|Diffraction: I would have thought that the waves wouldn't go through the screen because the wave was too long to recognize the holes in it. How did the light go through the screen?
When I sent laser light through a fine screen, it formed an interesting diffraction pattern on a distant wall. The holes in the screen were small, but not nearly as small as a wavelength of light. The light had no trouble going through these holes, but it did suffer diffraction effects. Because the wave passed through many separate holes, these waves interfered with one another and created the complicated pattern on the wall.