Difference Between Radar and Lidar Explained

by mphippen 15. May 2013 13:25

Everyone involved in traffic enforcement have no doubt heard the term "Laser Radar" used in reference to LIDAR speed enforcement. In actuality, LIDAR is far more target selective than RADAR.

It's quite the quandary that some 25 years later this contradictory reference is still being used in the field. I thought that for the record, to discuss the primary differences between RADAR and LIDAR technologies as they apply to speed enforcement was in order.

Then as if scripted, the Colorado Springs Police Department purchased a number of LTI Lasers and a local TV Station picked up the news and ran a feature story explaining the difference so we've included the news story to punctuate the difference.

Laser Speed Guns and their Technology
KOAA-TV in Colorado - 4-26-2013


Like many things associated with physics or science RADAR is an acronym meaning RAdio Detection And Ranging. Today RADAR is used for many things other than speed enforcement. Air traffic control, radar astronomy, air-defense systems, antimissile systems; aircraft anti-collision systems; ocean surveillance systems, outer space surveillance; meteorological precipitation monitoring; altimetry and flight control systems; guided missile target locating systems; and ground-penetrating radar for geological observations to name a few.

"Before the Second World War, researchers in France, Germany, Italy, Japan, the Netherlands, the Soviet Union, the United Kingdom, and the United States, independently and in great secrecy, developed technologies that led to the modern version of radar. Australia, Canada, New Zealand, and South Africa followed prewar Great Britain, and Hungary had similar developments during the war. But the first pulse RADAR system and apparatus is largely credited to the American Robert Page while working at the U.S. Naval research Lab in 1934.

The first police RADAR gun came from Bryce K. Brown of Decatur Electronics in March 1954. Utilizing the Doppler Effect, he measured the speed of cars by pointing the antenna in the general direction of either an oncoming or departing vehicle. Given the radio transmit frequency and the returning signal frequency are different a time over distance calculation could be made to measure speed. However, one of the disadvantages of RADAR is the unit’s beam divergence or width.” At 1,000 feet down range the average RADAR unit will have a divergence of 250 feet. Those vehicles equipped with a RADAR detector traveling behind the targeted vehicle are tipped off well in advance.


Light Detection and Ranging is yet another acronym to describe the technology used in LTI’s family of Lasers. Specifically pulse laser detection sends out a predetermined series of light pulses with a known time interval between each pulse to a target. Through an averaging process once again a time over distance calculation is able to measure the time of flight between the transmit and receive sensors resulting in an accurate speed and range.

"On March 24, 1959, Charles Townes and Arthur Schawlow were granted a patent for the maser. The maser was used to amplify radio signals and as an ultrasensitive detector for space research.

In 1958, Charles Townes and Arthur Schawlow theorized and published papers about a visible laser, an invention that would use infrared and/or visible spectrum light; however, they did not proceed with any research at the time."

Jeremy Dunn of Laser Technology Inc., developed the first police LIDAR unit in 1989 and revolutionized speed enforcement. With a beam divergence of 3 feet at 1,000 feet downrange, for the first time law enforcement was able to aim through a scope to select the suspect speeding car and secure an accurate speed regardless of its position in traffic. Subsequent LIDAR applications go well beyond simple speed and range. NASA utilized a specially designed LIDAR for all space docking missions. Laser tree height and width applications have totally changed the way Forestry is done. Blast profiling, GPS-laser off sets, Vegetation management, power line sag, construction, industrial sensors, golf, hunting, and many military operations now utilize this important technology.

So please do me a favor. The next time you hear someone describe LIDAR speed enforcement as LASER – RADAR politely remind them it's either RADAR OR LIDAR but certainly not both.

If you’ve not had the opportunity to test drive LTI's latest laser speed guns such as the TruSpeed series or the TruCAM, please call 1.800.OWN.A.LTI or email us for a practical demonstration.

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