Development Of The Novel Pyroelectric Sensor And Application For Acoustic Power Measurement

As an important measurement index to evaluate acoustic output of ultrasonic transducer,the acoustic power directly related to the safety and effectiveness of ultrasonic equipment.However,in the international standard acoustic power measurement methods,there are many problems such as long measurement time,high cost and low accuracy of measurement results.In this paper,a novel pyroelectric sensor has been introduced into the field of acoustic measurement,and applicated into the acoustic power measurement.This paper mainly studied on the acoustic power measurement mechanism of Polyvinylidene fluoride(PVDF)pyroelectric sensor,and established a theoretical model based on the pyroelectric effect of PVDF and the characteristics of acoustic transmission in the sensor.The energy conversion relation of sensor applied to acoustic power measurement was deduced by model calculation,and the theoretical equation between the acoustic power and the sensor output voltage was derived.In addition,the physical model of acoustic power measurement was established by using finite element analysis software,and the acoustic field and temperature rise in the sensor are simulated,and the waveform and amplitude of the pyroelectric sensor output signal are calculated.The simulation program was used to study the relationship between the pyroelectric signal and backing parameters,and it provided theoretical basis for the high sensitivity sensor.A PVDF pyroelectric sensor was fabricated.Besides that,an experimental system was built for sensitivity test and calibration of the sensor.In order to apply the pyroelectric sensor to acoustic power measurement,the experimental device and measuring hardware were standardized,the acoustic power measurement was carried out by the calibrated sensor,and the results were compared with the hydrophone scanning method.To evaluated the accuracy of measurement,the error sources of the sensor measurement was analyzed,and the A,B measurement uncertainty is calculated.Finally,the standard synthetic uncertainty was given.This paper shows that the new pyroelectric sensor developed is not only feasible in theory,but also accurate and reliable in simulation model.By comparing the acoustic power measurement of the sensor with that of hydrophone,it is proved that the sensor has good stability and the method of measuring acoustic power with pyroelectric sensor is fast and feasible.