Although optical coatings are designed for the control of light (anti-reflective, reflective, splitting, filtering, etc.) it is their mechanical properties which govern longevity. Scratches at any scale lead to excessive absorption of laser energy causing localized thermal stress and ultimate failure. This session is a live demonstration of dynamic nanoindentation with the KLA iMicro nanoindenter to measure Young’s modulus and hardness of optical coatings as a continuous function of penetration depth. Ms. Hay demonstrates sample preparation, instrument configuration, test specification, execution and data interpretation.