Drift-insensitive distributed calibration of probe microscope scanner: Virtual mode
Channel: Rostislav Lapshin
Date: 2016-05-18

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http://audioslides.elsevier.com//ViewerSmall.aspx?source=1&doi=10.1016/j.apsusc.2016.03.201

A short introduction to the research article: R. V. Lapshin, Drift-insensitive distributed calibration of probe microscope scanner in nanometer range: Virtual mode, Applied Surface Science, vol. 378, pp. 530-539, 2016 (DOI: 10.1016/j.apsusc.2016.03.201). The article is available for free at the following link: http://www.niifp.ru/staff/lapshin/en/index.htm#virtual2016


Slide 1. Title

Dear Colleagues!
My name is Rostislav Lapshin, I am a research scientist from the Institute of Physical Problems, Zelenograd, Moscow, Russian Federation.
I am going to briefly report about a new method, which is presented in my paper “Drift-insensitive distributed calibration of probe microscope scanner in nanometer range: Virtual mode” published online in Applied Surface Science journal in April 2016.


Slide 2. Key ideas of distributed calibration

The method of distributed calibration of a probe microscope scanner consists in a search for a net of local calibration coefficients in the process of automatic measurement of a standard surface, whereby each point of the movement space of the scanner can be defined by a unique set of scale factors. To eliminate the negative influence of noises, thermal drifts and creeps upon the distributed calibration results, the methods of feature-oriented scanning, feature-oriented positioning and counter-scanned images are used.


Slide 3. Positioning the virtual mode in the context of the study

The full description of the distributed calibration approach is available in a series of three papers. In the first paper, a general description is given, the paper has been published in the December, 2015 issue of Applied Surface Science. The paper under consideration, which is the second in the series, is devoted to the virtual calibration mode. In this mode, instead of measuring the real surface of a standard, the calibration program performs a “measurement” of surface image of the standard, which was obtained earlier by a conventional raster scanning. The virtual mode is used for simulating the process of calibration and validating the analytical solutions found in the first paper. In the third paper of the series, which is to be published later, the real calibration mode is described and experimental proofs are given of the practical feasibility of the method and its high precision.


Slide 4. Virtual calibration by graphite lattice

The left side of the slide shows an STM image of atomic surface of highly oriented pyrolytic graphite used as a length standard. The image is distorted by thermal drift and creep, which causes an 11% mean relative error of measurement of the crystal lattice constant. On the right, shown is a net of local calibration structures detected during the virtual distributed calibration.


Slide 5. Calibration database

During the course of distributed calibration, a calibration database is being acquired. The calibration database contains local calibration coefficients and the scanner coordinates where those coefficients have been determined. This slide shows regression surfaces built by the found local calibration coefficients.


Slide 6. Corrected image of graphite surface

On this slide, a corrected image of the graphite surface is shown. The mean lattice constant in the image corresponds to the nominal value of 2.464 Å, the residual relative error of the measurement makes 0.002%. Nonlinear correction of the image has been performed by the obtained regression surfaces using the formulae derived in the first paper of the series.


Slide 7. Research summary

Summary of the research conducted:
1. Simulation of the process of distributed calibration has been performed, validity of the previously suggested analytical solutions has been confirmed.
2. Operation of the probe microscope scanner has been analyzed in detail, the values and the character of raster distortions for both regular and counter types of scanning have been determined.
3. A possibility of estimating the values of thermal drift and creep acting during a raster scanning has been demonstrated.
4. Applicability of the distributed calibration for surface characterization in automatic mode has been proved.

Finishing, I wish you all success in your studies!