Abstract: An optical design for delivering or receiving light from a fluid being measured is disclosed. The optical design is capable of immersion in the fluid being measured, and is capable of operating with fluids that have a different index of refraction. The optical design includes a solid prism of optical material to which a fiber optic attaches by a suitable adhesive. In an optical delivery system, light from the fiber enters the prism and reflects off an internal mirror to a second internal reflective surface. The second internal reflective surface focuses the light to a fixed point through an exit surface of the prism. The second internal reflective surface may in the shape of an ellipse, or may comprise a diffractive surface. The exit surface has a spherical concave shape that is centered on the fixed point where the light is focused, so that light passes through the exit surface at substantially ninety degrees.

Abstract: A method for determining the relative motion of a surface with respect to a measurement device comprising: illuminating the surface with incident illumination; detecting illumination reflected from the surface to form at least one detected signal; and determining the amount of relative motion parallel to the surface from said at least one detected signal, characterized in that said determining includes correcting for the effects of relative motion perpendicular to the surface.

Abstract: Frequency domain velocity measurements and time domain velocity measurements are made using light from cells or other objects. An optical grating is used to modulate the light from an object so that it has a frequency proportional to the velocity of the object. Depending upon the embodiment, the pitch of the optical grating is uniform or varying. The modulated light is detected and various signal processing techniques, such as a Fast Fourier Transform function, are used to indicate the velocity of the object. Preferably, the velocity measured is applied in determining a timing signal employed for synchronization of an image of the object and an detector signal in an optical analysis system that uses a time delay integration detector to determine characteristics of the object in response to light from the object.

Abstract: The invention relates to a method for determining the relative movement between a target tracking missile and a target being located at a target distance from said missile. The missile is equipped with an image processing seeker head provided with a seeker detecting said target. The seeker head observes the target in an observation direction. A target image is generated on the seeker. The size of the target image depends on the observation direction. The target moves with a target velocity relative to the missile. The method has the method steps of: defining a seeker head-fixed coordinate system; defining a maximum absolute size of said target; measuring further relevant quantities; and running a recursive algorithm in order to obtain estimated values of a three-dimensional vector of the target velocity in the seeker head-fixed coordinate system by using as inputs the defined maximum absolute size of the target and the image dimension appearing on the seeker as well as further relevant quantities.

Abstract: An optical design for delivering or receiving light from a fluid being measured is disclosed. The optical design is capable of immersion in the fluid being measured, and is capable of operating with fluids that have a different index of refraction. The optical design includes a solid prism of optical material to which a fiber optic attaches by a suitable adhesive. In an optical delivery system, light from the fiber enters the prism and reflects off an internal mirror to a second internal reflective surface. The second internal reflective surface focuses the light to a fixed point through an exit surface of the prism. The second internal reflective surface may in the shape of an ellipse, or may comprise a diffractive surface. The exit surface has a spherical concave shape that is centered on the fixed point where the light is focused, so that light passes through the exit surface at substantially ninety degrees.

Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 &mgr;m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: A ballistic projectile velocity measurement apparatus including two screens spaced apart at a known fixed distance for providing time measurement start and stop signals indicative of the passage of a ballistic projectile through a light curtain formed by contiguous focused light beams from plural infrared light sources which causes a perturbation or fluctuation in the light intensity level received by one or more photo-optic sensors to calculate the speed or velocity of the ballistic projectile. A calculation and display unit for receiving the time measurement signals, calculating the speed or velocity of the ballistic projectile and storing and displaying the sensed and calculated information is connected to the screens and controlled by keyboard command.

Abstract: A traffic LIDAR device is presented with an increased laser power output in compliance with the IEC 825 standard for class one-type laser systems. Increased laser emitter power output is accomplished by reshaping the emitter source output using an optical fiber which has an inside diameter greater than the minimum dimension of the emitter source. The resulting increased cross-section of the output pulse overcomes the power output limitation that would otherwise be dictated by the emitter minimum dimension.

Abstract: An optic flow sensor is provided which employs a plurality of photoreceptors and which produces a final optic flow signal that is a robust measurement of the optic flow as seen by the photoreceptors. Each array of a plurality of feature detector arrays receives, as input, photoreceptor signals from the receptors and generates a plurality of feature signals based thereon. Each optic flow measuring circuit or algorithm of a plurality of optic flow measuring circuits or algorithms receives, as input, one of the plurality of feature signals. The optic flow measuring circuits or algorithms each generate an optic flow measurement signal so that a plurality of optic flow measurement signals are generated. A fusion circuit or algorithm, which can, e.g., employ a leaky integrator circuit or algorithm, receives, as input, the optic flow measurement signals and generates the final optic flow signal based thereon.

