Abstract: An electro-optical meter for indicating consistency of a liquid slurry, employs a light source and a detector of backscattered radiation. The light is caused to scan the slurry while holding the light intensity and the peak-to-peak value of the detected signal constant. The distribution of backscattered light is measured and the minimum to maximum intensity of backscattered light is controlled.

Abstract: An apparatus for the early detection of oncoming wind shear, without false indications arising through turbulence. A forward looking laser speed sensor (11) provides a signal (12) containing information on air velocity over a range of distances about a measurement distance (X). This is subject to spectrum analysis (15), to identify all velocities present in a time sample of the signal (12). These velocities are further processed (17) to establish the air velocity at substantially the measurement distance (X), and the highest and lowest velocities present over a distance range (L). A time sequence of results is combined to provide a wind shear hazard level for comparison with a hazard level limit computed (13) from the prevailing conditions.

Abstract: In a method of measuring velocity gradients in a sample volume (2) in a flowing medium, by which method radiation scattered by particles entrained by the medium and irradiated by spatially coherent electromagnetic radiation, in particular laser light, is detected and measured and the difference in Doppler shift in the radiation from different particles in the sample volume (2) used as a measure of the velocity gradient, an optical element (3) is inserted in the radiation path from particles in the sample volume (2) to the detector (4). The optical element (3) has such properties that essentially only radiation scattered simultaneously from particle pairs in the sample volume (2) spaced apart a distance determined by the optical element (3) are made part of the measuring signals to be combined to form the signal which is a measure of the difference in the Doppler shifts and thereby of the velocity gradient in the sample volume (2) defined by the measurement points.

Abstract: A probe tube which is introduced into a reaction container for measuring the operating condition of a medium in the interior of the container has a first seal which is resistant to temperature and a second seal which is resistant to pressure and gas-tight. Those seal respectively close the inner and outer ends of the probe tube. The interior of the probe tube communications with the interior of the reaction container by way of an opening, whereby the temperature-resistant seal at the tip of the probe tube is relieved of the loading of pressure forces.

Abstract: System for detecting the forming of depot inside a transport channel for transporting particles in a light transparent carrier fluid, comprising a light transmitter, a light receiver, a bifurcated glass fibre cable of which an end is installed in the wall of a transport channel. One branch of the cable is coupled to the light transmitter and the other branch is coupled to the light receiver, and the output of the light receiver is connected to a discriminator circuit comprising a converter for converting the effective ac voltage component in the received signal into a dc voltage component and a comparator in which the dc voltage signal is compared with a predetermined threshold signal, which discriminator circuit is coupled to a visual indicator unit.

Abstract: A method and system are described for the detection and imaging of objects and structures in scattering media using light radiation. The medium is scanned with a strongly collimated light beam (2). The light power (P.sub.b) scattered backward from the medium is detected by a receiver (17) and plotted along the scanning path. Objects (4) buried in the medium (9) are detected by the differential variation of the received light power. Information as to the size, location and depth of the objects can be obtained. The illumination by strongly collimated laser light at one or several wavelengths is preferred.

Abstract: Fiber content measuring instruments having radiation detectors are used to indicate the average radius and/or the average length of particles in a flowing medium. In order to determine the average radius, a signal based on the alternating current voltage portion of the signal from a radiation detector having a high resolution is divided by a signal based on the direct current voltage portion and the signal from a radiation detector having the same or another resolution. In order to determine the average length a signal based on the alternating current voltage portion of the signal from the radiation detector having a low resolution is divided by a signal based on the alternating current voltage portion of the signal from the radiation detector having a high resolution.

Abstract: An apparatus and method for determining the percentage of solid particles in a suspension (consistency) is provided. A source of diffused radiant energy is provided which energy is directed toward a suspension to be measured. The portion of the energy which is forward-scattered by the suspension is detected and a first signal indicative of the magnitude of the forward-scattered energy is produced. The portion of energy which is back-scattered by the suspension is detected and a second signal indicative of the magnitude of back-scattered energy is produced. The first and second signals are combined at a predetermined ratio to produce a feedback signal used to control the intensity of energy emitted from the radiant energy source. The intensity of energy emitted from the source is a function of the forward-scattered and back-scattered energy and is directly proportional to the consistency of the suspension being measured.

