With the Z-Stack tool of the topography measurement wizard you can configure an acquisition of the z-stack image to be used for the topography measurement. This Z-Stack tool works in a similar way as the one in the Acquisition tab, with one noteworthy difference: To increase the accuracy of the calculated height maps, the optimal spacing between images of the z-stack is reduced. See Optimal section below for details.

Z-stack images are always acquired from bottom to top automatically, irrespective of whether you have defined the top or bottom z-plane of your stack as the first z-plane. This acquisition sequence increases the accuracy of the z-positioning.

For manually configuring z-stacks you have two modes available:

Parameter

Description

First/Last

If activated, you are able to configure the Z-stack via setting the first and the last positions of the Z-stack, see Configuring a Z-Stack Manually (First/Last Mode).

Center

If activated, you are able to configure the Z-stack via setting the center plane of the Z-stack, see Configuring a Z-Stack Manually (Center Mode).

Depending on which mode you have activated, you will see the following parameters for configuring the z-stack:

Parameter

Description

Set Last/Set First

Only visible for First/Last mode.

By clicking on the Set Last and on the Set First button you determine the current position as last or first position of the Z-stack.

Range

Displays the range of the configured Z-stack from the last to the first section plane.

Slices

Here you can enter the number of Z-slices that the Z-stack will have.

Interval

Here you can enter the desired distance between the Z-slices.

Optimal

The number on this button shows the distance calculated for the channels set and the current microscope according to the Nyquist criterion. If you click on the button, this value is automatically adopted into the Interval input field.

The optimal distance depends on wavelength, numerical aperture and pinhole diameter. Oversampling in z, i.e. defining smaller distances between the planes of the image stack, can help to create smoother surfaces for topographical measurements. Changing the pinhole diameter can help to improve resolution or reduce measurement time as it directly influences the depth of field and the distance between the images of the z-stack. Note that the value for the optimal distance in the topography acquisition wizard is already five times smaller per default compared to the default settings on the Acquisition tab to increase the quality of the outcome.

Keep
  • Interval:
  • Keeps the set interval between the section planes constant if you change configuration parameters in the Z-Stack tool.
  • Slice:
  • Keeps the set number of Z-slices constant.

Center

Only visible for Center mode.

By clicking on this button, the current position is set for the central z-plane. You can also enter the value in the input field to the right of the button.

Offset

Here you can enter a value for an offset if desired.