Optimal focusing of laser radiation on the surface of a solid target

An investigation was made of the dependence of the electron temperature of a plasma, generated by heating a solid target with focused laser radiation, on the position of the focusing objective relative to the target surface. It was found experimentally that the position corresponding to the maximum electron temperature of the plasma did not represent exact focusing of the laser radiation on the target surface. The plasma heating process was most efficient when the focus of the objective was located ~ 100 μ above the target surface. A possible explanation of this result was considered.