speedking

Driving along a straight single carriageway (no junctions) at a reasonable speed when I noted a dark Volvo S40 parked up on the opposite verge. As I got closer the driver (inside the car) appeared to lower something from his face, looked like a video camera or possibly a laser speed gun Only one person in the car. No obvious signs it was police, e.g. aerials etc.

Qu. Can laser speed guns operate correctly through windscreens?

Presumably speed camera warning signs not required for this situation?

OllyK

LASER = Light Amplification by the Stimulated Emition of Radiation
in otherwords light - so assuming the tints weren't too heavy it should work just fine

Jen

Yes they can - probably someone (like me! ) from your local council just gathering information, nothing to worry about I would have thought

If we're taking measurements for traffic management studies we don't put out warning signs/wear jackets etc. we tend to hide in cars or it kinda spoils the data collection

Jen

speedking

@OllyK : I was thinking that distortion of the screen might affect the readings as due to shake the beam would be passing through different bits of windscreen during the measuring process? Also the light wouldn't pass through the screen normal to the surface(s) and could be subject to distortion. I guess that the speed of light through the glass would have no effect

No doubt the relevant tests have been done and written into the operating procedures. Just interested really.

Jen do you do this type of work at 10am on a Sunday?

Jen

According to my little handbook it has no effect, but I guess that might just be for my laser gun The only thing it mentions are reflective tints for some reason?!

We do that sort of work at all times - I've been out at 5:30am on a Monday morning, 8:30pm on a Saturday night - all depends what sort of complaint you've recieved or what sort of data you're trying to gather.

IIRC if they have a speed gun they have to have a couple of guys on bikes to stop you then and there anyway...so you should be fine

wrxtankie

Yes they do thats how i got done for speeding 80 kph in a 50 kph i might add.
Two german coppers sat in an un marked mercedes, Would have been just a fine but got done for same offence almost to the day a year before.
Because it was just under a year i got a 1 month ban as well. LOL

Oh well, Doesnt stop me from driving in the rest of europe though. Hee hee

hades

Olly - "light" is a pretty generic term, and certain wavelengths of Laser light well away from the visible spectrum will not pass well through glass. You can get Lasing effects at microwave frequencies, for example, at which frequency glass is not overly transparent (hence glass bits on microwave oven doors don't let you get cooked!)

Unfortunately, IIRC the laser speed guns operate in the near Infra-Red spectrum (as in barely any longer wavelength than visible red light), which sees through glass very nicely.

Kiwi

According to ACPO guidelines for use of laser units they should not be used through glass. If you got caught like this it would be a good defence !!!!

http://www.acpo.police.uk/policies/r...update_v21.pdf

Also quite interesting looking at this document

http://www.acpo.police.uk/policies/Speed_6.doc

Kiwi

speedking

Phew!

Two rubber strips have appeared across the road, so presumably it was a keeno council type working 10am on a Sunday! Hopefully the strips will record that when traffic is busy during the rush hour that speeds are slow, and the only time people go fast is 10 o'clock on a Sunday and 2am when the joyriders are out and about.