Game Tech Wiki has everything you'd ever want to know about CRT shaders
(emulation.gametechwiki.com)
I keep harping on this, but this is a massive regret - sure they were bulky and power hungry, but I would sell a kidney (not necessarily mine) to be able to buy a modern CRT to enjoy my old PS1 light gun games (Pount Blank, Ghoul Panic, Rescue Shot, Time Crisis etc.) again.