There are typically six steps involved in the laser printing process:
Fusing: The paper passes through a fuser assembly, which, having rollers that provide heat and pressure (up to 200 degrees Celsius), bonds the plastic powder to the paper.
Cleaning: When the print is complete an electrically neutral rubber blade cleans any excess toner from the photoreceptor and deposits it into a waste reservoir, and a discharge lamp removes the remaining charge from the photoreceptor.
Charging: A corona wire (in older printers) or a primary charge roller projects an electrostatic charge onto the photoreceptor, a revolving photosensitive drum or belt which is capable of holding an electrostatic charge on its surface as long as it hasn't been exposed to certain wavelengths of electromagnetic radiation.
Developing: The surface containing the latent image is exposed to toner, very fine particles of dry plastic powder mixed with carbon black or coloring agents. The charged toner particles are electrostatically attracted to the photoreceptor where the laser wrote the latent image.
Writing: A Raster Image Processor (RIP) chip converts incoming images to a raster image suitable for scanning onto the photoreceptor. The astronomy laser pointer is aimed at a moving mirror which directs the laser beam through a system of lenses and mirrors onto the photoreceptor. Lasers (now typically laser diodes) are used because they generate a coherent beam of light for a high degree of accuracy. Wherever the laser strikes the photoreceptor the charge is reversed, thus creating a latent electro-photographic image on the photoreceptor surface.
Transferring: The photoreceptor is pressed or rolled over paper, transferring the image. Higher end machines use a positively charged transfer roller on the back-side of the paper to pull the toner from the photoreceptor to the paper.
Different printers implement these steps in distinct ways. Some "laser" printers actually use a linear array of light-emitting diodes to write the light on the drum (see LED printer). The toner is based on either wax or plastic, so that when the paper passes through the fuser assembly, the particles of toner melt. The paper may or may not be oppositely charged. The fuser can be an infrared oven, a heated pressure roller, or (on some very fast, expensive printers) a xenon flash lamp. The Warm Up process that a laser printer goes through when power is initially applied to the printer consists mainly of heating the fuser element. Many printers have a toner-conservation mode or economode, which can be substantially more economical at the price of slightly lower contrast.