Abstract: Applicant's invention is a method and apparatus for inhibiting laser detection wherein the infrared laser light from a laser gun is absorbed, diffused, and dispersed, hindering the quick response needed for accurate laser readings. The laser detection inhibitor incorporates a rectangular acrylic lens panel and a filtering treatment which coats or is infused into the acrylic lens panel. The acrylic lens panel is suitably formed for placement over a vehicular license plate. The panel is adapted for placement over the license plate. After the panel is sprayed or infused during molding with the filtering treatment, the panel is affixed over the license plate using the existing attachment means for the vehicular license plate. Applicant's invention uniformly covers the license plate absorbing, diffusing, and dispersing infrared laser light and therefore, inhibiting laser detection.

Abstract: The initial movement of a spherical body is detected by detecting the intersection with a light beam emitted from trigger light illuminating portion 2 to trigger light-receiving portion 3, and as a result, measurement of time by an arithmetic processing unit is started. During flight, spherical body 1 intersects light beams emitted from surface velocity sensors 4 and 5, the reflected light therein is detected by these surface velocity sensors 4 and 5, and the surface velocity of spherical body 1 is then measured. Spherical body 1 continues in flight and intersects at least two light beams irradiated from multi-beam illuminating portion 6 which are detected by multi-beam light-receiving portion 7.

Abstract: The passive wind profilometer measures wind transverse to a line of sight as a function of range. Schlieren which are natural occurrences in wind act as refracting lenses which move along with the wind. The patches of refracted light are detected by use of a light-intensity-sensitive television. camera and a microprocessor. The range of the schlieren are determined from the scale size of the refracted patches of light. The microprocessor, using a specific algorithm for processing the light intensity data, then statistically compares the positions of the schlieren at different times to determine the wind velocity.

Abstract: A Mach number sensor comprises a first pulse speed sensor situated in direct contact with an open area through which a first pressure pulse can pass and a second pulse speed sensor situated in a thermally conductive tube with membrane-covered ends having stationary air through which a second pressure pulse can pass. Each of the first and second pulse speed sensors may comprise two total internal reflection detectors and a timer for determining elapsed time for passage of the pressure pulse between the two detectors.

Abstract: A system is provided that corrects the undesirable fast power modulation observed at an output of a wideband frequency modulated (FM) laser. The correction is accomplished by applying a corrective voltage to an amplitude modulated (AM) modulator. The response of the laser is first measured to characterize the laser. Iterative predictions of appropriate voltage correction waveform, based upon the observed power modulation and the laser's response are then applied to the AM modulator to reduce the unwanted laser power modulation.

Abstract: An apparatus for the three-dimensional determination of flows has a light source for briefly illuminating a light section (3) and a stereoscopic recording device (10). The stereoscopic recording device (10) comprises two equivalent objectives (11, 12) aligned parallel to each other as well as perpendicular to the plane (22) of the light section (3), and behind the objectives (11, 12) two optical sensor fields (15, 16) aligned parallel to the plane (22). A forward displacement device for the synchronized forward displacement of the projections of the light source (3) onto the two sensor fields (15, 16) has two revolving mirrors (13, 14) aligned parallel and rotating in synchronization about a common axis of rotation (23) as well as in synchronization with the light source, whereby the axis of rotation (23) runs parallel to an imaginary line joining the two objectives (11, 12).

Abstract: Laser beam speckle effects are mitigated by frequency chirping a single-mode laser beam, reflecting it off a speckling surface, and then integrating the reflected beam over at least one chirp period. The speckle reduction is comparable to the use of a multi-longitudinal mode beam having a bandwidth similar to the chirped frequency excursion, while leaving the beam compatible with nonlinear optical processes that are not compatible with multi-longitudinal mode beams. Where the nonlinear process is stimulated Brillouin scattering (SBS) phase conjugation, the beam can be chirped at a rate up to the order of ##EQU1## where .DELTA..nu..sub.B is the gain bandwidth and L is the effective SBS interaction length of the phase conjugator, and C is the speed of light. Other nonlinear processes with which the beam may be used include harmonic generation and Raman-based beam cleanup or wavelength conversion.

