Thermal shock effect on diamond-like carbon thin films induced by pulsed-laser

Abstract

When high power laser irradiates the infrared imaging system, the system will be injured or destroyed. The damage to the systems varies for different laser wavelengths. The infrared windows are generally coated with diamond-like carbon(DLC) thin films to protect itself and improve the permeation rate. When the incid ent laser's wavelength lies outside the infrared system response wave band, lase r destroys the DLC films firstly. The DLC films' damage mechanism induced by pul sed laser is studied with the 1.06μm laser. The thermal shock effect model of D LC films is proposed. The temperature and stress distributions are deduced throu gh solving the thermal conduction equation and stress-balance equation. The theo retical analysis shows that thermal stress fracture dominants in the damage mech anism. When the irradiation energy density is E0=100mJ·cm-2 , the pressu re on the surface of DLC films at about 40μm from the center of laser facula ex ceeds the rupture intensity, the film will break and peel off. The theoretical a nalysis matches the experimental results basically, and the correctness of the t hermal shock effect model is confirmed.