A parallel differential confocal method (PDCM) is proposed to obtain rapid surface height measurements with nanoscale precision with a conventional optical microscope. In contrast to existing differential surface profiling methods where multiple sensors are required and either pixel-by-pixel horizontal or layer-by-layer vertical scanning is necessary, the PDCM uses only a single sensor without scanning. It uses parallel pinholes to generate confocal images Ia and Ib at an equal distance but in opposite directions away from the focal plane. Then the method generates differential intensity signals by subtracting these two images, and then employs these signals to determine the heights of the object surface based on precalibrated curves. The precision and relative standard error of the proposed method were 1 nm and ≤ 0.2%, respectively. Its efficiency was 13 fps for $2018 \times 512$ horizontal locations. Due to its advantages in efficiency and precision, it can be considered as one of the ideal online surface height profiling methods for industrial metrological applications.

中文翻译：

---

一种用于高精度表面高度测量的平行差分共焦方法

提出了一种平行微分共焦方法 (PDCM)，以使用传统的光学显微镜获得具有纳米级精度的快速表面高度测量。与需要多个传感器且需要逐像素水平或逐层垂直扫描的现有差分表面轮廓方法相比，PDCM 仅使用单个传感器而无需扫描。它使用平行针孔以等距但在远离焦平面的相反方向生成共焦图像 Ia 和 Ib。然后该方法通过将这两个图像相减来生成差分强度信号，然后利用这些信号根据预先校准的曲线确定物体表面的高度。该方法的精密度和相对标准误差分别为 1 nm 和 ≤ 0.2%。对于 2018 美元 \times 512 美元的水平位置，其效率为 13 fps。由于其在效率和精度方面的优势，它可以被认为是工业计量应用的理想在线表面高度轮廓方法之一。