(Title stolen shamelessly from my postdoctoral advisor, who I assume will forgive me.)
As I’ve noted numerous times in previous posts, one of the fundamental properties that characterizes wave behavior (i.e. that makes a wave a wave) is wave interference. When two or more waves combine, they produce local regions of higher brightness (constructive interference) and lower brightness (destructive interference), the latter involving a partial or complete “cancellation” of the wave amplitude.
Researchers have long noted that the regions of complete destructive interference of wavefields, where the brightness goes exactly to zero, have a somewhat regular geometric structure, and that the wavefield itself has unusual behavior in the neighborhood of these zeros. In the 1970s this structure and behavior was rigorously described mathematically, and further research on this and related phenomena has become its own subfield of optics known as singular optics. Singular optics has introduced a minor “paradigm shift” of sorts to theoretical optics, in which researchers have learned that the most interesting parts of a light wave are often those places where there is the least amount of light!
In this post we’ll discuss the basic ideas of singular optics; to begin, however, we must point out that most people have the wrong idea of what a “typical” interference pattern looks like!
Skulls in the Stars 