Abstract: Disclosed is a particle sensor of the type having (a) a light beam, (b) an air tube flowing a stream of air across the light beam at a volumetric flow rate, and (c) an air pump providing the stream of air through the tube, across the light beam and along an air flow path. In the improvement, the particle sensor includes a flow-controlling apparatus in series with the flow path for slightly trimming or adjusting the flow rate, i.e., the rate usually set at the factory before shipping. Such flow-controlling apparatus is selected from a group of apparatus including a choke valve (preferably an adjustable choke valve), a slip clutch, a speed-adjustable blower drive motor and a plurality of conduits. The conduits may have the same passage cross-sectional area and differing lengths, the same length and differing cross-sectional area or a combination of such conduits. A new method for assaying an airborne particle is also disclosed.

Abstract: A particle analyzer which can maintain optical characteristics of an optical system which is one component thereof at a fixed level for a long period of time is provided. In the particle analyzer comprising a flow cell for forming a sheathed sample flow containing particulate components; an irradiating optical system for irradiating a sheathed sample flow formed in the flow cell; and a light receiving optical system for receiving light emitted from the sheathed sample flow in the flow cell irradiated by the irradiating optical system, the light receiving optical system comprises a rod lens to which the light emitted from the sheathed sample flow in the flow cell enters and an entrance surface of the rod lens is curved.

Abstract: The method for diagnosing malignancy diseases involving analysis of blood plasma by laser correlational spectroscopy (LSC) techniques includes the steps of: preparing a weak diluted solution of native blood plasma, determining a spectral density of light scattering intensity fluctuations within the frequency range between 1 and 1000 Hz, distinguishing a spectrum core and making a diagnosis from a frequency of a maximum and an intensity-to-half-width ratio of a spectrum core envelope, a malignancy disease being detected when the diagnostic parameters are less than the appropriate rates. The apparatus for diagnosing malignancy diseases includes a nephelometer and a series-connected correlation spectrum analyzer.

Abstract: For simplifying the optical measurement of a particle flow in a fluid and in particular for eliminating errors, in a device for measuring a particle flow in a fluid with at least one illumination system having a diaphragm and at least one receiver system having a diaphragm, the invention provides for a diaphragm (6a, 11a) to have an aperture (6, 11) with an edge (6b, 11b) constructed convexly towards the interior of the diaphragm aperture (6, 11). According to a method, the particle flow is illuminated and/or observed through a diaphragm aperture with an edge constructed convexly towards its interior and the maximum intensity of the particle flying through a first optical measuring range is measured and account is only taken of the particle if the intensity on flowing through a second measuring range exceeds a specific minimum percentage of the maximum intensity measured for this particle.

Abstract: A method and resulting system for directing generally collimated illumination from a source at an oblique angle to a surface under inspection (SUS) to produce scattered nonspecular energy substantially normal to the SUS and for observing the scattered nonspecular energy in one of a plurality of fractional windows of a viewed image of the SUS via a plurality of focussing elements. Such arrangement results in simultaneous and significant throughput and sensitivity enhancement over existing art. The method can be enhanced further wherein the observing step is performed through suitable relative motion of the scattering image over the imaging plane to permit over sampling. Furthermore, the DMT is significantly simplified because imaging is utilized to electronically scan the wafer instead of using opto-mechanical scanning means. Imaging sensors with an aggregate 2000.times.2000 pixel resolution could image a 200 mm wafer to 100 microns pitch.

Abstract: A resonant-cavity apparatus for cytometry or particle analysis. The apparatus comprises a resonant optical cavity having an analysis region within the cavity for containing one or more biological cells or dielectric particles to be analyzed. In the presence of a cell or particle, a light beam in the form of spontaneous emission or lasing is generated within the resonant optical cavity and is encoded with information about the cell or particle. An analysis means including a spectrometer and/or a pulse-height analyzer is provided within the apparatus for recovery of the information from the light beam to determine a size, shape, identification or other characteristics about the cells or particles being analyzed. The recovered information can be grouped in a multi-dimensional coordinate space for identification of particular types of cells or particles. In some embodiments of the apparatus, the resonant optical cavity can be formed, at least in part, from a vertical-cavity surface-emitting laser.

