UV AND IR OPTICAL CHANGES EFFECT ON LASER ABLATION

了解脉冲激光的组织消融对于 这些设备的医疗应用的发展。人们早就 假设激光辐射的吸收可以由下式描述： 恒定吸收系数然而，文学显然 表明主要组织成分，水， 作为水所处的化学环境的函数而变化， 例如，水的吸收随温度而变化。我们 初步数据显示了吸收系数变化的重要性 红外线吸收。我们建议探索那些导致 组织中UV和1 R吸收的变化，并将这些变化与 组织消融过程。我们提出了一系列的实验程序 以及消融模型的进一步发展，以帮助指导和 解释实验结果。我们提出的光谱研究 水和电解质溶液;这些研究构成了 理解组织对光的吸收。我们将延长最初的 软组织和硬组织的光谱学研究。而不是 以前的组织光谱研究，我们将集中在 温度和离子浓度的影响。低光谱 强度光之后将是使用高强度光的泵浦-探测光谱学。 强度泵浦光束。消融研究将涉及测量 羽流参数、切割速率和冲击波产生。消融 设计研究以验证和增强光谱研究。一个 烧蚀模型基于动态变化的吸收系数， 以及热力学状态方程将被用来理解 组织过热和消融的影响。

The understanding of tissue ablation by pulsed lasers is important for the development of medical applications of these devices. It has long been assumed that absorption of the laser radiation can be described by a constant absorption coefficient. The literature, however, clearly indicates that IR and UV absorption of a major tissue constituent, water, changes as a function of the chemical environment in which the water is found. For example, the absorption by water changes with temperature. Our preliminary data show the importance of a changing absorption coefficient on infrared absorption. We propose to explore those factors that cause changes in UV and 1R absorption in tissue and relate these changes to the tissue ablation process. We propose a series of experimental procedures and the further development of an ablation model to help guide and interpret the experimental results. We propose the spectroscopic study of water and electrolyte solutions; such studies form the basis by which to understand the absorption by tissue of light. We will extend the initial studies to the spectroscopy of soft and hard tissues. As opposed to previous spectroscopic studies of tissue, we will concentrate upon the effect of temperature and ion concentration. Spectroscopy with low intensity light will be followed by pump-probe spectroscopy using high intensity pump beams. Ablation studies will involve the measurement of plume parameters, cutting rate, and shock wave production. The ablation studies are designed to verify and augment the spectroscopic studies. An ablation model based upon dynamically changing absorption coefficients as well as thermodynamic equations of state will be used to understand the effects of superheating and ablation of tissue.