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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: 31 Jul 2019

Symptom

In uScope Navigator prior to v4.3, auto-focus settings were fixed and were not user-editable. Now, these settings may be edited from the Device Settings dialog (see below). The default settings are shown in the following table.

Focus Type Step Size
Microns
Focus Range
Microns (see note)
Coarse Focus 50
9.92µm
500
198.64µm
Medium Focus 20
3.97µm
140
55.76µm
Fine Focus 5
0.99µm
30
12.10µm

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 to about 8 microns.
  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
9.92µm
500
198.64µm
Medium Focus 20
3.97µm
140
55.76µm
10x Fine Focus 12
2.38µm
24
9.72µm
20x Fine Focus 6
1.19µm
30
12.11µm
40x Fine Focus 3
0.60µm
27
10.91µm
60x Fine Focus 2
0.40µm
24
9.72µm

Refer to the following knowledge base articles for a step size calculator you can use to accurately determine step measurements:

Notes

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.

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). Refer to Step Size and Range Settings for more information.

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