Influence of the laser wavelength on the threshold of plasma formation as a result of irradiation of opaque materials

An analysis is made of a large number of experimental values of the thresholds of formation of a plasma by laser irradiation of opaque materials. An empirical equation is obtained for predicting the moment of plasma formation in a wide range of conditions. The influence of the laser wavelength on the ''flash'' process is considered, together with the question of accuracy of prediction of the moment of plasma formation.