Abstract: An apparatus for calculating optical flow and camera motion using correlation matching and a system model in a moving image, in which the calculation of the optical flow is executed accurately in real time, even when an image rotation or zoom change has occurred.

Abstract: An improved optic flow sensor is provided which affords enhanced bandwidth without the use of a lens. A plurality of photoreceptor circuits, arranged in a linear array, sense light received from a visual field and produce a plurality of photoreceptor signals in accordance with the light sensed. A negative iris, disposed between the visual field and the photoreceptor circuits, blocks a portion of the light from the visual field so that the light blocked by the negative iris is not received by the photoreceptor circuits. The photoreceptor signals are used in determining optic flow in the visual field. The invention is useful for implementation using micro electromechanical system (MEMS) techniques.

Abstract: An apparatus and method for measuring residual stress and photoelastic effect of an optical fiber is disclosed.

Abstract: A passive electro-optical range and total velocity measuring system having first and second cameras positioned along a common baseline. Control systems activate the first and second cameras at a first instance to capture a target image of a target at location T1 and at a second instance to capture a target image of the target at location T2. A range computer calculates ranges from the first camera, the second camera, and a baseline midpoint to a target at location T1 and location T2. An angles computer calculates target displacement. A velocity computer calculates total total target velocity, track velocity, and cross-track velocity. The present invention also includes a method for measuring the range and total velocity of a target using a passive electro-optical system.

Abstract: A light beam from a light-emitting device is applied to a measurement object via a collimator lens and an object lens, and reflected light concentrated via the object lens among the reflected light from a light spot formed on the measurement object is split and concentrated by a beam splitter and a light-receiving lens. The reflected lights from the two regions inside the light spot located at a prescribed interval on a straight line parallel to the travel direction of the measurement object are made to pass separately through two pinholes, respectively, and the resulting reflected lights are respectively made incident on two light-receiving sections. Then, on the basis of the outputs of the two light-receiving sections, the travel speed and the quantity of movement of the measurement object are measured by an operating unit.

Abstract: A distributed laser based obstacle awareness system for use on-board an aircraft comprises: a plurality of obstacle detecting sensors disposable at a corresponding plurality of locations of the aircraft for emitting laser energy from the aircraft into a predetermined region of space and for receiving return laser energy from an obstacle in the predetermined region of space; a laser source for emitting a laser beam along an optical path; and a plurality of bistatic optical channels. Each channel comprises a plurality of transmission fiber optic cables and at least one receiver fiber optic cable and extends from the laser source to a corresponding obstacle detecting sensor of the plurality to direct the laser beam from the optical path to its corresponding obstacle detecting sensor of the plurality for emission into the corresponding predetermined region of space; and a light detector.

Abstract: A method and apparatus for measuring fluid motion with micron scale spatial resolution has been developed. Here, micron or submicron solid fluorescent particles are injected into the fluid body. The particles are chosen to closely follow the motion of the fluid. Pulses of light, at the excitation wavelength, broadly illuminate the test device and the fluorescent particles, The flourescent particles absorb the excitation light and emit pulses of fluorescent light, at the emission wavelength. The fluorescent light is collected by a microscope objective lens, and relayed through a fluorescent filter to an image recording device, such as a CCD camera. Subsequently, discrete images of discrete particles at two or more instances in time are recorded. These images can then be analyzed using correlation analysis to obtain velocity measurements.

Abstract: A miniature laser Doppler probe includes a laser, lens, another lens with a diffraction grating etched thereon, and a focusing lens. The focusing lens focuses the diffraction grating on an interrogation volume which has the particles whose movement is to be detected.

Abstract: An apparatus for measuring exit velocity of a round from a muzzle of a gun barrel includes a first optical fiber having a first fiber optic Bragg grating (FBG) circumferentially attached to the gun barrel at the muzzle and a second FBG circumferentially attached to the gun barrel further from the muzzle than the first FBG; a coupler that receives one end of the first optical fiber; a light source connected by a second optical fiber to the coupler for supplying light to the first optical fiber; a third optical fiber comprising an FBG notch filter, the third optical fiber being connected to the coupler to receive light reflected from the first optical fiber; a notch filter mount attached to the gun barrel, the FBG notch filter being disposed in the notch filter mount; a photodetector connected to an end of the third optical fiber; and data processing electronics electrically connected to the photodetector.

