A major challenge in atomic force microscopy is to reduce the scan duration while retaining the image quality. Conventionally, the scan rate is restricted to a sufficiently small value in order to ensure a desirable image quality as well as a safe tip–sample contact force. This usually results in a conservative scan rate for samples that have a large variation in aspect ratio and/or for scan patterns that have a varying linear velocity. In this paper, an adaptive scan scheme is proposed to alleviate this problem. A scan line-based performance metric balancing both imaging speed and accuracy is proposed, and the scan rate is adapted such that the metric is optimized online in the presence of aspect ratio and/or linear velocity variations. The online optimization is achieved using an extremum-seeking approach, and a semiglobal practical asymptotic stability result is shown for the overall system. Finally, the proposed scheme is demonstrated via both simulation and experiment.

中文翻译：

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基于在线优化的原子力显微镜自适应扫描：理论与实验

原子力显微镜的主要挑战是在保持图像质量的同时减少扫描时间。按照惯例，扫描速率必须限制在足够小的值，以确保获得理想的图像质量以及安全的尖端与样品的接触力。这通常会导致宽高比变化较大的样本和/或线速度变化的扫描图案具有保守的扫描速率。本文提出了一种自适应扫描方案来缓解这一问题。提出了一种兼顾成像速度和准确性的基于扫描线的性能度量，并调整了扫描速率，以便在存在宽高比和/或线速度变化的情况下在线优化度量。在线优化是使用极值搜索方法实现的，给出了整个系统的半全局实用渐近稳定性结果。最后，通过仿真和实验对所提方案进行了论证。