Abstract: A vehicle control system (12) is provided which comprises a range measurement system (14) which transmits a signal (20) to a target (22) and receives an echo signal (24) returned from the target (22). The range measurement system (14) comprises a transmitter system (26) and a receiver system (28). The receiver system (28) generates an analog signal representative of the range. The target (22) transmits the range signal to a processor (30). Processor (30) may be used to provide warning signals and to control a conventional speed control system (16) coupled to the throttle (18) of a vehicle (10).

Abstract: A light based distance, velocity and acceleration sensor which uses phase difference to determine the desired measurement. A laser signal is modulated by an oscillator signal and reflected off an object to a signal receiver. The reflected laser signal and the oscillator signal then pass through a dual path conditioning circuit, where the path lengths and circuit elements of the two paths are identical to cancel the effects of propagation delays in an output signal. The conditioned signals are passed through a phase comparator, to produce a signal indicative of the phase difference between the oscillator signal and the reflected laser signal. The phase difference is directly proportional to the distance between the sensor and the object.

Abstract: The velocity of a photoreceptor belt is measured by sensing the passing of illuminated slits in the belt, as the belt moves in a process direction. Two linear position sensors are positioned so as to view the passing of the illuminated slits. The sensors are aligned in a staggered configuration so that there is an overlap region. The slits are positioned so that as one slit is moving off of a downstream sensor, a second slit is moving over the upstream sensor. The output from an illuminated sensor is alternately switched to the second sensor. The sensor outputs are differentiated to provide an output signal representing a belt velocity. The velocity is compared to said velocity in the belt drive system and error signals generated to compensate for detected changes in the belt velocity.

Abstract: This invention relates to a method for simultaneously determining particle concentration and velocity in multi-phase streams. These determinations may be made by use of a fiber optic probe that establishes an illuminated sensing zone of finite dimensions. The probe collects light backscattered from the zone at discrete points in time. The collected light is converted to a voltage waveform. By taking the mean of the voltage values, concentration can be determined, and, by taking a derivative of the voltage waveform, the velocity can be determined.

Abstract: A five step method is used to produce an optical wave. The first step is to pick the desired far field pattern of the diffractive optical wave. The second step entails transforming the desired far field pattern to the desired source using a fast fourier transform (FFT). In the third step we use the formula exp[j.phi..sub.i (.sigma..sub.i)]=A.sub.i exp(j.phi..sub.i) to find the standard deviation .sigma..sub.i for each pixel i that produces the desired/average amplitude. Next, we use a pseudo-random number generator to select phases .phi..sub.i from distributions of standard deviation .sigma..sub.i for each pixel. Finally, we check the solution with the FFT and our analyses of performance.

Abstract: The invention relates to a method and to a system for reducing the distance-dependent amplification factor when measuring fluid flow movements with the aid of an image-producing laser-Doppler technique, in particular when measuring blood perfusion through tissue. A laser beam source (1) directs a laser beam (2) onto a measurement object (5), which scatters and reflects the beam (2). The reflected light is received by a detector (9) which senses the broadening in frequency caused by the Doppler effect. One or more lenses (12: 15, 16) are placed in the path of the beam (2) and are intended to maintain constant the number of coherence areas on the detecting surface of the detector and independent of the distance between detector and measurement object.

Abstract: A laser speed detector is described which includes a laser rangefinder which determines the time-of-flight of an infrared laser pulse to a target and a microprocessor-based microcontroller. The device is small enough to be easily hand-held, and includes a trigger and a sighting scope for a user to visually select a target and to trigger operation of the device upon the selected target. The laser rangefinder includes self-calibrating interpolation circuitry, a digital logic-operated gate for reflected laser pulses in which both the "opening" and the "closing" of the gate can be selectably set by the microcontroller, and dual collimation of the outgoing laser pulse such that a minor portion of the outgoing laser pulse is sent to means for producing a timing reference signal.

