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So, I do electronics repairs every once in a while and I got a customer that wants me to replace the ‘photon gun’ on his CRT-based arcade cabinet.
This customer, in particular, is a really, really smart guy. In fact, he is one of the most educated, most reasonable, most informed people I have ever met. Customer or not.
He wants me to come fix his display, and he referred to a component as a ‘photon gun’. I had no idea what he was talking about.
Making CRT Displays a Little Clearer
Although they have been replaced by much higher resolution and much cheaper LCD technology, how a CRT works is actually pretty amazing.
There is gun in the back of the display that faces the user. This gun emits electrons towards the user. They strike a ‘screen’ on the front of the display. There is a phosphorus coating on the inside of the screen. When the beam of electrons hits the phosphorus material, it excites the electrons in that material and puts them into a higher energy state.
So, it’s not a photon gun that emits light in a CRT. It’s an electron gun that emits physical particles of matter. Those particles of matter excite other particles of matter that then produce visible light. Then, when those newly excited electrons settle back down, they lose energy. The entire CRT system is designed so that when those phosphorus atoms lose that added energy, they release it in the form of photons that the user can see.