UV AND IR OPTICAL CHANGES EFFECT ON LASER ABLATION

对脉冲激光消融组织的了解对于 开发这些设备的医疗应用。一直以来都是 假设激光辐射的吸收可以用一个 恒定吸收系数。然而，这部文学作品显然 表明组织的主要成分水的红外和紫外线吸收， 随着水所处化学环境的变化而变化 找到了。例如，水的吸收率随温度的变化而变化。我们的 初步数据显示了改变吸收系数的重要性 关于红外线吸收。我们建议探索那些导致 组织中紫外线和1R吸收的变化，并将这些变化与 组织消融过程。我们提出了一系列实验程序 以及进一步开发消融模型，以帮助指导和 解释实验结果。我们建议进行光谱学研究。 水和电解质溶液；这样的研究形成了 了解组织对光的吸收。我们将延长最初的 软硬组织光谱学研究。而不是 以前对组织的光谱研究，我们将集中在 温度和离子浓度的影响。低电平的光谱学 强度光之后将使用高强度的泵浦-探测光谱 强度泵浦光束。消融研究将涉及测量 羽流参数、切割速度和冲击波产生。消融 研究的目的是验证和加强光谱研究。一个 基于动态变化吸收系数的烧蚀模型 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.