A quarter century ago we used a well characterized laser at a known power level that given a very precise wavelength and total power results in a very precise n

A quarter century ago we used a well characterized laser at a known power level that given a very precise wavelength and total power results in a very precise number of photons per second, like on the order of somethingE15 photons per second. From what I remember of filters neutral density transmission is log, so its pretty easy with a laser power meter to prove a ND2.0 outputs 1e-2 of input photons and turns the remainder of photons into heat or reflects them. Show an easily measurable somethingE15/sec photons out of a laser and the meter will read 1% power. Now you can buy neutral density filters of all kinds of measurable density. And filters stack, 1% of 1% is what you'd expect, not something crazy like average or RMS or whatever. So my numbers above might be all messed up but conceptually it boiled down to create a "normal scale human brightness" fountain of a knowable number of photons per second and filter it such that theoretically about one sneaks thru every second or once in awhile or whatever. Unfortunately we didn't have time to fool around with looking at it. From memory, I think we used it as some kind of quantum proof lab. So part one is diffraction patterns prove photons totally are definitely waves, and part two of the lab was this really sensitive photometer (essentially a geiger counter for photons) shows that each light photon is a distinct and countable bullet. And look, varying the density of the filter stack has no effect on the energy of each photon bullet it merely affects the rate at which they arrive isn't quantum mechanics spooky and wonderful? If that wasn't what we did with it, it probably should have been, or at least from memory I think that's pretty close to what we did. I suppose in the modern era lasers are a lot more powerful so you would need a better filter and rather than the weird vacuum tube photon sensor you'd just use a COTS solar panel and measure the single electrons produced by the single photons (within solar panel efficiency correction factor etc) You know whats really fun to do with quantum mechanics, is do a dual slit diffraction graph with a source that's like 1 photon per second so you know the apparatus only has one photon in flight at any given time. Rather than doing the two parts of my undergrad lab separately, do them together. In my infinite spare time that would be fun to build at home. I would imagine it would take a long time to gather the data, perfect for home amateur scientist types. I know what that graph looks like, and it freaks people out every time.