Editing Laser printing (section)

===Exposing===
[[File:Laser printer-Writing.svg|thumb|Laser light selectively neutralizes the negative charge on the photoreceptive drum, to form an electrostatic image.]]
[[File: Laser unit dell p1500 print.jpg|thumb|Laser unit from a Dell P1500. The white hexagon is the rotating scanner mirror.]]
A laser printer uses a laser because lasers are able to form highly focused, precise, and intense beams of light, especially over the short distances inside of a printer.  The laser is aimed at a rotating [[polygon]]al mirror which directs the light beam through a system of lenses and mirrors onto the photoreceptor drum, writing [[pixel]]s at rates up to sixty-five million times per second.<ref>{{cite web|title=how Laser Process Technology animation (''sic'')|url=https://www.youtube.com/watch?v=MDLM5fMFyA4| archive-url=https://web.archive.org/web/20131221054838/http://www.youtube.com/watch?v=MDLM5fMFyA4&gl=US&hl=en| archive-date=2013-12-21 |publisher=Lexmark|date=14 July 2012}}</ref> The drum continues to rotate during the sweep, and the angle of sweep is canted very slightly to compensate for this motion. The stream of rasterized data held in the printer's memory rapidly turns the laser on and off as it sweeps.

The laser beam neutralizes (or reverses) the charge on the surface of the drum, leaving a [[static electricity|static electric]] negative image on the drum's surface which will repel the negatively charged toner particles. The areas on the drum which were struck by the laser, however, momentarily have no charge, and the toner being pressed against the drum by the toner-coated developer roll in the next step moves from the roll's rubber surface to the charged portions of the surface of the drum.<ref>{{cite web
|title=CompTIA A+ Rapid Review: Printers |website=MicrosoftPressStore.com
|url=https://www.microsoftpressstore.com/articles/article.aspx?p=2201308
|quote=Laser printers .. complex imaging process ... charge neutralizes ... the drum}}</ref><ref>{{cite book |last1=Bhardwaj |first1=Pawan K. |title=A+, Network+, Security+ Exams in a Nutshell: A Desktop Quick Reference |date=2007 |publisher=O'Reilly Media |isbn=978-0-596-55151-3 |quote=in most laser printers. ... the surface of the drum. }}{{pn|date=February 2024}}</ref>

Some non-laser printers ([[LED printer]]s) use an array of [[light-emitting diode]]s spanning the width of the page to generate an image, rather than using a laser. "Exposing" is also known as "writing" in some documentation.