Troubleshooting - Stray Light Report Unavailable
The Stray Light Report and the Raytrace Paths Report, both available by selecting Tools > Reports from the FRED menu, are very useful tools for looking at ghost / scatter paths in the system.
If these options are grayed out, it is because you must first perform a raytrace using the Advanced Raytrace dialog with the "Determine raypaths" option selected.
The reports rely on raypath information, which is not automatically saved during a "normal" raytrace. This option must be selected in the Advanced Raytrace settings, as shown below:
Note: It is also valuable to select the "Create/use ray history file" option as discussed in this article: Raypaths and ray history