Laser damage to plasticized polymethylmethacrylate

An experimental investigation was made of the stability of polymethylmethacrylate containing different amounts of dibutylphthalate plasticizer under the action of neodymium laser radiation (λ = 1.06 μ, τ_p = 30 nsec). The concentration of the centers responsible for damage is estimated. The dynamics of the absorption initiation process in the matrix due to thermoelastic stresses is discussed. The proposed model is used to determine the absorption coefficients of inhomogeneities and the absorption of the matrix under the conditions of optical breakdown. The dependence of the breakdown intensity on the plasticizer concentration is due to blocking of bridge bonds by plasticizer molecules.