Fresnel Lens, Large, 8 in. by 10 in. by Go Science Crazy - fresnel lens large
Good idea, it’s been done before (saw this online a few months ago) but I’m not sure about the video. I don’t think an LED will work on 1.5 volts. Maybe those were 3.6v lithium cells but they didn’t look like it.
Even if the camera does have good IR filters as some of rhe more expensive ones do pointing both a green and red laser pointer at the lens is usually enough to stop even the most expensive of CCTV cameras by mucking up the AGC circuit.
InterstateGratings
A red laser diode from a DVD burner (~250mW, which is a lot!) will pretty much destroy any camera you aim it at, because of the lens, which conveniently focuses the laser beam into a tiny spot on the CCD. Anyone using a DSLR will also be permanently blind when you use this, and because of the reflection of the lens, the person aiming the laser is at serious risk of permanent eye damage, too.
Which gives me a thought, you can get some very small BW cameras. Small enough to be mounted behind the bridge of your sun glasses and as it’s lens is behind the out facing LEDs it will not be directly effected by them, but if you are having a clandestine chat down the proverbial dark alley then it will be more than sufficient to illuminate your opposit numbers face.
Steelgratings
What they do not say is the other reason it will probably not work against high end cameras be it SLR’s or Video recorders is that the optics of your camera has to be pointed towards their scanner. So using an appropriate lens with a very narrow field of view from the right angle will probably defeat their system as well.
As far as the comment about hot-filters (what IR-filters are called) in professional DSLRs: There quality varies depending on the camera. The D200 (as I recall) has a very good filter while the S2 has a relatively poor one. (On the up side, this means that I can use it for infrared photography with no modifications.)
Hmm – I wonder if one or two LEDs placed at the collar would be enough to do the trick? A crafty individual could make a small apparatus to clip beneath the collar of a dress shirt… so you don’t look like a tool walking around with sunglasses all day. (The bluetooth earpiece already fills that role!)
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Cheap BW CCTV’s using silicon based sensors are considerably more sensitive to IR than you would think, likewise home video camcorders etc (especialy with low light options where the IR filter is switched out).
The only new bit appaears to be the target aquisition and tracking system and white light jamming laser (not good). However as they note it will not work very well (or possibly at all) against “proper SLR” cameras (digital or otherwise). Their stated reason is due to the SLR mirror obscuring the silicon sensor.
This may work for defeating some inexpensive security cameras, but digital SLR cameras (weapon of choice for paparazzi) won’t be so easily beat.
It seems that at least some cameras are not shielded from IR, which of course is invisible to us. You can test this by pointing your television remote control at your cell phone camera. In the case of my Sony-Ericsson w300i the screen appears completely white when the remote is activated. So the IR glasses are at least plausible.
I like the idea of the glasses to frustrate the DOJ contractor/observers on my tail, now can someone puhleeze hack me outta the database I’m in?
Having read the page I would say there is absolutly nothing new in their detector design over and above what I described (and is comercialy available already) in my above post of July 7, 2008 5:04 PM.
Bar Grating Sizes
@Laser dude: ofcourse, the laser diode has a lens that produces a highly convergent beam (which ofcourse becomes divergent after a few mm), so you do need a lens or set of lenses to produce a parallel or very slightly convergent beam.
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Counter measures could be as simple as having multiple false targets in view these can be very low tech devices made up as lapel pins (think a clear water LED mounted behind a cheap plastic lens for a home brew one 😉
Building them is a snap: just take a pair of sunglasses, attach two small but powerful IR LEDS to two pairs of wires, one wire per LED. Then attach the LEDs to the glasses; the video suggests making a hole in the rim of the glasses to embed the LEDs. Glue or otherwise affix the wires to the temples of the glasses. At the end of the temples, attach lithium batteries. They should make contact with the black wire, but the red wires should be left suspended near the batteries without making contact. When you put them on the red wire makes contact, turning the lights on. It’s functional, but we’re thinking that installing an on/off switch would be more elegant and it would allow you to wear them without depleting the batteries.
Most, if not all cameras, with the exception of specific “night vision” cameras which utilize IR reflection to capture an image in the dark, have filters placed on the sensor itself to filter out infra-red light.
Ditto to what Mark says. I work in security sales and the vast majority of CCTV cameras are very sensitive to IR. Quite a few of them have built in IR diodes to illuminate the area they are viewing. Large IR illuminators effective up to 500 or more feet are used to flood areas so cameras can easily see while visible light is turned off to reduce light pollution.
I personally like the idea of an optical slave linked to a flash to overexpose the image of someone taking a photo, but as mentioned, this hinges on the photographer using a flash in the first place.
There was talk of using this to blind the cameras of Scientologists wanting to take pictures of Anonymous members at protests.
