33 results about "Laser Doppler vibrometer" patented technology

Disclosed is a detection device for laser spot welding micro-weld spot quality based on laser ultrasound, comprising: a nanosecond pulsed laser configured to emit a laser; a half-wave plate configured to generate a phase difference of the laser; a scanning galvanometer configured to focus the laser as a point source and excite an ultrasonic wave on a surface of a sample; a multi-axis displacement platform configured to place and / or move the sample; a laser Doppler vibrometer configured to emit a probe light; an image sensor configured to acquire image data of the sample in a plurality of attitudes; an optical filter configured to receive the probe light to adjust an intensity of the probe light; and a processor configured to be in communication connection with the image sensor, the optical filter, the nanosecond pulsed laser, the scanning galvanometer, the multi-axis displacement platform, and the laser Doppler vibrometer.

The invention discloses a three-dimensional full-wave field measurement method based on a single-point laser Doppler vibration meter, and the method achieves the multi-angle and automatic scanning of the surface of a structure through the installation of the single-point laser Doppler vibration meter at the tail end of a multi-degree-of-freedom mechanical arm and the combination of a preset scanning path control program. Under signal excitation, the measurement system obtains vibration response signals in different incident directions, and reconstructs a complete vibration component of the structure in a three-dimensional space in combination with a space vector projection reconstruction algorithm. Compared with a traditional measurement scheme in which three beams of laser are needed and accurate alignment is carried out, the system hardware structure is greatly simplified, the complexity and the operation difficulty of the measurement system are reduced, and the flexibility, the precision and the adaptability of three-dimensional wave field measurement are improved.

Disclosed in the present invention is an on-tree peach hardness inversion method based on finite element simulation and transfer learning, comprising the following steps: step 1, using a laser Doppler vibrometer to collect vibration signals of an on-tree peach at different growth stages, using preprocessed signals as inputs to a model, using a texture analyzer to measure a peach hardness reference value as an output of the model, and constructing an experimental data set; step 2, establishing a peach vibration finite element model having a high degree of biomimicry, and calculating a simulated vibration response; step 3, changing the material properties of the finite element model in step 2 to obtain peach vibration responses having different hardness, and constructing a simulation data set; and step 4, constructing a domain adversarial neural network, and implementing domain adaptation and hardness inversion by means of adversarial training. In the present invention, simulated vibration data is generated by using a finite element method, and the domain adversarial neural network is constructed for feature transfer, thereby improving the accuracy of on-tree peach hardness inversion under a limited number of samples.

A system and a method for non-destructive characterizations of objects using Laser Acoustic Resonance Spectroscopy (LARS)-based diagnostic techniques are provided. The system includes using a laser doppler vibrometer to measure vibrational responses of objects. The method includes measuring vibrational frequency responses of a first object and a second object, performing a spectra analysis of the vibrational frequency responses, determining a frequency shift based on the spectra analysis, and indicating a difference between the first object and the second object or a presence of a defect in the second object if the determined frequency shift exceeds a predefined threshold value. The difference between the first object and the second object may indicate the presence of a void, a crack, or a plurality of pores in the second object, or can be used for validating or authenticating the second object as a defective or counterfeit item, in various embodiments.

The present invention discloses a method for inverting the hardness of peach fruit on the tree based on finite element simulation and transfer learning, comprising the following steps: Step 1, using a laser Doppler vibrometer to collect vibration signals of peach fruit at different growth stages on the tree, and using them as model input after preprocessing. Using a texture analyzer to measure the peach fruit hardness reference value as the model output, an experimental data set is constructed; Step 2, establishing a peach fruit vibration finite element model with a high degree of biomimetic and calculating the simulated vibration response; Step 3, changing the material properties of the finite element model in Step 2 to obtain the vibration response of peach fruit of different hardness, and constructing a simulation data set; Step 4, constructing a domain adversarial neural network, and achieving domain transfer and hardness inversion through adversarial training. The present invention produces simulated vibration data through the finite element method, and constructs a domain adversarial neural network for feature transfer, thereby improving the accuracy of inversion of peach fruit hardness on the tree with limited samples.

