Hysteresys calibration file generation

To create a Hysteresys calibration file user should do the following:

• Nodal points with known distances between them should be marked using poly line (Curve) on the obtained image of a calibration sample. To make poly line drawing easier option "Cursor/Snap to Maximum" can be selected (see pic.2.11).

  Figure 2.11: Scanned image with points that was marked us described.

  

• Then Operations/ Create Calibration Curve menu command should be chosen. Then two columns in appeared window can be seen (see pic.2.12).

  Figure 2.12: Table that allow to define points that are needed for calibration plots generation.

  

  In the left column parameters (lengths of marked intervals) are denoted, and in the right column values of this parameters should be entered. So we enter distances between marks (that we know with rather good precision) in the right column (it can be a period of a grating for example).

• Then program ask if we want to save the calibration file. And we save it to some directory on a hard drive.

• Afterwards program generates two calibration curves - X-calibration and Y-calibration-slow (for X and Y axis of piezoscanner) and shows them on the screen (see pic.2.13).

  Figure 2.13: X-calibration plot.

  

  On the X-axis of the plot there are values of coordinates projection to X-( or Y- ) axis for these points and on the Y-axis of the plot are real values of these points. This plot is drawn with green line, and the red plot is obtained by reflecting the green one relatively to the line that is bisector of a angle between axis of coordinate gird. This red curve is used to correct the voltage that is drive piezomanipulator. Note: If values of poly line points projection to X- or Y-axis are small (this could happens, for example, if this poly line is almost parallel to the one axis and perpendicular to another) a large error can arise. In this case user should obtain two separate calibration files for fast and slow scanning direction(x-calibration è y-calibration-slow). To do this user should draw two curves on the obtained image in a way to get "good" projection values for both axis (see pic. 2.14). To start drawing new poly line without connecting it with the previous one hold CTRL button when checking first point of the second curve.

  Figure 2.14: Drawing two curves for the histeresys calibration on the image.

  

  Then we should unite these two files in one. This can be done by choosing correct calibration data from every file and unite them into one.

• Obtained histeresys calibration file is used in server configuration (see 2.1.2).

The configuration file obtained can be used to images correction while scanning in one direction only (we've described here the case for X-direction of slow scanning axis). To obtain histeresys calibration for both scanning directions the same operations should be done under the test sample image that was obtained by scanning in Y-direction of slow scanning axis. Then user should unite these calibration data into one file.