The History of the Mouse
Nobody clearly knows, who invented the mouse. One of the concepts was developed by Douglas Engelbart at the Stanford Research Institute back in the early sixties. The Engelbart's mouse utilized two wheels located perpendicular to each other. The device could naturally move either horizontally or vertically and probably was not a thing that was comfortable to use. Another concept was invented by the company called Telefunken, which actually used a ball instead of two wheels. The company based in Germany shipped its mouse with its computers eventually. But the very early mice did not become mass products simply because there were not a lot of personal computers with graphics user interfaces (GUI).
Computer mice as we know them started to emerge with PCs made by Apple and Xerox, which had GUI. Those pointing devices used a ball coupled with two wheels and two sensors. As the ball rolled, the wheels also did and sensors could detect the direction and speed of rolling using infrared beams, then a special chip converted that information into X and Y vectors. The mechanical mice were inexpensive and easy to manufacture and given that display resolutions were not high, those products survived the eighties and the nineties.
Xerox Alto mouse. Image by Digibarn web-site.
But mechanical mice did not behave well in case of high resolutions, they also continuously collected dirt from the surface and had a number of other drawbacks. As a result, the optical mouse was born. In fact, although the first prototypes of optical mice were shown back in the eighties, they were expensive to manufacture and only worked on certain surfaces. The first commercial optical mice from companies like Logitech and Microsoft emerged in early 2000s.
Optical mice use LED image sensors that detect motions based on offset of the surface's texture from the previous position. The sensors "check" the offsets for over a thousand of times per second, thus, they can detect even a tiny move. Naturally, the higher resolution the sensor can scan, the more sensitive mouse is. Usually, manufacturers of mice use dots per inch (DPI) measure of spatial dot density to mark mice with higher or lower LED sensitivity. While optical mice were generally much better than mechanical mice, they did not work well on all types of surfaces. Laser mice generally fixed the issue and the latest generation laser mice can even work on glass surface.
Throughout its evolution, mice not only obtained scrolling wheels, but they also got programmable buttons, abilities to regulate weighs and many other features that could not be imagined just fifteen years ago.
But the evolution of the mouse does not stop on new sensors or lasers. Apple installed a multi-touch surface onto its Magic mouse and companies like Gyration and Logitech installed gyrascopes into their models to enable motion sensing. But let's think, do we really need motion-sensing mice?