Camera Mouse...!

Yeah.. no kidding... there is a camera inside the optical mouse. This is not a very comprehensive one. It is just a CMOS sensor (CMOS sensors are actually being used in inexpensive(?) cameras) which sends images to digital signal processor (DSP) for analysis. This DSP then analyses the image and identifies the patterns in the image to compare it with previous images. Based on the change in patterns, the DSP determines how far the mouse has moved and sends the corresponding coordinates to the computer. Pretty cool huh...