A Study of Burst-mode Ultrafast-Pulse Laser Ablation on Soft Tissues and Tissue Proxies

This thesis research presents an experimental study of both the physics mechanisms and biological effects of burst-mode ultrafast-pulse laser ablation. A 3D living-cell-culture tissue-proxy based on agar hydrogel was developed, and this tissue-proxy was used to quantify the cellular necrosis range, to identify the types of cellular death, and to measure the volume of material removal post burst-mode laser ablation. The potential hazards of cellular DNA damage were also evaluated. A time-resolving energy-partition diagnostics system was designed and built for characterizing the dynamic scattering and absorption of pulses during burst-mode ablation. Such characterizations were carried out on soda-lime glass, aluminum, porcine tissues, distilled water, and agar gels using this diagnostic system. Each type of target materials displayed distinct features in their absorption patterns. An array of characteristics of the absorption and their relation to the ablation dynamics were analyzed, and valuable insight about the burst-mode ablation process was gained. The characterization of the dynamic absorptions allowed the evaluation of the roles of different physics mechanisms in the resulting cellular damage and material removal.Ph.D