Also those very expensive little CCTV detectors use a high power pulsed IR source (occasionaly laser diode) that uses the internal reflection principle (red eye / rodent eyes in head lights) to detect a focused lens and sensor of a CCTV camera and they are very effective. If you realy do have a lot of money you can get one which has an integral high sensitivity heat sensor that also will pick up the heat being disipated by the electronics of a concealed camera/transmitter.
Just try and point a IR device at your standard webcam. Mac users can try opening PhotoBooth and pressing some buttons on their IR-remote that iMacs an MacBook Pros come with. Makes a nice flash on the video…
If this works, the more it’s posted, the more thieves will learn of it. If it doesn’t work, HAH! I love the thought of thieves walking into crime scene with their protective sunglasses, thinking they’re safe and anonymous.
Which makes me think that they are using IR spectroscopy to actualy determin if the retroreflective surface is silicon or not (so posibly high sensitivity Galium based sensors won’t get picked up 😉
Quite a few optics apear to be foggy to UV and others (photography) are deliberatly designed to stop it almost entirely. Also quite importantly a number of fire sensors use UV light to detect petro/alcohol flames so you could set off fire alarms in or around areas which need to rapidly detect hydrocarbon fuel based fires (think petrol stations etc)
Slightly off-topic, but here is another interesting hack for fooling cameras: http://www.juliusvonbismarck.com/fulgurator/idee.html
Steel Bar Grating
In other words: you’ll need a really high-power, wide-angle IR LEDs, which eat batteries for breakfast and get seriously hot.
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Also what they do not appear to have considered is how easily their own system will be detected and blocked “Counter Counter Measures (CCM). Detection is fairly easy, either when the detector is scanning or when the blocking laser is used.
Bar Grating
I have no idea whether it works, but it creates an obvious opportunity for “the authorities” – get an IR-sensitive camera and watch for any strange blobs where faces ought to be – obvious suspects.
The DVD claims only work if you get yourself a good lens system that is well matched for the laser. There beams are too divergent over meters to be really bad, because you see in red you tend to blink and turn away….
Have fun and if you realy do want to stop a CCTV dead in it’s tracks, get hold of one of the older green laser pointers and take the wavelength converter crystal out of it which leaves you with a laser diode with 50mW or more output, focus this through a cheap “telescope” (golf range finder) and point it directly at the CCTV camera lens. The result if close enough is to damage the camera sensor in cheaper CCTVs at other ranges it can effectivly jam it in the same way as having a spotlight pointed in your face.
I’ve long thought about the design of an IR-grenade; a ball covered in IR LEDs with a core battery, which you can turn on and throw into a room to blind cameras. Alternatives like IR pen lasers directed at the camera lens seem a little more practical to me.
EDITED TO ADD (7/8): Doubts have been raised about whether this works as advertised against paparazzi cameras. I can’t tell for sure one way or the other.
I believe that glass IR filters to place in front of the lens are availible, that can be utilised on cameras that do not have a IR filter in front of the cameras sensor.
Aluminum grating
” And for those further doubters why do you think you can buy CCTV cameras with integral rings of IR LEDs to use in the dark to distances of upto 30 meters from your local hardware store.”
Not realy, to block the camera the light source has to get through the optics and then have sufficient energy in the wavelengths the sensor is suseptable in to block it.
Also, try the remote control trick outside, in bright sunlight. It won’t work, because the relative intensity is much lower.
Most, if not all cameras, with the exception of specific “night vision” cameras which utilize IR reflection to capture an image in the dark, have filters placed on the sensor itself to filter out infra-red light. My D200 is particularly insensitive to IR.
Characters in Cory Doctorow’s short story ‘I, Robot’ use this technique to avoid detection by the image recognition algorithms watching the cameras of a future totalitarian state, allowing them to move around “invisibly”. – http://craphound.com/overclocked/Cory_Doctorow_-Overclocked-_I_Robot.html
More high tech would be putting appropriate filters on your camera lense to either stop the detector or even using a high tech specialised filter that stops the narow band component frequencies of the white light laser whilst allowing the broad band frequencies of the film or whatever the target is to pass.
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You REMEMBER my impromptu s.p.a.m reports in such detail, that you are able to CLASSIFY their flavour(?) well after the fact????
The easy way to demonstrate this is to set your camera up in a room and connect it up to your TV then take your TV remote control stand in front of the camera point the remote control at the camera lens and press a button whilst looking at the TV screen you will usually see bright white flashes where the remote control is.
@ Clive “yet more repeat link s.p.a.m, that got @ianf huffing and puffing the other day (good cardiovascular excercise did nobody any harm 😉”
Diffractiongratings
And for those further doubters why do you think you can buy CCTV cameras with integral rings of IR LEDs to use in the dark to distances of upto 30 meters from your local hardware store.
Many video cameras are quite sensitive to both UV and IR. Also security cameras tend not to use IR filters. The obvious drawback here is that this is effectivly “active jamming”. Whilst the camera may not be able to see someone’s face it’s more attention grabbing, to a camera operator, than a regular mask.
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