Constant-force contact-mode atomic force microscopy (AFM) relies on a feedback control system to regulate the tip-sample interaction during imaging. Due to limitations in actuators and control, the bandwidth of the regulation system is typically small. Therefore, the scan rate is usually limited in order to guarantee a desirable image quality for a constant-rate scan. By adapting the scan rate online, further performance improvement is possible, and the conditions to this improvement have been explored qualitatively in a previous study for a wide class of possible scan patterns. In this article, a quantitative assessment of the previously proposed adaptive scan scheme is investigated through experiments that explore the impact of various degrees of freedom in the algorithm. Further modifications to the existing scheme are proposed and shown to improve the closed-loop performance. The flexibility of the proposed approach is further demonstrated by applying the algorithm to tapping-mode AFM.

中文翻译：

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基于性能指标优化的AFM成像扫描速率自适应

恒力接触模式原子力显微镜（AFM）依靠反馈控制系统来调节成像过程中尖端样品的相互作用。由于执行器和控制的限制，调节系统的带宽通常很小。因此，通常限制扫描速率，以保证恒定速率扫描所需的图像质量。通过在线调整扫描速率，可能会进一步提高性能，并且在以前的研究中已针对各种可能的扫描模式定性地探索了这种改进的条件。在本文中，通过探索算法中各种自由度的影响的实验，对先前提出的自适应扫描方案进行了定量评估。提出并示出了对现有方案的进一步修改，以改善闭环性能。通过将该算法应用于分接模式AFM，进一步证明了该方法的灵活性。