Abstract: An allergen particle detecting apparatus has a passageway through which environmental air is directed. A light beam is directed across the passageway so that portions of the beam will be scattered if any particles are present in the path of the beam. A beam blocking device on the opposite side of the passageway blocks any non-scattered portion of the beam while transmitting any scattered portions of the beam along a light path in the apparatus. Any light scattered by allergen size particles will be traveling in a predetermined angular range, and a pinhole device is positioned in the light path so as to transmit only light traveling in that angular range. Light transmitted through the pinhole device is detected by a light detector and an alarm output signal is produced if the detected amount of light is above a predetermined level.

Abstract: A sensor for measuring the concentration of water in liquid phase in a gas moving relative to the sensor. The sensor itself comprises a device for illuminating the water drops transiting a measurement volume, an optical screen, a device imaging the measurement volume onto the optical screen, and photo-detectors to sense the light radiation transmitted by the optical screen.

Abstract: A light scattering type smoke detector arranged such that even if the range in which light from an LED is emitted has a dispersion, a labyrinth member 90 in the light emitting range has no edge or only a predetermined labyrinth member exist therein. The labyrinth member 90 is preferably formed by a single plate larger than the other labyrinth members 9. The edges of the labyrinth members 9 are preferably formed to a curved surface or chamfered, and the dispersion of the 0 point of a detection output is reduced and the level of the 0 point of the detection signal is lowered to thereby accurately detect light scattered by smoke.

Abstract: In an ink jet recording device having a print head wherein an expanding bubble formed in ink ejects an ink droplet from an orifice, a method for testing wafers on which a large number of print heads are formed is provided wherein the head is filled with pure water, water droplets of the pure water is ejected by application of a start signal to the print head, ejected water droplets is irradiated with condensed light, and the condensed light scattered by the ejected water droplets is detected. The time at which the scattered light was detected is correlated with time of the start signal, and it is determined whether the head is good or not according to the correlation of the time at which the scattered light was detected and the time of the start signal.

Abstract: The present invention describes an optical technique for analyzing undiluted, multi-phase fluid flows as typically encountered inside reactor vessels or flow lines in the chemical industries. In particular the technique uses a pulsed, coherent light source and measures the back-scattered light collected over a wide scattering angle. A light beam is relayed via a set of lenses down a long probe tube, through a window at a probe tip to illuminate the material that is passing past the window. The light beam is pulsed to "freeze" the motion of the particles streaming past the window. The backscattered light is collected by the same set of optics and is focused on the front surface of a CCD chip.

Abstract: A self-testable photoelectric smoke detector incorporates a housing which defines an internal smoke chamber. The housing carries a laser diode and a radiation sensor along with a supplemental source of test radiant energy. When a test is initiated, the operational characteristics of the laser diode are monitored simultaneously with energizing the source of test radiant energy. Signals from a scattered radiant energy sensor are evaluated via control circuitry, along with signals indicative of performance of the laser diode to determine whether or not the laser diode as well as the radiation sensor are functioning properly.

Abstract: An inexpensive ink tank having an ink remaining amount detection section which can be used with ink of any color is disclosed. An optical ink detection section formed from a light transmitting material has an inclined interface and is formed integrally with the ink tank. Incident light from a light source is refracted, when ink is present in the ink tank, at the interface to make refraction light and does not emerge to a visual observation portion. When no ink is present, the incident light is totally reflected by the interface to make total reflection light, which can be visually observed at the visual observation portion. A roughened face is formed at the visual observation portion so that light emerging to the visual observation portion may be scattered to facilitate visual observation.

Abstract: A system and method are disclosed for optically aligning a capillary tube and an excitation laser beam for fluorescence detection applications by utilizing the Raman scatter signals of the capillary tube's contents. For example, Raman scatter by an electrophoretic separation matrix may be used for alignment in a capillary electrophoresis system. Fluorescent material may be present and may also be used for alignment purposes, but is not necessary. The invention employs a parabolic reflector, having apertures through which the capillary tube and the laser beam are guided so that they intersect, preferably at right angles and at the focal point of the reflector. The Raman scatter signals of the material within the capillary tube are collected via a series of filters and this information is used to reposition, if necessary, a focusing lens that directs the excitation beam into the reflector and the capillary tube, so that the Raman scatter signals are maximized.

