First, Fig. 4(a) shows the geometries of the platinum B-tip and the grating sample scanned in CD-AFM1. Figure 4(b) shows the resultant CD-AFM1 image composed of nine traces. The trace in front is for the tip moving to the right, the second trace is for the tip retracing and moving to the left, and so on. The measured profiles exhibit a slight re-entrance, consistent with the actual profiles, which indicates that the tip is functioning in concert with the two-dimensional feedback to track the actual sidewall. Due to the scale of the image, the sidewall re-entrance is not obvious, but it turns out to be ~10 nm, as observed both by silicon CD tips and CNT tips. More details on this sample are given in the Appendix, but our main goal here was the evaluation of CNT tip performance and not measurement of the grating. The length of each trace or scan line in Fig. 4(b) is nominally 4 µm, and each trace is offset by ~170 nm from the next one. The lines connecting the ends of the traces are not real but are just artifacts due to different numbers of adaptive sampling points in a trace and the plotting software used. This plotting artifact also appears in the rest of the CD-AFM1 and CD-AFM2 images in this paper.