Optical Mouse Saves Space in Cellphones

Chris writes "Researchers at Philips have integrated a space-saving optical mouse into a mobile phone for the first time. Dutch researchers at the Philips Center for Industrial Technology have developed a compact, optical interface for portable electronic equipment. The team says that its new input gadget can be easily integrated in cellphones, laptops and PDAs, providing an space-efficient alternative to a mechanical trackball or touch-pad for example. The device is made up of a low-power red laser diode and a detector placed beneath a lens. Light from the 650 nm laser is focused on an object, such as a fingertip, creating an external cavity. It is not necessary to touch the lens. A small portion of this light is then reflected back and mixes with the light within the internal laser cavity."