This invention discloses a method and system for detecting the strongest Rayleigh acoustic current in immobilized microdroplets. Specifically, it involves: calculating the acoustic current suppression coefficient through experimental quantitative testing to establish a quantitative mapping relationship between acoustic current intensity and droplet contact angle; utilizing an electrowetting structure composed of interdigitated electrodes, a dielectric layer, and a hydrophobic layer to actively regulate the droplet contact angle through an applied voltage; and dynamically adjusting the applied voltage in real time by monitoring the droplet vibration amplitude, particle velocity, and contact angle through a collaborative control program to maintain the acoustic current intensity at its strongest. This invention also provides a detection system for implementing the above method, including an indium tin oxide transparent interdigitated electrode substrate, a lead zirconate titanate piezoelectric transducer, a laser Doppler vibrometer, a microscope, and a collaborative control module. This invention can maximize and dynamically maintain the Rayleigh acoustic current intensity in immobilized microdroplets, significantly accelerating the solid-liquid interface mass transfer process, and is applicable to biochemical analysis fields such as rapid immunoassay and biological particle mixing.

The application discloses a vibration wave measuring system for traditional Chinese medicine shallow needle manipulation analysis, and belongs to the technical field of vibration wave measurement, and specifically comprises the following steps: a first beam splitter in a laser Doppler vibrometer is used to divide outgoing laser into a measuring light beam and a reference light beam, the measuring light beam is vertically focused on the surface of a needle handle, the reference light beam is vertically focused on an adjacent unoperated skin area, after the two light beams are reflected, interference occurs when the light beams return to a probe to form a first interference light signal, meanwhile, a part of the returned reference light beam is separated to interfere with local light of the system to form a second interference light signal, after photoelectric conversion, common-mode background noise is eliminated through a differential amplifier, and finally, a pure needle handle vibration wave is output, and high signal-to-noise ratio non-contact measurement of high-frequency weak vibration signals generated by traditional Chinese medicine shallow needle manipulation is realized.

The present invention discloses a laser vibrometer method and system with resistance to baseline drift based on synchronous carrier recovery, which relates to the field of laser vibrometer technology. The method comprises: theoretically analyzing the causes of baseline drift in the demodulated signal of a laser Doppler vibrometer system and identifying the key optical path components that cause baseline drift; improving the optical path of the laser Doppler vibrometer system based on the causes of baseline drift and the key optical path components, adding a reference arm to change the optical path transmission mode and recover the synchronous carrier signal; using the improved laser Doppler vibrometer system, using a high-speed analog-to-digital converter to collect the Doppler signal and synchronous carrier signal, and using a lookup table method to perform temperature-gain and offset compensation on the collected signals; and processing the compensated Doppler signal and synchronous carrier signal using an adaptive filtering algorithm based on error trends and an I&Q orthogonal demodulation algorithm to demodulate and extract the vibration signal. The present invention can effectively eliminate baseline drift in the demodulated signal.

The invention discloses a piezoelectric transducer surface micro-deformation detection method and system based on high-speed camera shooting, and belongs to the field of piezoelectric material dynamic deformation detection. According to the method, a non-contact, full-field and high-temporal-spatial-resolution detection scheme is provided for solving the problems of low frame rate of single-point measurement of a laser Doppler vibration meter and common optical measurement. According to the system, a binocular high-speed camera is adopted, a digital speckle correlation method (DIC) is combined, and accurate measurement of three-dimensional coordinates, micrometric displacement and a strain field of the transducer is achieved by synchronously collecting working images of the transducer underwater or in the air. The method comprises the key steps of binocular camera calibration, speckle marking, image preprocessing, obtaining of a sub-pixel displacement field through a DIC algorithm, and reconstruction of a three-dimensional shape and full-field strain distribution. According to the method, the surface vibration mode can be identified, three-dimensional vibration modeling and vibration-sound field data fusion are supported, the analysis capability on the resonance characteristic and the energy conversion efficiency of the transducer is effectively improved, and the method is suitable for scenes such as ocean exploration, underwater search and rescue, transducer optimization and the like.

