Using Ray Detectors
A Ray Detector is a domain or boundary feature that provides information about rays arriving on a set of selected domains or surfaces from a release feature. The feature provides convenient expressions that can be used in the Filter attribute of the Ray Trajectories plot, which allows only the rays which reach the ray detector selection to be shown. The following variables are defined by the Ray Detector feature, assuming a physics interface with tag gop and a detector with tag rd1:
gop.rd1.Ntf is number of transmitted rays from the release feature to the ray detector at the end of the simulation.
gop.rd1.alpha is the transmission probability from the release feature to the ray detector.
gop.rd1.rL is a logical expression for ray inclusion. This can be set in the Filter node of the Ray Trajectories plot in order to visualize the rays which connect the release feature to the detector.
 
The Ray Detector feature defines new variables but does not otherwise affect the solution. Therefore, you can add a Ray detector to a completed model and evaluate the variables it defines without recomputing the solution. To do so, right click on the Study node and select Update Solution. The new variables described above will be immediately available for results processing.