I was referring to standard office paper copy machines although very similar technology is used in laser printers too. They use high voltage to electrostatically transfer the toner to the drum, the light is used to discharge it where necessary by making the drum coating conductive. It occurs to me that if you are trying to store analog information in the same way, rather than modulating the high voltage to apply the charge, it would be easier to charge the whole surface and selectively discharge it.
I'm not sure what you are trying to achieve with this project, can you explain more please.
Brian.