Ophir Photonics Blog
Laser Power & Energy Meters

Calibration for Cops

As more and more people try to fight speeding tickets by claiming the police LIDAR guns are not precise, it has become necessary to have a high standard of calibration for police speed guns.  These speed guns emit a low power pulsed laser beam which bounces off the target and returns to the gun’s sensor.

It is of the utmost importance that the laser used in the speed gun has been calibrated.  That way, when challenged in court, a law enforcement officer can produce the calibration certificate, clearing away any suspicions about the device’s accuracy.

There is just one hitch.  When measuring low power laser beams, a photodiode sensor is the obvious choice.  However, photodiodes have a relatively quick response time.  Usually this is an advantage, but when trying to measure the average power of a pulsed beam, a fast response time will see each pulse and fluctuate rapidly.  This can make it difficult to get an accurate reading and the speeder will point to this difficulty as a flaw in the police equipment.

The most obvious solution would be to use a low power thermal sensor, which would automatically smooth out the reading, since it has a slow response time.  Thermal sensors are more expensive though, and it seems almost unfair that a photodiode sensor can’t be used even though we’re dealing with a low power laser.

The truth is that a photodiode sensor can be used here.  What about the fluctuations in the reading?  Since Ophir’s sensors use a digital output, it is quite easy to have the electronics average the signal.  So it turns out that a photodiode sensor really is the cheap, easy, and accurate answer that we were looking for all along.  Ophir OEM Solutions prides itself on finding the best sensor for any application.

Now the police officers can sleep easy, knowing that they won’t be publically humiliated in court – uhh, I mean, knowing that justice will be upheld.

Read more from a different point of view – can you really slip out of paying a speeding ticket?


You might also like to read:

 Can you really get away from paying a fine by claiming the police lidar meter was incorrect?

Laser Power Meter Usage in Law Enforcement



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