The simulation below models the wave pattern created by several point sources next to each other. By increasing the number of sources and reducing the spacing, these waves can be made to interfere with each other in such a way that they form a focused beam. The beam can be steered by tuning the phase delay. This arrangement of point sources used to generate a tuneable beam is known as a phased array, and is widely used across many areas of technology.
This simulation also works as simple model of diffraction of a plane wave through a number of slits. We assume the slits are infinitely thin, which allows us to model them as point sources. The field amplitude is then just computed by summing the contribution from each slit. This is most accurate at large distances from the point sources, and gets less accurate as we get closer to the “slits” and the point-like approximation breaks down. For a more accurate simulation of wave propagation through a diffraction grating, see the full diffraction grating simulation page.