Non-diffracting beams

Non-diffracting beams are special light or wave patterns that maintain their shape and size over long distances, unlike typical beams that spread out or fade. They achieve this by constructing the wave so that different parts interfere in a way that keeps the overall pattern stable. A common example is the Bessel beam, which can stay focused and tight over extended ranges. These beams are useful in applications like precise imaging, optical trapping, and medical procedures, where maintaining a tight, consistent focus is crucial, even deep within a medium or at a distance.