Hard tissues are irradiated with combined beam of Er:YAG and Ho:YAG lasers to achieve highly efficient ablation with lower laser power. We controlled the delay time between pulses of the two lasers and irradiated alumina ceramic balls that are used as hard tissue samples. By optimizing the delay time, the combined laser beam provides 40% higher perforation depth compared with the result with independent radiation of Er:YAG or Ho:YAG laser. The ablation mechanism are observed and investigated by using an ultra-high-speed camera and infrared thermography camera.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.