Check this link out before you are convinced
Clicky
The show was very interesting. Used the gun to show a building doing 40mph and a vehicle known to be doing 20mph as doing 40 mph, which was the speed of a vehicle overtaing it. Also problems when the red dot moves from the cars windscreen down the bonnet.
Yes, all of those things can actually happen when the Lidar isn't used properly. But, I can say this about pretty much everything in the world! When you skew the settings of just about anything, you can get it to malfunction or function in a way it wasn't designed.
The FIRST thing that is required when using a Lidar unit that alleviates ALL of the claims on that show is sight and unit testing. Turn it on, complete the self diagnostics, and then go through the steps to insure it is working properly. Those steps include taking a reading of an object at a known distance and verifying that the Lidar is obtaining the same distance. This insures that the pulses and reading of said pulses are working. In our department, every precinct has an area that is marked and measured for this purpose. The officer takes the Lidar, stands on the mark, aims at the wall or object at the other end of the 150' or farther end and gets a reading of 0mph. Then he checks the distance and verifies it is the same as the marked off object. Next, he checks the sighting mechanism (the most common thing to cause errors). The officer puts the unit into test mode, finds a reflective surface 150' or farther, then depresses the trigger while looking through the scope. The officer then strafes across the reflective surface (usually a street or stop sign), and the moment the visual indicator (dot) transitions from not hitting the reflective surface to hitting the reflective surface, the audible tone will change dramatically. The officer must do this side to side and up and down. If the audible tone changes at the moment the sighting dot transitions, this insures that the sighting dot and the laser are in fact pointed at the same object.
Then, at the end of shift, if the officer has written any tickets, he has to do it again at the end of shift (or in our case, at the beginning of the next shift since many Lidars are issued). Any errors found will cause the tickets issued between the two checked times to be voided.
Once all of this is done, there is no error with a laser.
But, that is also only part of the equation. EVERY ticket I have ever written with a Lidar (and we're talking thousands over the years), I watched the vehicle speeding, made a mental note of my perception of it's speed, and then used the Lidar to confirm my visual estimation. For anyone that's ever been on a ride along with me, they'll tell you, I am never off by more than 1-2mph in my visual estimation. The reason for this isn't because I'm a good estimate of speed in all circumstances, but because I used to sit in the same areas and the experience that came as a result.