Abstract: An optical flow sensor determines the velocity of a moving flow of air or other gas utilizing a plurality of photodetectors spaced apart in a direction parallel to the direction of gas flow. An optical beam is transmitted across the flowing gas and falls upon the photodetectors. Scintillations that occur in the flowing gas due to eddies and particulates in the gas are detected in all of the photodetectors, but at slightly different times due to the longitudinal separation of the photodetectors in the direction of gas flow. The output signals of the photodetectors are conditioned and amplified and transformed to digital form. Temporal cross correlation analysis is then performed on the digitized signals in a digital signal processor. A time differential between signals from the different photodetectors is then calculated electronically.

Abstract: A method for determining the relative motion of a surface with respect to a measurement device comprising: illuminating the surface from a source with incident illumination, such that illumination is reflected from portions of the surface toward a detector; spatially filtering the reflected illumination such that the phase of the detected optical illumination from a given scatterer on the surface is substantially constant or linearly related to the translation of the surface; generating a signal by the detector responsive to the illumination incident on the detector; and determining the relative motion of the surface from the signal.

Abstract: The invention relates to a device for speed measurement with two sensors arranged at a predetermined distance from each other in a direction of movement of an object and arranged at a distance from the surface of the object, which emit signals to an evaluation device with two input channels, the evaluation device being a delay correlator which digitizes the signals occurring at its input channels and forms a closed control loop for determining the time shift of the signals emitted by the sensors, the control loop having a phase detector for a comparison of the time shift of input signals, a controller and an adjusting circuit for the controlled variable or parameter to be controlled by the controller, the delay correlator having a shift register of a constant length and variable clock frequency, wherein a phase comparison of the instantaneous values of the digitized signals of the two sensors, one of which is delayed by the controller, can be performed by the phase detector, the clock frequency of the shift r

Abstract: A velocity such as wind velocity is measured based on a Doppler shift of a backscattered or returned laser signal. The Doppler shift of the backscattered beam is determined from a change in the polarization state or intensity shift of the received or backscattered signal after it has passed through a polarization-dispersive element (PD) and through a polarization analyzer (PA). The electrical signals (I1 and I2) generated from two partial beams provided by the polarization analyzer (PA) represent an the intensity shift. The signals are processed in a computer and the resulting information is displayed, for example.

Abstract: A method for determining the lift and drag coefficients of a golf ball includes launching the ball along a flight path, measuring the velocity at two positions along the flight path, using the measured velocities to determine the coefficients of lift and drag. The step of measuring the velocity includes taking two images of the ball at the two positions, where the time interval between images at each position is less than about 0.01 seconds.

Abstract: The present invention provides an optical device for the measurement of flow rates of fluid through a pipe. The device broadly comprises a narrow frequency light source, an optical delivery system, a collector for light scattered from particles in the fluid, and a photo detector. In a preferred embodiment, the optical delivery system and the collector are contained within the pipe.

Abstract: A method and apparatus for determining angular displacement of one or more parts of an object (10) comprising detecting in at least one first image sensor first and second one or more distributions of Fourier-transformed speckles before and after angular displacement, respectively, and determining the displacement of the detected images; a method and apparatus for determining twist of a rotating shaft between two or more parts of the shaft subjected to a load; a method and apparatus for simultaneously determining angular displacements and surface translations of one or more parts of an object, and a method of determining the radius of angular displacement of one or more parts of an object.

Abstract: A pitching practice device includes a frame with four sides and a net portion composed of longitudinal and latitude strings is defined within the frame. Each string has an end connected to a connection member and the other end of the string is connected to a handle. Each connection member is connected to a spring and an emitting member is connected to the connection member. Each connection member is received in a tube fixedly located in the frame and has a receiving member. When the strings are hit by a ball, the emitting members send a message to the corresponding receiving members to calculate the speed of the ball by the displacement of the strings.

