59 results about "Laser Doppler velocimetry" patented technology

New devices and methods are provided for noninvasive and noncontact real-time measurements of tissue blood velocity. The invention uses a digital imaging device such as a detector array that allows independent intensity measurements at each pixel to capture images of laser speckle patterns on any surfaces, such as tissue surfaces. The laser speckle is generated by illuminating the surface of interest with an expanded beam from a laser source such as a laser diode or a HeNe laser as long as the detector can detect that particular laser radiation. Digitized speckle images are analyzed using new algorithms for tissue optics and blood optics employing multiple scattering analysis and laser Doppler velocimetry analysis. The resultant two-dimensional images can be displayed on a color monitor and superimposed on images of the tissues.

An optical circuit can include a bidirectional amplifier connected so as to amplify source light prior to emission through an output device such as a telescope as well as amplification of reflected light received by the telescope. Such an optical circuit can be used in laser doppler velocimeter applications as well as other applications. The optical circuit can also include passive splitters or active switches to provide for advantageous multiplexing.

A photonic integrated circuit and related method are presented. A photonic integrated circuit comprises a source of radiation, one or more optical amplifiers, a transceiver, and optical waveguides. The optical waveguides couple light between the source of radiation, the one or more optical amplifiers, and the transceiver. The one or more optical amplifiers are configured to increase an optical power of the light up to at least 10 mW. The photonic integrated circuit may be used to perform laser Doppler velocimeter type measurements.

Systems and methods for laser based measurement of air parameters are disclosed. An example system includes a coherent source of radiation, a transceiver, an optical mixer, and an intelligent optical device. The coherent source produces a coherent radiation beam that is then transmitted to a target region by the transceiver. The transceiver is further configured to receive a scattered radiation signal from the target region. The optical mixer is configured to receive the scattered radiation signal from the transceiver, receive a reference radiation beam from the coherent source, and to determine a difference between the scattered radiation signal and the reference radiation beam. In certain embodiments, the intelligent optical device is configured to steer, modulate, or condition, at least one of the coherent radiation beam, the scattered radiation signal, and the reference radiation beam.

The invention discloses a secondary-projection-algorithm-based on-line non-contact contour detection system and method of an intermediate-thick plate. In the system, an area array CMOS (Complementary Metal-Oxide-Semiconductor) camera is used for acquiring an image of linear laser entering a band steel surface of the intermediate-thick plate; the shot image is processed by utilizing the secondary projection algorithm to precisely extract the longitudinal position coordinate of a laser line and the end point position coordinate of the laser line from the image; height information of the surface of the intermediate-thick plate can be calculated through the longitudinal position coordinate of the laser line; the space position coordinate of the edge of a band steel to be detected can be determined according to the height information of the surface of the intermediate-thick plate and the end point position coordinate of the laser line by virtue of vision calibration of the camera; a contour curve of the band steel of the intermediate-thick plate can be obtained after the speed data of the band steel, which is measured by a laser Doppler velocimetry, is processed by a computer. Through adoption of the system and method disclosed by the invention, on-line non-contact type high-speed detection of the contours of two sides of the band steel of the intermediate-thick plate is realized and on-line non-contact type high-speed detection of the contours of the head and the tail of the band steel of the intermediate-thick plate is realized.

The invention discloses a phase modulation direct detection laser Doppler velometer and a velocity measuring method thereof, and relates to a direct detection laser Doppler velometer. In order to solve the problem that a method of converting frequency change of back scattering light into the change of transmittance by utilizing edge filters of a Fabry-Perot (F-P) interferometer in the current direct detection mode to obtain Doppler frequency shift is low in measuring accuracy relative to a coherent detection mode, the invention provides the phase modulation direct detection laser Doppler velometer and the velocity measuring method thereof. According to the method, a beat frequency signal of which the vibration amplitude is changed with the Doppler frequency shift of a moving target is generated by an electric-optical phase modulator and the FP interferometer; a vibration amplitude item is extracted by a phase shifter, a multiplying unit and a low-pass filter, and optical wave frequency information is identified by utilizing the vibration amplitude item; and the frequency of emitted laser and target back scattering light is measured by utilizing the turning-on state and turning-off state of a mechanical switch, and difference of two-time frequency measuring values is used as a measuring value of the Doppler frequency shift. According to the phase modulation direct detection laser Doppler velometer, the influence of the change of light intensity on a measuring result is removed by the energy detection of backward waves, so that the phase modulation direct detection laser Doppler velometer is used for measuring the movement velocity of targets in the field of optics.

