Acquisition Mode Tool in Topography Measurement Wizard

Frame Size

Adjust the frame size (in pixel) of the displayed image by entering the desired value in the two input fields.

To change the frame size you must stop the live image acquisition.

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Presets

By clicking on this button you can select from a list of default frame sizes (e.g. 128 x 128 or 512 x 512).

The number of pixels in a given scan area defines the pixel size, see also the Optimal button.

Scan Speed

Set the scan speed by adjusting the slider from 1 (slow) to 16 (very fast).

Note that the available maximum scan speed depends on the selected Frame Size and zoom factor. In Airyscan MPLX mode the speed is indicated in frames per second, an estimate of pixel time and pixel number (without scanner return time). The actual frame rate might be lower especially with very small frames.

For topographical measurements there is no reason to limit the scanning speed.

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Optimal

By clicking on this button the frame size (image resolution) will be set to an optimal value corresponding to the optical magnification (objective) and the zoom factor.

This provides an image where no information is lost and no empty data are generated as optimal sampling is achieved. The optimal value is calculated for the given objective and magnification settings matching a 2-fold oversampling according to 2 fold Nyquist. Rectangular image dimensions are preserved. Sometimes compromises between lateral resolution and measurement time are necessary.

Direction

Following scanning directions can be selected:

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Unidirectional

The laser scans in one direction only, then moves back to scan the next line.

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Bi-directional

The laser also scans when moving backwards, i.e. the scan time is halved.

In case a pixel shift between forward and backward movement (double image), resulting from bidirectional scanning, is visible, use the Correction X/Correction Y sliders to correct it.

By clicking on the Auto button, an automatic scan correction will be performed.

Averaging

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Number

Selects the number of images you want to average (1 - 16).

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Method

Selects the method which will be used for averaging:

• Mean Intensity:
  Uses the mean average of all images
• Sum Intensity:
  Uses the sum of all images.

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Bits per Pixel

In the drop-down list you can adjust the color bit depth to 8 Bit or 16 Bit (i.e. 256 or 65536 gray values).

To change the bit depth you must stop the live image acquisition. 16 bit increases file size and processing time. It does not increase acquisition time. Higher bit depth can increase accuracy of the calculated height map and improve contrast of the EDF image on samples with a high dynamic range.

Scan Area

In this section, you can adjust the position of the scan area.

The outer frame corresponds to the field of view of the microscope.

The inner frame represents the scan area. All changes (Offset, Rotation, Zoom) made in this section will be immediately applied to the scan area.

Following functions are available:

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Offset

Adjust the offset by using the Left/Right or Up/Down sliders. You can also enter a specific value in the input field.
By clicking on the C button behind the input filed, the offset position will be reset to center position.

If you left-click on the inner frame and hold down the mouse button, you can move the scan area freely. The positions in the input fields will be adopted according to your adjustments.

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Rotation

Adjust the rotation degree by using the Rotation slider. You can also enter a specific value in the input field. By clicking on the O button behind the input field, the rotation degree will be reset to default position (zero degree).

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Zoom

Adjust the zoom level (from 0.5x - 40x) by using the Zoom slider. You can also enter a specific value in the input field.

If you click on the 1/2 button behind the input field, the zoom level will be reset to default (0.5x).

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Reset Scan Area

Resets all adjustment to the system defaults.