Abstract: The invention relates to an apparatus and a method for measuring rotation quantity of a spherical object. A recording device photographs and records a rotating spherical object from one definite direction as a plurality of stationary circular images at definite intervals. An instrumentation device measures positions of definite two points in each of the recorded stationary circular images. An arithmetic unit calculates rotation quantity of the spherical object on each axis of a three-dimensional coordinate-system on the basis of the positions of the two points in each of the stationary circular images.

Abstract: A highly precise range measurement instrument is made possible through the use of a novel and efficient precision timing circuit which makes use of the instrument's internal central processing unit crystal oscillator. A multi-point calibration function includes the determination of a “zero” value and a “cal” value through the addition of a known calibrated pulse width thereby providing the origin and scale for determining distance with the constant linear discharge of capacitor.

Abstract: An error component such as an eccentricity implicated in an encoder itself is superimposed upon a detected value from an FG due to an assembly error of assemblies themselves and in the manufacturing process. As a result, a speed could not be controlled with a high accuracy and wow and flatter could not be reduced. A tape speed (TSS) signal detected and corrected from the tape transport by FG and PG is inputted into a PLL loop within a data controller (TBC) of a reproducing system. A reproduced signal is converted by an A/D converter in response to a reference clock generated therein and this data is temporarily stored in an FIFO. When this data is reconverted by a D/A converter into an analog signal, if this data is sequentially converted at a timing of an absolute control clock of a quartz oscillator, then it is possible to eliminate the error component superimposed upon the head reproduced signal.

Abstract: This invention is a one-dimensional optic flow sensor that operates in a small region of the two-dimensional visual field. The heart of the sensor is an linear array of photoreceptors that generates a one-dimensional image representation of the visual field region of interest. The linear photoreceptor array has an orientation in the two-dimensional image space. Information in the two-dimensional image space parallel to the photoreceptor array's orientation is preserved while information in other directions is discarded. The result is that a one-dimensional optic flow algorithm using the photoreceptor array output produces a measurement of the optic flow vector onto the sensor orientation vector. In a preferred embodiment, the photoreceptor array circuitry is implemented on a focal plane chip on which an image is focused by a lens. The focal plane chip is placed slightly off the lens's focal point to blur the image.

Abstract: An apparatus for measuring the speed of an object includes a first laser source for emitting a first laser plane at an intended path, and a second laser source for emitting a second laser plane at the intended path, with the second laser source positioned from the first laser source at a known distance. The apparatus further includes a detector system positioned to receive a first laser light and a second laser light that have been reflected from the first laser plane and the second laser plane, respectively, upon reflection of the first and second laser planes off the object. The detector system generates a first pulse signal and a second pulse signal, respectively, in response to the receipt of the first and second laser lights, respectively. The apparatus also includes a signal processing circuit coupled to the detector system for calculating the speed of an object passing through the intended path based on the first and second pulse signals generated by the detector system.

Abstract: A measurement device has a laser light source for irradiating a laser light, a reflecting mirror for reflecting the laser light irradiated from the laser light source in a preselected direction and/or for scanning the laser light within a preselected angle range, and an oscillating motor for driving the reflecting mirror to reflect the laser light in the preselected direction and/or oscillating the reflecting mirror within the preselected angle range to scan the laser light. The oscillating motor has a main shaft for undergoing rotational oscillating movement and for supporting the reflecting mirror for rotational oscillating therewith, a connecting device for removably connecting the reflecting mirror to the main shaft, and a detecting device for detecting a rotation angle of the main shaft. A reflector reflects the laser light reflected and/or scanned by the reflecting mirror. A light receiving element receives the laser light reflected by the reflector.

Abstract: An automotive obstacle detecting system is provided which includes a radar to measure the distance to a target present within a detectable zone. The system monitors a distance limit measurable by the radar and determines a reduction in ability to measure the distance to the target by comparing the distance limit with a given reference value.

Abstract: A laser Doppler velocimeter is formed using erbium-doped fiber as the lasing medium. The fiber is diode-pumped. By properly modulating the lasing in the fiber, pulses of radiation may be generated. A telescope acts as the transmission device to focus the radiation at a specified point, and may also act as the receiving system for reflected radiation. The portion of the reflected radiation collected by the receiving system is analyzed to determine the Doppler shift caused by aerosols or objects at the focal point of the telescope.

Abstract: The present invention provides an optical device for the measurement of flow rates of fluid through a pipe. The device broadly comprises a narrow frequency light source, an optical delivery system, a collector for light scattered from particles in the fluid, and a photo detector. In a preferred embodiment, the optical delivery system and the collector are contained within the pipe.

