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Turning a Blind Eye to Big Brother
SiliconRedox writes: "An article in the NYTimes (user reg.) details what many of us who have worked with video or electronics have known for quite awhile: Shine a laser beam (or infrared, but the article doesn't get into that) at a video camera, and you can effectively blind certain viewpoints of the camera. The article follows one man trying to cope with the surveillence society by removing his own image from everyday video footage using this technique. The most interesting part? What kind of culpability does the individual or institution have in utilizing this kind of technology?"
Argh, that text is nearly unreadable (no line spaces and such)... try the Google Partner link to bypass the login.
It's illegal in most states to conceal your face in public, i.e. by wearing a mask, unless your work dictates it, or it is a "recognized holiday", whatever that means.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
Point a digital camera at one of those IR cordless headphone transmitters. What do you see? Why, really bright spots where those almost invisible to the human eye LEDs are! And those LEDs are really low power. High power IR LEDs pointed at a camera might not knock it out for good, but it would glare-blind it.
Boobies never hurt anyone. - Sherry Glaser.
It is perfectly legal to stick a microphone out your window and record everything that happens to make sound. In NYS it is perfectly legal to record a private conversation so long as *one* of the actual participants knows it is happening.
I also happens to be legal to record the image of anything, by still or moving pictures, that happens in a public setting.
This is why the cops don't just arrest everyone with a camera.
There is an assumption, like it or not, that when you appear in public you are appearing. . . ummmmm, in public.
This is true even for celebraties who have trademarked their image.
If you don't want to be seen don't stand up from behind the bush.
KFG
Google news link is:
A P.html?ex=1034654400&en=67f6d3a765aded4c&ei=5062&p artner=GOOGLE
http://www.nytimes.com/2002/10/07/technology/07ZZ
Silicon is basically transparent to light of wavelengths longer than about 1000nm, so only very near-IR will work. The LEDs and photodiodes that let you surf from your LaZBoy with a remote operate at about 800nm, and a CCD is sensitive enough at this wavelength to be affected by an 800nm laser -- but this is invisible so you aren't going to find laserpointers in this "color." (Experiment -- shine your remote at your handicam... see anything? Cool, eh?)
Anyway, many surveillance cameras are black and white, with no color filtering or separation, so really, any color laser is useful as long as the CCD is sensitive to it. The quantum efficiency of most CCDs peaks around 400-600nm, but it is still quite high at the most common laser diode wavelength of 650nm, so there isn't really a problem. At 300nm and lower, CCDs are virtually blind without expensive processing called "backside thinning," and you won't see backside-thinned devices on common surveillance cameras because they are very expensive.
Yes, color surveillance cameras are more and more common. For a color camera, a strong enough laser beam will still overwhelm a color CCD that uses a mosaic filter (as opposed to a three-chip camera with beamsplitters). This works because the princple that the author uses is that of "blooming." Basically, if your bright source creates too many photoelectrons, the excess flows over the walls of the pixels (which are really just potential barriers, not physical walls) into neighboring pixels. Make even a one-pixel source bright enough and you can flood a whole region of the array. Since the readout electronics can't tell which pixel any given electron originated in, it just looks like one big, bright extended source on the image.
This phenomenon is often encountered by anyone who works with focal plane arrays or uses data collected by them... ever seen an astronomical photograph with long bright lines emanating from either side of the brightest stars on the image? That's blooming, and it looks like bars instead of a smudge because astronomers pay extra for CCDs with "antiblooming" sinks to the substrate -- think of them as drains between pixel columns. But the chipmakers can't put drains between rows because that is the direction in which the pixels are shifted to be read out. In addressable pixel devices, like CMOS active pixel sensors, 2D antiblooming is easier, but it cuts down on the available area for collecting light, so it often isn't used on inexpensive CMOS APS chips found in surveillance applications.
Three-chip color cameras are only used for professional video production -- they're just not cost effective for surveillance or consumer applications when color mosaic CCDs are so much cheaper. There may be some high-end consumer cameras with three-CCD technology but they aren't common at all.
Of course, all bets are off for military applications -- only the military and their suppliers know for sure what's in their surveillance gear, and I suspect that they have already contended with the problem of laser-blinding CCDs used in night vision.