Abstract: A device for counting and measuring the particles provides a precise analysis of the particle characteristics and includes an ellipsoidal mirror system, having two different sizes ellipsoidal concentric mirrors (4) and (5) connected towards to each other by their cross-section lateral areas, and a first ellipsoidal mirror (4) is smaller than a second ellipsoidal mirror (5), includes also a light beam and a particulates flow passing inside the first ellipsoidal mirror (4) through a first focus of the first ellipsoidal mirror (4), concurred with a second focus of the second ellipsoidal mirror (5), also includes a light detector (20), which is placed inside the second ellipsoidal mirror (5) at a first focus of the second ellipsoidal mirror (5), concurred with a second focus of the first ellipsoidal mirror (4). An improved device comprises also an electronic control system, including an analog-digital subsystem (45) and a microprocessor subsystem (32), which provide the signal processing and control functions.

Abstract: A specimen measurement apparatus and method includes sequentially moving individual specimens, radiating first and second radiation beams on first and second positions spaced apart from each other in a moving direction of the specimens, time-serially detecting light components emerging from specimens passing the first and second positions using the same light detector, and an optical selector, arranged in an optical path between the radiation positions and a light detector, for, when a specimen passes the first position, selectively guiding a light component having a first optical characteristic emerging from the specimen to the light detector, and for, when the specimen passes the second position, selectively guiding a light component having a second optical characteristic emerging from the specimen to the light detector.

Abstract: A machine for washing articles is provided with a turbidity sensor that is activated by an electromechanical timer. When activated, the turbidity sensor determines the magnitude of turbidity of water within the machine for washing articles and decides whether or not to inhibit a subsequent drain operation. If the turbidity of the water is sufficiently low, the drain operation is inhibited and the machine for washing articles is prevented from purging the existing water from its interior. This allows the relatively clean water to be reused at a savings of both water and energy.

Abstract: Interacvity particle detection is disclosed using optically pumped laser media. A laser medium, positioned within a laser cavity, is end-pumped by an optical pump source to excite the laser medium to provide laser light within the laser cavity, and a detecting region, also positioned within the laser cavity and capable of having particles, or particle-containing fluid, therein, is exposed to the laser light whereby light is effected, as by being scattered, by particles in the detecting region with the scattered light being indicative of particles, such as small particles having a size of between 0.05 and 10 microns, causing the light to be scattered so that the scattered light, when collected, can be used to provide an output indicative of particles at the detecting region.

Abstract: The present invention provides for a smoke detection chamber and a photoelectric smoke detector containing the smoke detection chamber. The smoke detection chamber has side walls with openings provided therein for ingress and egress of smoke particles, a top and a bottom. A photoemitting diode is mounted in a mounting arrangement in the side wall of the smoke detection chamber to transmit a light beam across the smoke detection chamber without directly impinging upon either the top or the bottom surfaces. The bottom of the smoke detection chamber has an opening with a shielding arrangement thereabout open to the chamber located between the centerline of the smoke detection chamber and the mounting arrangement in the side wall of the chamber.

Abstract: A condensation nucleus counter features an entropy control mechanism to regulate the entropy of a vaporized fluid present in a saturator, thereby facilitating supersaturation of the same about particulates entrained in a sample gas stream before the same passes through a condenser. The condensation nucleus counter includes a supply of sample gas, conduits adapted to allow the sample gas stream to flow therethrough, a saturator, a condenser and an optical detector, all of which are in fluid communication with each other. The manifold is disposed between the conduit and the saturator, and also a temperature control device. The manifold comprises a feed chamber and a plurality of channels positioned so that the sample gas stream entering the feed chambers evenly divides into a plurality of flows, with each flow entering the saturator. The temperature control device regulates the temperature difference between the flows entering the saturator and the vaporized fluid contained so as to be within a specified range.

Abstract: Device and method are disclosed for optically detecting particles in a free (i.e., unenclosed) stream of liquid. The free liquid stream is produced by ejecting liquid under pressure from a nozzle so that the stream has a smooth round surface. A laser beam intersects the free liquid stream and light scattered by particles in the free liquid stream is collected and processed to provide an output indicative of size and/or number of particles causing the light to be scattered. The free liquid stream is preferably directed vertically downward, and the laser beam and light collector are angularly positioned with respect to the free liquid stream and one another with the light collector collecting scattered light at the intersection of the light beam and the free liquid stream.

