Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers
Buy Site Supporter Role (remove some ads) | LPF Donations
Links below open in new window
FrozenGate by Avery
Can you channel laser light with fiber optic cable?
- Thread starter LanceLink
- Start date
NO4H99
0
- Joined
- Sep 9, 2013
- Messages
- 552
- Points
- 0
Absolutely. When the laser comes out the other end, however, it won't be collimated any more. The fiber optic cable just channels the diffuse reflections to the other end, with minimum (close to zero) loss of light due to refraction.
NO4H99
0
- Joined
- Sep 9, 2013
- Messages
- 552
- Points
- 0
Are you asking if it will be precisely the same wavelength, or very close? I should be within about 1nm or so of the original wavelength - if not less. (just depends on possible imperfections in your FO cable, etc.)
OK, this is what I'm getting at. I have a radar/lasere detector that I'm mounting behind my bumper. The bumper is plastic, so it poses only minor loss of radar detection abilities. The laser detection is kaput though. I was thinking I could run a f/o cable from a spot near the license plate - which is where they usually aim - to the part of the detector that looks for the laser from the tax collector. Their laser is 904nm if that tells you anything.
SKeeZ
0
- Joined
- Sep 2, 2013
- Messages
- 463
- Points
- 28
Noah hit it on the head, you wont get a nice collimated beam/dot but it will preserve almost all the light you channel into it.
- Joined
- Jan 13, 2010
- Messages
- 2,516
- Points
- 63
Can you maintain the wavelength? Sure can. I wish you could change the wavelength with a fiber. So 904nm in is 904nm out.
Though you won't be able to "channel" a laser beam from a radar gun. The problem is that the radar gun isn't much of a laser beam. It's more of a flashlight. I'm not sure if you have ever seen a fiber optic cable before but some of them are as small as a human hair and even smaller. Theres no way you will be able to collect all the light from the radar gun and redirect it.
To get an idea what I'm saying, try redirecting the light from a flashlight through your fiber. You may notice that some light does go into the fiber but you have 99.9% of the light just shining in the direction of where you are pointing the flashlight.
You "could" focus the light into the fiber with a lens but there is no way you will ever be able to redirect the light of a radar gun with a fiber. Just not gonna happen. Especially when you include all of the variables of human error and even worse, moving targets.
Though you won't be able to "channel" a laser beam from a radar gun. The problem is that the radar gun isn't much of a laser beam. It's more of a flashlight. I'm not sure if you have ever seen a fiber optic cable before but some of them are as small as a human hair and even smaller. Theres no way you will be able to collect all the light from the radar gun and redirect it.
To get an idea what I'm saying, try redirecting the light from a flashlight through your fiber. You may notice that some light does go into the fiber but you have 99.9% of the light just shining in the direction of where you are pointing the flashlight.
You "could" focus the light into the fiber with a lens but there is no way you will ever be able to redirect the light of a radar gun with a fiber. Just not gonna happen. Especially when you include all of the variables of human error and even worse, moving targets.
Last edited:
The radar is not concentrated, but from what I gather, the laser is such that they have to truly aim it at your car to get a reading.
"LIDAR is an acronym for LIght Detection And Ranging. A police laser emits a highly focused beam of invisible light, in the near infrared region of light, that is centered at 904nm of wavelength and is only about 22 inches (56cm) in diameter at 1000 feet (300m). Unlike police RADAR which directly determines a vehicle's speed by measuring its doppler shift, police laser-lidar calculates speed by observing the changing amount of time is takes to "see" reflected pulses of light over a discreet amount of time."
Given that the gun measures reflected light, is it possible that an amount traveling through the f/o cable is enough tor trigger the detector?
"LIDAR is an acronym for LIght Detection And Ranging. A police laser emits a highly focused beam of invisible light, in the near infrared region of light, that is centered at 904nm of wavelength and is only about 22 inches (56cm) in diameter at 1000 feet (300m). Unlike police RADAR which directly determines a vehicle's speed by measuring its doppler shift, police laser-lidar calculates speed by observing the changing amount of time is takes to "see" reflected pulses of light over a discreet amount of time."
Given that the gun measures reflected light, is it possible that an amount traveling through the f/o cable is enough tor trigger the detector?
NO4H99
0
- Joined
- Sep 9, 2013
- Messages
- 552
- Points
- 0
Not that I condone what you're doing 
, but I don't see how this is doing you any good. You would get the signal that you're being radar-ed milliseconds before the cop gets a reading on your speed - faster than your reflex speed.
Also, I wouldn't trust that article that you quoted as it has a few glaring errors. The biggest of which, is that LIDAR does not measure speed using a doppler shift because the speed of your car is ≈1/(10^7) the speed of light. If you plug 67mph (30m/sec) into the doppler equation with 904nm light, you get a result of ±9*(10^-7)nm. At this miniscule of a difference, it would also have to take into account such elements as the chemical composition of the air and so forth. More likely it sends out pulses of light, assumes a near constant velocity, and uses a motion equation to detect the change in time needed to travel your car and back.
, but I don't see how this is doing you any good. You would get the signal that you're being radar-ed milliseconds before the cop gets a reading on your speed - faster than your reflex speed.Also, I wouldn't trust that article that you quoted as it has a few glaring errors. The biggest of which, is that LIDAR does not measure speed using a doppler shift because the speed of your car is ≈1/(10^7) the speed of light. If you plug 67mph (30m/sec) into the doppler equation with 904nm light, you get a result of ±9*(10^-7)nm. At this miniscule of a difference, it would also have to take into account such elements as the chemical composition of the air and so forth. More likely it sends out pulses of light, assumes a near constant velocity, and uses a motion equation to detect the change in time needed to travel your car and back.
- Joined
- Dec 29, 2009
- Messages
- 3,136
- Points
- 63
If the detector is broken, sending more light at it might not be the way to fix it.
NO4H99
0
- Joined
- Sep 9, 2013
- Messages
- 552
- Points
- 0
Is there a reason why you can't mount it on the outside of your bumper. might be a simple fix to your problem.
NO4H99 - Agreed that you have a short time to react, but from what I understand, they have to aim and and it's 'possible' for the detector to 'see' while they are still aiming.
Bshanahan14rulz - It's not broken, just not where it can see the light.
NO4H99 - I live in a state that has chosen to ignore federal law and pass their own law forbiding me to receive certian radio frequencies. I don't speed as a matter of course, but I live in an area where they chose to post speed limits below the 85th percentile and then aggressively 'farm' these areas for revenue.
Bshanahan14rulz - It's not broken, just not where it can see the light.
NO4H99 - I live in a state that has chosen to ignore federal law and pass their own law forbiding me to receive certian radio frequencies. I don't speed as a matter of course, but I live in an area where they chose to post speed limits below the 85th percentile and then aggressively 'farm' these areas for revenue.
NO4H99
0
- Joined
- Sep 9, 2013
- Messages
- 552
- Points
- 0
I don't know what you could do, besides get a larger diameter FO cable, which isn't very practical, and would be very noticeable - so here's my suggestion.
Tell your car/truck/prius that your wheels are 3" bigger than they actually are. Then you can feel like you beat the system when you're in a 45 zone, pass a cop, look down at your speedometer (which reads 53mph), and not get pulled over. :beer:
Would also be useful to freak out anyone riding with you...
Tell your car/truck/prius that your wheels are 3" bigger than they actually are. Then you can feel like you beat the system when you're in a 45 zone, pass a cop, look down at your speedometer (which reads 53mph), and not get pulled over. :beer:
Would also be useful to freak out anyone riding with you...