Abstract: The present invention is directed to an optical range measurement device which is able to compensate for lens contamination. The optical range measurement device includes one or more windows having at least two sections positioned at an angle to one another, a transmitter for producing a main beam and transmitting the main beam into the atmosphere, and a receiver for receiving the main beam back scattered by the atmosphere. The device also includes a transmitter producing a reference beam which illuminates the at least two sections and a receiver for receiving the reference beam.

Abstract: A long-range, wide-area remote sensor system(s) to detect trace levels of atmospheric constituents using bistatic configurations to measure differential absorption (BDIAL) of source beams tuned to the absorption line center and off-peak "wing" in the spectra of species of interest. Potential platforms for the probe beam and detector subsystems include satellites and airborne vehicles, and mapping of large geographical regions is accomplished by tomographic reconstruction of recorded columnar absorption data. The use of bistatic geometries reduces power requirements on the probe beam, as compared to standard backscatter DIAL, and allows detection with platforms at large stand-off ranges, subject to atmospheric conditions. Operation in spectral regions including UV, visible and IR is feasible, provided that there are no overlapping absorption lines when many substances are present. Use of multiple frequency sources and multi-spectral detectors will reduce identification ambiguities.

Abstract: A smoke detecting apparatus for a fire alarm has a smoke chamber into which smoke to be detected is introduced, a light emitting lamp disposed in the smoke chamber, a light receiving element disposed in the smoke chamber so as to receive the light emitted from the light emitting lamp, an amplification device for amplifying an output signal from the light receiving element, a detection device for detecting the density of the smoke on the basis of an output signal from the amplification device, a comparison device for comparing the value of the output signal from the amplification device with a fixed value, an abnormality output device for outputting an abnormality indication when the value of the output signal from the amplification device is judged to be smaller than the fixed value by the comparison device, an augmentation command switch for commanding augmentation of the value of the output signal from the amplification device, and an augmentation device for augmenting, in accordance with a command from the

Abstract: Ice in particular and also other substances such as water and glycol-containing anti-icing fluids can be detected and distinguished by means of differences in their optical index of refraction. A plurality of beams at different angles of incidence are multiplexed onto the reverse side of an optical surface which is embedded in a surface to be monitored or otherwise positioned in a sampling environment. The reflected beams at the different angles are measured and refractive indexes calulated form the measured reflected beams. If the calculated refractive indexes are the same at all angles, then the substance is positively identified. If the values do not agree, then there is partial coverage, and the substance may be identified by comparison with predetermined values. The system is applicable to aircraft, where in-flight and pre-flight monitoring of icing conditions and surface contamination is needed.

Abstract: A light scattering type smoke sensor of the present invention has a plurality of labyrinth members for facilitating an inflow of smoke entering from the outside, and for cutting off light entering from the outside; a plurality of smoke inlets each of which is formed by a space between paired ones of the labyrinth members being adjacent to each other; a smoke detecting chamber which is formed in a center portion by the labyrinth members; light emitting device for radiating light toward the smoke detecting chamber; and light receiving device for detecting light which is scattered by the smoke in the smoke detecting chamber, the light receiving device having an optical axis which intersects in the smoke detecting chamber an optical axis of the light emitting device at a scattering angle in the range of 60.degree. to 80.degree.

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 analytical device for detecting and analyzing the population of neutral or electrically-charged solutes, including providing a light source for producing a collimated beam, providing a solution vessel containing the sample solution to be analyzed, directing the light beam through the sample solution to thereby produce scattered light, a photomultiplier or a photon counter for detecting the scattered light, said photomultiplier being positioned at an angle to receive the scattered light from the collimated beam, an analog-to-digital converter communicating with the photomultiplier, converting the electrical signals output into a digital output, a digital correlator for receiving the digital output and to calculate a time autocorrelation function of the motion of the solutes in the fluid medium, immersing two electrodes in the solution vessel, generating an electrical field between the two electrodes, positioning the electrodes such that a field gradient is created between the electrode, and such that the li