The invention relates to a signal processing device and a laser Doppler vibration measurement system. The signal processing device comprises a receiving module and a demodulation module. The receiving module comprises an analog compensation unit and a closed-loop calculation unit; the analog compensation unit compensates the received tested analog signal based on the compensation signal provided by the closed-loop calculation unit, performs analog-to-digital conversion on the compensated analog signal, and outputs a corrected digital signal; the closed-loop calculation unit collects, analyzes and corrects the direct-current component of the digital signal, and updates the compensation signal based on the direct-current component; the problem that an existing laser vibration measurement technology is insufficient in anti-interference performance is solved, the simulation compensation unit and the closed-loop calculation unit form a high-precision direct-current servo system, the direct-current component removal effect is improved, and the vibration measurement accuracy is improved.

The invention discloses a composite material defect detection method and system based on double-wave interference laser ultrasound, and relates to the technical field of laser ultrasound nondestructive testing, the composite material defect detection method and system based on double-wave interference laser ultrasound realize high-precision detection of composite material defects through double-wavelength laser interference and multi-mode signal processing; the dual-wavelength laser excitation module enables interference light spots to directionally excite sound waves of different depths through dynamic modulation of phase difference, the problem that traditional single-wavelength excitation depth resolution is insufficient is solved, and the depth detection precision reaches 0.1 mm; multi-mode sound wave collection is combined with a laser Doppler vibration meter and self-adaptive Kalman filtering, the signal-to-noise ratio is increased to 20 dB or above, 15-25 MHz high-frequency transverse waves and 1-5 MHz low-frequency longitudinal waves are effectively separated, and the bottleneck that traditional ultrasound is insufficient in micron-order defect sensitivity is broken through; and the signal processing module realizes type identification of defects such as interlayer debonding and fiber fracture through wavelet packet decomposition and DCNN classification, so that the accuracy is improved.

A system for detecting an underground object based on seismic surveying includes a seismic wave generator configured to transmit seismic shock waves from an Earth surface into a subsurface region, and a laser Doppler vibrometer (LDV) configured to emit a plurality of LDV beams toward a plurality of drones. Each drone carries an optical beam steering unit operable to redirect the LDV beams toward the Earth surface. The LDV is further configured to detect LDV beams reflected from the Earth surface, the reflected beams modulated by surface vibrations induced by the seismic shock waves, and to generate a seismic dataset. A processing unit is configured to process the seismic dataset to identify underground objects based on seismic reflections. The system enables non-contact, high-resolution, and wide-area seismic surveying for detection of natural and artificial subsurface features including landmines, trenches, and hydrocarbon reservoirs.

The invention discloses a screen module fault original positioning method and system. The method comprises the following steps: spraying a quantum dot solution on key nodes of a to-be-detected screen module; collecting a vibration spectrum of the screen module by using a laser Doppler vibration meter; the acoustic impedance Za of the screen module is obtained through analysis; the electrical impedance Ze, measured by the three-dimensional impedance vector field, of the screen module is utilized, and the acoustic impedance Za and the electrical impedance Ze are combined to obtain acoustic-impedance joint confidence; the first layer is used for judging the fluorescence intensity threshold value of each key point quantum dot, the second layer is used for carrying out acoustic-impedance joint confidence evaluation on the acoustic-impedance joint confidence model, the third layer is used for outputting a maintenance strategy of reinforcement learning, a decision tree model is constructed, and fault positioning is carried out on the screen module through the decision tree model. According to the invention, the fault is positioned through the change of the quantum dot response state of each key node, and the method has the advantages of high efficiency and high accuracy.

This application discloses a bridge bearing detection system and a multi-load joint detection method thereof, relating to the technical field of bridge structure health monitoring. The detection system includes a camera, an eddy current thickness sensor, an acceleration sensor, a laser Doppler vibrometer, a strain gauge, a data acquisition module, a data processing module, and a data transmission module. At least one camera is fixed to the side or directly above the bridge bearing via an adjustable bracket, with its optical axis facing the bridge bearing surface to ensure comprehensiveness and clarity of image acquisition. The system uses image processing algorithms to detect cracks on the bearing surface, combines dynamic response analysis with model predictions to predict stiffness degradation and voiding, and assesses the degree of corrosion through thickness monitoring, thereby achieving full life cycle management of the bearing.

