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uScope Navigator (Device Settings)

Auto-Focus Settings
uScope Navigator (Device Settings)

Information in this article applies to:

  • uScope Navigator V4.3 and Later

Article ID: NDS1136 — Created: 29 Jan 2018 — Reviewed: 2 Feb 2018

Symptom

In uScope Navigator prior to v4.3, auto-focus settings were fixed and were not user-editable. The default settings are shown in the following table.

Focus Type Step Size
Microns
Focus Range
Microns (see note)
Coarse Focus 50
6.875
500
≈137
Medium Focus 20
2.75
140
≈38
Fine Focus 5
0.6875
30
≈8

Auto-focus works by performing three separate focus operations:

  1. Coarse Focus
    Coarse focus narrows the focus range to approximately 20 microns.
  2. Medium Focus
    Medium focus narrows the focus range even further.
  3. Fine Focus
    Fine focus narrows the focus range to a point within the depth-of-field of the objective.

Three focus operations with different step sizes achieve focus very quickly. It typically takes about two seconds to autofocus in SD camera mode.

At 20x, the settings above work quite well. However, at 40x (and even more so at 60x) the fine focus step is larger than the depth of field of the objective. So, autofocus did not work well for 60x objectives.

Resolution

Auto-Focus Settings Starting with uScope Navigator v4.3, auto-focus settings are editable by the end-user.

To access these settings, open the Device Settings — Scan Options under the uScope Control Panel. Auto-focus settings are shown at the top of the settings dialog.

Default settings for the various objectives are shown in the following table:

Focus Type Step Size
Microns
Step Range
Microns (see note)
Coarse Focus 50
6.875
500
≈137
Medium Focus 20
2.75
140
≈38
10x Fine Focus 12
1.65
24
≈7
20x Fine Focus 6
0.6875
30
≈8
40x Fine Focus 3
0.4125
27
≈7
60x Fine Focus 2
0.275
24
≈7

Note
The step size specifies the number of motor steps to move the objective (0.1375 microns per step). So, 10 steps is 13.75 microns. The step range specifies the range (in motor steps) above and below a mid-point. So, a step range of 500 is equivalent to 1,001 steps in total (500 motor steps above and 500 motor steps below a mid-point).

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