Abstract: A system for measuring components of the velocity of wind along two axes that are transverse to the line of sight of the system includes first and second light emitter arrays disposed along crossed first and second axes, respectively, for illuminating the distribution with light, a detector for receiving light backscattered from the distribution, and a controller to activate the arrays, receive detector signals, and calculate the projections of the velocity of the distribution onto the first and second axes. The light emitters of each array can be positioned at irregular distances and provide the system with the capability of discerning the direction of movement of the distribution along the two axes.

Abstract: An efficient system (10) for measuring target characteristics via a torsion mode beam of electromagnetic energy. The system (10) includes a first mechanism (34, 38, 40, 42, 16) for transmitting the torsion mode beam toward a target (12). A second mechanism (16, 18, 20) receives the resulting target return beam and provides a first signal in response thereto. A third mechanism (26, 28) employs the first signal to determine rotational characteristics of the target (12). In a specific embodiment, the system (10) further includes a fourth mechanism (20, 26) that reduces or eliminates noise in the return beam based on common mode noise rejection. A fifth mechanism (32) identifies the type of the target based on the target rotational characteristics via comparison to predetermined target rotational signatures (36). An additional mechanism (24, 40, 42) selectively switches the mode of the beam between a first mode and a second mode.

Abstract: A method and device for analyzing and quantifying flows for the three-dimensional determination of flow velocity components or the visualization of flows in fluids or gases. An illuminating device generates electromagnetic radiation of a predefined color to scan a detection space in the form of light planes arranged spatially one behind the other that are at least roughly parallel, and that are generated temporally one after the other. As a result, electromagnetic waves are generated in the detection space by particles characterizing the flow, and are detected using at least one image detector which records two-dimensional color images. The frequency, frequency spectrum, and/or intensity detected by at the least one of the image detectors is changed by an as a function of time.

Abstract: A water monitoring system for a nuclear reactor is provided. In an exemplary embodiment, the water monitoring system includes a fiber optic cable having a first end and a second end, with the first end configured to optically couple to the reactor cooling water distribution system, and at least one laser light source optically coupled to the second end of the fiber optic cable. The water monitoring system also includes a spectrophotometer optically coupled to the second end of the fiber optic cable.

Abstract: An apparatus for determining the rotational speed of an object returning diffuse reflections where no reflective singularity exists on the object or no clearly distinct light pulse is produced. A light source illuminates a target area on the object. An optical system receives the reflected light, selectively filters by wavelength, and focuses the light on a detector for signal processing. The reflected light signals may be a series of complex patterns that repeat once per revolution. A Fourier Transform with additional processing enhancements is performed on the signals and used as a basis to calculate the speed of the object The signal processing may be automated, resulting in a speed (RPM) solution being displayed for the operator of the device.

Abstract: Surface shape determination and an exact speed measurement of a moving object is undertaken with an arrangement including semiconductor elements and having two spaced semiconductor sensor lines. Illumination of the moving object occurs via at least one laser diode that is arranged in the proximity of the semiconductor sensor lines. The semiconductor sensor lines are used to perform a registration of cross-sectional profiles by integrating a number of range vectors calculated from sensed reflected light pulses at times when the moving object is not present and present. Successively registered cross-sectional profiles of a vehicle are converted into cross-sectional areas and into longitudinal profiles. The speed can be identified on the basis of the time-offset between identical registration in the first and second semiconductor sensor lines.

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 to the photodetectors across the flowing gas. Scintillations that occur in the flowing gas due to eddies and particulates in the gas are detected in the photodetectors at slightly different times. The output signals of the photodetectors are conditioned, amplified and transformed to digital form. Temporal cross correlation analysis is then performed on the digitized signals in a digital signal processor utilizing a fast correlation algorithm in which the total number of calculations is proportional to 2N, as contrasted with conventional systems in which the number of correlations is proportional to N2. A time differential between signals from the different photodetectors is then calculated electronically.