Abstract: A laser echoe ranging device (lidar) is used both to measure cloud height and to measure slant range visibility. For the latter purpose at various elevation angles, the distance for which the echoe gets down to the noise level is measured by a counter and the echo voltage for a distance selected by a time switch is also stored, for example for various distances in 100 meter steps. These values can be used to compute the slant visual range and, with reference to the data for the different angles of elevation, also the layer structure of an inhomogeneous scattering characteristic of the atmosphere.

Abstract: A steam wetness measuring apparatus comprises a light source, a part defining a measuring space when the apparatus is inserted into a wet steam flow, an optical fiber bundle for transmitting the incident light beam from the light source to the measuring space, and optical fiber bundles for transmitting to a photo-electric converter element a plurality of scattered light beams of different scattering angles obtained by radiation of the incident light beam on the measuring space. The fact that the intensity of the scattered light beam changes with the wavelength of the incident light or changes with the scattering angle of the scattered light beam, in accordance with the particle size distribution of water droplets in the wet steam is used to determine the particles size distribution. The steam wetness is determined from the particles size distribution and the physical properties of the wet steam flow.

Abstract: A method of determining the size of spherical particles, comprising the operations of illuminating with a beam of circularly polarized light particles the size of which is to be determined, detecting light backscattered by the particles, measuring the angular intensity distribution of the backscattered light and deriving therefrom an indication of the size of the particles.Various forms of apparatus for carrying out the method also are described.

Abstract: The invention provides a photometric method of determining courses of reaction in a specimen, in which method the intensities of the transmitted light and of the stray light are measured, wherein the two intensities are measured simultaneously and the electrical signals corresponding to the transmitted light and to the stray light are combined to form one signal. The invention makes it possible to perform reliable measurement even with low levels of transmitted and stray light.The method is preferably used in determining the coagulation times of blood. Apparatus for carrying out the method is also disclosed.

Abstract: Apparatus for transmitting light and detecting resultant scattering in order to derive information relating to a light-scattering object. A fiberoptic cable has one end adjacent a light generator and the other end aimed at a light-scattering object. A receiver gathers light scattered by the object at which the light output of the cable is aimed. An information processor is connected to the receiver and is operative to generate values relating to properties of the light-scattering object.

Abstract: A suspended sediment sensor system for determining concentrations of particles and their size distribution in a submitted fluid sample. The particles being measured range from 50-1000 microns in dimensions and the concentrations range from <50 to 50,000 parts per million (ppm) of fluid. Equipment used includes a fall tube, laser light source, light scattering detector system, optical equipment, and a system to control the movement of the sample and other fluid past the laser and detector system. The detector system measures background scatter from particles impinged upon by the laser source at an angle of about 165.degree.. Contemplated to be used with the foregoing is a computer and associated controls to allow an unattended in situ system for a river, lake, etc.

Abstract: The specific surface distribution of a pulp may be obtained by fractionating the pulp in a hydrocyclone means into an overflow and an underflow fraction and measuring the specific surface of each of the fractions and the amount of each of the fractions and based on a cumulative normal distribution relationship of cumulative weight fraction as a percent of feed to specific surface, determining the specific surface distribution for said pulp.Also disclosed is a method and apparatus for determining the specific surface of a pulp sample by measuring the light scattering characteristics to obtain a turbidity measurement of the pulp sample, measuring the consistency of the sample and determining the specific surface of said pulp based on the relationship of specific surface to the turbidity measurement for the measured consistency of the pulp.

