Now that the Source Ray is defined, we can more easily analyze the reason for the error. 

Turn Ignore Errors back ON, open the Ray Trace/Detector Control dialog (Analysis > Detectors > Ray Trace/Detector Control) and run a Monte Carlo ray trace using the following settings.  Make sure to “Save Rays” so that the Source Ray may be analyzed in more detail after the completion of the trace.

To evaluate the propagation of the ray, open the Ray Database Viewer (Analysis > Database > Ray Database Viewer).  Make sure that the previously saved filename is listed as the “File:” in the settings of the Ray Database Viewer:

Even as we follow the propagation of the ray in the Ray Database Viewer, it is already known (from the geometry error), that the problem occurs at Object 5.  It is apparent from the Rdb that when the ray reaches Object 7 (the Detector Rectangle), ZEMAX assumes that the ray is inside of Object 5, as is denoted by the “In” and “Hit” columns.  After passing through the detector, the ray becomes terminated, indicated by the * in the “Z” column of the viewer.

The ray should have exited the Polygon Object (Splitter_2.POB) prior to hitting the detector.  Therefore, it is imperative that the definition of the .POB file be reviewed.  From the Shaded Model, it appears that the splitter is missing its entire back face, which is most likely the cause of the problem.

Review the definition of the Polygon Object by viewing the .POB file in the text viewer.  Through careful evaluation of the defined faces and syntax, it is apparent that the line representing the back face of the polygon object is “commented” out.

Remove the “!” from the line indicated above and re-save the .POB file.  Once it is saved, select “Reload All Objects” from the Edit menu in the NSC Editor.

Remove the Ignore Errors flag and update the system.  ZEMAX should no longer issue a geometry error.  Thus, the Source ray can be removed, and the system analysis can once again be performed with the Source Rectangle.

This is a good example of how a user error in the definition of an object can cause problems within the ray trace.  In this particular example, the ray never hit the back face of the Polygon Object.  Therefore, as far as ZEMAX was concerned, the ray never exited the Polygon Object.  The problem is, ZEMAX internally continued to trace this ray, but never found a point in which the ray finally exited the volume.  Thus, a geometry error was identified.