Newer speed detection devices use pulsed laser light, commonly referred to as LIDAR, rather than radio waves. Radar detectors, which detect radio transmissions, are unable to detect the infrared light emitted by LIDAR guns, so a different type of device called a LIDAR detector is required. However, LIDAR detection is not nearly as effective as radar detection because the output beam is very focused. While radar's radio waves can expand to across at from their source, LIDAR's light beam diffuses to only about . A police officer targeting a car will most likely aim for the center mass or headlight of the vehicle and, because radar detectors are mounted on the windshield away from the beam's aim, they may not alert at all. With such a focused beam, an officer using a LIDAR gun can target a single car in close proximity to others at ranges of up to . This has resulted in some manufacturers producing LIDAR jammers. Unlike those of radar, LIDAR's frequencies and use are not controlled by the FCC. These jammers attempt to confuse police LIDAR into showing no speed on the display. They are often successful, and therefore many LIDAR manufacturers produce LIDAR guns that have "jam codes" that show when they are being jammed. They will work against some LIDAR jammers, but not all. In spite of this, police can often tell when they are being jammed when they see no reading on their LIDAR gun. Many jammer-equipped motorists try to counter this by reducing their speed to legal limits before turning off their jammer equipment, a technique known as "kill the equipment", referred to as "JTK" or "Jam to Kill." Officers can often detect this by observing that their LIDAR equipment is unable to lock in a speed properly, along with visual indication of sudden deceleration of the targeted vehicle. They will then pull the offending vehicle over and look for LIDAR jammers on the front of the vehicle, potentially ticketing the motorist with an obstruction of justice charge. Some states also have laws against jamming of police radar or LIDAR: California, Colorado, Illinois, Iowa, Minnesota, Oklahoma, South Carolina, Tennessee, Texas, Utah and Virginia. In these states, the penalties can be severe.