Abstract: A multiple-exposure fluorescent image tracking velocimeter (FITV) detects and measures the motion (trajectory, direction and velocity) of small particles close to light scattering surfaces. The small particles may follow the motion of a carrier medium such as a liquid, gas or multi-phase mixture, allowing the motion of the carrier medium to be observed, measured and recorded. The main components of the FITV include: (1) fluorescent particles; (2) a pulsed fluorescent excitation laser source; (3) an imaging camera; and (4) an image analyzer. FITV uses fluorescing particles excited by visible laser light to enhance particle image detectability near light scattering surfaces. The excitation laser light is filtered out before reaching the imaging camera allowing the fluoresced wavelengths emitted by the particles to be detected and recorded by the camera.

Abstract: This system measures the speed of an airborne vehicle relative to the surrounding atmosphere. The measurement is based on the scattering of pulses of coherent laser radiation, generated in the vehicle, preferably in the infrared region of the electromagnetic spectrum, by particles naturally present in the atmosphere at all times. The pulses are focused into the atmosphere at a sufficient distance from the vehicle, preferably 10-30 meters, to be beyond that region perturbed by the passage of the vehicle. The frequency of the radiation scattered by the particles differs from the frequency of the transmitted pulses by virtue of the relative motion of the vehicle and the atmosphere. Equipment in the vehicle digitally processes the received energy to determine this frequency difference for each pulse, and hence the component of the vehicle's velocity in the direction of the pulse transmission.

Abstract: The invention is directed to an optical instrument comprising a housing and at least one optical assembly enclosed by said housing and mounted on a stage plate. The stage plate is supported on the base plate with the aid of supporting means which guarantees on the one hand a precise fixing of the stage plate compared to the base plate and thus the housing, and on the other hand allows the base plate to distort by whatever attacks without a transfer to the stage plate. There are three supporting structures of different kinds which fix three different points in a special way. Upon the disconnection of the third supporting structure the stage plate can be lifted like a lid around an axis which is the middle axis of the first and second supporting structure.

Abstract: Disclosed is an apparatus for transmitting an optical signal. The apparatus includes a transmitter (12, 14, 18, 20, 26) for transmitting a burst of optical radiation, the burst including first periods of optical radiation having a first wavelength (.lambda..sub.1) and second periods of optical radiation having a second wavelength (.lambda..sub.2). The first and second periods alternate with one another for a duration of the burst, and each of the periods begins with substantially zero transmitted power, increases to a maximum transmitted power, and decreases to substantially zero power. Also disclosed is a receiver (30) and demodulator (90) that includes a wavelength separator (DG) for separating the received optical radiation into a first portion comprising of radiation of wavelength .lambda..sub.1 and a second portion comprising of radiation of wavelength .lambda..sub.2.

Abstract: A beam system for traffic monitoring which comprises transmitters for two pairs of beams which constitute a start and a stop pair of beams which in use are spaced from each other by a known distance; receivers for each beam; electronic means connected to detect when reception of the beams by the receivers are interrupted; and means for manipulating data including that derived from the receivers according to desired algorithms, wherein there are provided two pairs of beams, one pair of beams being located at a different level from the other with means for comparing speed or other quantities with the option of rejecting the detection if they do not sufficiently agree.

Abstract: A laser survey instrument is described which includes a laser rangefinder which determines the time-of-flight of an infrared laser pulse to a target, a magnetic compass module which produces an electronically readable compass signal, a vertical angle sensor module which produces an electronically readable inclination signal, and a microprocessor-based microcontroller. The device is small enough to be easily hand-held, and includes a trigger and a sighting scope for a user to visually select a target and to trigger operation of the device upon the selected target. The sighting scope preferably has means for measuring the apparent width of the target.

Abstract: An optical contour detector (11) having a source of electromagnetic radiation (12) aimed at a contoured surface is provided. A first detector (13) and a second detector (14) are positioned near the contoured surface for detecting electromagnetic radiation reflected from a first portion of the surface. Outputs of the first detector (13) and the second detector (14) are differentially amplified to produce an output signal indicting when a change in contour or discontinuity in the surface is illuminated by the source of electromagnetic radiation (12).

