Editing Computer mouse (section)

=== Optical and laser mice ===
[[File: HP Mouse M-U0031-O-1681.jpg|thumb|The underside of an optical mouse]]
{{Main|Optical mouse}}

Early optical mice relied entirely on one or more [[light-emitting diode]]s (LEDs) and an imaging array of [[photodiode]]s to detect movement relative to the underlying surface, eschewing the internal moving parts a mechanical mouse uses in addition to its optics. A laser mouse is an optical mouse that uses coherent (laser) light.

The earliest optical mice detected movement on pre-printed mousepad surfaces, whereas the modern LED optical mouse works on most opaque diffuse surfaces; it is usually unable to detect movement on specular surfaces like polished stone. Laser diodes provide good resolution and precision, improving performance on opaque specular surfaces. Later, more surface-independent optical mice use an optoelectronic sensor (essentially, a tiny low-resolution video camera) to take successive images of the surface on which the mouse operates. Battery powered, wireless optical mice flash the LED intermittently to save power, and only glow steadily when movement is detected.