First of all, you have Shadow set to 0.0 on your spotlight parameters panel, and shadows are disabled in properties. This means the light will pass through everything, even if you have shadows enabled in your render options. Set Shadow to 1.0, and enable shadows for that spotlight. Second, you'll need something that isn't visible at render-time, but will still catch the light and prevent it from going any further. The holograms are transparent, so they might not be sufficient on their own. I'd recommend placing a square prop just behind the holograms, with the Shadow_Catch_Only option enabled in the Material Room. As for the dotty rays, try reducing the Atmosphere node's Volume_StepSize value.