The wall voltage in a barrier discharge has been directly measured using an electro-optic crystal, KDP. One of the barriers is made up of a plate of KDP. A wall voltage due to charges accumulated on KDP surface is measured at various discharge conditions from the change of polarization of a laser transmitting through KDP. The value of the wall voltage at applied voltage of 1 kV and Ar gas pressure of 3 Torr is about 120 V. This indicates that the accumulated charge is about 1.1 nC.

The lifetime of metastable excited atoms for barrier discharges in a glass cell and plasma display panel (PDP) has been measured by an laser induced evanescent-mode fluorescence (LIEF) and compared with values measured in a bulk plasma. No significant differece between lifetimes of metastables in the vicinity of a wall and in a bulk plasma is found. An additional optical technique using pockels effect of an electro-optic crystal is introduced in order to observe a temporal and spatial behavior of a wall voltage due to charges accumulated on a dielectric surface.