The Ray Properties node is added by default. Only one instance of this node can exist for each physics interface. The
Ray Properties node defines the equations for ray propagation and may also include inputs for some ray properties.
This section is shown when Monochromatic is selected from the
Wavelength distribution of released rays list in the physics interface
Ray Release and Propagation section. Otherwise the frequency or vacuum wavelength of released rays is controlled separately by each ray release feature.