Abstract: A particle detector employs a laser having a solid-state lasing medium, such as an Nd:YAG crystal, disposed in a resonant cavity, and includes an intracavity view volume. The resonant cavity is defined by two spaced apart mirrors, with the laser medium positioned between them, defining a light path. A pump source is optically coupled to drive the laser medium to produce coherent light having a first wavelength. The view volume is positioned in the light path, between the first mirror and the laser medium, to introduce particles into the resonant cavity so that light impinging thereupon produces scattered light. A detector is disposed to sense light scattered from the view volume and produces signals proportional to the light sensed. A displaying device, such as a pulse height analyzer, is in electrical communication to receive the signals produced by the detector to quantitatively display the intensity of the light sensed.

Abstract: A method of determining cloud points is provided which comprises: bringing a sample into contact with a high precision cloud point meter which includes a waveguide sensor of a total-reflection type connected to both incidence and emergence optical fibers and a cooling/heating means located in contact with the total-reflection type sensor to cool/heat it within a desired temperature range; cooling/heating the sample; and then determining the sample temperature at which total-reflection of light has taken place as the cloud point of the sample. The sensor includes a waveguide of a structure which consists of an incidence channel and an emergence channel formed on a substrate and which intersect along a detection surface with which a liquid whose cloud point is to be determined comes in contact.

Abstract: An ionization chamber for use in a smoke detector includes first and second outer electrodes and a non-reflective center electrode. The non-reflective center electrode can be formed as a metal electrode having a non-reflective coating or as a non-reflective, conductive plastic elements. The ionization chamber can be incorporated into combination smoke detector which includes a photoelectric sensor. A non-reflective center electrode, associated with the ion-type sensor is symmetrically located in the detector and displaced from the photoelectric sensor.

Abstract: A pseudo telecentric flow cytometric optical system for the simultaneous detection of several characteristics of particles suspended in a flowing medium. The system is made up of a flowcell through which the particles pass substantially one particle at a time, an optical system for directing light from a light source onto the flowing particles in the flowcell, a side angle optical collection system for receiving light from the flowing particles and for directing the light to one or more of a first set of detectors, and a forward angle collection system for receiving light from the flowing particles and for directing the light to one or more of a second set of detectors.

Abstract: A particle-containing fluid in a sample cuvette is irradiated by a laser beam from a light source section. The scattered light thus produced passes through converging lenses and a mask and impinges on an etalon interferometer. The etalon only transmits scattered light (Rayleigh scattered light) that is of the same wavelength as the light emitted by the laser light source. The transmitted scattered light components impinges on a photomultiplier, and based on the intensity of the light a calculating section sorts the particles according to size and calculates the number of particles per unit flow amount, the particle size distribution and so forth. To enable adjustments to be made to compensate for the environmental dependency characteristics of the etalon, a control unit is provided which consists of a photodiode and mirrors.

Abstract: The chemical properties of an aqueous liquid, the liquid comprising a solvent having an index of refraction which is the same as or closely approaches that of water, are determined by Raman spectroscopy wherein a sample of the liquid is delivered into an optical waveguide. The waveguide is in the form of a capillary having a reflective surface defined by a material having a refractive index of less than 1.33. Excitation light is transmitted axially into the liquid at an end of the waveguide. The excitation light is transmitted the length of the waveguide, by reflection from the reflective surface, causing the fluid to emit Raman spectra. The Raman spectra is transmitted along the waveguide, collected and delivered to a spectrometer.

Abstract: A nephelometer instrument capable of measuring from zero to 10,000 NTUs. The instrument includes four light detectors, three of which are positioned such that they measure light scattered at specific directions by a liquid sample. The fourth detector measures light transmitted through the sample. A removable light filter is also included. The light beam is focused on the front surface of the sample cell.

Abstract: Disclosed is a particle sensor having a light beam with a beam long axis and an air flow tube with an inlet end and a particle exit mouth. In an aspect of the invention, the cross-sectional area of the flow passage at the inlet end is greater than the cross-sectional area of the exit mouth. This enlarged area dramatically reduces pressure drop along the tube. The exit mouth is in registry with the light beam and is elongate in a direction substantially parallel to the beam long axis. Thus, particles flowing through the mouth pass through the beam. In another aspect, the invention includes a centrifugal blower which is light in weight and which may be battery powered.

