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、能量密度和脉冲数，将ArF准分子激光束照射到合成石英玻璃上。随着入射角的增加，出现了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。而当入射角大于83 °时，在表面上没有发现任何条纹，因此入射角对排列有很大的影响。形成条纹的阈值能量密度为4J/cm ~ 2。用AFM观察到的条纹长度、深度和宽度分别为15 mm、130 nm和1.5mm。此外，为了研究形成机制，从晶体结构或193 nm光的低吸收率的角度选择了钠钙玻璃、石英、硅藻土和氟化钙，并以相同的方式照射它们。只有在石英上出现了类似的条纹。这些结果得出结论：低吸收率和SiO2成分容易形成细条纹。其次，以同样的方式照射薄的聚酰亚胺。制作了4个与玻璃表面相似的典型几何表面。为了评估这些表面对LG显示器的液晶取向的适用性，制备了单元单元。结果表明，液态晶体是有取向的。然后将本研究所获得的表面应用于电器设备。

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.