Abstract: An apparatus for determining distance coordinates along two orthogonal axes for a computer system, where the coordinates represent the position of a cursor on a screen of a display unit of the computer system. The apparatus includes a pair of velocity detectors and an operating device such as a CPU. When the velocity detectors are moved by an operator, each of the velocity detectors detects velocities along a respective one of the orthogonal axes. The detected velocities are converted into moving distances representative of the coordinates through a calculation of the operating device.

Abstract: A laser Doppler velocimeter is formed using erbium-doped fiber as the lasing medium. Within the velocimeter, all optical signals, transmitted and received, are handled by optical fibers. A telescope with a single optical fiber input/output interface acts as both the transmission device to focus the radiation at a specified point, and as the receiving system for collecting reflected radiation. The portion of the reflected radiation collected by the receiving system is analyzed to determine the Doppler shift caused by targets at the focal point of the telescope.

Abstract: An apparatus for detecting velocity of an object, includes a light source for generating light having a wavelength .lambda., a light-transmission block for receiving the light from the light source, and guiding the light onto the object, and a photosensor for detecting the light from the object on which the light from the light-transmission block is incident. The light-transmission block is integrally constituted by a diffraction grating for diffracting the light from the light source to produce two diffraction lights, and an optical element for causing the two diffraction lights from the diffraction grating to be incident onto the object at a predetermined incident angle. The diffraction grating and the optical element are arranged so as to have substantially constant sin.theta./.lambda. independently of a change in wavelength .lambda. of the light from the light source where .theta. is the incident angle of each diffraction light onto the object.

Abstract: A laser radar system capable of measuring windspeed to within 1 m/s at distances in the range of 10 km. The system comprises two Faraday atomic line filter/detectors combinations, a first filter-detector which consist of a metal vapor cell located between crossed polarizers. A magnetic field is applied to the cell which Zeeman splits the energy levels resulting in different absorption lines for left and right circularly polarized light. Near these lines the filter acts as a Faraday rotator providing rotary power only in the vicinity of an absorption line, which provides the 90 degree rotation necessary to pass the second polarizer. At higher fields and vapor densities multiple rotations lead to rapid modulations in the transmission spectrum. Away from the absorption line the filter provides an out of band rejection that is determined by the extinction ratio of the crossed polarizers. By tuning the temperature and the magnetic field in each Faraday filter sharply crossing response curves can be produced.

Abstract: A high intake, defined excitation, vertical profiling survey bioluminescence bathyphotometer system designed to measure, from a statistically significant sample with a calibrated hydromechanical stimulus, (1) the bioluminescence of phytoplankton and zooplankton organisms in the oceanic water column to depths of 400 meters in absolute units of photons per second per volume (intensity) or photons per volume (total flux), (2) the concentration of bioluminescent population in flashes per volume, (3) the average light intensity per bioluminescent event, and (4) population flash dynamics.

Abstract: The invention relates to a device for measuring the speed or length of a moved surface, where a measuring light beam from a laser is used. The laser light beam reflected from the surface to be measured is frequency-shifted by the Doppler effect so that the overlaying of the outgoing light beam and the incoming one results in a beat which is a measure of the speed of the surface. Before the speed can be determined, digital signals occurring in large numbers must be processed in an evaluation system. The evaluation system is characterized in that there is downstream of a counter intended for detecting the incoming signals and having a high counting speed an intermediate store which is connected to an adding mechanism for pulse-wise monitoring of the counter contents. A control mechanism handles coordination of the counter, the intermediate store and the adding mechanism, upstream of which is a pulse generator.

Abstract: The device described for the measurement, without physical contact, of the speed, displacement distance and/or range of a reflecting object has a laser diode as light source, transmission and receiver optics for aiming the laser light from the laser diode at the object and for feeding part of the laser light reflected by the object back to the laser resonator, and a detector unit for detecting and analyzing the laser light emitted by the laser diode. Fitted to determine the modulation frequency of the laser light, which is frequency-modulated as a function of the feedback to the laser resonator, is a frequency discriminator, a photodiode and a processing circuit with a spectrum analyzer.