Abstract: A turbidity sensor is provided in which a light source, a first photosensitive device and a second photosensitive device are arranged in a manner that permits easy removal and replacement of a cover which is used to protect the components. The cover is attachable to a support structure. The light source, which can be a light emitting diode, is attached to the support structure. The first and second photosensitive devices are also attached to the support structure. Light scattered by particulates in a fluid are directed toward the support structure and received by the second photosensitive device. Light which passes through a detection zone and is not scattered by the particular matter in the monitored fluid passes to a first photosensitive device. Many different types and shapes of covers can be used in conjunction with a single style support structure.

Abstract: A turbidity sensor is provided with two light sensitive components or elements. One light sensitive component is displaced from a light source, such as a light emitting diode, so that a fluid can pass therebetween. A second light sensitive component is disposed within a common compartment with the light source so that it can measure the intensity of light provided by the light source. The light source and the second light sensitive components can be individual elements, or chips, within a common component package. A regulator is provided to control the magnitude of current provided to the light source so that its light intensity can be regulated. In this manner, the intensity of light emitted by the light source, such as a light emitting diode, can be controlled regardless of the aging of the LED, the variability of LED characteristics and the temperature surrounding the LED.

Abstract: The present invention provides a method of measuring particles and an apparatus for the same, which count only particles in liquid by distinguishing between the particles and bubbles in liquid. In order to fulfill the above requirements, in the present invention, liquid to be measured flows through a flow cell at a fixed flow rate, and a laser beam is irradiated thereto. Scattering light is generated when particles and bubbles pass through a laser beam irradiation region, and the scattering light is converted into a pulse signal by a photoelectric converter. In the pulse signals, a pulse signal having a pulse width of 100 .mu.S is regarded as corresponding to light scattered by a bubble, which is omitted from the number of pulse signals. Thus, only a pulse signal corresponding to light scattered by a particle in liquid can be measured.

Abstract: A smoke detector that operates on the principle of scattered light is disclosed that has the capability of an operating sensitivity that is tens of times greater than that of smoke detectors presently available. Plural light sources are used, their light rays directed radially toward the center of a cylindrical detector chamber having a mirrored wall that reflects light back toward the chamber's center, thereby to brightly illuminate a central detection zone. Scattered light from smoke in this zone is detectable by a photocell at right angles to the converging multiple light rays. To obtain highly improved stability of the light output that enables ultra-high sensitivity, the light sources are light-emitting diodes in series connection and they are driven by a very stable constant voltage source that also powers the photocell detector. This system gains impressive sensitivity while reducing nuisance alarms that have been a common problem regarding efforts to increase smoke detector sensitivity.

Abstract: An improved method of monitoring condensate quality in a condensate return system and of controlling the level of particulate matter in the condensate flow so that when this level exceeds an acceptable limit, valves for discharging the condensate flow from the system open automatically or, alternately, an alarm is sounded. Utilization of the method facilitates the conservation of hot steam condensate for reuse in a boiler while preventing water contaminated with particulate matter from returning to the boiler, thereby protecting it from certain types of deposits and corrosion. The improved method includes measuring, on a continuous basis, relative numbers of particulate-type impurities under conditions in which rust or other particles large enough to block flow into a particle counter can be produced in sudden surges. Tests show that a suitable instrument for measuring the impurities under such conditions is a particle monitor.

Abstract: An improved particle monitoring sensor is described which uses a variety of techniques to prolong the effective life of the optical surfaces within the particle monitoring sensor. Substantially inert purging gas is directed over the particle monitoring sensor windows, which are normally exposed to a harsh operating environment. The surfaces of these windows are heated by heating elements in direct thermal contact with the windows. In addition, a restrictive slit is placed over the detector window to reduce the exposed area and to increase the velocity of gas flowing over the window surface. While this slit reduces the detector's field of view, the signal loss is reduced by using a linearly polarized light source and aligning the elongated slit's major axis with the direction of polarization.

