SIGMA LBA-708 - Manual (Page 81)

• If the Set Reference Source is set to Auto Gauss, and the Gauss Fit item in the
Computations dialog box is checked, then the beam profile resulting from a computed
Gaussian fit to newly acquired frames will be automatically copied to the Reference
frame. In this mode, setting a reference frame manually does not make any sense
because the next frame brought into view will automatically update the contents of the
reference frame.
Note: In the last two examples, if the Gauss Fit item is not checked and set to Whole Beam, then no fit data will be
available and therefore nothing will be copied to the Reference frame.
3.2.7.9 Display Thresholds
You can add Display Thresholds to the beam display that permit you to see when energy
intensities fall into regions that may be of significance to your application. You can set a Lower
and an Upper threshold. Setting the Lower threshold to zero will disable its operation. Setting
the Upper threshold to its maximum value will likewise disable its operation. If the Energy of
Beam setting is set to zero then the maximum value is 255 for the LBA-300PC; 1023 for the
LBA-400PC; 4095 for the LBA-500PC. If you have calibrated the beam energy, then the
maximum value will be scaled accordingly.
The visual effect of setting active threshold values is to force the displayed beam intensities that
fall between the two threshold settings, to follow the Beam Color selection. Beam intensities
that lie below the Lower threshold, or above the Upper threshold, will revert to a different color
style. Intensities that lie within the threshold region are defined as being in-bounds. Intensities
that lie outside the threshold region are said to be out-of-bounds.
If your Beam Colors is set to one of the colored selections, i.e., Color Bands, Color Continuous,
Green, or Yellow; then the out-of-bounds colors will be replaced with the Gray Scale palette.
If your Beam Color is set to the Gray Scale selection, then the out-of-bounds colors will be
replaced with the Color Continuous palette.
Hint: Program both the Lower and Upper threshold values to visually indicate that your Top Hat beam’s intensity
remains within a certain range. Program just the Upper threshold value to see if your beam’s peak intensity
exceeds a certain maximum value.
Note: Using the Lower threshold feature in 2D, combined with a colored beam selection will have the effect of
making your beam profile displays disappear. Use a Gray Scale selection if you want to preserve the beam profile
displays.
3.2.7.10 Color Bar
If you check the Color Bar item, a color-coded Z axis intensity scale will appear along the right-
hand edge of the beam display window. This scale will reflect the colors that are currently
operating on the beam display. The numerical amounts indicate the intensity value that is
required to produce the associated color. Use this only as a guide, unless you have perfect
color/gray-scale acuity.
Operator’s Manual LBA-PC
Doc. No. 10654-001, Rev 4.10
81