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Ask Slashdot: Anti-Camera Device For Use In a Small Bus?
Paul server guy writes "I am building a limousine bus, and the owners want to prevent occupants from using cameras on board. (But they would like the cameras mounted on the bus to continue to operate; I think they would consider this optional.) They would also like to do it without having to wear any 'anti-paparazzi' clothing (because they also want to protect the other guests on board), and without destroying the cameras. (So no EMP generators, please). We've done some testing with high-power IR, but that proved ineffective. Does anyone have any ideas that they are willing to share?"
Got a couple of problems. As you found IR is ineffective, I think you will find anything that allows normal human sight to work will be ineffective or inconsistently effective. Have to assume that total darkness is not acceptable as well (though would be somewhat effective)
I have heard that its possible to detect cameras by IR lasers that they use for autofocus. So that leaves some ideas:
1. Detection rather than nullification. Maybe you can't prevent but you can at least know when,
2. Maybe you can use IR to fool the autofocus to one extreme or another?
Nothing is perfect of course, but if those could be done for the majority of smart phones, then it may still be worth doing for some purposes.
"I opened my eyes, and everything went dark again"
Suspect it is likely some sort of stripper bus / limo. They have them in some areas as a dodge for monitoring and rules in the private dance areas. Likely the owner wants to prevent having the patrons take pictures of the talent, but would like to have evidence in case a drunk fool takes things too far.
You've tried ultra bright IR but you really need flickering ultra-bright IR strobing at different rates and levels. A solid IR just sets things up for a better photo. Providing the camera didn't have an IR filter and did photograph IR a flickering IR would cause differing light needs within the exposure window which the camera would be unlikely to adapt to. If you are able to link the timing of the flickering in with your own cameras you'd be able to shut it off momentarily (electronically) and grab the photo.
To allow officials to accept bribes without fear of being photographed in the act? To allow folks to get rowdy and/or affectionate without being photographed in the act? To allow... I think you're seeing the theme here: what happens on the limo-bus, stays on the limo-bus. Or as someone else mentioned, to drum up business for the officially sanctioned photographer.
I can only think of one way to implement it safely though, and that is unlikely to be acceptable: black out the windows and remove all interior lighting so that the cameras can't see.
The challenge is that you want to let human eyes see, while electronic eyes cannot (if we're talking film cameras then it becomes essentially impossible - those things are generally even more reliable and durable than human eyes). If you're not allowed to destroy the cameras then you're limited to a few options:
1) Applying enough light that the sensors saturate - which is likely to damage human eyes with prolonged exposure since cameras are intentionally filtered to only be able to see roughly the same spectrum as human eyes, and high-intensity IR is known to cause eye damage due to overheating of the cornea and lens - the only part of the human body without an active cooling system.
2) Disrupting the electronics so that a photo can't be taken - which is pretty much going to require either a camera-destroying EMP, or a sustained string of low-grade EMPs that are just strong enough to reliably disrupt all electronics in the area without actually damaging them, and frequent enough that the cameras don't have a chance to finish rebooting before the next pulse arrives. Unfortunately EMPs are not exactly gentle to living tissue either, not to mention the pulse that will reliably disrupt a piece of high quality electronics will likely do at least some damage to low-quality electronics. Multiply that by maybe a hundred pulses an hour and you're going to end up with some fried electronics (and probably damaged neurons as well). Plus passengers are unlikely to appreciate having all their electronics forcibly rebooted and their hard drives potentially scrambled. And heaven hep you if anyone has a pacemaker or other implant.
I can think of a few ways to make the camera take really *bad* photos, but that's only relevant to the "official photographer" scenario, and I will not willingly contribute to exploitation via artificial scarcity.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Imagine if this sort of technology was within reason to implement. Police of all kinds would jump on the chance to forbid others from taking pictures and allowing their own pictures. Riot squads would love it. There would be one of these devices on the front of every cop car.
I'd be willing to bet they didn't do it right. It needs to be strobed at a high rate. But it will affect the vehicle cameras as much as others, unless they have good IR filters.
Strobed high intensity NIR is the right track. Sync the vehicle camera shutters with the strobe dead time. Use a shuttered camera so the IR doesn't leave lingering effects on the focal plane. Heck, you can even use the NIR for camera illumination and use very fast shutter speeds.
I'd be willing to bet they explored this and found that either a) the necessary intensity of the NIR was beyond safe limits, or 2) the cameras necessary to work in this scheme would be prohibitively expensive. Or both.
My solution: confiscate the passengers' cameras and enforce the no photos policy strictly.
Alternately, make them ride in the dark. Naked.
I can see the fnords!