radar detectors

**wkid_one** · 25th May 2004, 18:07

Paint your bike in the paint used for the Stealth Aircraft - that will sort'm out.

**marty** · 25th May 2004, 18:47

sorry k14, but i just can't see it. cops target the number plate regardless, so how do CD's help you at all?

i'm just doing an experiment to see how it works

**marty** · 25th May 2004, 19:10

here's a little test i have just done. i placed a CD and an ABS plastic item next to each other.

i pointed a laser light at both, one at a time.

the laser was obvious on the black ABS, but it did not reflect back in my eyes.

when projected onto the CD though, when the light was relflected, it was as strong, if not stronger than looking into the original laser.

i tried to take photos of it, but without a tripod it was difficult. you can see the glare off the CD though, the red dot just looks bright on the black.

the red dot on the ceiling is the reflected light off the CD, on the wall behind me. There is a cresent shaped reflection on the ceiling at about the 2 o'clock position, which must be reflecting off the curve of the CD.

from what i see i reckon that CD's actually ENHANCE the laser reflection back to it's source, and also spreads it around, so that others with laser detectors can pick it up.

yes i'm bored....

**k14** · 25th May 2004, 20:05

Originally Posted by marty

sorry k14, but i just can't see it. cops target the number plate regardless, so how do CD's help you at all?

i'm just doing an experiment to see how it works

I never said that they help me and I never said that they would help you, I just objected to someone saying that it never works. I have no idea how accurate the aiming mechanism on the laser guns are and how they work, I was just saying that if the laser beam hit the CD dead on then it would make the gun not get a speed reading. The chances of that happening are pretty slim.

Don't worry marty, I have done lots of experiments along those lines, in labs with proper equipment and know what happens. Actually today's physics lecture was about Fraunhofer diffraction, which is what this is a case of.

I don't want to step on your toes and I know absolutely nothing about how to use the laser guns etc, but I am just explaining some simple (to me) physics.

**spudchucka** · 25th May 2004, 20:39

Originally Posted by marty

sorry k14, but i just can't see it. cops target the number plate regardless, so how do CD's help you at all?

This one really cracks me up. I'll be looking for CD's on the grill from now on, if only to have a laugh to myself.

**wkid_one** · 25th May 2004, 21:38

Originally Posted by marty

when projected onto the CD though, when the light was relflected, it was as strong, if not stronger than looking into the original laser.

Now there is a super intelligent thing to do.....

**scumdog** · 25th May 2004, 22:05

Originally Posted by marty

sorry k14, but i just can't see it. cops target the number plate regardless, so how do CD's help you at all?

i'm just doing an experiment to see how it works

Dead right! at 200 metres or so there is no way you can "aim" the laser gun at just one piece of the car as it comes towards you, have a look at one, it only has a pretty crude sighting system and even if you had ten c.d.'s across the front of your car it would only equal a small fraction of the total frontal area. :disapint:

**Jackrat** · 25th May 2004, 22:17

Originally Posted by k14

I never said that they help me and I never said that they would help you, I just objected to someone saying that it never works. I have no idea how accurate the aiming mechanism on the laser guns are and how they work, I was just saying that if the laser beam hit the CD dead on then it would make the gun not get a speed reading. The chances of that happening are pretty slim.

Don't worry marty, I have done lots of experiments along those lines, in labs with proper equipment and know what happens. Actually today's physics lecture was about Fraunhofer diffraction, which is what this is a case of.

I don't want to step on your toes and I know absolutely nothing about how to use the laser guns etc, but I am just explaining some simple (to me) physics.

Here's some more simple physics for you.
NOTHING reflects light at a greater strengh than the original source.
If there was anything in it at all we would all be riding or driving vehicules painted flat white because it has the greatest reflectivity of all.

**k14** · 25th May 2004, 22:24

Originally Posted by Jackrat

Here's some more simple physics for you.
NOTHING reflects light at a greater strengh than the original source.
If there was anything in it at all we would all be riding or driving vehicules painted flat white because it has the greatest reflectivity of all.

I never said that it did, that was marty. You can't get something from nothing, so next time you quote get the right quote

**Jackrat** · 25th May 2004, 22:27

Originally Posted by k14

I never said that it did, that was marty. You can't get something from nothing, so next time you quote get the right quote

Does it matter.
I found your statment interesting.
NOTHING ELSE.

**marty** · 25th May 2004, 22:31

Originally Posted by wkid_one

Now there is a super intelligent thing to do.....

it's amzing how slow one moves after a couple of jack danielssssss

**wkid_one** · 25th May 2004, 22:49

Originally Posted by marty

i tried to take photos of it, but without a tripod it was difficult.

Yes - Photographing stationary objects can be quite tricky at times!

Right. Now come on Marty - we are all dying to know.......how fast WAS the CD travelling in your living room? And will you ticket it?

**Lou Girardin** · 26th May 2004, 07:06

Cops target the number plate or headlight as they are the best reflectors. US tests showed that black TransAms and Camaros were the hardest cars to get a reading on. Retracted headlights, sloping fronts and no reg plates. red cars are easiest, they're called ticket red. Bikes are also difficult at times, especially at long range with high beam on. There is enough IR transmitted to slow the laser processor. Bikes are also difficult to target, a cop at Paeroa races was struggling to stay on target as they came around the kink at around 220 km/h at about 400m range.
CD's on your dash are about as effective as tinfoil in your hubcaps was against radar.

**Racey Rider** · 26th May 2004, 08:16

Originally Posted by Racey Rider

Are we allowed to have our headlights covered while riding during the day?
As this would further reduce the return signal.

Originally Posted by marty

only if you ride a katana. or drive an MX5, and only girls drive MX5's

Can you tell me the relevant law that says no?

**marty** · 26th May 2004, 08:54

Originally Posted by wkid_one

Yes - Photographing stationary objects can be quite tricky at times!

Right. Now come on Marty - we are all dying to know.......how fast WAS the CD travelling in your living room? And will you ticket it?

the CD was stationary - it was me having trouble standing still...

and it was a CD of Moto Rider........