Shown here is an opto-mechanical mouse.

Wondering what type of mouse you have attached to your computer? Well, if you are using a PC, you have a 99% chance of it being opto-mechanical. Optical mice are primarily used for Unix systems. Opto-mechanical mice operate using a few critical parts. The mouse contains a ball that moves according to the user’s horizontal and vertical movements. The ball "rolls" on two rollers that measure the movements on the X (horizontal) and Y (vertical) axis. The rollers contain wheels on their end, which rotate in u-shaped troughs. The wheels have small holes that allow light to be shown through by the optical sensor. The speed and patterns of the light pulses sensed by the photo sensor measure the speed and direction of the mouse. The information is then sent to the computer for processing, using the provided mouse software. 

This is the bottom and inside of an opto-mechanical mouse

All material and images on these pages are copyright Joseph,Ed. This page was developed for the Thinkquest1999 competition.