i worked with fibers before and its 100% possible to inject enough light into a fiber to cause errors at the Rx without melting the fiber, flash lights are not coherent light and are not focused enough for that (also not pulsed)
Im no expert here, but these drones have to fly many kilometers and they carry the spool on board, so the added weight is probably an issue. I assume the production would be much more complicated too. For normal industrial underground fibers the shielding can be quite thick and stiff, but for this you would need some kinda coating that can be incredibly thin while also somehow blocking all light.
Vapor deposited metal film. Expensive, but I wouldn’t be surprised if they already use exactly that to handle interference from the sun. Even non-coherent light can wash the sensors out if you have enough of it.
The space shuttle launch fuel tank was only painted for the first two launches. They stopped because the paint weighed 600 pounds and didnt offer any real benefit. So yeah, a little bit of paint does add up.
I thought that was only really an issue if the fiber was damaged in any way. (It would create a point where the external light could refract into the core) Then again, there isn’t going to be a sheath on that cable and its not exactly a sterile environment.
As long as the angle of attack is between 90°-45° between 0->50->0 % of the external light will enter. No matter your angle of attack, half of the light at least is always going to be reflected. The angle of total internal reflection is 45°, so as long as you are greater than that there wont be “total external reflection” aka no light can enter. The issue is that(barring the refraction of the light as it passes through the air/fiber medium) the angle of attack once in the fiber is still maintained, meaning it does not achieve total internal reflection and therefore passes through the cable without interfering at all(in the case of a atraight cable.
In practice, no cable is going to be perfectly straight, and i would imagine the air/fiber medium may bend certain angles enough to where they can enter above the needed angle of attack, but once inside are bent to be under the needed angle of attack. Both of those imperfections would allow this type of attack to work. In reality all you would need to fix this is to use rolling polarities with very minor error correction. On board the drone give it a 10$ thermal infared lens and a basic processor. Tell it if the cable either cannot be read or is missing while the drone is in flight, it targets the last heat signature it saw.
i worked with fibers before and its 100% possible to inject enough light into a fiber to cause errors at the Rx without melting the fiber, flash lights are not coherent light and are not focused enough for that (also not pulsed)
Into raw unshielded fibers tho probably, right?
With no computer error correction.
That’s what they’re using for the drones, tho.
Oh i see lol
why tho? a little bit of paint won’t be too much weight, right?
Im no expert here, but these drones have to fly many kilometers and they carry the spool on board, so the added weight is probably an issue. I assume the production would be much more complicated too. For normal industrial underground fibers the shielding can be quite thick and stiff, but for this you would need some kinda coating that can be incredibly thin while also somehow blocking all light.
Vapor deposited metal film. Expensive, but I wouldn’t be surprised if they already use exactly that to handle interference from the sun. Even non-coherent light can wash the sensors out if you have enough of it.
The space shuttle launch fuel tank was only painted for the first two launches. They stopped because the paint weighed 600 pounds and didnt offer any real benefit. So yeah, a little bit of paint does add up.
I thought that was only really an issue if the fiber was damaged in any way. (It would create a point where the external light could refract into the core) Then again, there isn’t going to be a sheath on that cable and its not exactly a sterile environment.
Meh, I’m an idiot and that’s OK!
As long as the angle of attack is between 90°-45° between 0->50->0 % of the external light will enter. No matter your angle of attack, half of the light at least is always going to be reflected. The angle of total internal reflection is 45°, so as long as you are greater than that there wont be “total external reflection” aka no light can enter. The issue is that(barring the refraction of the light as it passes through the air/fiber medium) the angle of attack once in the fiber is still maintained, meaning it does not achieve total internal reflection and therefore passes through the cable without interfering at all(in the case of a atraight cable.
In practice, no cable is going to be perfectly straight, and i would imagine the air/fiber medium may bend certain angles enough to where they can enter above the needed angle of attack, but once inside are bent to be under the needed angle of attack. Both of those imperfections would allow this type of attack to work. In reality all you would need to fix this is to use rolling polarities with very minor error correction. On board the drone give it a 10$ thermal infared lens and a basic processor. Tell it if the cable either cannot be read or is missing while the drone is in flight, it targets the last heat signature it saw.
ok so polarize the light in the fiber, gg no interference
Interesting, good to know! I would have thought they’d be pretty good at not scattering anything.