Police Camera Van - Windows Closed
Discussion
I don't know for sure but if they could, why would they not always keep the windows closed? Each piece of glass the beam has to pass through will create a reflection and a reduction in the intensity and cohesion of the beam passing through, driving the signal/noise ratio down. If that reflection masks the reflection from the target numberplate, that might prevent the machine from getting an accurate reading or might prevent it getting any reading. It could be that it works just fine through windows but is not approved by the home office for such use. Or it could be that it works fine and is approved for use in such a manner. Hopefully someone will be along in a minute to give us the answer.
This suggests the my first hypothesis is correct.
This suggests the my first hypothesis is correct.
If they work through the space shuttle window, I'm sure it will work through a closed window of a camera van/police car.........
http://www.lasertech.com/blogs/Professional-Measur...
http://www.lasertech.com/blogs/Professional-Measur...
LunarOne said:
I don't know for sure but if they could, why would they not always keep the windows closed? Each piece of glass the beam has to pass through will create a reflection and a reduction in the intensity and cohesion of the beam passing through, driving the signal/noise ratio down. If that reflection masks the reflection from the target numberplate, that might prevent the machine from getting an accurate reading or might prevent it getting any reading. It could be that it works just fine through windows but is not approved by the home office for such use. Or it could be that it works fine and is approved for use in such a manner. Hopefully someone will be along in a minute to give us the answer.
This suggests the my first hypothesis is correct.
Perhaps Paulinus Barnes shoudl stick to law rather than physics as his reasoning is nonsense. He did manage to convince a court and you though so well done to him for that. Doesn't make it right though.This suggests the my first hypothesis is correct.
j4ck100 said:
Does anybody know if they can laser you through shut windows?
Just passed one , wasn't speeding just interested as the windows at the back of the VW transporter were definitely closed shut.
Thanks
Home Office FOI response -Just passed one , wasn't speeding just interested as the windows at the back of the VW transporter were definitely closed shut.
Thanks
"The Home Office does not explicitly prohibit use of laser devices through closed windows or from moving vehicles. Officers, however, are expected to consider the guidance offered in the ACPO document Guide for the operational use of speed and red-light offence detection technology which advises against the use of laser speedmeters through glass or plastic screens, and only describes usage from a fixed point on the side of the road."
ACPO guideline:
"Laser speedmeters must not be used through glass or plastic screens ..."
No doubt the author of the (old) guideline will be along any minute.
tapereel said:
Your answers follow the theme set by your user name.
Paragraph 2 http://www.ukspeedtraps.co.uk/speed1.htmhttps://en.wikipedia.org/wiki/LIDAR_speed_gun
http://www.road-angel.co.uk/page/mobile-laser-guns - "It must be deliberately and carefully aimed, therefore the operator can't be moving. He must have a clear shot, preferably not through glass."
http://www.qebholliswhiteman.co.uk/practice-areas/... - "The beam must not be projected through glass or mirrors but may be used from within a vehicle, so this type could be used by the officer with his/her arm out of the window."
https://www.motorists.org/blog/what-everyone-shoul... - "Proper use means a steady rest, no sweeping or other movement of the gun when taking readings, not shooting through glass or in the midst of a rain storm or snow fall."
Court case:
"Linenhall Chambers’ Paulinus Barnes has won an appeal which could have implications for hundreds of motorists convicted of speeding offences.
The prosecution case collapsed at Mold Crown Court after expert evidence cast doubt on the reliability of laser devices when operated through a car windscreen. Paulinus Barnes said: "The very clear guidance from ACPO, the Association of Chief Police Officers, and from the device manufacturers, is that hand-held laser devices should not be operated through glass. Laser devices calculate the speed of a moving vehicle based on the speed of pulses of light between the device and the object – but the speed of the light pulse is assumed to be the speed through the atmosphere, and not through glass".
In this case the police office accepted that he had directed a laser device at the driver’s car through the windscreen of his police vehicle. The driver’s conviction – and fine of £250 – was quashed by the court at Mold after the prosecution accepted that there were doubts as to speed calculated by the device.
Paulinus Barnes was instructed in the case by MAJ Law Solicitors of Widnes"
I rest my case.
Monty Python said:
tapereel said:
Your answers follow the theme set by your user name.
Paragraph 2 http://www.ukspeedtraps.co.uk/speed1.htmhttps://en.wikipedia.org/wiki/LIDAR_speed_gun
http://www.road-angel.co.uk/page/mobile-laser-guns - "It must be deliberately and carefully aimed, therefore the operator can't be moving. He must have a clear shot, preferably not through glass."
http://www.qebholliswhiteman.co.uk/practice-areas/... - "The beam must not be projected through glass or mirrors but may be used from within a vehicle, so this type could be used by the officer with his/her arm out of the window."
https://www.motorists.org/blog/what-everyone-shoul... - "Proper use means a steady rest, no sweeping or other movement of the gun when taking readings, not shooting through glass or in the midst of a rain storm or snow fall."
Court case:
"Linenhall Chambers’ Paulinus Barnes has won an appeal which could have implications for hundreds of motorists convicted of speeding offences.
The prosecution case collapsed at Mold Crown Court after expert evidence cast doubt on the reliability of laser devices when operated through a car windscreen. Paulinus Barnes said: "The very clear guidance from ACPO, the Association of Chief Police Officers, and from the device manufacturers, is that hand-held laser devices should not be operated through glass. Laser devices calculate the speed of a moving vehicle based on the speed of pulses of light between the device and the object – but the speed of the light pulse is assumed to be the speed through the atmosphere, and not through glass".
In this case the police office accepted that he had directed a laser device at the driver’s car through the windscreen of his police vehicle. The driver’s conviction – and fine of £250 – was quashed by the court at Mold after the prosecution accepted that there were doubts as to speed calculated by the device.
Paulinus Barnes was instructed in the case by MAJ Law Solicitors of Widnes"
I rest my case.
agtlaw said:
j4ck100 said:
Does anybody know if they can laser you through shut windows?
Just passed one , wasn't speeding just interested as the windows at the back of the VW transporter were definitely closed shut.
Thanks
Home Office FOI response -Just passed one , wasn't speeding just interested as the windows at the back of the VW transporter were definitely closed shut.
Thanks
"The Home Office does not explicitly prohibit use of laser devices through closed windows or from moving vehicles. Officers, however, are expected to consider the guidance offered in the ACPO document Guide for the operational use of speed and red-light offence detection technology which advises against the use of laser speedmeters through glass or plastic screens, and only describes usage from a fixed point on the side of the road."
ACPO guideline:
"Laser speedmeters must not be used through glass or plastic screens ..."
No doubt the author of the (old) guideline will be along any minute.
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