Abstract: A method and an apparatus for the analysis of particles contained in a material, such as particles in a fluid or on a surface, such as the surface of a semiconductor, by two orthogonally polarized, intensity and phase modulated laser beams, wherein the detected scattered light is synchronously demodulated. The apparatus comprises a laser source producing a polarized laser beam, a state of polarization modulator, and a photoreceiver for detecting light scattered by particles at an angle to the incident light. A synchronous demodulator, such as a dual channel lock-in amplifier, separates the intensity and phase modulated portions of the scattered signals. A reference unit for detecting a non-scattered light produced by the sample to provide a reference is preferably provided, as well. The size, index of refraction and identity, of the particles, for example, can be determined.

Abstract: Disclosed is a particle sensor having a light beam with a beam long axis and an air flow tube with an inlet end and a particle exit mouth. In an aspect of the invention, the cross-sectional area of the flow passage at the inlet end is greater than the cross-sectional area of the exit mouth. This enlarged area dramatically reduces pressure drop along the tube. The exit mouth is in registry with the light beam and is elongate in a direction substantially parallel to the beam long axis. Thus, particles flowing through the mouth pass through the beam. In another aspect, the invention includes a centrifugal blower which is light in weight and which may be battery powered.

Abstract: A nephelometer instrument capable of measuring from zero to 10,000 NTUs. The instrument includes four light detectors, three of which are positioned such that they measure light scattered at specific directions by a liquid sample. The fourth detector measures light transmitted through the sample. A removable light filter is also included. The light beam is focused on the front surface of the sample cell.

Abstract: There is provided a method and apparatus of detecting minute impurities in the entire body of a fluid. Part of the passage through which the fluid flows is constituted by a transparent member. Light is emitted in a direction substantially parallel to the longitudinal axis of this part of the fluid passage so as to envelop the same. Light scattered by impurities in the fluid is observed from a direction substantially perpendicular to the direction of the passage to detect any minute impurities in the fluid. The method and apparatus is well-suited for use in systems which extrude molten resin in the formation of plastic products used in an electrical environment in order to detect impurities in the resin which could adversely affect the performance of the products.

Abstract: Turbidity and fluorescence measurements are taken simultaneously from a falling waste water stream in order to determine both the amount of solids and the amount of fluorescent material contained therein.

Abstract: The liquid of a flow cytometer itself acts as an optical waveguide, thus transmitting the light to an optical filter/detector combination. This alternative apparatus and method for detecting scattered light in a flow cytometer is provided by a device which views and detects the light trapped within the optical waveguide formed by the flow stream. A fiber optic or other light collecting device is positioned within the flow stream. This provides enormous advantages over the standard light collection technique which uses a microscope objective. The signal-to-noise ratio is greatly increased over that for right-angle-scattered light collected by a microscope objective, and the alignment requirements are simplified.

Abstract: A size of particle or defect in an object is measured. A laser beam is guided through an optical system into the object. A light receiving element receives scattered light from a particle or a defect in the object. A scattering image is formed by an image processor from the scattered light thus received. The size of particle or defect is obtained by integrating a scattering intensity of the scattered light. Also, a size distribution of particle or defect in an object may be acquired by detecting a maximum scattering intensity of each particle or defect. A polarization dependency of scattering may be checked as well.

Abstract: The disclosure involves a particle sensor having a mirror cavity unobstructed by masks and the like. A light detector is at the mirror secondary focal point and well outside the mirror cavity. A variation includes a beam splitter and a secondary light detector to improve detection of larger particles. A second embodiment includes a pair of elliptical mirrors offset along the light beam. Light reflected by the second mirror represents only changes in laser power and light scattered by gas molecules. The resulting signal is subtracted from that produced by the first mirror to obtain a relatively "clean" signal useful to assay very small particles.

Abstract: A particle detecting system for detecting the number and size of particles generated in a process chamber of a semiconductor manufacturing system. The particle detecting system includes a small detection chamber and a particle detector. The small detection chamber not only has an internal space thereof provided outside a wall portion forming the process vacuum chamber so as to communicate with the process vacuum chamber, but also laser beam transmitting windows and scattered light extracting windows. The particle detector is arranged in an atmospheric environment outside the detection chamber and including a laser diode for emitting a laser beam into the detection chamber through the laser beam transmitting windows and photosensors for detecting scattered light generated within the detection chamber through the scattered light extracting windows. The detection chamber has such a structure as to be detachably attached to the process chamber.

