A laser printer is basically a photocopier. Charge is sprayed onto a semiconducting drum, and the semiconductor laser is used to selectively cause areas to conduct and thus lose their charge.

* The charge is then used to attract toner, which is then transferred to the paper. Finally, a fuser unit melts the toner onto the paper so it doesn't just blow away again.

* It doesn't take much light to activate the semiconductor. Lasers are used because they can be focused on a precise point, not for power.