Hi Taeshin,

The reason rays refract at the water is the overlap rule. In non-sequential, if there is an overlap between objects then the region of the overlap is defined by the object that occurs last in the non-sequential component editor. In your design, the volume defining the water occurs last, so the ray encounters water at the edge of the wedge.

In the attached file, I made the cylinder occur after the wedge. Now the cylinder defines the overlap so the pipe penetrates the wedge.

To make this easier for me to do I changed the reference of all objects to global. I also changed the source orientation so we can see that the ray is guided by TIRs in the pipe, when surrounded by air, but does not TIR when the pipe is surrounded by water, Then we see a split. (This of course depends on the angle of the ray.)

I attach a ZAR of the modified design. (Note that you may occasionally see geometry errors with this design, but they occur in ray segments with little power.)