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: A fire alarm system comprises a first light emitting device (11), a first polarizing filter (31), a first light receiving device (21), a second light emitting device (12), a second polarizing filter (32), and a second light receiving device (22). With the above arrangement, the amount of the parallel polarized component to the scattering plane as well as the amount of the perpendicular polarized component to the scattering plane is detected. The ratio between these amounts of light has a correlation with the type of smoke. A calculation section (4) calculates this ratio from the outputs of the light receiving devices (21, 22). A decision section (6) compares the above-described ratio with a reference value which has been preset according to the type of smoke to be detected, whereby the judgement of whether there is a fire or not is performed depending on the type of smoke. Thus, the detection of a fire can be performed from the light scattered by smoke taking into account the type of smoke.

Abstract: An apparatus and process for accurately determining settling data for the settling of erythrocyte cells from a plasma fluid in a test specimen of blood. The apparatus includes a settling tube, a sensing assembly movably mounted proximate the settling tube. Preferably an infrared emitter and detector are provided in the sensing assembly, and a control assembly is provided which senses data at a high rate and is responsive to the sensed data to sample or store the time at which sensed reflectivity exceeds a threshold level. When the threshold is reached, data is sampled and the tracking head is moved by a very small step. This process is repeated to enable tracking of the descent of the separation boundary between the erythrocyte cells and plasma fluid. The apparatus senses changes in reflectivity of the erythrocyte portion of the specimen below and up to the separation boundary.

Abstract: A photoelectric type fire detector includes self-testing capabilities. An upper level threshold limit and a lower level threshold define a predetermined range for output levels of an amplifier connected to an output of a light receiving element. In a self-test mode, a gain set in the amplifier is increased automatically. The number of times in which the amplifier output level deviates from the predetermined range is counted. If the deviation count exceeds a predetermined count threshold, it is determined that the photoelectric type fire detector is abnormal.

Abstract: An optoelectronic sensor device includes a waveguide element for affixing to a transparent pane on one surface and connected to a housing by way of latching barbs provided on U-shaped arms which engage corresponding recesses in the waveguide element. Slide-like locking elements are guided by the housing, parallel to the waveguide element and the pane, into the spaces defined by the U-shaped arms to prevent the arms from disengaging their respective recesses. The locking elements are adjustable by way of a handle which is flush with the housing when the latching elements are in their locked position. The locking elements include dome-shaped protrusions which cooperate with an edge of the housing to secure the locking elements within the housing.

Abstract: An apparatus for detecting fire including a light source for generating light, a light sensor for receiving light from the light source and providing an analog signal representing the intensity of the received light, and a clear plastic light guide for transmitting the light from the light source to the sensor. The light guide include notches for allowing smoke to enter the notches. Smoke entering the notches decreases the intensity of the light passing therethrough. A calibration sensor is included. The sensitivity of the fire detector is increased by a lens assembly which collimates the light generated by the light source. The color of smoke entering the light guide may be determined by generating colored light. Temperature, humidity and carbon monoxide levels are also detected and the information is integrated with the smoke detection data to provide a reliable fire detector.

Abstract: A self-contained smoke detector system has internal self-diagnostic capabilities and accepts a replacement smoke intake canopy (14) without a need for recalibration. The system includes a microprocessor-based self-diagnostic circuit (200) that periodically checks sensitivity of the optical sensor electronics (24, 28) to smoke obscuration level. By setting tolerance limits on the amount of change in voltage measured in clean air, the system can provide an indication of when it has become either under-sensitive or over-sensitive to the ambient smoke obscuration level. An algorithm implemented in software stored in system memory (204) determines whether and provides an indication that for a time (such as 27 hours) the clean air voltage has strayed outside established sensitivity tolerance limits. The replaceable canopy is specially designed with multiple pegs (80) having multi-faceted surfaces (110, 112, 114).

Abstract: To detect a foaming contaminant in a moving container, an image of the moving container and any contents thereof is produced. Thereafter, image processing techniques are used to determine levels of low and high frequency spatial variations in intensity in the image. The levels of low and high frequency spatial variations in intensity are then compared to determine the presence of a foaming contaminant.

