Three-dimensional space-charge measurement in a dielectric using the acoustic lens and PWP method

A three-dimensional space-charge measurement system using the acoustic lens and PWP method has been developed. The resolutions on the x-y plane and in the z direction of this system are about and m respectively. It takes about 3 s for each sample position and 130 min for positions on the x-y plane for a mm specimen. This speed is much higher than that of the three-dimensional space-charge measurement system using the PEA method. Although the resolutions of this system on the x-y plane and along the z direction are not high, the three-dimensional charge profile of an electron-beam-irradiated PMMA specimen is successfully constructed.