lens. Before a particle size distribution is calculated from the measured light intensity distribution, measuring error of the scattered light intensity distribution caused by an aberration by the condenser lens and an attenuation on the optical path is corrected by comparing with data obtained through a ray tracing in advance. Thus, the scattered light in a wider angle area are spatially continuously measured to thereby obtain a light intensity distribution with a high resolution in a submicron area.

Abstract: The invention is a submersible laser scattering instrument that measures particle total volume, particle total area and Sauter mean diameter. It allows a single calibration for all particle sizes 1.2-250 &mgr;m. A beam of laser light is directed across a void where a sample of water containing particles is admitted. After passing through the water, the light which is forward scattered out of the direct beam falls on two detectors at the same time. The first detector has an active surface shape which is configured to produce an output signal proportional to total particle area at varying total particle areas. The second detector has an active surface shape which is configured to produce an output signal proportional total particle volume varying total particle volumes. Each detector falls within in a radius surrounding the unscattered beam of light.

Abstract: A turbidity sensor apparatus and method for measuring very low concentrations of particles in a fluid. The turbidity sensor comprises a laser light source for emitting laser light through a fluid. Such a fluid may be hydraulic fluid, oil, water utilized in water purification systems, or other translucent fluids. The turbidity sensor includes a first light-sensitive detector located 90 degrees to incident laser light emitted from the laser light source, and a second light-sensitive detector located at an angle obtuse to the incident laser light emitted from the laser light source, wherein the first and second light-sensitive detectors respectively measure side scattered light and forward scattered light reflected from particles contained within the fluid that come into contact with laser light emitted from the laser light source, thereby providing an accurate and reliable measurement of very low concentrations of particles within the fluid.

Abstract: An aerosol triggering device with an integrating sphere and direct air flow provides a simple and efficient biological aerosol trigger. A method for detecting biological aerosols using the aerosol triggering device also is disclosed.

Abstract: Unique methods and apparatus are provided for rapidly identifying microscopic particles, such as protozoa and other microbes suspended in a fluid or gas. In one embodied form, the method comprises illuminating the particles to be detected with an intense light source such as a laser, detecting scattered light by means of an array of optical sensors surrounding a detection zone, converting the detected light to an electrical signal, and comparing the derived signal with at least one frequency-of-occurrence/probability histogram curve to qualitatively and/or quantitatively identify the microscopic particles present.

Abstract: A laser beam optical adjusting mechanism for a particle size distribution measuring apparatus includes a light source to provide a laser beam for irradiating a sample cell and an optical detector unit for receiving an intensity pattern representing the impact of the laser beam on a cell. A mirror assembly is positioned adjacent the light source to reflect the laser beam to irradiate the sample cell. An actuator unit is provided for adjusting the mirror assembly to line an optical axis of the light source with an optical detector. The actuator unit can be automatically driven by a controller and can be of a compact configuration by the use of a pair of lever members that are pivotally supported and respectively driven by actuators.

Abstract: Methods and apparatus are provided for measuring component concentration in a liquid containing relatively large particles and relatively small particles. The invention may be utilized for measuring fat and casein concentrations in a dairy product, but is not limited to such use. A polarized light beam is directed through a scattering cell having first and second windows and containing a sample of the liquid. A normal to an exterior surface of the second window of the scattering cell is at or near Brewster's angle with respect to the light beam to reduce or eliminate reflections. A first light detector, positioned at an angle of about 5° to about 45° with respect to the light beam, detects scattered light from a first component of the liquid, such as fat particles. A second light detector, positioned at an angle of about 130° to about 160° with respect to the light beam, detects scattered light from a second component of the liquid, such as casein particles.

Abstract: An optical analyzer with a configuration particularly suitable for use with planar liquid sample flow cells is provided comprising a polarized light source and at least two large angle scattered light photodetectors positioned respectively at acute, and right or oblique angles to the incident light beams. Differences in intensities of light measured at the two photodetectors are used to quantify components of the sample.

Abstract: Particle detecting apparatus for detecting other particulate matter comprises a measuring section and an input/output section removably attached together. A measuring chamber receives gaseous fluid by diffusion from a receiving chamber connected via an inlet to an area being monitored. The measuring chamber comprises a cylindrical body housing pairs of light emitting diodes positioned diametrically opposite, and directing light towards, each other through a sampling volume viewed by a photo-diode through a viewing aperture. The photo-diode detects light scattered by particles in the sampling volume. A glass tube protects the LEDs from contamination and can easily be cleaned or removed. Each LED can temporarily be de-energised in turn so as to act as a light detector, its output in response to light received from the opposite LED being thus a measure of any contamination. The measuring and input/output sections can easily be separated for servicing or replacement.

Abstract: A method of measuring an internal property distribution of a scattering medium, comprises a step of injecting rays into a measured medium, a step of detecting rays having passed through the interior of the measured medium, a step of acquiring a measurement value of a predetermined parameter for each of combinations of a light injection position with light detection positions, a step of setting a reference value of an absorption coefficient, a step of acquiring an estimate of the parameter for each of the combinations of the light injection position with the light detection positions, a step of computing a weight function in each voxel, based on the Microscopic Beer-Lambert Law, a step of computing a deviation of the absorption coefficient in each voxel, based on the measurement value and estimate of the parameter, and the weight function, and a step of computing an absolute value of the absorption coefficient in each voxel.

