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How Laser works
LASER stands for Light Amplication by Stimulated Emission of Radiation
The laser speed gun uses a method that relies on the reection time of light. You have probably experienced the reection time of
sound waves in the form of an echo. For example, if you shout down a well or across a canyon, the sound takes a noticeable amount
of time to reach the bottom of the well and travel back to your ear. Sound travels at approximately 1,000 feet (300 meters) per
second, so a deep well or a wide canyon creates a very apparent round-trip time for the sound.
A laser speed gun measures the round-trip time for light to reach a car and reect back. Light from a laser speed gun moves a lot
faster than sound --about 984,000,000 feet per second (300,000,000 meters) or roughly 1 foot (30 cm) per nanosecond. A laser speed
gun shoots a very short burst of infrared laser light and then waits for it to reect o the vehicle. The gun counts the number of
nanoseconds it takes for the round trip, and by dividing by 2 it can calculate the distance to the car. If the gun takes 1,000 samples
per second, it can compare the change in distance between samples and calculate the speed of the car. By taking several hundred
samples over the course of a third of a second or so, the accuracy can be very high.
The advantage of a laser speed gun is that the size of the “cone” of light that the gun emits is very small, even at a range like 1,000 feet
(300 meters). The cone at this distance might be 3 feet (1 meter) in diameter. This allows the gun to target a specic vehicle. A laser
speed gun is also very accurate. The ocer has to aim the laser speed gun at a specic target therefore the ocer will only target
your vehicle if the ocer deems that you are speeding.
How Does Police Laser (LIDAR) Work?
LIDAR is an acronym for Light Distance And Ranging. A LIDAR gun emits a highly focused beam of invisible light, in the near
infrared region of light that is centered at 904nm of wavelength and is only about 22 inches (56cm) in diameter at 1000 feet (300m).
Unlike RADAR which directly determines a vehicle’s speed by measuring its Doppler shift, LIDAR calculates speed by observing the
changing amount of time is takes to “see” reected pulses of light over a discreet amount of time.
Radar Alerts
The 4ZERO Elite BT has been designed to detect a number of dierent radar bands including K, Ka, Ku and X band. When the unit
detects one of these three frequencies the display will show the radar band type plus display the signal strength. As you drive closer
to the signal the unit will beep faster and the display will indicate that you are getting closer by displaying a series of signal strength
blocks.
4Zero Elite BT V1.0 EN 05/18
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