基于平行板电容器的材料表面形貌测量仪

Surface topography measuring instrument based on parallel plate capacitor

利用平行板电容器的原理设计了材料表面形貌测量仪,将探针与电容器下极板固连,当探针在不平整的样品表面扫描时,两极板间距发生改变而引起电容变化.通过LabVIEW编程控制平移台蛇形移动,用平行板电容器厚度测试电路测量pF量级的电容改变值.两极板初始距离为50～200μm的工作范围内,测量误差稳定在2μm.通过实时捕捉探针的坐标和极板间距的变化量,该测量仪可以绘制出三维曲面图.

A surface topography measuring instrument was designed based on the principle of parallel plate capacitor. A probe was connected to the sub-plate of the capacitor. When the probe scanned on the surface of the sample, the distance between two plates changed, thus the capacitance changed. The translational table was controlled by LabVIEW, and pF magnitude capacitance change was measured by a parallel plate capacitor thickness test circuit. The error was 2 μm when the initial distance between the two plates was 50~900μm. Three-dimensional surface diagrams were drawn by the self-made instrument through real-time capturing of the probe coordinates and the change of the spacing.