Thermal stress mechanisms in optical storage thin films

Numerical calculations are presented that show that thermal stresses induced by laser heating in optical storage media may reach the failure strength of the materials used during the early stages of a laser pulse. It is shown how these stresses arise and how the failure process may then proceed by a combination of radial compressive stresses and axial tensile stresses producing damage by elastic buckling and interface failure. The formation of a stable blister for optical storage purposes is then possible. Alternatively such effects may contribute to the initial stages of current pit formation processes. Such thermal stresses may also have long term detrimental effects, producing interface damage, in many other multilayer optical storage systems, particularly those with high thermal expansion coefficients.