Abstract: A particle sensing system in which light is concentrated at an inspection zone and deflected light is concentrated at a photosensor. A first reflecting surface is shaped to direct light toward the inspection zone, and a second reflecting surface is shaped to direct light deflected by particles in the inspection zone toward the photosensor. These two reflecting surfaces can be shaped so that an overwhelming part of the directions around the inspection zone are utilized for illuminating it and to direct light deflected toward the photosensor. A third reflecting surface, having spherical curvature with the center of curvature at the inspection zone permits utilization of an overwhelming part of the remaining directions around the inspection zone.

Abstract: A method and apparatus for determining the absorption spectra, and other properties, of aerosol particles. A heating beam source provides a beam of electromagnetic energy which is scanned through the region of the spectrum which is of interest. Particles exposed to the heating beam which have absorption bands within the band width of the heating beam absorb energy from the beam. The particles are also illuminated by light of a wave length such that the light is scattered by the particles. The absorption spectra of the particles can thus be determined from an analysis of the scattered light since the absorption of energy by the particles will affect the way the light is scattered. Preferably the heating beam is modulated to simplify the analysis of the scattered light. In one embodiment the heating beam is intensity modulated so that the scattered light will also be intensity modulated when the particles absorb energy.

Abstract: An optical arrangement for a light scattering type smoke detector has a radiation transmitter and receiver which are each preceded by a lens for obtaining a generally parallel field of view for each of the transmitter and receiver. The radiation is directed at a detection zone which is surrounded by diaphragms and the fields of view for the transmitter and receiver terminate in a light trap for preventing unwanted scattering and reflection. The transmitter and receiver are disposed at an acute angle with respect to each other and the receiver detects only back-scattered radiation from smoke particles in the detection area. This structure allows a relatively short structural length to be utilized along a common optical axis of the transmitter and receiver.

Abstract: In certain light detection and ranging (LIDAR) systems it is necessary to move the normal aerosol backscattering signal of the atmosphere so that a weak atmospheric turbulence signal of interest, which is present on the backscattering, may be observed. In this disclosure, only one LIDAR pulse is used wherein the return signal is fed equally into four separate delay lines. The four different delayed signals are subtracted to cancel the background and are amplified to give an output signal for which the background is largely removed while retaining the signal of interest. The signal of interest is then amplified and displayed and/or analyzed.

Abstract: An optical system for direct measurement of vorticity in a flowing fluid is disclosed. Spherical particles suspended in the flow rotate with an angular velocity that is accurately equal to half the local vorticity; thus, measurements of the rotation rates of such particles indicate the vorticity. The particles are transparent, and preferably are less than 50 .mu.m diameter, and each contains embedded planar crystal mirrors. The particles are suspended in a refractive index matched liquid. Measurement of the particle rotation rate and thus the vorticity of the fluid is preferably accomplished by measuring the rotation rates of reflections of one or more light beams from the planar mirrors. The measurements may be carried out using any system of position sensitive optical detectors such as photo sensitive devices screened by suitable slits or photo diode arrays.

Abstract: Apparatus is disclosed for use on an aircraft for detecting clear air turbulence (CAT) and/or wake vortex (WV). In one embodiment of the invention, a beam of light from a continuous wave UV laser scans an area on the aircraft's flight path. A photodetector monitors optical radiation backscattered from the area, providing an intensity-controlling signal for a CRT display. Clear air turbulence is indicated by non-uniformities on the display. In another embodiment of the invention, a pair of beams of light from a pair nitrogen gas pulse UV lasers are arranged to converge at a region in front of the aircraft. The backscattered radiation from the region is monitored for turbulent areas by a receiver which includes a photodetector and which is connected to an oscilloscope where the return pulse amplitude is analyzed. Velocity determinations of the air parcel monitored are made by causing the two beams to scan either horizontally or vertically.

Abstract: A light scattering photometer including a rotating segmented mirror intercepting light from a laser source and alternately directing the light into a sample zone along an optical axis in first and second opposite directions. A mask annulus coaxial with the optical axis intercepts light scattered from the sample in an incremental angle .DELTA..theta. at a selected angle .theta. with respect to the axis. As the direction of sample illumination alternates, the annulus alternately intercepts forward scatter and back scatter of light from the sample at angles .theta. and 180.degree.-.theta., respectively, and passes the forward and back scatter in alternate succession to a detector. The detector output signal is demodulated to derive near-simultaneous forward and back scatter measurements from the sample. The photometer permits measurement at small values of .theta. approaching 0.degree. and hence permits near-simultaneous scatter measurements at forward and back scatter angles spaced by an angle approaching 180.

