Improve interference from "reflection" in single wave light screen for v2

When we just have one source in the first or second screens, the "reflection" or lack of complete absorption that is happening on the far right of the lattice is causing interference to be visible on the light screen. I would like to spend some time investigating options for reducing this for this v2 work (see oscillatory behavior here). Can the model be tweaked so that after the wave has propogated out of the window and to the edge it can no longer propogate backwards? Perhaps consulting with Mike D for additional options on suppressing that backward reflection? (Note - I am connecting this to a reflection of the back of the lattice because it takes a while for the oscillations to appear and at first they are not there).

Start by reproducing the oscillatory behavior in the first and second screens with a single source, using the linked image as a reference. Investigate how the wave reaches the far-right lattice edge and whether backward propagation causes the delayed reflection on the light screen. Done means the visible interference is reduced or eliminated without disrupting the v2 wave behavior.