Hot Spot is an image sensing system which makes use of infra-red cameras to find out if the batsman has nicked the ball. This technology was first introduced in cricket by a Melbourne based company, BBG Sports. Although two infrared cameras are enough, generally four infrared cameras are used to record the game continuously. The Hot Spot technology was originally founded by a French scientist Nicholas Bion. It uses the technology developed for tracking military tanks and fighter jets.
The basic principle is the thermal wave remote sensing. When the ball or bat makes contact with the bat, pad, or the batsman, friction is generated. This friction causes heat, the temperature change is detected by the infrared imaging camera system. And that is how the contact zone is detected. Any suspected snick or bat/pad event can be verified by examining the infrared image. This technology was first used in 2006 during the Ashes in Australia.