An optical mouse pad is, quite simply, a mouse pad that has been optimized to work well with an optical mouse. The differences between how an optical mouse and a traditional mouse work are pretty significant. For this reason, they have different needs as far as the qualities in a mouse pad.
The traditional ball and mouse setup made its appearance in the 1970s. It was introduced as a pointing device to interface with the computer and is usually represented onscreen as an arrow. It functions by detecting motion on a two-dimensional plane, when guided across the top of a cloth or plastic mouse pad. The ball sits inside the mouse but is partially exposed in order to contact the mouse pad. The mouse houses two perpendicular rollers pressed up against the rubber mouse ball. One roller registers vertical motion, the other horizontal. When the rollers move in response to the mouse ball, signals are sent to the computer that adjust the arrow's onscreen position on the X and Y axes.
One of the downsides of the mechanical mouse design is that the ball is exposed to dust and grime on the underside. Lint can be picked up by the ball and impede the rollers from properly registering mouse movement, which is reflected onscreen by erratic arrow movement. Periodically, users will have to remove the mouse ball and clean it as well as the rollers to restore smooth response.
Heeding the complaints of consumers, the optical mouse no longer relied on a ball and rollers to detect motion, replacing them instead with a light-emitting diode or infrared diode and photodiodes. In the earliest days, this new technology needed a specialized optical mouse pad with a reflective face. Grid lines were printed with infrared absorbing ink on a metallic surface. The computer could then track motion by calculating the mouse's speed and direction over the grid lines.
A modern optical mouse doesn't require a specialized optical mouse pad. Equipped with an image-processing chip, an optical mouse essentially uses a camera to take successive pictures of the mouse pad surface. Frame by frame changes are processed and translated to onscreen movement. An optical mouse can even function without a mouse pad. Conversely, the friction of a traditional mouse pad is essential for using a mechanical ball and mouse.
Although an optical mouse can be used on a wide variety of surfaces, it may have problems registering motion over glossy or transparent surfaces. Avoid optical mouse pads that are transparent, translucent, or reflective. Some manufacturers claim a hexagonal pattern enhances motion tracking. PC gamers who seek out great response time, speed, and sensitivity will value an optical mouse pad with a wide surface area that offers smooth gliding. A good pad is made of durable plastic with a rubberized nonslip bottom that grips the desktop. These features may also help extend battery life in wireless optical mice. Cloth pads are not recommended because snags may develop that can hinder smooth movement.