SurfaceXplorer :: Calculation of correction equation coefficients

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| SurfaceXplorer [Работа с СЗМ-изображениями] > [Расчёт коэффициентов коррекции]

3.12 Расчёт коэффициентов уравнения коррекции движения пьезосанера

Функция Расчёт коэффициентов уравнения коррекции движения пьезосанера программы SurfaceXplorer специализирована для применения в атомно-силовом микроскопе NT-206 и позволяет автоматизировать данную процедуру при калибровке прибора.

Функция рассчитывает коэффициенты a, b и c кубического уравнения (полинома третьей степени) вида:

y = ax3 + bx2 + cx,

которые затем могут быть непосредственно использованы программой управления измерительным модулем АСМ NT-206 для коррекции нелинейности движения используемого трубчатого пьезосканера.

To realize this function, you need to aquire at least one test image (assuming application of Microtestmachines' AFM NT-206 and control program). Test image is an AFM image of a test grating with known regular structure (e.g., Mikromasch' TGZ01) and set number 65535 for X and Y range in the Calibration panel. Additionally, scan area in Area panel is to be set to maximum.

Note that the function calculates two equations that are applied for cases of increasing and decreasing numbers of bits in hardware matrix based on one profile. The calculated data can be used for 'Simple cubic correction' in control program module Calibration panel. If you plan to activate 'Advanced cubic correction', use only that equation that corresponds to actual scanning direction at the preparation of the test image.

The procedure is as follows.

1. Open file with prepared test image. If necessary, use leveling commands to eliminate tilt and a spherical surface from the test image, for example

2. Activate cross section function pressing button in tool bar. After that, drag a line (with mouse at pressed left button) perpendicular to the imaged regular structures:

3. Create a cross section for the selected profile line (press button in the tool bar). A window with selecetd cross-section line will appear.

4. Place bookmarks in regular characteristic points of the profile. To place bookmarks, you can use a marker [a] or [b] in the plot, moving it to necessary point and pressing button Add in the panel [Profile] of tab Properties. Alternative way is simply moving a mouse cursor top the necessary point in the profile line and then clicking on it with left mouse button at pressed key Shift an the PC keyboard.

Note, that you need to place at least four bookmarks in the profile line.

5. After placing all bookmarks on the profile, call a context menu pressing right mouse button within the plot area. Choose command Calculate correction.

6. After choosing the command, a specialized window with correction functions curves and corresponding coefficients of the cubic polynom will appear:

You can then save the calculated parameters in a file by pressing button OK in the Curve window. Button Cancel will delete the Curve window.

Note that default file name for saving calculated data is 'SurfaceScan.ini'. It means that you can directly write the calculated coefficients into existing INI file of SurfaceScan program (the program should not run during this procedure). Necessary data will be added or inserted instead of old ones in the INI file. Structure of the saved information is as follows:

I.e. it is a section [Nonlinearity correction] with necessary data.

If necessary, you can also view calculated correction parameters in tab Data of SurfaceXplorer program when profile window is active:

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