Huygens Optics | The double beam experiment @HuygensOptics | Uploaded August 2023 | Updated October 2024, 1 hour ago.
A bit of optics fun and a little riddle: two coherent light beams of equal intensity and opposite phase meet up. They interfere destructively in the center, thereby creating a continuous plane of zero EM field (and so of zero intensity). The question is: how can the energy in either beam cross and area of zero intensity? Leave a comment if you want to show off your intellect ;-).

The experiment in the last 20 seconds of the video shows the cross section of 2 laser beams that meet up and part again. For the experiment I used a single coherent source (HeNe-laser), because that is the only way this experiment could work. It requires a fairly high degree of coherence. Basically it's just a 50% beam splitter and an adjustable mirror under 45 degrees, that create 2 beams of equal intensity, initially spaced 4mm apart, 1mm in diameter and are under an angle of 0.1 degrees with respect to each other. I moved the camera sensor over a distance of 6 meters and recorded 40 images around the area where the beams were crossing paths.

BTW: officially, I think there is no such thing as the "double beam experiment", I just made that name up...