Abstract: A technique for measuring golf swing tempo or clubhead speed for a golfer swinging a golf club through a tee area. Two parallel infrared (IR) transmitters transmit respective IR beams along predetermined lines toward the tee area. Respective IR sensors receive respective IR beams reflected from a reflector mounted to the shaft of the golf club, near the clubhead. Each IR sensors provides a respective output signal indicative of the passage of the golf club through a corresponding IR beam. Predetermined sequences of output signals from the IR sensors are detected and the differences in time between various output signals are measured to provide tempo and clubhead speed values for display on a LCD screen. The speed values can be compensated values as obtained from look-up tables.

Abstract: An apparatus for detecting the velocity information of an object comprises a light source; optical system for irradiating beam from the light source, which is provided with a first lens or lens group and a second lens or lens group having an identical focal distance which are arranged apart from each other substantially two times such focal distance along the direction of the optical axis, to irradiate the beam onto the measuring object through the first and second lenses or lens group, and the optical system being arranged so as to make the value of sin .theta./.lambda. substantially constant where .theta. is the incident angle of the beam irradiated onto the measuring object and .lambda. is the wavelength of the beam; and detector for detecting the scattering rays of light from the measuring object irradiated by the above-mentioned optical system to detect the velocity information of the measuring object.

Abstract: Optical receiving system (20) and method are provided for receiving optical signals used to determine vehicle velocity. The receiver system (20) comprises an optical receiver unit (22) mounted on a vehicle (30) to detect an optical signal incident thereupon. The optical receiver unit (22) includes a radio frequency transmitter (44) for generating and transmitting a radio frequency signal when the optical receiver unit (22) detects an optical signal incident thereupon. The detector system further comprises an indicator unit (24) which includes a radio receiver (46) for receiving the radio frequency generated by the radio frequency transmitter (44) and for providing an indication of the reception thereof. In one embodiment, the indicator unit is a convention radar detection device. In one embodiment, a plurality of optical receiver units (22') are provided for positioning at differing locations upon a vehicle (30'). In another embodiment, a linear array (122) of optical receivers is provided.

Abstract: A lidar with a laser transmitter for transmitting a laser beam and a receiver having receiving optics for detecting radiation reflected back from the beam by aerosol particles in the atmosphere, the receiver having an optical axis aligned with the beam. The receiver includes a number of radiation receiving elements such as concentric radiation detector elements placed in the receiving optics focal plane so that these concentric detector elements can measure backscatter radiation from the beam at several fields of view simultaneously. Backscattered signals at fields of view larger than the laser beams's divergence are due to multiple scattering. The unknown backscatter coefficient can then be eliminated by ratioing the lidar returns at the different fields of view.

Abstract: A coherent laser radar system operating at an eyesafe wavelength above 1.4 microns has been provided for measurement of the position and velocity of hard targets and aerosol targets, said system comprising a frequency-stable master laser and an injection-seeded Q-switched slave laser for generating signals for transmission to the target. Means for obtaining highly accurate velocity and range measurements are provided. Data from signal transmissions and receptions taken over a range of angles are analyzed to map target positions and velocities in time and space.

Abstract: There is disclosed an apparatus for monitoring and calculating the position and speed of a projectile as it is pitched over a target zone. A grid of infrared emitters aligned with respective infrared receivers are in continuous optical links until the ball passes an d cuts some of the links. Upon this cut, the position of the ball is stored in memory and the time of passage of the ball across the grid is recorded to later calculate the speed of the ball. The infrared grid is enclosed in a chamber to prevent interference of external light rays with the reception of the receivers.

Abstract: A laser transmitting and receiving speed and/or range detection device has coaxial internal beam directing and receiving paths for the transmitted and received (reflected) laser energy. A sight is provided having an optical combiner which presents a projected display of the detected speed or range of a target that may be observed by the operator while aiming the device at the target. A telephoto effect is utilized in the projection of the display onto the sight such that the operator need not divert his head from the sight or refocus his eye to read the projected target speed or range.

