PSV-400-M2 Laser Vibrometer1. Introduction:(1) What is PSV-400-M2?The PSV-400 Vibrometer is a cutting edge measurement tool for non-contact measurement, visualization and analysis of structural vibrations. It determines the operational deflection shapes and Eigen modes as easily as taking a photograph. The PSV-400 offers technical excellence with powerful software for dynamic measurement, analysis and real-time chromatic display of data. At the heart of every PSV-400 system is the laser-Doppler vibrometer-a precision optical transducer used for determining vibration velocity and displacement at a fixed point. The technology is based on the Doppler-effect; sensing the frequency shift of back scattered light from a moving surface. The feature of PSV-400-M2 is the wide bandwidth dual channel scanning vibrometer (No. of channels: 2; Max. frequency: 1MHz; Max. vibration velocity: 10m/s).(2) Applications(i) Product Development and Testing---Acoustic optimization and quality control on washing machines, vacuum cleaners, toothbrushes, electrical tools, motors etc.(ii) Car Development---Investigation of the structural dynamics and quality control of internal and external components---Determining the source of noise and acoustic properties(iii) Materials Research and Engineering Sciences---Measuring structural dynamics---Non-destructive determination of material parameters and damage analysis(iv) Ultrasonic Applications---Examination and optimization of ultrasonic tools in the production process, in joining technology, medical technology and sensor systems---Sound field pressure calculation from the surface vibration of Piezo transducers(v) Medical and Biological Appli cations---Physiological vibration measurements (hearing, pulse, breathing)---Investigation of hearing and communication mechanisms in the animal world (e.g. insects)(vi) Aviation and Aerospace Industry---Testing components in production control and investigation of material fatigue and flaws---Structural health monitoring of metallic and composite structures(vii) Acoustics---Optimization of deflection shapes of membranes in loudspeakers and microphones---Analysis and optimization of musical instruments(viii) Microsystems Technology and Data Technology---Dynamic testing and vibration analyses---Micro-mirrors, printer jets, micro-pumps, membranes, sensors and actuators(3) Application in our fieldWe can use the PSV-400-M2 for Structural Health Monitoring (SHM). We can use the internal function generator of PSV-400-M2 or external function generator to excite the ultrasonic wave by using

Piezoelectric Wafer Active Sensor (PWAS) which propagates on the structure. The propagation of ultrasonic wave is preserved in the PSV-400-M2 which allows the visualization of the waveform pattern as it propagates on the structure.2. Experiment on concrete(1) Setup of the experiment

Figure1 Setup of the experiment on concreteThere is two PWAS installed on the concrete which used as the transmitter and receiver. Function generator is used to provide input signal.(2) The signals of transmitter and the receiver

ComputerControllerJunction box

Function generator

Specimen

Laser head

Transmitter

Receiver

Figure 2 The signals of transmitter and the receiverThe distance between transmitter and receiver is 200mm. The input frequency is 210 kHz, the voltage of transmitter signal is 17V and the output voltage received from oscilloscope is 39mV which is the same as the output voltage received from laser vibrometer.(3) Wave propagation

Figure 3 Scanning points and wave propagation

Transmitter signal

Receiver signal from oscilloscope

Receiver signal from laser vibrometer

Scanning process

Scanning result

There are 200 x 200 scanning points in the scanning field. The green points denote which have been measured and the blue ones which have not measured. We can explicitly see the wave propagation from the scanning result.