Not only Magnetic interference can make Ball Lightning, lasers are more focused than EM string waves.
Heated String Knot Bubbles by an interfering laser, inside an acrylic block.5x5 cm. see fiber laser learning lab: https://www.youtube.com/watch?v=MDctYVg9pfU
The high area is the closest to the laser itself., so I suggest that therefor there are more bubbles to be seen.because the light pulses are damped /decreased by the Acrylic.
Below: A second possibility is the merging of two laser beams for better interference and production of ball lightnings.
Below, an other example, even of 4x artificial guided ball lightnings probable guide from above.
Just like all em waves ! all photonic waves could be observed as bunches of string particle waves ejected by the EM antenna.
