Optical switch
Also called light switch · optical mouse switch
An optical switch detects a press when the button interrupts a beam of light instead of closing metal contacts. With no contacts to bounce it can’t develop the classic double click chatter.
An optical mouse that double clicks is pointing at firmware or settings rather than a worn switch.
In practice
Optical switches trade metal contacts for a light beam and a shutter. They react slightly faster and they can’t develop contact bounce, which removes the most common reason mice fail. Some feel less crisp than good mechanical switches and some mice use optical switches only under the main buttons, leaving the side buttons mechanical.
How to check
If your mouse has optical main switches and still double clicks, run the mouse test. Flags under 50ms on an optical button point at software such as a macro or a stray setting rather than wear. Check the side buttons separately, since they may be mechanical and able to chatter even when the main buttons can’t.