Correlation steered scanning with spiral scanning path for AFM to correct image distortion with real-time compensation

In the field of atomic force microscopy (AFM), image quality is frequently compromised by distortions that impact measurement precision. These distortions are caused by a combination of factors such as the hysteresis, creep, and drift of the piezoelectric actuators during the scanning process. To address this issue, a spiral scanning path method is proposed in this paper. The block is used as the smallest scanning unit, with overlapping scanning parts between adjacent blocks, allowing for real-time calculation and compensation of distortions. Utilising the spiral scanning path method, compared with the formerly proposed correlation scanning method, a strong correlation between the blocks from the beginning to the end of the scanning process, effectively reducing the accumulation of drift during the scanning process, thereby significantly improving the issue of image distortion. An evaluation method for distortion correction based on scanning images is also introduced in this paper, which can assess the effectiveness of the proposed scanning method. Experimental results confirm that the spiral path scanning method proposed significantly improves the distortion correction compared to traditional methods. When the width of the scanning image is 600 pixels, the distortion is reduced by 94.9%. The proposed spiral correlated scanning method can be applied to long-term precise scanning scenarios in atomic force microscopy.