Thermal stresses in a film–substrate structure exposed to pulsed laser heating

An investigation is made of the stressed state observed in a film–substrate system exposed to pulsed laser radiation. According to the proposed physical model, a change in the viscosity of the dielectric substrate during a pulse results in deformation of the surface layer of the substrate during cooling, which gives rise to mechanical stresses in the film. An experiment was carried out to study the action of laser radiation in subthreshold regimes (below the evaporation threshold) on chromium films deposited on dielectric substrates. An investigation was made of the crack density as a function of the optical flux density, laser pulse duration, and also the type of substrate material. Irradiation conditions under which no cracking of the film occurs were formulated.