We will now take a look at the ray splitting capabilities of pure non-sequential mode in ZEMAX. Open the file "Samples > Non-sequential > Ray splitting > Beam splitter.zmx".

This example demonstrates the use of two adjacent prisms (modeled using the Polygon Object type) to model a cube beam splitter. By default, the Polygon Objects will simply transmit the incoming beam. By applying a partially reflective/partially transmissive coating, we can generate both reflected and transmitted beam paths. Coatings are applied in the Coat/Scatter tab of the Object Properties dialog. Double-click in the Object Type column for object 3 in the Non-Sequential Component Editor (NSCE) and click on the Coat/Scatter tab. This is where coating properties are assigned for each object.



TIP:  Users of the full, licensed version of ZEMAX can change coating assignments in this tab. For more information on how to do this, see the Knowledge Base article, "How To Model A Partially Reflective and Partially Scattering Surface".

Coatings have been applied to all surfaces of the beam splitter cube in this example. Anti-reflective coatings have been applied to each of the outer surfaces while a 50/50 reflective/transmissive coating has been applied to the interior splitting surface. You can see the rays splitting in the NSC 3D Layout window.

 

Open the settings for the NSC 3D Layout and observe that "Split Rays" and "Use Polarization" are both checked.



Polarization calculations are required in order for ZEMAX to split rays. As such, both boxes needed to be checked in order to see ray splitting. Uncheck both of these boxes and click "OK". Notice that there is no longer any ray splitting and the single ray that is launched transmits right through both halves of the cube.



Rays can also be split during analysis traces. Ray splitting and polarization calculations must both be turned on in the Ray Trace/Detector Control dialog.



TIP:  ZEMAX also supports an option called "Simple Ray Splitting" where either the reflected or refracted ray is traced at each splitting interface, but not both. The choice of which path to trace is random and the probability is proportional to the relative reflective/transmissive components of the splitting surface. Activating this option can speed up ray tracing in many optical systems. For more information, take a look at the Knowledge Base article, "What is Simple Splitting?".