Abstract: A method for accomplishing particle monitoring above the throttle valve of a turbo pump provides a particle sensor which is built into the throttle valve in such a way that it is insensitive to local plasma glows. Furthermore, the particle sensor is placed such that a particle monitoring laser beam of the particle sensor is offset from the centerline of the pipe, so as to maximize exposure to process gas flow which is diverted to the periphery of the pipe by the position of a butterfly valve plate.

Abstract: An apparatus and method of aligning a capillary with respect to a radiation source. More particularly, the capillary is aligned with a laser beam for laser induced fluorescence detection. The scatter or transmitted light pattern of the laser beam with respect to the capillary tube is utilized to determine optimum alignment. photosensors may be implemented to detect the light pattern which represents optimum alignment. For dynamic alignment during electrophoresis, the photosensors provide feedback to a controller which controls a positioning mechanism for alignment of the capillary.

Abstract: A smoke type fire detector accurately detects a smoke density even when an internal temperature thereof changes. An internal temperature detecting unit detects an ambient temperature at a light emitting element and a light receiving element. A correction coefficient having a value associated with the ambient temperature detected by the temperature detecting unit is used to correct an output level of the light receiving element.

Abstract: A probe for monitoring a fluid medium employing at least one fiber optic emitting a wave into the fluid medium. The fluid medium scatters or causes luminescence of the emitted wave which is then collected by at least one fiber optic. The probe includes a base having a hole and a window covering the hole of the base, wherein the window transmits electromagnetic waves. The probe collects scattered and luminescence of waves through one or more fiber optics placed behind the window and transmits the waves to a spectrometer connected to a computer which can analyze the fluid medium on a real-time on-line basis. Piezoresistive and temperature sensing elements are deposited on the window which can also serve as a force collector diaphragm. The elements are located primarily on the periphery of the diaphragm leaving a part of the diaphragm open for transmission and collection of the waves.

Abstract: A device (7) for testing the operation of smoke detectors (3) has a housing (1) which is open at one end and can be placed over the smoke detector (3). A test light source (5) in the housing provides light pulses which radiate into the inside of the smoke detector (3) under test. The test device also has a test light detector (4) that receives light coming from the smoke-indicating light source (15) of the smoke detector (3) and controls the test light source (5) in relation to the received light. The light pulse of the test light source (5) is received by the smoke-indicating light detector (14) of the smoke detector (3). By checking if the smoke detector (3) goes into the alarm state, it can be ascertained whether it is in an operational condition.

Abstract: The present invention provides a method for detecting whether an alarm circuit is operating outside its sensitivity range, the alarm circuit having a background signal and a preset alarm threshold signal. The method involves: a) multiplying the background signal by a first gain factor to produce a first test signal; b) comparing the first test signal against an alarm threshold signal; c) multiplying the background signal by a second gain factor less than the first gain factor to produce a second test signal; and d) comparing the second test signal against the alarm threshold signal. The alarm circuit is operating outside its sensitivity range when the first test signal is less than the alarm threshold signal or the second test signal is greater than the alarm threshold signal.

Abstract: A method and apparatus for gaining intravenous access including a source of radiation for irradiating an area of the patient wherein the radiation has a wavelength such that the radiation is absorbed in areas containing veins and reflected in all other areas thereby forming a view which is seen through a screen to be the area where venous structure appears as dark lines thereby enabling a user to position the tip of a hypodermic needle at an appropriate location for drawing blood. In one arrangement, the apparatus is mounted on the head of the user. In another arrangement the device is mounted on a floor stand. In another embodiment, the apparatus is equipped with an image intensifier. In another embodiment, a mirror is provided enabling the user to view the selected area and the image simultaneously.

Abstract: A coating system for detecting the presence of contaminants carried by a fluid that is applied as a coating on a workpiece. A tube guides the fluid along a flow path to the workpiece. A light source illuminates the fluid along at least a portion of the flow path, and this light is scattered by any contaminants present in the fluid. Light scattered by the contaminant particles is more intense than light scattered by the other fluid particles, and this brighter scattered light is detected by a light detector positioned adjacent to the fluid flow path. If one or more contaminant particles is detected in the fluid, a warning signal can be given and/or the flow of fluid can be stopped. This coating system is particularly well suited for use in a spin-on coating process that applies a liquid, such as a photoresist material or a dielectric material, to a semiconductor wafer or other workpiece that is secured to a rotating turntable.