Abstract: An optical particle analyzer in which the size of a particle in a particle stream is determined from the intensity or the duration of light scattered from it. A laser beam is directed transversely onto the stream and scattering occurs at the beam focus. To ensure that only particles which traverse the center of the beam are considered, a smaller, validating beam concentric with the main beam also produces scattered light. A pulse from the narrow beam coincident with one from the broad beam confirms that the associated particle has passed through the center of the broad beam and warrants consideration and assessment.A further narrow beam spaced from the first provides a time delay, dependent on particle velocity, between interception of the two narrow beams by a particle. Particle velocity is thus measured.

Abstract: A laser beam projected through a prism in a direction normal to the surface of a circular wafer is focused into a spot area and scanned along a spiral path on this surface. The focusing means comprises a relatively large aperture lens and the prism is on the lens axis. The retroreflected specular light passes through the lens and is prevented from reaching a light detector in the image plane of the lens by the prism. When the beam illuminates a microscopic surface defect on the wafer, the light is diffracted and reflected therefrom, and the lens captures that portion of the reflected light within the solid angle subtended by the lens, and passes that portion thereof not blocked by the prism, to the light detector. The output of the detector may be employed to intensity modulate the beam of a cathode-ray tube display, the beam of which is spirally scanned in synchronism with the scanning of the light beam.

Abstract: A clear air turbulence detector includes an ultraviolet laser for generating a coherent beam which scans an area on an aircraft's flight path. A photodetector monitors optical radiation backscattered from the area, providing an intensity-controlling electrical signal for a CRT display. Updrafts contain greater-than-normal amounts of ultraviolet-absorbing water vapor and result in a blank spot on the display while downdrafts contain less-than-normal amounts of water vapor and result in a bright spot on the display.

Abstract: The invention relates to the measurement of the shade of a particle. The particle is illuminated with light of variable intensity and viewed against a background level of illumination. A measurement is made of the ratio of time for which the intensity of light from the particle exceeds the intensity of the background to obtain a measurement of the shade of the particle.

Abstract: The specific surface distribution of a pulp may be obtained by fractionating the pulp in a hydrocyclone means into an overflow and an underflow fraction and measuring the specific surface of each of the fractions and the amount of each of the fractions and based on a cumulative normal distribution relationship of cumulative weight fraction as a percent of feed to specific surface, determining the specific surface distribution for said pulp.Also disclosed is a method and apparatus for determining the specific surface of a pulp sample by measuring the light scattering characteristics to obtain a turbidity measurement of the pulp sample, measuring the consistency of the sample and determining the specific surface of said pulp based on the relationship of specific surface to the turbidity measurement for the measured consistency of the pulp.

Abstract: Stray scattering in a scatterometer is removed by use of a lens and aperture system in conjunction with a beamsplitter. Backscattered light from a mirror being tested is deflected by a beamsplitter and focused by a lens through an aperture onto a detector. The distance from the beamsplitter to the lens is much smaller than the distance from the mirror to the beamsplitter in order to increase the detected signal as compared with detected noise caused by light scattered by the beamsplitter. The scatterometer system disclosed is further refined by use of a cavity dumper which absorbs stray light left after reflection from the mirror being tested. The cavity dumper is a silicon semiconductor on a metal backing which absorbs the light with minimum reflection back along the original incident light path.

Abstract: A diagnostic apparatus and method for measuring motion of flowing solid and fluid particles that utilizes a differential doppler system and makes measurements parallel to the optical axis of the system. The system includes a laser generating a light beam directed toward a light beam splitter. The splitter separates the light beams into a plurality of beams that are focused in a crossing and focusing area. Receiving optics aligned with a photodetector sense light scattered by particles moving in the focusing area. The photodetector converts the light signals to electrical signals. A signal mixer coupled to the photodetectors operates to produce a difference electrical signal established by the difference between the frequencies of the electrical signals produced by the photodetector. The difference electrical signal is converted with signal processors to a voltage proportional to the velocity of particles moving through the focusing area.

