A laser jammer is an electronic device used by drivers to prevent users of a LIDAR (or 'laser) gun from obtaining speed readings of their vehicle. Laser jammers are not to be confused with radar jammers.
To jam LIDAR, laser jammers first must detect the emitted light - normally infrared light on the 904 nm wavelength. After detecting the lidar gun's light, the jammer will send out light on the same wavelength at a higher intensity, effectively confusing the gun into returning no speed reading. Newer laser jammer models can detect the pulse rate (the rate at which the gun takes distance measurements, upon which it bases the speed measurement) of the laser gun, and then emulate that pulse rate, further increasing the difficulty of getting an accurate reading from the laser gun.
Because these jammers focus on blocking light emitted from laser guns, and not radio waves from radar guns, US federal laws prohibiting the use of radar jammers do not apply to these devices. While the U.S. Federal Communications Commission regulates transmission of radio waves, the U.S. Food and Drug Administration regulates light emissions. However, several states have passed laws that specifically prohibit the use of laser jammers, including: California, Colorado, Illinois, Minnesota, South Carolina, Tennessee, Texas, Utah, and Virginia. The legality of laser jammers in Nebraska and Washington, D.C. is disputed.
Laser jammers for civilian use have evolved in recent years. The first laser jammer ever produced was by K40 Electronics in April 1994, known as the K40 Laser Defuser. Next came the Lidatek LE-10 Laser Echo by Lidatek LLC, then the Blinder M06 HP by blinder.dk, then the Blinder M10 Twin, then the LE-20 to LE-30. Blinder remade the M10 Twin into the smarter M20 X-treme series. Laser diode based jammers came out in 2006, known as the Anti-Laser, Laser Pro Park, and Privacy-Plate is using the newest technology that only jams and does not safeguard privacy by blocking IR cameras from performing Image Recognition on a vehicle's license plate. Most cameras take 1 photo with normal light and 1 with IR light.