Abstract: An apparatus for measuring exit velocity of a round from a muzzle of a gun barrel includes a first optical fiber having a first fiber optic Bragg grating (FBG) circumferentially attached to the gun barrel at the muzzle and a second FBG circumferentially attached to the gun barrel further from the muzzle than the first FBG; a coupler that receives one end of the first optical fiber; a light source connected by a second optical fiber to the coupler for supplying light to the first optical fiber; a third optical fiber comprising an FBG notch filter, the third optical fiber being connected to the coupler to receive light reflected from the first optical fiber; a notch filter mount attached to the gun barrel, the FBG notch filter being disposed in the notch filter mount; a photodetector connected to an end of the third optical fiber; and data processing electronics electrically connected to the photodetector.

Abstract: A miniaturized laser Doppler velocimeter is formed in a housing that is preferably 3 mm in diameter or less. A laser couples light to a first diffractive optical element that is formed on the fiber end. The light is coupled to a lens that also includes a diffractive optical element. The same lens is also used to collect receive light, and receives includes another diffractive optical element to collect that received light.

Abstract: A system and a method is provided for measuring three-dimensional velocities at a plurality of points in a fluid employing at least two cameras positioned approximately perpendicular to one another. Image frames captured by the cameras may be filtered using background subtraction with outlier rejection with spike-removal filtering. The cameras may calibrated to accurately represent image coordinates in a world coordinate system using calibration grids modified using warp transformations. The two-dimensional views of the cameras may be recorded for image processing and particle track determination. The tracer particles may be 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.

Abstract: When utilized in a flow imaging instrument, calibration beads provide a known data source that can be employed in various self-diagnostic, calibration and quality metric applications for the both the optical system of the flow imaging instrument, as well as the flow cell of the flow imaging instrument. Such data can be used to determine point spread functions associated with an imaging system, to determine a sensitivity of an imaging system, and to determine a focal point of the imaging system. Imagery collected from calibration beads can be used to determine core size and stability and TDI/flow speed synchronization. Calibration beads can be beneficially employed to enable stable system operation, even when very low sample concentration, or very small sample sizes are to be analyzed.

Abstract: A light beam from a light-emitting device is applied to a measurement object via a collimator lens and an object lens, and reflected light concentrated via the object lens among the reflected light from a light spot formed on the measurement object is split and concentrated by a beam splitter and a light-receiving lens. The reflected lights from the two regions inside the light spot located at a prescribed interval on a straight line parallel to the travel direction of the measurement object are made to pass separately through two pinholes, respectively, and the resulting reflected lights are respectively made incident on two light-receiving sections. Then, on the basis of the outputs of the two light-receiving sections, the travel speed and the quantity of movement of the measurement object are measured by an operating unit.

Abstract: A method for determining the relative motion of a surface with respect to a measurement device comprising:

Abstract: In an optical movement detecting device, two semiconductor lasers irradiate an object with respective light beams to form two light spots on the object. Two light-receiving elements receive the two light beams reflected from the two light spots respectively and travelling in a predetermined direction. Based on a difference in phase between two signals S1, S2 outputted from the two light-receiving elements, a signal processor derives a movement speed of the object.

Abstract: An optical endoscopic fluid flow measurement probe assembly is disclosed having a user end and a distal end. The distal end having a light sheet generator and at least one reflected light acquirer, and the endoscope is provided with transmission means to transmit information away from the distal end. The light sheet generator is adapted in use to generate a sheet of light and the light acquirer being adapted to image light reflected from the light sheet, the light sheet generator and light acquirer being provided in the same endoscope.

Abstract: A method and system are provided for measuring water current direction and magnitude. A plurality of beams of radiation are transmitted radially outward from a location above a body of water. Each beam is incident on the water's surface at an angle with respect thereto. Each beam experiences a Doppler shift as a result of being incident on the water's surface such that a plurality of Doppler shifts are generated. Each Doppler shift is measured with the largest one thereof being indicative of water current direction and magnitude.