Abstract: A vehicle headlight is disclosed comprising a dirt sensor for sensing dirt on a diffuser disk of the headlight. The dirt sensor receives the light of a lamp of the headlight scattered back due to dirt on the diffuser disk and is shielded against the light emanating directly from the lamp and emanating indirectly via a reflector. The dirt sensor of the headlight is arranged at a point outside of the reflector to which the scattered-back light passes via reflection on the reflector whereby changes to the reflector for accommodating the dirt sensor and the concomitant reduction of the effective surface area of the reflector are avoided.

Abstract: There is disclosed an illuminator and collector apparatus and method for fluorescence analysis wherein illumination of a stream of particles produces fluorescent light. A reflector, having a concave reflector surface with a first focus disposed in the stream of particles, has reflected therefrom organized illuminating radiation, such radiation converging upon the first focus to stimulate the particles into producing the fluorescent light. The fluorescent light emanates from the first focus, a portion of which is reflected from the concave reflector surface. This fluorescent light which is focused on the second focus contains no (or negligible) amount of illuminating radiation and is collected for subsequent detection and processing.

Abstract: Optical apparatus for measuring the amount of light reflected and/or scattered by particles suspended in a fluid, such as scrubber carryover appearing as a spray of dispersed water droplets. The amount of light reflected and/or scattered is an indication of the volume and mass of the suspended particles. A beam of light is caused to pass diagonally across a stream of purging gas used to keep the optical components clean and is directed onto the suspended particles at a point outside the purging gas stream. The light reflected back through the purging stream is then measured in intensity to determine the total volume of the particles from which mass may be determined. The invention overcomes the disadvantages of prior art devices in which the purging gas can disrupt the environment in which particle density is to be measured.

Abstract: A system is disclosed which will sense the image-development state of toner in the development subsystem of an electrophotographic copier apparatus. This image-development state is related to both toner concentration and the charge-to-mass ratio (q/m) existing on toner particles. The sensing system employs an optical fiber bundle having both transmitting and receiving fibers. At one end, herein referred to as the common end, and transmitting and receiving fibers are interspersed. This common end is positioned flush with the inside chamber wall on a developer housing. At the other end, the transmitting and receiving fibers are bifurcated. The transmitting fibers of the optical bundle are used to guide light from a light source to the common end, and part of the transmitted light is backscattered and guided through the receiving fibers to an optical sensor. The signal received is inversely proportional to the amount of toner deposited on the end of the bundle and the toner on the surface of carrier particles.

Abstract: A system for detecting a reflected light beam includes a source of coherent light such as a laser beam, an optical fiber spaced away from the source for receiving an incident beam of coherent light from the source at one end of the fiber, means for reflecting a portion of the incident beam back through at least a portion of the fiber to radiate a reflected beam which includes narrow angle signals having a beam width corresponding to that of the incident beam and wide angle signals having a beam width substantially wider than that of the incident beam, receiving means between the source and the optical fiber for receiving the reflected beam and having an optical aperture therein for transmitting the incident beam and the narrow angle signals in the reflected beam, and a projector lens between the receiving means and the optical fiber for directing the incident beam into the optical fiber and for directing the narrow angle signals in the reflected beam into the optical aperture of the receiving means.

Abstract: Apparatus for laser anemometry comprises a device for producing coherent radiation, a beam splitter device adapted to divide the beam from this device into two beam portions, focussing means adapted to focus these two beam portions on to two adjacent spots, and two photodetector means each adapted to measure the scattered illumination from one said spot. In order to enable the direction of the path between the two spots to be altered without moving the entire apparatus, an image rotation device is provided and mounted to effect both the beam portions and the scattered radiation from the spots which falls on the photo-detector means.