基于球壳内壁反射的球形换能器自易校准方法

基于球形换能器发射的脉冲球面声波及其在同心球壳内壁的反射,应用机电互易定理,导出了在球面波发射回波声场中,用于校准球形换能器的互易常数。以此为基础,提出一种使用封闭球壳反射器的自易校准方法,通过一次测量即可得到球形换能器的5个基本电声参数。进一步,将自易法校准所得的电压灵敏度换算成平面波声场中定义的标准灵敏度,给出了换算系数。为确定该换算系数,发展了对换能器散射系数进行测量的方法。在25~63 kHz频率范围内,对半径10 mm的球形换能器实施了自易校准。结果表明,测得的电压灵敏度的标准不确定度估计优于0.9 dB。

Self-reciprocity calibration for spherical transducers based on acoustic reflection of spherical shell inwall

Based on the emission of pulsed spherical acoustic waves from a spherical transducer and their reflection on a concentric spherical shell inwall,the electromechanical reciprocity theorem is applied to derive a reciprocity coefficient for the calibration of a spherical transducer in a spherical acoustic field.On top of this,a self-reciprocity calibration method using a closed spherical shell reflector is proposed to obtain the five fundamental electroacoustic parameters of the spherical transducer from a single measurement.Further,a conversion factor is given for converting the voltage sensitivity obtained by the current method to the standard sensitivity defined in plane wave fields.To determine this conversion factor,a method for measuring the scattering coefficient of the transducer is developed.Calibration of a10-mm-radius spherical transducer is performed in the frequency range 25~63 kHz.The results show that the standard uncertainty of the measured voltage sensitivity is up-bounded by 0.9 dB.