How does a RD detect laser though glass?

[Mavrik]

I keep reading that in order to use a laser speed gun can't be used thought glass. If laser can't go though glass, how does a RD detect it?

[9500ier]

I am not a scientist, but how do you see through glass?


Just think about light, you can see the stuff outside of your car when the light is shinning in, just like your RD can see the laser. If you try to shine a flashlight through your windshield at night, you cannot see much better because the reflected light is blinding you from what is now lit up outside the car.

Do we have a scientist that can confirm this?

[corkguykev]

i have had no problems clocking cars with my marksman through the windshield. if i remember correctly i was able to get a rear hit on a car that had passed by at over 850 feet.

it does reduce the range severely though but it doesnt stop it from working altogether.

the only thing i have seen that completely blinds a LIDAR gun (other than a jammer) is fog. no readings whatsoever even up close but then again you cant speed in fog either

[9500ier]

I was thinking it makes it more unreliable in court, rather than impossible. Who's to say the cop wont lie though. Maybe when you went flying past him he didn't have time to get the window down, but he knows you were speeding...

[jimbonzzz]

Laser can be used through glass, in fact it is mentioned in some of the operators manuals. For example, Kustom recommends that if you must use the Prolaser III through glass, to target through a side window instead of the windshield, because the oblique angle of the windshield will cause the greatest performance reduction, and some windshields have coatings that block a lot of the infrared. LTI recommends using the weather filter when shooting through the windshield, and shooting through the center if the windshield is "bubble-shaped".

Jim

[9500ier]

In NC, IF I REMEMBER CORRECTLY, the law stated that you had to use under 1000feet (or was it yards?), not through glass, not in rain, and not in fog. I guess I need to read up on Florida's laws... if they have any addressing this matter.

[Zapple]

In NC, IF I REMEMBER CORRECTLY, the law stated that you had to use under 1000feet (or was it yards?), not through glass, not in rain, and not in fog. I guess I need to read up on Florida's laws... if they have any addressing this matter.

Interesting... I would like to know Florida's stance on this as well.

[9500ier]

This is only about distance in FL...



15B-2.014 Minimum Design Criteria for Laser Speed Measurement Devices.


[I skipped a lot because this is really long]

(2) Beginning June 30, 2004, all new LSMD’s sold in the state of Florida must meet all requirements of this chapter and:
(a) The Model Minimum Performance Specifications for Lidar Speed Measurement Devices, July 1, 2001, NHTSA document #DOT HS 809 239, which is incorporated by reference. This document is available by contacting the Office of Law Enforcement Standards, c/o National Institute of Standards and Technology, 100 Bureau Drive, Stop 8102, Gaithersburg, Maryland 20899-08102.
(b) Shall be restricted to reading vehicle speeds at a distance not greater than 3000 feet.
Specific Authority 316.1905 FS. Law Implemented 316.1905, 316.1906 FS. History–New 10-18-94, Amended 5-23-04.


So, what are the chances of LEOs using Lidar guns made before 6-30-2004... ?? I have no idea, but I think if you are targeted at a distance that greater than 3000 feet, you have a pretty strong argument in court based on this law and that of most other states.

You can read a lot more here about FL "speed measuring devices":

https://www.flrules.org/gateway/Chap...?Chapter=15B-2

I will keep looking for FL law about shooting laser through glass...

[9500ier]

Someone should ask this question on yahoo answers and see what kind of responses we get...

"Can LEOs in FL use Lidar through glass for speed enforcement?"

[Zapple]

Someone should ask this question on yahoo answers and see what kind of responses we get...

"Can LEOs in FL use Lidar through glass for speed enforcement?"

I'm sure we would get some pretty funny answers from people that have no idea what we are asking.