How to set the standard focus (z-height)?

How to set the Standard Focus (Z-height)?

1. Adjusting the "OBJ Focus" knob, bring the DV (Defocus Value) to just slightly +0 from -0.
   The microscope is calibrated at DV = 0 by the manufacturer. It is hard to obtain a high-quality image if you deviate far from the DV = 0.

2. Under WOBBLER, select "IMAGE X" or "IMAGE Y" (just only one).

3. Use "Z up" and "Z down" buttons to minimize the image movement (shaking).
   You may insert the small viewing screen with the binoculars to judge the shaking.

4. When the movement is minimized, deactivate "IMAGE X" (or "IMAGE Y").

Notes:

• The z-height control is for coarse focusing while the "Obj Focus" know is for fine focusing.

• The eccentric height (z-height) is a specimen stage position where the specimen does not move when it is tilted.

• In the wobbling process, double deflection coils below the condenser lens are imposed with a small cyclical fluctuation of current.

• The electron beam is repeatedly tilted in a slightly positive and negative direction with respect to the optical axis.

• We adjust the specimen Z-height to bring it close to the eccentric height – the image shift is minimized.