Abstract: A system and method of efficiently obtaining distance measurements of a target. A modulated optical beam may be used to determine the distance to the target. A first beam splitter may be used to split the optical beam and a second beam splitter may be used to recombine a reference beam with a return ranging beam. An optical mixing detector may be used in a receiver to efficiently detect distance measurement information.

Abstract: The invention relates to a method for the determination of physical properties of flows or currents using at least one sensor head, wherein fluctuations of a parameter are detected by at least three sensor heads, said detected fluctuations of a parameter are converted into measuring signals. A time of flight between a first pair of sensor heads of said at least three sensor heads is determined from correlating said measuring signals created by the two measuring signals of said first pair of sensor heads. Then, a quotient of a distance between said pair of sensor heads and said time of flight is evaluated, a time of flight, a distance and a quotient are evaluated for a second pair of sensor heads of said at least three sensor heads, and from the quotients evaluated for the two pairs of sensor heads, a two dimensional velocity is calculated.

Abstract: A homodyne interference system splits first and second light beams from a common light source and causes the first and second light beams to impinge upon an irradiating point of an organism at different directions. An optical heterodyne system splits a third beam from the common light source and imparts a frequency shift to the third beam. The outputs of the homodyne and heterodyne systems combine to permit extraction of a beat component of the homodyne system at a high SNR level. The output of the homodyne and heterodyne system are output as an image, which may be timed to a phase timing mechanism to provide an improved output.

Abstract: An improved optic flow sensor is provided which affords enhanced bandwidth without the use of a lens. A plurality of photoreceptor circuits, arranged in a linear array, sense light received from a visual field and produce a plurality of photoreceptor signals in accordance with the light sensed. A negative iris, disposed between the visual field and the photoreceptor circuits, blocks a portion of the light from the visual field so that the light blocked by the negative iris is not received by the photoreceptor circuits. The photoreceptor signals are used in determining optic flow in the visual field. The invention is useful for implementation using micro electromechanical system (MEMS) techniques.

Abstract: In an apparatus for measuring an ejection velocity of a liquid droplet ejected from a nozzle orifice of a head device which is provided with a pressure chamber communicated with the nozzle orifice and an actuator which varies pressure of liquid contained in the pressure chamber, a driver generates a drive signal to drive the actuator to eject a liquid droplet from the nozzle orifice. A photo emitter emits a light beam so as to intersect a space through which the liquid droplet passes. A photo receiver receives the light beam which has been passed through the space. A calculator calculates an ejection velocity of the liquid droplet based on a timing at which the actuator is driven and a change in a photo-receiving state of the photo receiver.

Abstract: A method and a device suitable for carrying out the method are proposed for analyzing and quantifying flows, in particular for the three-dimensional determination of flow velocity components or the three-dimensional visualization of flows in fluids or gases. For this purpose, electromagnetic waves, especially light, are detected, which at least partially emanate from or are scattered by particles that are contained in the detection space and that characterize the flow to be analyzed, the waves being detected using at least one detection device, in the form of two-dimensional images that are recorded in a frequency-selective or frequency-band-selective manner, from which the flow is determined. The illuminating device for this purpose generates at least two, at least approximately parallel light sheets, arranged in spatial succession, generated in temporal succession, having electromagnetic waves of different frequencies or different frequency spectrums, which scan the detection space at least in areas.

Abstract: A planar velocity measurement system (100) is operative to measure all three velocity components of a flowing fluid (106) across an illuminated plane (108) using only a single line of sight. The fluid flow is seeded with small particles which accurately follow the flow field fluctuations. The seeded flow field is illuminated with pulsed laser light source (102) and the positions of the particles in the flow are recorded on CCD cameras (122,124). The in-plane velocities are measured by determining the in-plane particle displacements. The out-of-plane velocity component is determined by measuring the Doppler shift of the light scattered by the particles. Both gas and liquid velocities can be measured, as well as two-phase flows.

