The default boundary condition is the Material Discontinuity condition on all interior and exterior boundaries. The
Material Discontinuity causes rays to be reflected and refracted if the two adjacent domains have different refractive indices.
The total number of released secondary rays in a model can sometimes grow rapidly and exhaust all of the preallocated secondary degrees of freedom. For example, a single ray reflecting back and forth between two Material Discontinuity boundaries can create an inordinately large number of rays, each with extremely low intensity. Remember that the total number of secondary rays that can be produced in the model is limited by the number specified in the
Maximum number of secondary rays field.
It can be useful to constrain the release of secondary rays at boundaries so that only the most important rays are produced. If reflected rays are not of any interest, then in the Rays to Release section, select
Never from the
Release reflected rays list. If reflected rays are only relevant to the model under a certain condition, such as hitting a specific part of the surface or having a certain direction, instead select
Based on logical expression and then enter a user-defined
Evaluation expression that must be satisfied.
If ray intensity is solved for, you can also specify a Threshold intensity. If a reflected ray would have intensity below the threshold, it is not released at all. Similarly, if ray power is solved for, you can specify a
Threshold power.