1. Find a device that will allow you to measure vertical distances on your Z axis. Many microscopes have accurate markings on the focusing knob. Otherwise, it can be as simple as a desk ruler held vertically close to the edge of the stage, with one end resting on the desk.
2. Open the Tango Setup utility, select your stage entry and press the Setup button. Make sure that the Pitch for the Z axis is at 1 µm / microstep. Click OK and close the Tango Setup utility.
3. Open Clemex Vision (or CIR). Make sure the measuring units (in Preferences) are microns. Use the joystick to move the stage down several millimeters.
4. At the bottom of your range, make a note of the Z coordinate displayed in the Stage Pattern window, as well as the height indicated by your measuring device.
5. Use the joystick to move the stage up by several millimeters. A travel range of at least 10 mm is recommended to get a reasonable precision.
6. At the top of your range, note the Z coordinate in the Stage Pattern window, and the height indicated by your measuring device.
7. Find the difference in measured height, in microns. Divide this value by the difference in Z coordinates. This is the number of microns per microstep. (If negative, just use the absolute value.)
8. Close Vision (or CIR) and open Tango Setup again. Copy this value into the Z Pitch box. Click OK and close Tango Setup.
9. The next time you use Vision or CIR, the displayed Z values will reflect the physical distances on your Z axis. You can verify this using your measuring device.