It introduces the principle of local tomography algorithm with a new filter.The second order error estimation is obtained.The local reconstruction of simulation and experimental projection data show that the local tomography algorithm is simple and fast,by which the resolution and Gibbs effect of the reconstructed images can be improved.

A theoretical model to describe the discharges in the RF excited planar CO₂ lasers is established.The spatial distributions of electron density,electric field,power density and the excitation efficiency for the upper laser level are obtained by numerical method.The discharge striations in RF excited lasers observed by experiments are explained.The relations between parameters and characters of the discharge are analyzed.