A laser velocimetry system that employs a low power laser. The laser has a power of up to about 100 mW. Light from the laser, in one embodiment, is directed through a multimode optical fiber and an optical probe to a surface of a moving sample. Doppler-shifted light from the surface is reflected back through the optical probe and multimode optical fiber to a circulator, which directs the light reflected from the surface to a second multimode optical fiber. Unshifted (i.e., non-Doppler shifted) light is also introduced into the optical signal path. The Doppler shifted reflected light and the unshifted light are then transmitted through the second multimode optical fiber to a detector, which converts the reflected light into an electronic signal. The electronic signal of the “beat” between the Doppler shifted light and unshifted light may then be digitized by an analyzer and used to determine the velocity of the moving surface. A method of determining the velocity of a moving object is also described.

A method and system for remotely inspecting the integrity of a structure. This can be performed by a method creating a vibratory response in the structure from a remote location and then measuring the vibratory response of the structure remotely. Alternatively, this can be performed by a system for remotely measuring the integrity of a structure using a vehicle and an artificial neural network, where the vehicle is equipped with a vibratory response device. The vibratory response can be produced by infrasonic and audio frequencies that can be produced by at least a vehicle, motor, or sound recording. The vibratory response can be measured with a laser vibrometer or an audio recording device.

Method of measuring the velocity of an aircraft at a given instant, by laser Doppler anemometry, by performing the steps of acquiring a backscattered signal on at least three oriented line-of-sight axes, and calculating the spectrum of the backscattered signal on each of the line-of-sight axes. Further, acquiring an additional backscattered signal on at least one additional line-of-sight axis (X4) not coincident with one of the three first line-of-sight axes (X1, X2, X3), and calculating the spectrum of the backscattered signal on the additional line-of-sight axis (X4). Several candidate velocity vectors ({right arrow over (V)}c) and of the projections of the candidate vectors on at least one line-of-sight axis (X1, X2, X3, X4) are calculated. The consistency of the candidate vectors ({right arrow over (V)}c) is calculated as a function of their projections and as a function of each spectrum of the corresponding backscattered signal on the respective calculation axis (X1, X2, X3, X4). The measured velocity vector ({right arrow over (V)}c) is chosen from among the candidate velocity vectors ({right arrow over (V)}c).

The invention discloses a laser Doppler velocity-measuring system with all-optical fiber light-frequency modulation. The system comprises a laser emission unit, a transceiving isolator, a laser lens, a beam combiner, a receiving detector and a computation unit, and the all optical functional units or devices are connected mutually by optical fibers. By using the system, the detection sensitivity of a laser Doppler velocity-measuring technology reaches quantum noise theory limit, and an optical system of the laser Doppler velocity-measuring technology is upgraded completely. A laser Doppler velocity-measuring meter using a new technology has the advantages that the power consumption is lower, the volume is smaller, the weight is lighter, the structure layout is more reasonable, the construction is more convenient, a transmitting lens and a receiving lens become one, no sensitiveness to impact vibration and high-low temperature changes exists, and requirement for cleanness degree of environment is low.

The invention discloses a tight combination method for calculating a pseudo range/pseudo range rate by using a Doppler velocimeter. The method comprises: step 1, installing a strapdown inertial navigation system, a laser Doppler velocimeter, and a Beidou satellite navigation system at a moving carrier, and electrifying the combined navigation system for starting up; step two, carrying out initial position parameter binding; step three, keeping the moving carrier to be still for five minutes, carrying out initial alignment to obtain an initial attitude angle; step four, starting a tight combination mode and starting the moving carrier; and step five, carrying out calculation to obtain a pseudo range value and a pseudo range rate value, and carrying out tight combination navigation by using differences between the pseudo range value and pseudo range rate value and pseudo range and pseudo range rate values outputted by a Beidou satellite navigation system as observation values of the combined navigation system. According to the invention, tight combination with the Beidou satellite navigation system is carried out by using the pseudo range value and pseudo range rate value calcualtd by the laser Doppler velocimeter and function complementation is realized; and the pseudo range value and pseudo range rate value of the moving carrier are deduced based on the location of the moving carrier and the Beidou satellite, so that high-precision navigation is realized.

A platform for a handheld wind profiler includes a housing containing a three-axis magnetic compass module generating a compass signal, including the orientation of the housing relative to magnetic north at a time. A two-axis inclinometer module generates a inclinometer signal including the orientation of the housing relative to a horizontal plane at the time. A GPS module generating a GPS signal indicating a time and position solution including a terrain position of the housing based upon the time. A processor receives a first velocimeter signal at the time from at least one laser Doppler velocimeter. The velocimeter signal includes a first radial velocity of a first wind-borne aerosol and a first orientation of the at least one laser Doppler velocimeter relative to the housing. The processor resolves the first velocimeter signal to determine an orientation of the at least one laser Doppler velocimeter relative to the terrain position.

