Fine Striae Forming by Laser Beam Irradiation

本研究的目的是玻璃和聚酰亚胺的几何表面改性。首先改变入射角度、脉冲强度和脉冲数，将准分子激光束照射到合成硅玻璃上。随着入射角的增大，出现平行于辐射方向的条纹。特别是当角度大于80时，条纹沿辐射方向排列。而当角度大于83时，表面没有出现条纹。结果表明，入射角对排列有极大的影响。形成条纹的阈值为4J/cm2。从AFM观察，条纹的长度、深度和宽度为15mm；L30nm, 1.5mm。为了考察钠钙玻璃的形成机理，从晶体结构或193nm光吸收比低的角度选择石英、刚玉和氟化钙，并以相同的方式照射。只有石英上出现了类似的条纹。这些结果表明，低吸收比和sio2成分容易形成细条纹。然后用同样的方法辐照薄聚酰亚胺。制作了4个与玻璃相似的典型几何表面。为了评估这些表面对LG显示器液晶取向的适用性，制备了一个电池单元。结果表明，液晶是定向的。然后，本研究获得的表面将应用于电气设备。

The aim of this research is the geometrical surface modification of glass and polyimide. First varying the incident angle, the fluence and the number of pulses, ArF excimer laser beam was irradiated on to a synthetic silica glass. As the incident angle increased, striae parallel to the radiation direction appeared. Particularly when the angle was larger than 80 , the striae lined up in the direction of radiation. However when the angle larger than 83 , no striae could be found on the surface.As the results, incident angle extremely effects the lining up. Threshold fluence to form striae was 4J/cm2. From the observation by AFM, the length, the depth and the width of a stria were 15mm ; l30nm, 1.5mm, respectively. Moreover to examine the formation mechanism soda-lime glass, quartz, corundum and calcium fluoride were chosen from the viewpoint of crystal structure or low absorption ratio of 193nm light, and they were irradiated on the same way. Only on the quartz similar striae appeared. These results draw the conclusion that the low absorption ratio and Si02 composition easily form fine striae.Secondly thin polyimide was irradiated on the same way. 4 typical geometrical surfaces similar to those on glass were produced. To estimate the applicability of these surfaces to the liquid crystal orientation of LG display, a cell unit was prepared. As the result, liquid cry-stal was confirmed to be oriented. Then the surface obtained in this research will be applied to electrical equipment.