FocusvLPos.spt

Graphs | Data | Data Interpretation

This script plots focus sum, focus difference and focus difference divided by focus sum versus lens position. Surface reflectivity and receiver gain settings at the start of execution are used. These two values, as well as dmodsync and LPosCal, are displayed at the bottom of each graph.

Note: Your system must be properly configured before running this script. See <%= htmlCedirLinkAlternateTitle(20695, "Note 2") %> for more information.

FocusvLPos Graphs

1. FDiffSumVLPos.ps: This graph shows focus difference divided by focus sum versus lens position, in microns.
2. FDiffVLPos.ps: This graph shows focus difference versus lens position, in microns.
3. FSumVLPos.ps: This graph shows focus sum versus lens position, in microns.

FocusvLPos Data

There is one output file, FocusVLPos_data.txt. The file contains eight columns:

1. Commanded lens position in microns.
2. The actual lens position in microns.
3. The focus difference in raw units.
4. The focus sum in raw units.
5. The focus difference divided by the focus sum.
6. This column contains no useful data.
7. This column contains no useful data.
8. This column contains no useful data.

Interpretation of the Data

At least two things should be checked: first, the sum signal should not be saturated (see <%= htmlCedirLinkAlternateTitle(20695, "Note 5") %> ). There is no measure of how straight the data is, so perhaps some sample graphs should be provided.