A Novel Approach to the Restoration of AFM Images by Employing an Estimated Impulse Response for the AFM Calculated Using a Square Pillar Sample

The Atomic Force Microscope (AFM) is a very important instrument for use in nanotechnology and biology since it can be used to measure a wide variety of objects, such as nano-particles and cells, either in air or liquid. However, the images that are measured using AFM are distorted because of the influence of the tip geometry and the dynamic response of the instrument. This influence means that the images do not accurately represent the real shape of the measured particles or cells. Therefore, it is necessary to reconstruct the AFM tip shape. This paper proposes a new approach (impulse response technique) to reconstruct the AFM tip shape from a square pillar sample that is measured using AFM. Once the tip shape is known, a deconvolution process is carried out between the estimated tip shape and typical AFM ‘distorted’ images in order to reduce the distortion effects. The experimental results and the computer simulations validate the performance of the proposed approach, in which it illustrates that the AFM image accuracy has been significantly improved. The blind tip estimation approach is the industrial and research standard algorithm for the restoration of AFM images. We therefore also compare the proposed algorithm with the blind tip estimation algorithm, via the use of both computer simulations and real AFM images, and our algorithm gives enhanced results.