Abstract: A speed measuring apparatus includes a light projecting unit having a light source for emitting light, a projection optical system for projecting the light from the light source onto a relatively moving object and a first polarizer included in a part of the projection optical system for allowing the passage of polarized light from the light source as projected light. A light receiving unit includes a second polarizer allowing the passage of polarized light in a direction at right angles to the direction of polarization of the projected light reflected from the relatively moving object and a spatial filter detector for taking out a predetermined spatial frequency of the light passed through the second polarizer and outputting an electrical signal representing the frequency. The relative speed of the relatively moving object is calculated on the basis of the signal from the spatial filter detector.

Abstract: An apparatus and method for indicating a contour of a surface relative to a vehicle, in which a first electromagnetic radiation source projects a first beam to create a first reflection pattern on the surface. A second electromagnetic radiation source projects a second beam to create a second reflection pattern on the surface. An apparatus is provided for coupling the first and second electromagnetic radiation sources to the vehicle, such that a movement of the vehicle results in a movement of the first and second reflection patterns on the surface.

Abstract: In apparatus, such as a weapon sight, the speed of an object moving relative to a scene is determined by processing a plurality of successive frames of data, each obtained by scanning the scene, and detecting motion of the object relative to the background/foreground features of the scene. Each frame is compared with a reference comprising a different one of the frames and corresponding background features registered. Once the frames are registered, light intensity values of corresponding elements of the frames are subtracted. The registered background features, being stationary, cancel leaving the object features. Displacement of the object features over a predetermined number of frames is used to calculate the crossing speed of the object relative to the background features.

Abstract: A method and an apparatus for monitoring simultaneously the temperature and the velocity of sprayed particles. The system is comprised of a sensor head attached to the spray gun, an optical fibre transmitting the collected radiation to detection apparatus, and a protective detection cabinet having the detection apparatus that incorporates two detectors. A two-slit or multiple-slit mask is located in the sensor head at the end of the optical fibre. For the temperature measurements, the particle emitted radiation collected by the sensor head is transmitted to two photodetectors, filtered by interference filters at two adjacent wavelengths. The particle temperature may be computed from the ratio of the detector outputs. To measure the velocity, the two-slit system collects radiation emitted by the in-flight particles travelling in the sensor field of view, which generates a double peak light pulse transmitted through the optical fibre.

Abstract: For measuring the flow rate of a thin stream of molten materials such as that of glass, the diameter of the thin stream is measured, as is the velocity. The velocity is measured on the basis of the measurement of the time separating the successive appearance of an emission sequence emitted at first and second points on the path of the molten material. A correlation is then established between the sequences and the time interval corresponding to the passage of the same irregularities at the two selected points identified by this correlation.

Abstract: A laser radar system for measuring wind velocities including apparatus for permitting the system to measure the direction of the atmospheric flow field. A modulator is used to chirp the laser frequency toward increasing frequencies. The local oscillator frequency available for homodyning will be offset from the initial transmitted frequency by an amount equal to the chirp rate multiplied by the round trip transit time to the aerosols at the focal point of the converging laser beam. During the up-ramped chirps of the optical beam frequency, the Doppler shift frequency of aerosols moving toward the laser beam will be translated to a lower frequency, and the Doppler shift frequency of aerosols moving away from the laser beam will be frequency translated upward.

Abstract: A detector for sensing speed/direction of movement of apparatus including a reticle with alternate transparent and opaque portions coupled to the apparatus and having a light source mounted on one side and two spaced apart light sensors on the other side, which sensors produce alternate output signals with movement of the reticle. The sensor output signals are differentially compared to produce a digital output signal with a constant duty cycle. A second pair of light sensors is utilized to produce quadrature digital signals.

Abstract: A continuous wave Doppler LIDAR with an enhanced signal-to-noise ratio (SNR) that greatly enhances its ability to determine relative fluid velocity. A laser source (12, 50, 102) produces coherent light that is split between a reference beam and a test beam by a beam splitter (16, 106). A quarter-wavelength plate (26, 108) changes the linear polarization of the test beam to a circular polarization. The circularly polarized test beam is focused on a target cell (30) having a very small volume. Any particle in a fluid moving relative to the CW Doppler LIDAR system that passes through the target cell causes a Doppler shift in the frequency of the coherent light reflected from the particle and reverses the rotational direction of circular polarization of the reflected beam. The light reflected from the particle is combined with the reference beam, creating an interference pattern (or difference signal) incident on a photodetector (44, 118).

