Digital angle reference by referring atomic array on crystalline surface

当晶体无应力时，晶体表面的原子阵列在大面积范围内是稳定和均匀的。因此，由于其二维对称性，晶体表面的原子阵列也被认为是一种角度参考。利用扫描隧道显微镜(STM)可以在空气中获得晶体表面的原子图像。将晶面晶体阵列与扫描隧道显微镜相结合，可以实现参考晶面晶体阵列的超精密单位角基准和数字角尺。在本课题的资助下，我们构建了以晶面晶体阵列为基准，以扫描隧道显微镜为探测器的超精密单位角转台。以石墨晶体为参比晶体，以石墨晶面上相邻的两个晶向的夹角为参比单位角，该角度应为60度。利用超精密单位角转台，将相邻晶向的夹角与多边形镜的标定角度进行比较。

An atomic array on crystalline surface is stable and uniform over wide area when the crystal is stress free. Therefore, the atomic array on crystalline surface is also thought to be a kind of angle-reference due to its 2-dimensional symmetry. Using a scanning tunneling microscope (STM), it is possible to obtain an atomic image on crystalline surface in air. An ultra precision unit-angle- reference and digital angle scale by referring a crystalline array on a crystalline surface can be achieved by combining it and STM.With the research fund, we have constructed an ultra precision unit-angle-rotation stage by combining a crystalline array on crystalline surface as a reference and a STM as a detector. Graphite crystal is selected as a reference crystal, an angle between the two neighboring crystalline orientation on the graphite crystalline surface, which should be 60 degree, is chosen as reference unit-angle. Using the ultra precision unit-angle-rotation stage, the angle between the two neighboring crystalline orientation is compared with calibrated angle of polygon mirror.