Abstract: An automatic calibration system is disclosed for an apparatus that measures the presence of s selected component in a test liquid sample. The system includes a transparent test liquid holder having an inlet and outlet for conducting a test liquid into and out of the holder. There is a transparent calibration element immersed in a test liquid in the holder and including a first sealed compartment that contains a full scale calibration standard and a second sealed compartment that contains a zero calibration standard. A pulsed flow of the test liquid is directed through the holder from the inlet to the outlet to reciprocate the calibration element within the holder. A light source is directed at the holder for establishing an incident beam of light that sequentially strikes the full scale standard, the zero standard, and a test liquid sample as the calibration element reciprocates through the holder.

Abstract: An improved particle monitoring sensor is described which uses a variety of techniques to prolong the effective life of the optical surfaces within the particle monitoring sensor. Substantially inert purging gas is directed over the particle monitoring sensor windows, which are normally exposed to a harsh operating environment. The surfaces of these windows are heated by heating elements in direct thermal contact with the windows. In addition, a restrictive slit is placed over the detector window to reduce the exposed area and to increase the velocity of gas flowing over the window surface. While this slit reduces the detector's field of view, the signal loss is reduced by using a linearly polarized light source and aligning the elongated slit's major axis with the direction of polarization.

Abstract: A modular particle detecting device is disclosed for nonintrusive in-situ detection of particles passing through a sensing region. The device is particularly useful for microcontamination control in semiconductor processing environments, and includes, as separate components, a viewing unit and a sensing unit. The viewing unit has a detecting window and heated illuminating and discharge windows for condensation control. A fluid passage connectable to a flow line enables particle-carrying fluid to pass through a sensing region within the passage. The sensing unit has illuminating circuitry for providing light through the illuminating window to the sensing region, and has detecting circuitry to receive, through the detecting window, light scattered at the sensing region to thereby detect particles in fluid then at the sensing region without physical intrusion of the sensing unit into the sensing region.

Abstract: A plurality of fluid condition sensors are combined together to provide a sensor cluster that senses turbidity, temperature, conductivity and the movement of a ferromagnetic object. The plurality of sensors are attached to a substrate and encapsulated, by an overmolding process, with a light transmissive and fluid impermeable material. The sensor cluster can be disposed at numerous different locations within a body of fluid and does not require a conduit to direct the fluid to a particular location proximate the sensor. In a preferred embodiment of the present invention, a circuit is provided which monitors the signal strength of first and second light sensitive components to determine turbidity and, in addition, those signal strengths are also used to advantageously determine the most efficient magnitude of current necessary to drive a light source, such as a light emitting diode.

Abstract: A turbidimeter including a sensor apparatus that has a housing with first and second receptacles. An incident light beam is established within the housing by a light source module that is releasably engaged with the first receptacle. A test liquid holder is removably engaged with the first receptacle. A test liquid holder is removably received by the second receptacle for positioning a liquid to be tested in the path of the incident beam. A photodetector or analogous instrument is provided at an angle to the incident light beam for sensing light scattered by the test liquid. An analyzer apparatus includes appropriate circuitry that is responsive to the photodetector for determining the turbidity of the test liquid. The turbidity is then displayed in both graphic and instantaneous alphanumeric form.

Abstract: A plurality of fluid condition sensors are combined together to provide a sensor cluster that senses turbidity, temperature, conductivity and the movement of a ferromagnetic object. The plurality of sensors are attached to a substrate and encapsulated, by an overmolding process, with a light transmissive and fluid impermeable material. The sensor cluster can be disposed at numerous different locations within a body of fluid and does not require a conduit to direct the fluid to a particular location proximate the sensor. In a preferred embodiment of the present invention, a circuit is provided which monitors the signal strength of first and second light sensitive components to determine turbidity and, in addition, those signal strengths are also used to advantageously determine the most efficient magnitude of current necessary to drive a light source, such as a light emitting diode.

Abstract: A device for analyzing fine particles in a sample gas includes a light source for emitting light, a convergent device for converting the light emitted by the light source into a convergent light beam having a light focus point and an energy density sufficient to dissociate the fine particles to be analyzed. The device also includes a transparent analyzer tube having a window for admitting the convergent light beam and a throat located at the light focus point of the convergent light beam, the analyzer tube receiving the sample gas and passing the sample gas through the throat. The device includes a light collecting device for collecting, through the analyzer tube, light emitted from dissociated fine particles, dissociated by the convergent light beam in the throat of the analyzer tube, and an analyzing device for analyzing the light from the dissociated fine particles collected by the collecting device.