Abstract: An apparatus is described for measuring the velocity of an object by measuring the Doppler frequency shift of a reflected laser beam. A laser beam is projected onto a target area which is moving with respect to the inertial frame of the laser transmitter and the laser receiver. The reflected laser energy is mixed with a local oscillator beam and the mixed beam is focused onto a radiation detector. The Doppler frequency shift is measured, thus indicating the object's velocity. A sacrificial mirror is employed so that internal projectile velocity measurements may be made on the projectile. The laser beam permits measurement both external and internal to the barrel for large and small caliber weapons. Additionally, integration and differentiation means may be provided so that instantaneous position and acceleration data can also be generated for the projectile.

Abstract: A velocimeter measures flow characteristics of a flow travelling through a chamber in a given direction. Tracer particles are entrained in the flow and a source of radiant energy produces an output stream directed transverse the chamber and having a sufficient intensity to vaporize the particles as they pass through the output stream. Each of the vaporized particles exploding to produce a shock wave and a hot core, and a flow visualization system tracks the motion of the hot cores and shock waves to thereby measure velocity of each tracer particle, and temperature of the flow around the tracer.

Abstract: A laser velocimetry technique for the measurement of the three dimensional components of velocity of a particle in a fluid flow has been described. It is based on the use of a measurement region consisting of two optical probe volumes. The two optical probe volumes are physically separate and each consists of an optical fringe pattern formed by the interference of two coherent beams of the same wavelength. Two of the components of velocity are determined experimentally from the doppler signals arising from the frequency change of light scattered from a particle suspended in the fluid flow as it passes through probe volumes. The third component of velocity is derived from measuring the time of flight of a particle in the fluid flow as it passes from the center of one probe volume to another probe volume.

Abstract: A photoluminescence sensor for detecting a photoluminescent light from a toluminescent material is disclosed. In a preferred embodiment the photoluminescence sensor comprises: a source of light; a concave mirror having at least one perforation for passing the source light through the at least one perforation; an optical waveguide having proximal and distal ends with the photoluminescent material being disposed at the distal end; an objective for directing the source light into the proximal end of the waveguide; an objective for receiving photoluminescent light and for focusing the photoluminescent light onto the perforated concave mirror; a liquid filter for passing the photoluminescent light reflected from the perforated concave mirror to a detector to detect the photoluminescent light.

Abstract: A refractive velocimeter apparatus for measuring fluid velocity in a stack includes an optical instrument positioned on the stack for generating an optical signal, which instrument includes a lens for collimating light and positioned for detecting the collimated light along a first direction through the stack and through the fluid flowing within the stack, and a first reflector positioned for reflecting at least some of the collimated light along a second direction, parallel and opposite to the first direction, through the stack and through the fluid flowing through the stack. A second reflector is positioned for reflecting collimated light away from the second path and out of the instrument as the optical signal. A laser is positioned remotely of the stack and light from the laser is provided to the optical instrument through a fiber optic cable.

Abstract: A method and apparatus for measuring liquid flow, particularly milk, includes directing the liquid to flow through one or more flow channels, while exposing the liquid to electromagnetic radiation; measuring the transparency to electromagnetic radiation of the liquid flowing through the flow channel; and measuring the momentary attenuation of electromagnetic radiation by the liquid flowing through the flow channels, to determine the momentary volume of the liquid flowing through the flow channel. The momentary velocity of the liquid flowing through the flow channels is also determined, thereby permitting a determination of the momentary flow rate of the liquid flowing through the flow channels.

Abstract: An apparatus detects the azimuth of the migration of groundwater containing suspended microscopic particles. The apparatus comprises a probe consisting of a light source which emits light in a vertical orientation and a photodigitizer which faces the light source and is separated from the light source to permit the flow of groundwater between the light source and the photodigitizer. When the probe is submerged in migrating groundwater, the eclipses of light created by the suspended microscopic particles as the groundwater passes between the light source and the photodigitizer are detected by the photodigitizer. Information from the photodigitizer is processed and then visually displayed.