Side-view mirror Laser encounter

**IamDatDude** · 05-02-2007, 07:48 AM

Yesterday I crested over a slight hill and was hit with laser by an HPD officer sitting on the shoulder. Oddly enough he was shooting cars with his laser via his sideview mirror. He was driving a slick-top car so it made it very difficult to see him, especialy since you didn't see anything out of his window.

I believe he was using a Kustom ProLaser III. My question is, how accurate of a reading would he get by using his mirror? His window was down but I would think there would possibly be some error there. He was shooting apprx 300 ft from the crest of the hill so perhaps that mitigates some error.

Another question, would I pick up a laser indication if I'm a 1/4 mi behind a rabbit who is hit with Laser? I apologize if I'm asking something that's already been answered.

**MetalFlame** · 05-02-2007, 08:20 AM

Are you joking!!! This is illegal! Did you see if he was stopping people based on this readings,or was he only fooling around with laser gun?He cant write a ticket based on this readings!Totally ILLEGAL!!!

**IamDatDude** · 05-02-2007, 08:28 AM

Originally Posted by MetalFlame

Are you joking!!! This is illegal! Did you see if he was stopping people based on this readings,or was he only fooling around with laser gun?He cant write a ticket based on this readings!Totally ILLEGAL!!!

I didn't see if he stopped anyone but he was using his mirror...

**bauzer71487** · 05-02-2007, 10:16 AM

Originally Posted by MetalFlame

Are you joking!!! This is illegal! Did you see if he was stopping people based on this readings,or was he only fooling around with laser gun?He cant write a ticket based on this readings!Totally ILLEGAL!!!

It isn't illegal. Worst case scenario it inadmissible in court, but its definitely not illegal.

I actually believe they could do it. What would make it inaccurate? It is firing an infared beam against a mirror at an object he can clearly see. It is taking the times and using the equation of time traveled over distance to get the speed. I would say it is just as accurate as firing at the object itself.

There is absolutely no way that I can think of that would make it A) illegal or B) inaccurate.

**jimbonzzz** · 05-02-2007, 11:41 AM

I've heard multiple accounts of them doing this :?

**kpatz** · 05-02-2007, 12:04 PM

Accurate? How accurately can you aim a lidar gun while pointing it at a tiny rear view mirror? How can you guarantee that whatever speed reading it gets is from the car you see in the mirror? It just adds another variable that can lead to inaccurate readings, especially if the gun is handheld and wobbling a little.

Bouncing a lidar off a mirror would work if the gun is kept stationary, such as on a tripod, but any movement would affect the reflection, especially when a small side-view mirror is used. When aiming directly at cars, you can move the gun up, down, left, or right to keep the car you're clocking in the HUD. When aiming at a mirror, you are limited by the size, angle, and shape of the mirror. What if it's one of those convex mirrors that says "OBJECTS IN MIRROR ARE CLOSER THAN THEY APPEAR?"

**JeepinJeff** · 05-02-2007, 12:11 PM

this could lead to a sneaky way to catch people.

Set up a mirror around a corner while you're out of site, point at the mirror that bounces back to the road of oncoming traffic.

**IamDatDude** · 05-02-2007, 02:04 PM

Originally Posted by bauzer71487

It isn't illegal. Worst case scenario it inadmissible in court, but its definitely not illegal.

I actually believe they could do it. What would make it inaccurate? It is firing an infared beam against a mirror at an object he can clearly see. It is taking the times and using the equation of time traveled over distance to get the speed. I would say it is just as accurate as firing at the object itself.

There is absolutely no way that I can think of that would make it A) illegal or B) inaccurate.

I was just wondering if using a mirror and essentially adding additional variables into the speed measurement could affect the results that the leo would get. As Kpatz stated, sideview mirrors aren't exactly flat nor ideal and I would think that a potential for Cosine error would be introduced.

I'm not that big on physics and I was hoping that, prehaps, Jimbonzzz or some other genius could offer insight. :wink:

**bauzer71487** · 05-02-2007, 09:46 PM

I don't think cosine error would be in affect here, but Jim will know better.

Kpatz is right - it does add a variable - it will add much more variation to the ability to sweep. Move 1" on the mirror is 3-4 feet on the car perhaps - maybe less/more depending on the distance the car is at.

But if its on a tripod - sitting there . . or the officer is deadly steady. I see no reason why it couldn't be used.

Hopefully suf daddy will drop in too. He's a genius of lidar guns.