Abstract: The invention is a Method and Apparatus for detecting the application of a liquid drop into a transparent reaction chamber or other reflecting surface in the presence of ambient light and transient motion of the chamber. A light source is modulated into two or more discrete levels at a fixed or variable modulation rate. These levels include an off level where there is no light from the optical source. Light from the source is specularly reflected into an optical detector which is sampled at least once for each modulated light level. Differences between modulated levels and the off level represent the amount of reflectivity of the surface or chamber. When liquid enters the chamber or is applied to the surface, the reflectivity changes. This leads to detectable changes between the modulated levels and the off level. Ambient light simply shifts the absolute values of the levels.

Abstract: A separate type photoelectric smoke sensor having a light emitting section for emitting a light beam to a reflecting plate disposed at a certain distance from the light emitting section, a light receiving section for receiving reflected light from the reflecting plate, and a judgement section for outputting a sense signal if a received light output from the light receiving section is smaller than a threshold value previously set.

Abstract: A photoelectric sensor of the present invention includes a light emitting device and a light receiving device for detecting scattered light due to smoke, a light emitting confirming device which lights up when a quantity of light received by the light receiving device is greater than or equal to a threshold and a test light emitting device for emitting light to the light receiving device during the test, wherein a blinking of the light emitting confirming device is started at a time of a test start, and a quantity of light received by the light receiving device is increased in steps so that the blinking is stopped when the quantity is greater than or equal to the threshold. Accordingly, the sensitivity test can be performed by visually counting the number of blinkings of the light emitting device.

Abstract: For testing or/and adjusting a scattered-light smoke detector as to sensitivity to smoke, a transparent body with included scattering centers is introduced into the measurement volume of the detector. Aluminum oxide powder particles can serve as scattering centers. The distribution of light scattering centers is preferably uniform, and their concentration chosen to simulate a smoke density corresponding to the alarm threshold of the smoke detector. Thus, scattered-light smoke detectors are readily calibrated to a desired output signal as a function of smoke density. With a different density of scattering centers, the technique can be used for testing scattered-light smoke detectors in the field. If the scattering centers are distributed outside a measurement volume of an uncontaminated detector, the technique can be used for testing as to contamination.

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: A closed loop feedback control for enhancing the response of electrorheological fluid having a light source and a photodetector measuring the light transmission through the electrorheological fluid. A manually controllable signal generator generates a reference signal indicative of the desired transmission through the electrorheological fluid. A control amplifier responsive to the difference between the measured transmission and the reference signal changes the value of the electric field being applied across the electrorheological. The change in the electric field selected to significantly reduce the time required for the electrorheological fluid to change from its current state to the desired state.

Abstract: Light the intensity of which is modulated to the initial intensity by a modulating signal having an ac component with a predetermined frequency and which is from the intensity tuneable light irradiating unit irradiates the scattering and absorption medium which is an object to be measured. The modulated light incident on the scattering and absorption medium propagates in the scattering and absorption medium, emerges therefrom and is incident to the photodetecting unit, and the photodetecting unit converts the incident light into an electric signal corresponding to the intensity of the incident light, and thereafter, outputs the electric signal as an optically detected signal. The feedback unit extracts the ac component from the input optically detected signal, and the intensity of the ac electric signal and the adjusting value are compared and the variation of the quantity of generating light is sent to the intensity tuneable light irradiating unit.

Abstract: An apparatus and process for accurately determining settling data for the settling of erythrocyte cells from a plasma fluid in a test specimen of blood. The apparatus includes a settling tube, a sensing assembly movably mounted proximate the settling tube. Preferably an infrared emitter and detector are provided in the sensing assembly, and a control assembly is provided which senses data at a high rate and is responsive to the sensed data to sample or store the time at which sensed reflectivity exceeds a threshold level. When the threshold is reached, data is sampled and the tracking head is moved by a very small step. This process is repeated to enable tracking of the descent of the separation boundary between the erythrocyte cells and plasma fluid. The apparatus senses changes in reflectivity of the erythrocyte portion of the specimen below and up to the separation boundary.