Abstract: The high numerical aperture flow cytometer of the present invention includes a flow cell and a laser input. The laser input emits a beam of light that is oriented substantially orthoganilly to the flow of blood cells through the flow cell such that laser light impinges upon the blood cells as they pass through the flow cell. A portion of the beam from the laser input that impinges upon the blood cells in the flow cell is scattered at a substantially right angle to the beam of laser input (“right angle scatter”). A second portion of the beam from the laser input that impinges upon the cells in the flow cell is scattered at a much lower angle than 90°. This scatter is termed “low angle forward scatter light” and has an angle of from about 2° to about 5° from the orientation of the original beam from laser input. A right angle scatter light detector is oriented to receive the previously mentioned right angle scatter light.

Abstract: The present invention includes a method and an apparatus for the quantitative determination of particles in fluid. The apparatus of the invention includes an emitters set of one or more light emitters, in combination with a detector set of one or more light detectors sensitive to the output of the emitters. During analysis of the sample, data from a plurality of signal paths between the emitter and detector sets are gathered. This information is subsequently evaluated by comparison with known data for different fluid particle contents. Some differentiation between different particles in a fluid sample are possible in many embodiments. Typical uses include analysis of milk and dairy fluids, blood samples, lubricants, suspensions of pigments, etc.

Abstract: A surface inspection system and method is provided which detects defects such as particles or pits on the surface of a workpiece, such as a silicon wafer, and also distinguishes between pit defects and particle defects. The surface inspection system comprises an inspection station for receiving a workpiece and a scanner positioned and arranged to scan a surface of the workpiece at the inspection station. The scanner includes a light source arranged to project a beam of P-polarized light and a scanner positioned to scan the P-polarized light beam across the surface of the workpiece. The system further provides for detecting differences in the angular distribution of the light scattered from the workpiece and for distinguishing particle defects from pit defects based upon these differences.

Abstract: An inspection system using dark field imaging includes a multiple beam laser scanning unit and at least one multiple beam dark field imaging unit. The laser scanning unit generates multiple beams which illuminate multiple spots on a surface to be scanned. The imaging unit separately detects light scattered from the multiple spots. The spots are separated by a separation distance which ensures that scattered light from each associated spot are received only by its associated photodetector. Each imaging unit includes collection optics and multiple photodetectors, one per spot. The collection optics and photodetectors are mounted so as to separate the light scattered from the different scan lines. In one embodiment, this separation is provided by arranging the collection optics and photodetectors according to the principles of Scheimpflug imaging.

Abstract: Disclosed are photometric methods and devices for determining optical pathlength of liquid samples containing analytes dissolved or suspended in a solvent. The methods and devices rely on determining a relationship between the light absorption properties of the solvent and the optical pathlength of liquid samples containing the solvent. This relationship is used to establish the optical pathlength for samples containing an unknown concentration of analyte but having similar solvent composition. Further disclosed are methods and devices for determining the concentration of analyte in such samples where both the optical pathlength and the concentration of analyte are unknown. The methods and devices rely on separately determining, at different wavelengths of light, light absorption by the solvent and light absorption by the analyte. Light absorption by the analyte, together with the optical pathlength so determined, is used to calculate the concentration of the analyte.

Abstract: A particle size distribution analysis apparatus wherein there are provided a sample measurement zone adapted to contain a sample of particles, a light emitting means adapted to provide a source of light incident upon the measurement zone, and a detection means adapted to measure light levels at different scattering angles and to output signals to a computation means, enabling the size of particles contained within the sample to be determined, wherein the light emitting means comprises a first light source emitting a substantially monochromatic first wavelength of light and a second light source emitting a substantially monochromatic second, different, wavelength of light.

Abstract: An apparatus for photometric analysis and/or identification of properties of a material object comprises a collection of light sources having substantially distinct wavelength envelopes and activated in a rapid sequence of distinct combinations. The apparatus comprises a collection of spatially distributed light detectors which detect radiation from the object and produce detected signals. A signal processor for controlling the light sources and analyzing the detected signals synchronizes the detected signals with the activation of the sequence of distinct combinations of the light sources to produce associated combinations of detected signals which are then analyzed to determine a physical property of the object and/or compared for similarity to previously detected signals from known objects. The photometric data may be combined and correlated with other measured data to enhance identification.

Abstract: Devices and methods for measuring the concentration of airborne fibers are provided. The devices include flow means for providing laminar flow to a portion of the fibers in an air sample and a light source for generating a light beam directed to the laminarly flowing fibers to produce a scattered light. The device further includes a sensor for sensing a portion of this scattered light and for producing an output from which a respirable fiber concentration estimate can be measured.

Abstract: The invention relates to a method for identifying the particles contained in a gaseous or liquid or carrier medium by measuring scattered light aimed at the medium. The method of the invention identifies particles of very small size and also measures the geometric shape of the particles. This is accomplished by simultaneously operating at least three light sources aimed at the volume to be analyzed, and detecting the scattered light with at least three detectors. The measured values of the detected light are correlated and evaluated to identify the particles.

Abstract: The present invention relates to an instrument for determining the light scattered by a sample comprising a platform rotatable about an axis of rotation; a sample holder disposed along the axis of rotation; a light source for producing a beam of coherent light that can be focused on a sample in the sample holder; and a plurality of detectors disposed and rotatable about the axis of rotation and adapted so that each detector can be adjusted to focus on a common point along the axis of rotation by reference to the beam.