Measuring electrostatic charge by ultrasound impulse excitation

A novel method is proposed for non-contact measurement of electrostatic charge on a surface using focused impulse ultrasound to excite movement of a charged object. The focused impulse ultrasound is generated by turning the 40 kHz ultrasound signal on/off and a phased-array method using airborne ultrasound transducers. The impulse excitation of the electrostatic charge induces impulse electric field. A measuring technique of the electrostatic charge for short time periods is established by detecting impulse response of the induced electric field.