The light modulation of Hertzian microcracks on optical glass with thin film

Abstract

The research investigated the light modulation of Hertzian microcracks on K9 optical glass with SiO2 thin film by simulations. The simulations considered parameters such as crack degree, crack opening width, and crack depth. It was observed that the internal light intensity is positively correlated with the crack degree of the microcrack. At a crack degree of 55°, the peak of light intensity occurs at the thin film, indicating that the film layer may be damaged earlier by the laser. Laser damage may first occur in the thin film with a small opening width (<0.6 μm), and as the opening width increases, damage may occur inside the substrate of the optical element. Peak points of light intensity appeared inside the thin film and substrate at a crack depth of 1 μm, and as the depth increased, the substrate became more susceptible to laser damage.