Principle Of Atomic Force Microscope Research Articles

Measurement and Analysis of Three-Dimensional Surface Topography of Sawn Timber Based on Scanning Probe Method

In order to explore the characteristics of the three-dimensional surface morphology of sawn timber, a threedimensional wood surface morphology tester based on the scanning probe method and the principle of atomic force microscope was used to test the three-dimensional surface morphology of three kinds of sawn timber and calculate its surface roughness. This study also analyzed the reasonable plan for the value of wood surface roughness and the advantages of the three-dimensional shape tester, as well as the influence of tree species, three sections, air-dry density and other factors on the surface roughness of the specimen after mechanical processing. The results have shown that it is a more appropriate method to select the calculated values of Sa and Sq as the evaluation of the surface roughness of wood with random surface characteristics. The three-dimensional wood surface topography tester can efficiently, conveniently and accurately display the three-dimensional topography of wood at a micron-level resolution, and is characterized by high efficiency and good durability. The three-dimensional surface morphology characteristics of the three sawn woods correspond to their roughness. The surface roughness of woods is arranged as follows: Sitka spruce > Larch > Beech. For the same tree species, the roughness of the corresponding section after sawing is as follows: chordwise section > crosswise section > radial section. The radial section has lower roughness than the other surfaces. The surface roughness of the wood after sawing is mainly related to its air-dry density. The above is intended to provide a useful reference for the application of measuring and evaluating the surface roughness of sawn timber using the three-dimensional surface topography test method.

Study on effects of scan parameters on the image quality and tip wear in AFM tapping mode

Due to the tip-sample interaction which is the measurement principle of Atomic Force Microscope (AFM), tip wear constantly occurs during scanning. The blunt tip caused by the wear process makes more tip geometry information involved in the image, and correspondingly it increases the measurement error. In the present study, the scan parameters of AFM in tapping mode which affect the wear of single crystal silicon tips, such as the approaching rate, the scan rate, the scan amplitude, and the integral gain are investigated. By proposing a parameter reflecting the imaging quality, the tip state tracing the sample surface is evaluated quantitatively. The influences of scan parameters on this imaging quality parameter are obtained by experiments. Finally, in order to achieve the perfect images with little tip wear influence, tip wear experiments are carried out and then the optimal parameter settings which can lighten the tip wear are obtained.

Global Shape Reconstruction of the Bended AFM Cantilever

Principle of atomic force microscope (AFM) is on the basis of cantilever's deflection. However, up to now, there are still no effective methods to model the cantilever's deflection with high precision, which will usually result in a poor measurement accuracy of AFM and has greatly limited further applications of AFM in more different fields. Thus, a global shape from defocus method, which is only based on a single vision sensor, is introduced in this paper to reconstruct the bended shape of AFM cantilever. First, the model of the defocus imaging is given using the concepts of relative blurring and diffusion equation. Second, the relationship between the relative blurring and the interested depth information is built with basic imaging formulas. Subsequently, the depth measurement problem is transformed into an optimization issue and an algorithm is designed to compute the deflection of cantilever. Finally, extensive experiments are conducted and results are analyzed to show the feasibility and the effectiveness of the proposed method.

Development of Surface Image Scanning Device Measurement Head Mechanism Based on AFM

For the measurement of ultra smooth surface topography, a surface image scanning device measurement head mechanism based on the principle of atomic force microscope (AFM) was designed. It uses coarse adjustment, semi-delicate adjustment, delicate adjustment triple-stage adjustment mechanism, and tests the atomic force between the sample and the probe by using laser generator, position sensitive detector (PSD), cantilever and probe. This mechanism has high setting accuracy and resetting accuracy, combined with two-dimension movable table, can scan the surface topography of samples.