The application discloses a system for laser ultrasonic detection of surface damage of carbon fiber composite materials, which comprises an excitation module, an interference detection module and a signal processing unit; the excitation module is used for vertically incident laser on the sample surface; the interference detection module is used for capturing vibration information in the sample and propagation information of ultrasonic waves; the signal processing unit carries out noise reduction processing on the received signal to obtain smooth and interference-free ultrasonic wave information; the application adopts a full non-contact laser galvanometer, a laser interference defect detection system, a nanosecond pulse laser as an excitation source and a laser Doppler vibrometer as a receiver; the distance between the excitation module, the detection module and the carbon fiber composite material sample is changed according to the actual working environment within the working distance; and the sample is rapidly scanned in a non-contact and non-damage manner by using the propagation of low-order mode Lamb waves in the sample.

A test device for measuring bolt axial force and detecting loosening is disclosed. The test device for measuring bolt axial force and detecting loosening includes a fastening jig on which a bolt is fastened, an exciter for applying vibration to the fastening jig, a load cell for measuring the axial force of the fastened bolt while vibration is applied by the exciter, a laser Doppler vibrometer for detecting whether the fastened bolt rotates while vibration is applied by the exciter, a display for displaying information regarding the measured axial force and the detected rotation, and a processor that converts the output voltage of the load cell into a load to calculate the change in axial force of the fastened bolt while vibration is applied, and calculates whether the fastened bolt rotates based on the output signal of the laser Doppler vibrometer. Accordingly, it is possible to quantitatively confirm the trend of change in the bolt's axial force and to easily identify the point of bolt loosening through monitoring using the laser Doppler vibrometer, thereby enabling precise measurement of the bolt's axial force and verification of loosening.

This invention discloses a method for measuring cavitation in plant xylem, comprising: calculating image parallax in an image sample set and recovering scene depth information; extracting the center line of the main stem based on the segmentation results of the main stem; determining the two-dimensional pixel coordinates of the target vibration measurement point above the plant roots along the direction of the center line of the main stem; and calculating the three-dimensional spatial position of the target vibration measurement point by combining the scene depth information corresponding to the target vibration measurement point; automatically coarsely aligning the target vibration measurement point above the plant roots; obtaining the optimal alignment posture of the laser Doppler vibrometer; collecting vibration signals from the target vibration measurement point above the plant roots; and measuring the cavitation in the plant xylem using the collected vibration signals. This invention addresses the problems of manual reliance, low efficiency, poor repeatability, and unstable signal quality caused by on-site interference in existing technologies for measurement point identification and LDV alignment, and achieves automatic positioning, automatic alignment, and cavitation event measurement of the position above the plant roots.

The present application relates to a kind of vibration velocity demodulation systems of laser doppler vibrometer, the laser doppler vibrometer includes laser vibration measurement and laser ranging two modes, the probe of laser vibration measurement mode is converted into beat frequency electric signal after the frequency shift laser interference signal collected and exports, including high-precision heterodyne conditioning circuit, the down-conversion module with multiplier, high-speed ADC circuit and high-speed acquisition and demodulation module, its down-conversion module includes analog multiplier, first switch, second switch and the measurement channel of different down-conversion frequency suitable for low vibration speed, the first input end of analog multiplier is connected after the intermediate frequency signal processed by high-precision heterodyne conditioning circuit, other end is connected with second switch.This application simultaneously provides the vibration velocity demodulation method for realizing the vibration velocity demodulation system of the described.

The present invention provides a laser Doppler vibrometer signal optimization method for measuring torsional vibration of a transmission shaft system. The method comprises: estimating the maximum rotational speed of a measured shaft in the transmission shaft system and setting the laser Doppler vibrometer range; adjusting the laser Doppler vibrometer and determining offset points to be traversed based on the measured shaft; acquiring the vibration signal of the measured shaft based on the offset points to be traversed and calculating an improved signal-to-noise ratio index; determining an optimal incident offset based on the improved signal-to-noise ratio index by interpolation; and measuring the vibration signal based on the optimal incident offset to obtain a smoothed torsional vibration signal for measuring torsional vibration of the transmission shaft system. Based on the Vold-Kalman filtering algorithm, the EEMD algorithm, and the median filtering algorithm, the method has a fast computational speed and high accuracy, and can assist in the real-time and rapid measurement of shaft system torsional vibration.

