As in an optical mouse?
Here is an semi-article on Optical versus mechanical mice
The Logitech iFeel optical mouse uses a red LED to project light onto the tracking surface.
Unlike mechanical mice, which can become clogged with lint, optical mice have no rolling parts; therefore, they do not require maintenance other than removing debris that might collect under the light emitter. However, they generally cannot track on glossy and transparent surfaces, including some mouse-pads, sometimes causing the cursor to drift unpredictably during operation. Mice with less image-processing power also have problems tracking fast movement, though high-end mice can track at 2 m/s (80 inches per second) and faster.
Some models of laser mice can track on glossy and transparent surfaces, and have a much higher sensitivity than either their mechanical or optical counterparts. Such models of laser mice cost more than LED based or mechanical mice.
As of 2006, mechanical mice have lower average power demands than their optical counterparts. This typically has no practical impact for users of cabled mice (except possibly those used with battery-powered computers, such as notebook models), but has an impact on battery-powered wireless models.
Optical models will outperform mechanical mice on uneven, slick, soft, sticky, or loose surfaces, and generally in mobile situations lacking mouse pads. Because optical mice render movement based on an image which the LED illuminates, use with multi-colored mouse pads may result in unreliable performance; however, laser mice do not suffer these problems and will track on such surfaces. The advent of affordable high-speed, low-resolution cameras and the integrated logic in optical mice provides an ideal laboratory for experimentation on next-generation input-devices. Experimenters can obtain low-cost components simply by taking apart a working mouse and changing the optics or by writing new software.