Abstract: A photoelectric type fire detector has: a detector body; a printed circuit board disposed on the upper side of the detector body; conductive connecting members provided on the lower side of the detector body; terminal screws for simultaneously fixing the printed circuit board and the conductive connecting members to the detector body; an optic base directly placed on the upper side of the printed circuit board and having a labyrinth formed on the upper side thereof; hooks for fixing the optic base to the upper side of the printed circuit board; a light-emitting element and a light-receiving element arranged in a pair for detecting smoke; a bug screen provided on the outer periphery of the labyrinth of the optic base; an optic base cover covering the upper side of the optic base; and a protective cover covering the printed circuit board, the optic base, the bug screen and the optic base cover.

Abstract: A turbidity sensor is provided with two plates which each have an aperture formed therethrough. The apertures are aligned to define a light passage from a light source such as a light emitting diode. By properly selecting the gap between the two plates and the size of the two apertures, the angle of divergence light emanating from the light source can be controlled and reduced to a magnitude that prevents light from passing directly from the light source to a scattered light detector of the turbidity sensor. The arrangement avoids the necessity of using expensive focusing lenses.

Abstract: A method and device for measuring the concentration of solids within a liquid medium, or other optical properties of a liquid solution or suspension, by the technology of reflectance. In a preferred embodiment, the reflectivity measuring device of the present invention comprises a measuring head or probe having at least one radiation source and at least one radiation sensor positioned therein. The head or probe is attached to a controller/data readout having a microprocessor control system housed therein. The head or probe is positioned within or adjacent a body of liquid. Thereafter, the radiation source is caused to emit radiation and the radiation sensor is utilized to sense the relative amounts of radiation reflected by the body of liquid and/or solids contained therein.

Abstract: A light emitting device for projecting a light beam onto a monitor area, and a light receiving device, arranged so that a light beam is not directly received by the device, for receiving diffused light caused as a result of fine particles, such as dust, or smoke caused by a fire, entering the monitor area, are provided. Also, an amplifying device for amplifying an output from the light receiving device, and a counting device for counting the output from the amplifying device in units of time are provided. In addition, a computing device for computing an average value or an integrated value of the output from the amplifying device in units of time, and a determining device for determining the level of contamination of the monitor area on the basis of the count value of the counting device and for determining the level of the fire on the basis of the average value or the integrated value computed by the computing device, are provided.

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: The incorporation of certain classes of solid state lasers into light scattering instrumentation is desirable because of their compact structure. However, mode hopping often causes the output power produced by such lasers to be unstable. The frequency of such output power fluctuations is often so broad that output power monitoring means, characteristic of the light scattering instrumentation into which such lasers are incorporated, cannot track accurately the temporal output power fluctuations. A method, and associated apparatus, is described whereby the laser drive current is modulated at low frequency and amplitude sufficient to induce and thereby control mode hopping so as to permit accurate measurement of the ratio of light scattering signals to the laser output power.

Abstract: A portable scatterometer and/or an angular radiated light measurement instrument that uses a measurement head which includes a double tapered fiber optic bundle with a concave front face to simultaneously collect partial or full hemispherically scattered light reflected from a point on a surface illuminated by a depolarized, telescopically focused, laser diode source, the light rays being received by each fiber normal to its face. The image of the collected light beams is minified and coupled by the fiber optic bundle into an anti-blooming CID camera with an x-y scanning area array which converts the light beams to electrical signals. In a unique real time, computer-controlled data acquisition and reconstruction process, a frame grabber and a unique algorithm are used to collect over 200,000 points of light, reconstruct the data into a 2D or 3D scatter profile and display the results, all within one second.

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: Optical apparatus having an optical fiber to receive light incident thereon at one end, and a detector located adjacent the other end of the optical fiber to receive light passing through the optical fiber and emitting from the other end thereof to be incident on the detector for analysis purposes.

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.