This invention belongs to the field of vibration testing and isolation technology, and relates to a non-contact seismograph-based active-passive combined vibration isolation testing system and method. The system includes active and passive isolation platforms, connecting brackets mounted on the active and passive combined isolation platforms, a laser Doppler vibrometer, and multiple vibration acceleration sensors and acquisition systems mounted on the isolation platforms and the laser Doppler vibrometer. This invention combines the laser Doppler vibrometer with the active-passive combined isolation platform to ensure high-precision acquisition of target vibration signals even in environments with external interference. By synchronously acquiring vibration data from the laser Doppler vibrometer and acceleration sensor signals, and performing comparative analysis, the performance of the isolation system can be accurately verified and evaluated. This invention also incorporates various flexibly combinable and controllable excitation devices to simulate the actual working state of the isolation system under different external loads and excitation positions, thereby comprehensively evaluating the performance of the isolation system under different operating conditions.

The invention discloses a peach vibration measurement point positioning and alignment control method based on vision. The method comprises the following steps: carrying out tree peach image enhancement processing by using an automatic multi-scale Retinex algorithm; training an on-tree peach fruit recognition model based on YOLOv8, and obtaining pixel coordinates of a center point of an on-tree peach fruit recognition frame; acquiring depth information of a target object based on binocular stereoscopic vision, and calculating to obtain three-dimensional coordinates of a central point of a peach recognition frame; a laser Doppler vibrometer, a binocular camera and a holder are utilized to construct an acoustic vibration response automatic acquisition device for peaches on a tree, and combined calibration of the laser Doppler vibrometer and the binocular camera is completed based on a PnP algorithm. The mapping relation between the peach vibration measurement points and the rotation angle of the laser Doppler vibration measurement instrument under a camera coordinate system is solved based on a PnP algorithm, the laser Doppler vibration measurement instrument is controlled to rotate through a holder, one-by-one automatic alignment of the peach vibration measurement points on the tree is achieved, and the method is used for assisting field automatic collection of sound and vibration response data of the peaches on the tree.

The invention discloses a continuous laser-induced broadband thermoacoustic coupling confocal detection system and method. The continuous laser-induced broadband thermoacoustic coupling confocal detection system comprises a controllable movable sample placement table, and a laser generator emits a frequency-modulated laser signal to the surface of a sample; the infrared signal acquisition module acquires an infrared signal reflected by the surface of the sample; the laser Doppler vibration meter is used for collecting a vibration signal of the sample; the data acquisition card is connected with the optical signal acquisition module to receive vibration signals; the upper computer is respectively connected with the laser generator, the infrared signal acquisition module and the data acquisition card; the upper computer collects the vibration signals and the infrared image signals of all the frequency bands and then carries out matched filtering, then the vibration signals and the infrared image signals are used for reconstructing the size and the position of the sample defect through a frequency chirp signal processing algorithm, and sample defect detection is completed; according to the invention, accurate detection of materials with different thermal conductivities and different defect burial depths / sizes under a single continuous laser source can be realized.

A coating dressing system including a laser Doppler vibrometer in operative communication with a controller; the laser Doppler vibrometer comprising a laser configured to emit a laser beam toward an object, the laser Doppler vibrometer comprising a sensor configured to sense a reflected laser pattern, wherein the reflected laser pattern comprises a reflection of the laser beam bouncing off the object; and a cutting tool in operative communication with the controller.

