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 +/- 1 mm(2) and +/-60 mu m respec tively. It takes about 3 s for each sample position and 130 min for 51 x 51 positions on the x-y plane for a 20 mm x 20 mm specimen. This speed is muc h 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 p lane and along the z direction are not high, the three-dimensional charge p rofile of an electron-beam-irradiated PMMA specimen is successfully constru cted