Abstract: The disclosed method of measuring the flow of a fluid with a porous particulate ceramic tracer and an optical instrument is characterized in that spherical particles having diameters in the range of 0.5 to 150 .mu.m are used as the tracer. Inasmuch as the tracer particles for flow measurement are spherical, the sectional area of scattered light to be detected by an optical sensor means is constant regardless of the orientation of particles. Furthermore, spherical particles have no surface irregularities that might cause concatenation so that individual particles are not agglomerated in tracking a fluid flow, thus contributing to improved measurement accuracy.

Abstract: A speed and/or position determining device for determining the speed or position of a target object includes a head-up display for simultaneously viewing both the target object and an image of information regarding the target object. An optical projection system for projecting the information image from a light emitting display to a combining sight of the head-up display passes along a short straight optical axis between the light emitting display and the combining sight. The device may also incorporate a novel method for determining the length of a time period that elapses between the time that a radiation emitter emits a pulse of radiation and the time a reflected portion of the emitted pulse of radiation is received back at the device. The novel method makes use of one or more electronic delay modules having a plurality of tap lines. An electronic state of each of the tap lines changes as a signal input to the delay module propagates through the delay module.

Abstract: A method of image correlation includes providing one or more image arrays of pixel values wherein each pixel value is associated with one of a number of pixels. Pixel values in the image array which are beyond a pixel threshold value are selected and a correlation process is performed on the selected pixel values. The correlation process is preferably performed according to an error correlation function. The sparse array correlation process provides several orders of magnitude in increased processing speed over known correlation processing techniques and is useful for Particle Image Velocimetry analysis.

Abstract: A method for the quantitative acquisition of flow patterns in fluid flows in which a medium (e.g., a gas or a liquid) and the particles contained therein and carried in the flow are set in motion in a transparent flow object. The method provides that a flow object is transilluminated by a laser light fanned out on a plane parallel to the longitudinal axis of the flow object. A scattering of the laser light by the particles is detected by a camera positioned at a right angle to the longitudinal channel axis and moving in the vertical and horizontal directions, and can be analyzed with an analysis unit connected downstream from the camera. The analysis unit is calibrated by quantitatively comparing an image, which has an object-to-image ratio and which is recorded inside the flow object by the camera, to an image having an object-to-image ratio and recorded outside the flow object.

Abstract: A method for speed measurement according to the laser-Doppler-principle with which with the help of a beam splitter the light beam of a laser is converted into two part beams crossing on or in the measured object and with the help of an optical receiver the spectral maximum of the intensity modulation of the reflected light is measured. A Koster prism is used as a beam splitter such that the part beams formed intersect at the desired angle on or in the measured object.

Abstract: A highly precise range measurement instrument is made possible through the use of a novel and efficient precision timing circuit which makes use of the instrument's internal central processing unit crystal oscillator. A multi-point calibration function includes the determination of a "zero" value and a "cal" value through the addition of a known calibrated pulse width thereby providing the origin and scale for determining distance with the constant linear discharge of capacitor.

Abstract: A device for measuring the speed of an object. The device includes a spatial filter scheme to provide quick-response photodetectors and an efficient use of light. The device projects light onto the object by a light source 1, and the light reflected by the object is received by a lens. This light passes through aperture stop 4 and strikes prism array 7, where it is split alternately into two paths at a fixed pitch with respect to the optical axis. The two split beams are received respectively by two photodetectors. The speed of the object moving relative to the measuring device can be calculated based on the data collected by photodetectors.

Abstract: An optical velocimetry probe used in avionics. A measurement volume through which particles can pass is illuminated with a light beam. Light which is backscattered by the particles causes interference with a reference beam which is taken from the original beam. A photodetector detects the interference.

Abstract: A chronograph for determining the muzzle velocity of a projectile fired from either a small arm or a rifle includes two IR light beam assemblies attached to a platform with respective photodetection circuits and a clamp for holding a vertical shot dispersion monitoring target plate at a rear extremity of the platform. The photodetection circuits provide start and stop signals for gating clock pulses of known frequency to an internal counter, the velocity being a scaled inverse of the measured interval. Each light beam assembly has two facing parabolic slit mirrors or reflectors with a photoemitter placed at one focal point and a photodetector at the other focal point for forming thin spaced beams oriented orthogonal to an intended path of the projectile. The photodetector circuit responds to a rapid drop in the total photocurrent of the photodetector in response to the partial blocking of the beam by a passing projectile.

