If geometry errors arise when working in hybrid mode in ZEMAX, it is most likely due to some improper placement of the entry and/or exit ports. Determining whether or not an entry and exit port is misplaced in ZEMAX is straightforward. To demonstrate this, we will use the sample file indicated below, which is available via download on the very last page (Summary and References) of this article.

FILE:  "Revised Core Clad Fiber_Geometry Error.ZMX"

Note:  This file is a revision of the “Core clad fiber.ZMX” file located in the ZEMAX > Samples > Non-Sequential > Fibers directory.  A few alterations were made to demonstrate the errors associated with misplacing entry and exit ports.

Once you have downloaded the file, open the file from within ZEMAX.  This file uses a hybrid mode to trace a sequential cone of rays through a K5/FK3 Core/Clad fiber.

Note that upon opening the file, a geometry error is issued because there is a deliberate invalid placement of the system’s exit port.  Exit the error windows, and note that the sequential rays are not reaching the detector plane (the IMA surface):

Currently, the Ignore Errors option is turned ON.  Since ZEMAX will continually issue an error until the problem is resolved, it is frustrating to continually have to close every error dialog each time the system is updated.  Therefore, the Ignore Errors option is user-selectable.  Let’s turn Ignore Errors OFF so that ZEMAX will issue the geometry error in the current lens file.  As a reminder, Ignore Errors may be turned on/off by selecting “Ignore Errors” under the “Errors” menu on the NSC Editor menu bar.  Note that a checkmark next to the Ignore errors is indicative of Ignore Errors being turned ON.

Once Ignore Errors has been turned OFF, update all windows by pressing Ctrl+Shift+U on the keyboard.  Upon doing so, ZEMAX will issue the following error message: