Mesh surfaces with small triangle sizes generate points behind surface

[NixtonM]

When simulating a scan of an object with a high-detail mesh (edge lengths below 1mm), we observe that the mesh becomes (semi-)transparent to the simulation. The number of points simulated on the actual surface becomes quite low. Instead, we obtain mixed-pixel-like behavior behind the surface (within the object's volume) and even see points on surfaces fully occluded by our object.

Has this behavior been observed previously, and if so, do you have a recommendation on triangle size vs. beam diameter (divergence and distance setting)?