レーザアブレーションが引き起こす生体系組織コラーゲン膜の光-熱変換機

为了更好地了解水在准分子激光消融角膜过程中的作用机制，我们采用时间分辨成像的ArF准分子激光直接光蚀刻技术，从宏观上研究了膨胀状态下胶原凝胶的消融行为，并利用FTIR-ATR光谱研究了热效应对胶原分子微观结构的影响。对于干燥的胶原膜（DF）， AFM在辐照区观察到一个明确的周期结构，归因于激光束在孔径边缘的菲涅耳衍射，而对于水合胶原膜（HF）， HF的表面结构的不规则性是由光热转换和/或凝胶基质中水的沸腾产生的热量造成的。FTIR-ATR光谱结果表明，水的存在抑制了辐照区表面胶原蛋白向明胶的变性。综上所述，在HF烧蚀过程中，激光能量以水蒸发潜热的形式消耗，同时抑制了辐照区表面温度的升高，进而抑制了胶原蛋白的变性。

In order to gain obvious insight into the role of water in the mechanism of the excimer laser ablation of the cornea, we have macroscopically investigated the ablation behavior of collagen gel in swelled states by direct photoetching using an ArF excimer laser with time-resolved photography, and furthermore the thermal effects on the microscopic structures of collagen -olecules by FTIR-ATR spectroscopy. As for the dried collagen film (DF), a well-defined periodic structure ascribed to a Fresnel diffraction of the laser beam at the edge of the aperture was observed in the irradiated region by AFM, whereas for the hydrated collagen film (HF), the irregularity of the surface structure for HF was created by the heat through photo-thermal conversion and/or boiling of water in the gel matrix. FTIR-ATR spectroscopic results revealed that the existence of the water suppressed the denaturation of collagen to gelatin on the surface in the irradiated region. After all, it was inferred that during the ablation process for HF,the laser energy would be consumed as the latent heat of evaporation of water, accompanied by the suppression of the increment in the surface temperature in the irradiated region and further for the denaturation of the collagen.