Abstract: A LIDAR system for measuring flow velocity in three axes comprises: a LIDAR arrangement of optical elements for generating a coherent beam of light and directing the coherent beam of light by at least one rotationally operated optical element from the system with a predetermined pattern, the at least one rotationally operated optical element also for receiving reflections from particles along the predetermined pattern and directing the beam reflections to a light detector which converts the beam reflections into representative electrical signals; and a processor for detecting bursts from the electrical signals which are representative of light beam reflections from at least one particle substantially at a corresponding position along the predetermined pattern, and for computing a Doppler frequency for each of a selected plurality of detected bursts from the signal content thereof.

Abstract: In this invention, the detection result indicating physical characteristics obtained from sensor sections and associated with a to-be-detected object for which it is determined that determination of detection thereof by a high-speed detecting process is difficult to make is stored in a data storage unit. Then, in a precise examination processing section, the detecting process is effected on the non-real time basis for a to-be-detected object for which it is determined that the precise examination is necessary by the high-speed detecting process by use of data stored in the data storage unit and the to-be-detected object is distributed into a storage box corresponding to a category of the to-be-detected object as the detection result from the precise examination processing section.

Abstract: A method measures the three dimensional position of particles in a fluid medium contained in a sample by recording a digital hologram of the particles on an image sensor and by reconstructing the image of the particles from the hologram. The recording includes providing a source beam with a coherent source, and generating at least two beams from the source beam, namely a reference beam and at least one object beam, wherein the reference beam and the object beam are mutually coherent. The sample is illuminated by condensing the object beam onto the sample in order to obtain a scattered object beam for each particle. The scattered object beam is scattered into a spherical converging object beam toward the image sensor for each particle.

Abstract: The present invention relates to methods and apparatus useful for detecting and measuring flow of a fluid along a flow path. In a method according to the invention, the temperature of a flowing fluid is altered at a selected location for a selected duration so as to generate a pulse in the fluid moving in a downstream direction along a flow path, and the fluid is monitored at a sensing region to detect the pulse passing therethrough. An apparatus according to the present invention may comprise a conduit, a sensor element disposed therein, an energy source proximate to the conduit, and a controller operative to generate an on signal and an off signal respectively operative to activate and deactivate the energy source. The present invention also relates to a liquid chromatography device having a fluid flow detecting and measuring apparatus according to the present invention.

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: A method and device for measuring the speed of at least one object by Doppler effect, whereby the light diffused by an object illuminated by a laser sheet is transmitted to a CCD video camera by spectral filtering means which are substantially tuned to the laser illumination frequency, means being provided to generate reference monochromatic luminous fluxes having frequencies which are different from the laser illumination frequency by fixed known amounts, and the reference luminous fluxes being transmitted to the CCD video camera.

Abstract: A Fast Chirp Transform (FCT) for the digital processing of chirp signals and exemplary applications. The FCT is a generalization of a multidimensional Fast Fourier Transform. Phase coefficients for boundary intervals are calculated using phase functions describing the time dependent frequency characteristics of an input signal in the time domain. A multidimensional FFT is performed on the dot product of the phase coefficients and the input signal resulting in a multidimensional representation of the input signal in the frequency domain. The FCT and its inverse can be used to enhance the signal to noise ratio in applications involving chirp signals.

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, producing an analog signal that is then digitally sampled. Time domain signal processing techniques are used to determine the velocity of the object from the digital samples. 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 (TDI) detector to determine characteristics of the object in response to light from the object.

Abstract: An improved optic flow sensor is provided which affords enhanced bandwidth without the use of a lens. A plurality of photoreceptor circuits, arranged in a linear array, sense light received from a visual field and produce a plurality of photoreceptor signals in accordance with the light sensed. A negative iris, disposed between the visual field and the photoreceptor circuits, blocks a portion of the light from the visual field so that the light blocked by the negative iris is not received by the photoreceptor circuits. The photoreceptor signals are used in determining optic flow in the visual field. The invention is useful for implementation using micro electromechanical system (MEMS) techniques.

Abstract: A reduced noise optical system is provided for use in measuring distance, range-finding and scanning. The system comprises at least one lens, at least one receiver operably positioned to receive a return beam of light reflected from an object and a limiting aperture operably aligned with the lens to limit the signal, and thus the noise, transmitted in the return beam.

