The improvement in the AFM image after applying a Lucy- Richardon
deconvolution algorithm using a new technique for estimating the AFM
tip shape from the square sample
AHMED AHTAIBA
Electrical and Electronic Engineering Department
Sirte University
Sirte
LIBYA
Abstract: - The images measured using AFM are distorted because of the influence of the tip geometry. This
influence let 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 proposed a new approach (impulse response
technique) to reconstruct the tip shape from a square sample. Once the tip shape is known, erosion or
deconvolution process has been carried out between the estimated tip shape and the distorted image. 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 greatly improved. Also, we have compared the proposed
algorithm with the blind tip estimation algorithm using computer simulations and real AFM images, and our
algorithm has given better results. It is worth mentioning here that the blind tip estimation is the industrial and
research standard algorithm for the restoration of AFM images.
Key-Words: - AFM, image restoration, tip estimation, Square sample, deconvolution.
Received: June 11, 2022. Revised: August 16, 2023. Accepted: September 17, 2023. Published: October 4, 2023.
1 Introduction
The Atomic Force Microscope (AFM) is very
important instrument for use in nanotechnology and
biology since it can be used to measure a variety of
objects such as nano-particles and cells.. An AFM
image is represented as the distorted sample due to
the convolution effect, which produced by the finite
size of the AFM tip. The image restoration problem
has been studied by many researchers in terms of
determining the cantilever tip shape for the AFM
and then using it to restore the AFM images using a
deconvolution algorithm. This formulation of the
image restoration problem ignores the other
parameters that affect the image acquisition process
in the AFM such as the scanning speed, the response
of the x, y and z piezo materials, and the bandwidth
of the feedback loop system. As is well-known in
digital image processing theory, the impulse
response of a linear time invariant system “fully
characterises” this system. This implies that our
proposed algorithm aim of finding the impulse
response of the AFM should take all these
parameters inherently into consideration and should
produce better and more faithful image
restoration algorithm than those that already exist in
the literature.
The first essential step in front-end digital image
processing systems is that of capturing digital
images. Many distortions occur during the image
acquisition process and these distortions should be
eliminated or alleviated using image restoration
algorithms. Examples of systems where these
distortions occur are in astronomical imaging using
telescopes, confocal microscopy, computed
tomography (CT) scanners and many other
applications. These are similar research problems to
the image restoration of AFM images [7-9].
In this paper we proposed a new method ( impulse
response technique), which is suitable for estimating
the AFM tip from the AFM image of the square
sample. Computer simulation and experimental
results have been used for estimating the AFM tip
shape. Then, in computer simulation an erosion
operation has been used between the estimated
AFM tip and the AFM image for obtaining more
accurate an AFM image. In experimental results, a
Lucy- Richardson deconvolution algorithm [1-2]
has been used between the estimated AFM tip and
WSEAS TRANSACTIONS on SIGNAL PROCESSING
DOI: 10.37394/232014.2023.19.11