A laser Doppler velocimeter is formed using a fiber laser as the lasing medium. Within the velocimeter, all optical signals, transmitted and received, are conveyed by optical fibers. An amplifier amplifies a source laser, which is then transmitted to one or more transceivers. The one or more transceivers, each projecting along a different axis, and each with a single optical fiber input/output interface act as both the transmission device to focus the radiation at a target region, and as the receiving system for collecting reflected radiation. The transceivers each include an amplifier to further amplify the radiation received from the laser source. The one or more transceivers transmit radiation simultaneously to the target region, and may be located remotely from the laser source. 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 one or more transceivers.

An airborne wind profiler for an aloft aircraft includes a system bus for receiving a GPS signal including a time and position solution and an attitude signal representing heading, roll, pitch, and yaw of the aircraft. An optical module includes at least one laser Doppler velocimer including an mount allowing the at least one laser Doppler velocimeter to articulate in at least two axes, thereby to orient the laser Doppler velocimeter below a horizon to generate at least one first velocimeter signal. The velocimeter signal includes at least one first radial velocity of a first wind-borne aerosol and a first orientation of the at least one laser Doppler velocimeter relative to the aircraft. A processor module receives the first velocimer signal at the time from at least one laser Doppler velocimeter.

The invention relates to a method and an apparatus for contactlessly determining the structure and/or speed of a thread (8) running in the thread run (6) of a textile machine using a sensor device, wherein a laser beam (3) is produced by a light source (1, 2) and is divided into at least two partial beams (5a, 5b), which meet again at the thread (8), using a device (4) for dividing and guiding the laser beam (3), wherein the laser beam (3) which is produced by the light source (1, 2) is divided into a reference beam (5a) and a scattering beam (5b) by the dividing and guiding device (4), wherein the intensity of the scattering beam (5b) is at least twice as high as the intensity of the reference beam (5a), wherein the beams are oriented at an angle (ss) with respect to one another, even when emerging from the dividing and guiding device (4), such that they cross at the thread (8),; and wherein the transverse dimension of the reference beam (5a) is greater than the transverse dimension of the running thread (8), wherein that portion of the reference beam (5a) which passes the thread (8) is guided into the optical sensor device (9, 10, 11) which is provided for carrying out the laser Doppler anemometry method.

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.

The invention relates to the technical field of photoelectric transient state testing and provides an optical control system, a control method and a laser Doppler velocimeter. The optical control system includes an optical power reference value input module, a reflected light power detection module, a controller and an optical power adjusting module. According to the technical scheme provided by the invention, dynamic adjustment of emitted light power can be performed according to the change of reflected light power, so that the reflected power is kept constant and is equal to or in a fixed proportion with the reference light power; amplitude stability and base line stability of coupling interference signals of reflected light and reference light can be ensured; a condition that a to-be-detected object can reflect light of sufficient power can be ensured; testing signal quality can be improved; signal-to-noise ratio of signals can be improved; and a phenomenon of signal loss caused by too weak reflected light can also be inhibited; and the testing reliability is improved.

The invention discloses a propellant charge exhaust plume flow velocity measurement device, which solves the problem that the existing laser Doppler velocimeter and particle image velocimeter can only measure the particle velocity in the fluid, rely on tracer particles and cannot be accurately characterized Fluid velocity issues. The invention includes a tunable semiconductor laser, a laser control system, an optical system, and a data acquisition and processing unit. The invention can realize the measurement of the exhaust plume flow velocity of the solid, liquid, colloid and paste propellant charge within the high precision and wide velocity measurement range (0-3000m/s). The invention is applicable to the measurement of the flow velocity of the exhaust plume generated when different kinds of propellants are burned in the engine, and has important significance for the optimization of the propellant composition, the design of the propellant charge and the design of the engine.

The invention discloses a Doppler signal period distribution demodulation method of a laser Doppler velocimeter. The time domain processing principle based on a period counting method is adopted, the average frequency in all periods in each set time period is not calculated, but the time value distribution of each period in each time period is analyzed, and the most frequent time value in the time value distribution is taken as the period length in the time period and is converted into the signal frequency in the time period. The Doppler signal period distribution demodulation method has the main advantages of improving the calculation precision of Doppler frequency shift signal processing and effectively reducing the influence of widening or narrowing of the Doppler frequency shift signal period, losing of part of signals and noise, which are caused by the instability of the scattered light, on the test result of the target movement velocity.