Abstract: This invention is a one-dimensional elementary motion detector that measu the linear optical flow in a small subsection of the visual field. This sensor measures motion by tracking the movement of a feature across the visual field and measuring the time required to move from one location to the next. First a one-dimensional image is sampled from the visual field using a linear photoreceptor array. Feature detectors, such as edge detectors, are created with simple circuitry that performs simple computations on photoreceptor outputs. The detection of the feature's location is performed using a winner-take-all (WTA) mechanism on feature detector outputs. Motion detection is the performed by monitoring the location of the high WTA output in time to detect transitions corresponding to motion. The correspondence problem is solved by ignoring transitions to and from the end lines of the WTA output bus. Speed measurement is performed by measuring the time between WTA output transitions.

Abstract: A method for particle size detection comprises passing particles in a fluid medium relative to a light source which generates a light field the optical axis of which is transverse to the direction of fluid movement relative to the said light source and having a plurality of non-interferometrically formed variations in intensity spaced along the direction of movement of the particles relative to the light field, detecting variations in light intensity caused by the particles as they pass through the variations in the light field, and measuring the size of a detected particle substantially independently of the optical characteristics of the particle by plotting the mean peak signal as a function of the normalised peak-to-trough variation in the output pulses generated by the passages of the particle through the light field.

Abstract: Fluid velocity measurement apparatus which utilizes Doppler-shift spectral analysis includes a narrow line width light source, the light from which passes through a beam expander to provide an irradiated region, for example a two-dimensional plane, in which velocity measurements may be taken. Light scattered from small particles in the irradiated region is collected in an imaging system which enables spectral analysis of the scattered light for determining the velocity of the light scattering particles in the irradiated region. A single camera is used in the imaging system to obviate the need for costly electronics to synchronize images obtained Also to improve the accuracy of measurement, selected parameters of the apparatus may be measured to allow for perturbations in the velocity measurements obtained.

Abstract: The device uses the principle of the Doppler effect laser velocimeter. It comprises emitter and receiver optic guides formed by integrated optics techniques on a single substrate, preferably made of glass. The emitter guides, connected to a light source, produce two mutually coherent beams inclined with respect to one another in such a way as to constitute interference fringes in a measuring volume situated outside the substrate. The receiver guides transmit the light diffused by the passage of particles in movement through the measuring volume to a detection and processing circuit. The substrate is mounted in a support fixed in an orifice of a wall along which a fluid flows transporting the particles to be examined. The substrate comprises a face which comes into contact with the fluid. This device enables the velocity, size and/or number of particles in movement in a fluid moving along a wall to be determined.

Abstract: There is described a motion-to-sound apparatus which provides for musical scores and accompaniments, and lyrics and in response to a movement in three-dimensional space along more than one plane. Further disclosed is a motion-to-sound apparatus for producing sounds responsive both to the final position, or direction of movement, of the detector in space and the acceleration of the device towards that position or along that plane. Control of sound production is oriented such as to be intuitively familiar.

Abstract: A system and a method for measuring three-dimensional velocities at a plurality of points in a fluid employing at least two cameras positioned approximately perpendicular to one another. The cameras are calibrated to accurately represent image coordinates in world coordinate system. The two-dimensional views of the cameras are recorded for image processing and centroid coordinate determination. Any overlapping particle clusters are decomposed into constituent centroids. The tracer particles are tracked on a two-dimensional basis and then stereo matched to obtain three-dimensional locations of the particles as a function of time so that velocities can be measured therefrom. The stereo imaging velocimetry technique of the present invention provides a full-field, quantitative, three-dimensional map of any optically transparent fluid which is seeded with tracer particles.

Abstract: A method and system for deriving a travel distance of an object which travels. As one aspect, a travel velocity of the object producing a pulse signal in response to travel of the object on the basis of a number of pulses of the pulse signal per unit time is calculated, and a plurality of unit travel distances corresponding to a plurality of travel states of the object every travel state are calculated. The plurality of travel states are different from each other and the unit travel distance is a travel distance per pulse calculated by dividing the calculated travel velocity by the number of the pulses of the pulse signal per unit time. And the plurality of calculated unit travel distances are memorized individually, from the plurality of memorized unit travel distances, the unit travel distance corresponding to the travel state of the object which is under travel is selected, and the travel distance of the object on the basis of the selected unit travel distance and the pulse signal is derived.

