October 13, 2021

About speed measurements with laser ("laser gun")

Laser measurements are very popular, in particular the so-called laser guns used by the police are known to many drivers. If the speed is increased, you will be waved immediately after the measurement and confronted directly by the police with the speeding violation. With this speed measurement there is no photo that is later sent to the driver.

Principle of laser measurement

With a laser, incoming and outgoing traffic can be checked up to a distance of around 300m and more. The laser measuring device, the "laser gun", is operated by hand or on a tripod. Invisible light pulses are emitted, which reflect the license plate. The speed is calculated from the duration of these impulses. For a valid measurement, the front of the car, usually the license plate, must be aimed at with the aid of a laser gun sight. Measurements through car windows are not permitted. In some countries, e.g. France, such lasr measurement is also done from the rear. Then, the police will follow the car and stop it.

Invalid laser measurements

If not all the laser signals emitted are received as reflections without interference, for example because of a heavily soiled car, the laser gun automatically stops the measuring. This also applies if individual signals are outside the tolerance, for example due to jamming.

Since no photo is taken with the laser, the vehicle must be stopped immediately after the measurement in order to log the driver and car data in addition to the measured speed.

If the measured car emits its own laser light waves, this can lead to overlapping so that the laser gun cannot clearly assign the reflection. The speed measurement does not lead to any result, it is jammed.

Warning and / or jamming of laser measurements

Laser measurements are used in Germany and are also very popular across Europe. An ideal protection solution is the complete prevention of a laser speed  measurement by using a laser jammer (e.g. Stinger Freedom Laser or, as an extension of a fixed installation system like the Stinger VIP radar detector).

Mobile radar detectors with laser warnings can register any laser signals at the moment of measurement and thus also warn optically and acoustically. However, since there is no active jamming of the laser, the speed measurement has usually already taken place and is finished before the driver can reduce the speed.

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Also in Radardetector and Laserjammer - FAQ