91 results about "Laser 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.

The invention relates to the field of road surface deflection measurement, and in particular relates to a laser beam parallelism adjustment system and a laser beam parallelism adjustment method for the road surface deflection measurement. The system comprises a laser test common beam which is arranged on a movable steel beam frame; the movable steel beam frame is arranged on a linear guide rail platform; the laser test common beam is provided with more than three laser velocimeters; each laser velocimeter is connected with a controller by a speed signal acquisition device; and the system also comprises a servo control device used for controlling the laser test common beam to make vertical uniform motion. The system can be used for judging whether laser beams of the laser velocimeters are parallel or not. The system also comprises a laser beam included angle adjustment device, so that the included angles between the laser velocimeters and the vertical direction can be adjusted by the laser beam included angle adjustment device. After the system is adopted, the actual installation angle value of a reference laser velocimeter can be rapidly and accurately obtained when a deflection test vehicle travels at the normal speed.

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.

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.