Abstract: Methods and apparatus for detecting biological activities in a specimen such as blood are disclosed. The present invention provides a system whereby the intensity of light with a wavelength within the range of about 600 nm to 800 nm introduced into a sample at a first location is measured as it reemerges at a second location. A significant change in the intensity of the reemerging light indicates the presence of biological activity. Preferably, the intensity is also measured at a fourth location, or alternatively, a second light source is disposed at a third location to permit comparative intensity data to be collected. These data are useful in partially identifying the types of microorganisms present in the sample. In preferred embodiments, light emitting diodes are used as the light sources and multiplexed to a plurality of samples.

Abstract: A multiple angle and redundant visibility sensor includes a plurality of optical transmitter/receiver pairs, each pair cooperatively coupled so as to transmit and receive in conically controlled beams along a common optical axis such that each transmitter faces, and directs optical energy directly into, its receiver pair. The plurality of pairs are staggered in angular orientation with respect to each other, with a common volume of intersection through which the approximate center of each optical axis passes. Each transmitter propagates a substantially conical beam of light which passes through an aerosol media which causes molecular scattering of the light. A single transmitter outputs optical energy at any given time, and the receiver intercept the appropriate scattered energy at different scattering angles depending on the relative axial orientation with respect to the scattering volume and the incident radiation.

Abstract: In a particle detecting instrument, a sapphire detecting cell is provided with a square flow path. The sapphire cell is assembled from four sapphire pieces which extend throughout the length of the cell. The cell has a central section containing the square flow path with planar exterior walls and cylindrical end sections. The pieces are separated by black gaskets which are sandwiched between the opposed faces of the pieces. The pieces are clamped together by shape memory alloy rings which engage the cell in the cylindrical end sections. Each sapphire piece has a polished planar interior surface defining one of the walls of the square flow path.

Abstract: A molecular characterization detector includes a scattering cell containing a sample for molecular characterization, a light source for directing a light beam through the cell so that the light beam is scattered by the sample, optical elements for selecting from the scattered light a measurement beam comprising light that is scattered by the sample from a predetermined portion of the cell in a predetermined range of angles relative to the optical axis, and a detector for detecting the measurement beam and providing an output electrical signal representative of the measurement beam. The detector typically selects light scattered from a central portion of the scattering cell at angles in the range of 14.degree. to 16.degree.. A single spherical lens is preferably utilized. As a result, interference from stray scattered light is minimized. A beam dump attenuates the light beam after it passes through the scattering cell. Additional detectors detect light scattered at 90.degree. to the light beam.

Abstract: A tubular test chamber of square cross-section minimizes reflection of stray light from the interior surface of the test chamber onto the detector during measurement by an optical system which is based upon right angle light scattering by the dust particles of a test sample. A rotary solenoid is utilized to open a trap door through which a sample is dropped into the test chamber during energization so that the internal spring of the solenoid can be used to bias the door closed upon deenergization thereof. The electronic circuitry which supports the measurement process provides an output in the form of a single "characteristic number" for each sample measured and has a novel feedback circuit used in auto-zeroing of the device.

Abstract: A machine for cleansing articles, such as a dishwasher, incorporates a device for measuring the turbidity of an at least partially transparent liquid. The device includes a sensor for detecting scattered electromagnetic radiation, regardless of polarization, and a sensor for detecting transmitted electromagnetic radiation, regardless of polarization.

Abstract: A plurality of fluid condition sensors are combined together to provide a sensor cluster that senses turbidity, temperature, conductivity and the movement of a ferromagnetic object. The plurality of sensors are attached to a substrate and encapsulated, by an overmolding process, with a light transmissive and fluid impermeable material. The sensor cluster can be disposed at numerous different locations within a body of fluid and does not require a conduit to direct the fluid to a particular location proximate the sensor. In a preferred embodiment of the present invention, a circuit is provided which monitors the signal strength of first and second light sensitive components to determine turbidity and, in addition, those signal strengths are also used to advantageously determine the most efficient magnitude of current necessary to drive a light source, such as a light emitting diode.