Abstract: An optical probe for analyzing a sample illuminated by a laser includes an input optical fiber operably connectable to the laser where the input optical fiber has an entrance end and an exit end. The probe also includes a first beam splitter where the first beam splitter is adapted to transmit an alignment portion of a light beam from the input fiber exit end and to reflect a homodyning portion of the light beam from the input fiber. The probe also includes a lens between the input fiber exit end and the first beam splitter and a first and a second output optical fiber, each having an entrance end and an exit end, each exit end being operably connectable to respective optical detectors. The probe also includes a second beam splitter which is adapted to reflect at least a portion of the reflected homodyning portion into the output fiber entrance ends and to transmit light from the laser scattered by the sample into the entrance ends.

Abstract: The invention of a Low-Cost alternating color-pulse digital particle-image velocimetry DPIV (Digital Particle Image Velocimetry) system is proposed. In the proposed system Low-Cost basic equipments are used such as a continuous-wave laser in mixed mode, a CCD (Charge Couple Device) camera, a PMT (Photo-Multiplier Tube), an image-processing card, a PC (personal computer) etc., with an add-on alternating-color planar laser-sheet generating facility to achieve the purpose of DPIV (Digital Particle Image Velocimetry) of planar velocity measurements. With the add-on facility, the laser beam from the continuous-wave laser operated in mixed mode is turned into a planar laser sheet with alternating color at a designated frequency. The CCD (Charge Couple Device) camera captures the alternating-color images of the flowfield seeded with small particles. The images are then sent to a personal computer for analysis of the magnitude and direction of the velocity distribution of the flowfield.

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 to the photodetectors across the flowing gas. Scintillations that occur in the flowing gas due to eddies and particulates in the gas are detected in the photodetectors at slightly different times. The output signals of the photodetectors are conditioned, amplified and transformed to digital form. Temporal cross correlation analysis is then performed on the digitized signals in a digital signal processor utilizing a fast correlation algorithm in which the total number of calculations is proportional to 2N, as contrasted with conventional systems in which the number of correlations is proportional to N2. A time differential between signals from the different photodetectors is then calculated electronically.

Abstract: Flexible belts, and electrophotographic machines that use such flexible belts, that having embedded sensor fibers that run across the belt's width. Such sensor fibers enable sensors located along the side of the belt to sense belt position and/or motion.

Abstract: A vehicle detection and classification sensor provides accurate 3D profiling and classification of highway vehicles for speeds up to 100 mph. A scanning time-of-flight laser rangefinder is used to measure the distance to the highway from a fixed point above the road surface and then measure the distance to the surfaces of any vehicle that is viewed by the sensor. The beam is pulsed at a high repetition rate for determining vehicle speeds with a high accuracy and uses the calculated speed and consecutive range measurements as the vehicle moves past the sensor to develop a three-dimensional profile of the vehicle. An algorithm is applied to the three-dimensional profile for providing a vehicle-classification. A laser is also used to count the number of axles associated with the vehicle.

Abstract: A pre-crash sensing system is provided for sensing an impact of a target vehicle (46) with a host vehicle (12). The target vehicle (46) has side transponders that generate side identification signals. The host vehicle (12) has a remote object sensor (20) that generates an object distance signal in response to the target vehicle. A countermeasure system (42) resides in the host vehicle (12). A controller (14) in the host vehicle is coupled to the remote object sensor (20) and the countermeasure system (42). The controller (14) activates the countermeasure in response to the object distance signal and side identification signal.

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: A method for non-invasive measurement of the velocity of a medium selected from either a gas or a fluid at an examination location by boosting atoms and molecules of the medium into an excited atomic or molecular state with a focused first pulsed light beam in the investigation location, allowing the excited atoms and/or molecules to relax into a metastable state and then boosting the atoms and/or molecules in the metastable state into an excited atomic or molecular state with a second pulsed light beam that is weaker than the intensity of the first beam to transirradiate the investigation location and to produce a characteristic luminescence, detecting the characteristic luminescence of the selectively excited atoms and/or molecules and determining the coordinates of the investigation location and of the occurrence of the luminescence of a luminescent cloud in an image field and then calculating the velocity of the medium on the basis of the distance between the investigation location and the mid-point of th