Abstract: An alternate formulation is derived for predicting acoustic radiation from a vibrating object in an unbounded fluid medium. The radiated acoustic pressure is shown to be expressible as a surface integral of the particle velocity, which is determinable by using a non-intrusive laser Doppler velocimeter. Solutions thus obtained are unique. Moreover, the efficiency of numerical computations is high because the surface integration can be readily implemented numerically by using the standard Gaussian quadratures. This alternate formulation can be desirable for analyzing the acoustic and vibration responses of a lightweight, a flexible or a structure with a hostile environment for which a non-intrusive laser measurement technique must be used.

Abstract: A method and device for sensing three-dimensional flow structures, which is distinguished in that at least two, preferably three light sheets of a different wavelength or light intensity are produced in a flow measuring field. When a particle carried along by the flow traverses the light sheet, scattered light produced by the particle is optically detected as a particle trace, separately for each light sheet. The detected particle traces of the light sheets are combined into one particle path, and on the basis of the composite particle path, the three velocity components of the flow are calculated.

Abstract: A highly precise range measurement instrument is made possible through the use of a novel and efficient precision timing circuit which makes use of the instrument's internal central processing unit crystal oscillator. A multi-point calibration function includes the determination of a "zero" value and a "cal" value through the addition of a known calibrated pulse width thereby providing the origin and scale for determining distance with the constant linear discharge of capacitor.

Abstract: The invention measures the flow of a liquid by measuring the effect of that flow on a laser beam which travels from a laser source, through the flow, and landing upon a detector oriented to receive that laser source. Interfaces within the flow stream will refract the laser beam and cause variations in strength of the energy reaching the detector. These variations in the forward scatter occur at audio and super audio frequencies. The flow rate is proportional to audio frequency which can be measured and correlated by comparison to known flow rates.

Abstract: A method and optical system is disclosed for measuring an amount of stress in a film layer disposed over a substrate. The method includes steps of: (A) applying a sequence of optical pump pulses to the film layer, individual ones of said optical pump pulses inducing a propagating strain pulse in the film layer, and for each of the optical pump pulses, applying at least one optical probe pulse, the optical probe pulses being applied with different time delays after the application of the corresponding optical probe pulses; (B) detecting variations in an intensity of a reflection of portions of the optical probe pulses, the variations being due at least in part to the propagation of the strain pulse in the film layer; (C) determining, from the detected intensity variations, a sound velocity in the film layer; and (D) calculating, using the determined sound velocity, the amount of stress in the film layer.

Abstract: For optical detection of the velocity of gas bubbles in the cooling liquid of an internal combustion engine, light is radiated into the coolant by means of at least one emitter, and the scattered light caused by the gas bubbles, or rather, the change in intensity of light radiation emitted into the coolant, is measured by an optical sensor. The scattered light or intensity change is measured in at least two adjacent areas, and the velocity of the bubbles is determined from the travel time between the measurement signals.

Abstract: A method of image correlation includes providing one or more image arrays of pixel values wherein each pixel value is associated with one of a number of pixels. Pixel values in the image array which are beyond a pixel threshold value are selected and a correlation process is performed on the selected pixel values. The correlation process is preferably performed according to an error correlation function. The sparse array correlation process provides several orders of magnitude in increased processing speed over known correlation processing techniques and is useful for Particle Image Velocimetry analysis.

Abstract: This monostatic LIDAR system is a pulsed-radiation LIDAR system comprising, for the separation of the laser emitter beam from the laser echo backscattered by the photodetector of the receiver, an optical separator that deflects an incident light beam in different directions, depending on whether it transmits or reflects this beam, the coefficient of transmission or the coefficient of reflection of this optical separator varying as a function of the energy density of said incident light beam. Advantageously, this optical separator is constituted by a layer of vanadium dioxide VO.sub.2 deposited on a transparent plate. An optical separator of this kind is used to obtain a total transmission/reception output greater than that of an optical separator with semi-reflective plate while, at the same time, preserving the advantages that an optical separator of this kind brings about in the optical architecture of a LIDAR, these advantages being simplicity, easy setting, compactness and low-level parasitic reflections.