Properties of a blood vessel are determined by use of a laser Doppler vibrometer in which laser beams are directed to a patient or subject's skin over two regions, the chest and a superficial artery region (for example carotid neck region) where a pulse in an underlying blood vessel may be experienced. The pulse vibrations are detected by the vibrometer and their time of arrival at the regions determined. A time difference is calculated and from an understanding of the distance of the blood vessel travelled between the two regions a propagation speed or pulse wave velocity is calculated. The speed will vary in accordance with the stiffness or elasticity of the blood vessel. Thus, the condition of the blood vessel may be determined by calculating the stiffness (or elasticity) from the propagation speed.

The invention discloses a vibration spectrum and spectrum synchronous acquisition nondestructive testing device and method for internal quality of small and medium-sized fruits, and relates to the technical field of rapid nondestructive testing of quality of agricultural products. Wherein the small and medium-sized fruits include but are not limited to apples, pears, peaches, oranges, mangoes, kiwi fruits and the like, and the internal quality includes but is not limited to hardness, brittleness, soluble solid content, internal defects, maturity and the like. Airflow jet impact is provided to excite the fruits in an extremely short time, and the laser Doppler vibration meter senses tiny vibration. The visible-near infrared spectrum detection system can collect total transmission, diffuse transmission and composite transmission (combining total transmission and diffuse transmission modes) spectrums. The device can obtain a vibration signal and a visible near infrared spectrum at the same time, and the two signals are converted into images and input into a deep learning model for discrimination. The method can provide a necessary scientific basis for research and development of a small and medium-sized fruit internal quality on-line detection technology in future, and has great significance for promoting healthy development of the fruit industry.

Described are systems and methods for vibrational analysis of ultrasonic motors. These include the use of a quadrature oscillator circuit configured to produce a dual signal output that includes two sinusoidal waves separated by a non-zero phase shift of 90 degrees or less. The ultrasonic motor is configured for simultaneous excitation of a bending mode and an expanding mode in response to the dual signal output from the quadrature oscillator. A laser doppler vibrometer is used to analyze the ultrasonic motor being operated under simultaneous bending mode and expanding mode excitation.

To provide a simple and compact configuration that is tolerant to deviations in angle θ and working distance D. [Solution] The device is configured to include a light source unit that splits laser light into two to generate illumination light and local light, an interference light detection unit that has a photodetector and irradiates a measurement object with the illumination light, causes the measurement light generated by reflection of the illumination light from the measurement object to interfere with the local light to generate interference light, receives the interference light with the photodetector, and generates an interference signal, which is an electrical signal, and a signal processing unit that acquires information about the vibration of the measurement object from the interference signal. At the light receiving surface of the photodetector, the beam diameter of the local light that constitutes the interference light is larger than the light receiving diameter of the photodetector, and the beam diameter of the measurement light that constitutes the interference light is sufficiently smaller than the light receiving diameter of the photodetector.

A method for controlling at least one radial blower in a cooling system. The radial blower includes a housing in which a shaft is rotationally mounted, which receives at least one impeller wheel of a compressor at one end, which is secured to the housing. The housing includes at least one radial bearing and at least one axial bearing via which the shaft is rotationally mounted in the housing. The radial blower also includes a motor which is driven by a rotor and a stator and which drives the shaft. By means of at least one laser Doppler vibrometer assigned to the shaft, operating points of the shaft are detected and forwarded to a controller for determining an operating status of the radial blower.

1. The name of the design product: laser Doppler vibrometer shell. 2. The use of the design product: for product vibration test and analysis. 3. The design features of the design product: the overall shape of the product shown in each picture. 4. The picture or photo that best indicates the design features: perspective view 1.

This invention discloses a three-dimensional full-wavefield measurement method based on a single-point laser Doppler vibrometer. By installing the single-point laser vibrometer at the end of a multi-degree-of-freedom robotic arm and combining it with a preset scanning path control program, it achieves multi-angle, automated scanning of the surface of a structure. Under signal excitation, the measurement system acquires vibration response signals from different incident directions and, combined with a spatial vector projection reconstruction algorithm, reconstructs the complete vibration components of the structure in three-dimensional space. Compared with traditional measurement solutions that require the use of three laser beams and precise alignment, this invention significantly simplifies the system hardware structure, reduces the complexity and operational difficulty of the measurement system, and improves the flexibility, accuracy, and adaptability of three-dimensional wavefield measurement.