My physics teacher once told us in class:
– Now, we’re going to do an experiment that you (little ones) will never understand.
– By the way, I don’t either.
It is a continuous stream of particles = laser. Photons are particles yet they behave like a wave at the same time. That is a very strange thing, when you come to think about it. It is not hard to prove experimentally and nowadays anyone can buy a pocket sized laser.
A laser has an exact wavelength (it is noting like a very strong torch) in this case the wavelength is λ = 650 nm and a couple of mW. Coupled with physical effects such as diffraction, infraction and possibly a gitter.
I have one of my own. A tiny one. The supreme photon source? That would be Helios our own sun.