Blind estimation of general tip shape in AFM imaging

The use of flared tip and bi-directional servo control in some recent atomic force microscopes (AFM) has made it possible for these advanced AFMs to image structures of general shapes with undercuts and reentrant surfaces. Since AFM images are distorted representations of sample surfaces due to the dilation (a.k.a. convolution) produced by the finite size of the probe, it is necessary to obtain the tip shape in order to correct such tip distortion. This paper presents an approach that can for the first time estimate a general three-dimensional tip shape from its scanned image including the noise effect in these AFMs. It extends an existing blind tip estimation method. With the samples, images, and tips described by dexels, a representation that can describe general 3D shapes, the new approach can estimate general tip shapes, including undercuts or reentrant features.