Question

What predictive focus method settings are available and how are they used?

Answer

Prior to uScope Navigator v4.3, the only predictive focus setting was the grid spacing which specified the maximum number of fields between prediction points.

Starting in uScope Navigator v4.3, the predictive focus method was enhanced as follows:

• Prediction point scanning is now bidirectional (it was previously uni-directional). This speeds up prediction point acquisition.
• After the initial prediction point is acquired, subsequent prediction points use the previous prediction point focus value as the mid-point of their focus scan. This has the effect of capturing prediction points more quickly.
• Option settings allow user configuration of the initial prediction point range, the step size, and the range for subsequent prediction point focus.

Predictive Focus Range Settings

The following settings control the predictive focus algorithm. You may change these parameters to suit your requirements.

• Grid Size
  The Grid Size controls the maximum number of fields between prediction points. The default grid size is set to 9. However, this distance may be too large for some specimens. Reducing the grid size to 5 will cause more prediction points to be acquired and the focus map to be more accurate, but scan time to increase.
• Initial — Range
  The Initial Range specifies the range (above and below the initial focus) to scan for best focus for the first (initial) prediction point. The default range is set to 100 steps.
• Run — Steps
  The Run Steps specifies the number of steps to move the objective for each image in the focus stack when determining the best focus for each prediction point. The number of steps is based on the objective magnification and NA.
• Run — Range
  The Run Range specifies the range (above and below the last prediction point focus) to scan for best focus for subsequent prediction points.

Note
The step size specifies the number of motor steps to move the objective (0.1984 microns per step). So, 10 steps are equivalent to 1.984 microns (0.001984mm). The step range specifies the range (in motor steps) above and below a mid-point. So, a step range of 100 is equivalent to 201 steps in total (100 motor steps above and 100 motor steps below a mid-point).

Refer to Step Size and Range Settings for more information.