I can see the fnords!
No they don't. Casually shining a single laser pointer across someone's eye is not going to cause anyone any damage - unless they punch you out for it.
Most laser pointers are less than 1 milliwatt in power. That's really, really low. Factor in vibrations and movement and there is no way your going to damage an eye.
The reason a laser can harm your vision is that the eye sees a laser beam as a point source - it is unable to focus on it directly. Instead, the eye focuses to infinity. The beams light is also virtually parallel, allowing for the entire beam to be focused onto one very small part of the retina.
The good thing here in terms of pointers and safety is that any movement of the beam in relation to the eye (be it a person in motion, or the natural jitters in your hand) will cause the focal point on the retina to move.
Thus, in order for a laser to damage your eye it must have sufficient power to burn quickly - the spot being affected changes before cumulative affects can take place.
Laser pointers don't have that power. Short of bolting someone's head to a table, along with a pointer, then forcing their eyelids open, AND keeping the eyeball still, it's not going to happen.
This is not to say that staring into your pointer for kicks is a good idea! Don't do it. Don't do it to others. Don't say I told you you could. If nothing else it is incredibly annoying. But it's not about to permanantly blind anyone.
Now, if you have an unusually high powered pointer (ie those groovy YAG pens) you might be talking a different story.
I've had much nastier beams in the eye than any laser pointer will ever generate - luckily I've gotten away with it too.
Frankly I'm much more worried about these yahoos who are taking a wad of them and bundling them together and pointing the results at low flying helicopters or other aircraft.
Note to anyone tempted to do this: lasers in the sky make a very nice YOU ARE HERE indicator. You're basically pinpointing your position for the Cops. None to bright (ack, pun) if you ask me.
"They do not preach that their god will rouse them, a little before the Nuts work loose." Kipling, 'The Sons of Martha'
It is really not that easy to put in line filters at 635, 650, 670 (need that one, too), and 532 without really losing a high fraction of the desired signal. And that impairs the ability of the cameras to work in low light, which is a big deal for survalence. While a given laser has a very narrow linewidth, cheaply manufactured laser pointers have wild variations in the actual laser frequency, and cooling or heating the diode can shift that even more. Bare diodes are available relatively cheaply at probably 20 different wavelengths between 600 and 800nm.
If someone seriously wants to block out all handheld laser pointers, they are going to have to throw out everything over 600nm, as well as 532 in the green. That is hard to do with high enough extinction that the laser doesn't overwhelm the CCD while maintainting high sensitivity.
Here's Michael Naimark's current draft article:
How To ZAP A Camera
ObMSFT-Jab: ...or maybe he just thinks security through obscurity is a good thing.
"The best argument against democracy is a five minute chat with the average voter."
--Winston Churchill
Many people today, especially in the US, seem to have gotten it into their heads that they have something like a "natural right" to privacy.
I will acknowledge that a pretty good argument can be made that we have a right to privacy regarding the most intimate portions of our lives and our bodies. But that's a far cry from expectations of privacy in the public sphere--such as the expectation that one has a right to walk down the street unobserved and unrecognized. Part of what it means to be a member of society is to be accountable for one's actions within that society--anonymity should be the exception, not the rule. Look at how anonymity affects the level and quality of discourse all over the Internet. This is why I have used my real world identiy as my online identity for many years now.
From the article:
There is a perfect two-word response to this: Rodney King.18.2-422. Prohibition of wearing of masks in certain places; exceptions.
It shall be unlawful for any person over sixteen years of age while wearing any mask, hood or other device whereby a substantial portion of the face is hidden or covered so as to conceal the identity of the wearer, to be or appear in any public place, or upon any private property in this Commonwealth without first having obtained from the owner or tenant thereof consent to do so in writing. However, the provisions of this section shall not apply to persons (i) wearing traditional holiday costumes; (ii) engaged in professions, trades, employment or other activities and wearing protective masks which are deemed necessary for the physical safety of the wearer or other persons; (iii) engaged in any bona fide theatrical production or masquerade ball; or (iv) wearing a mask, hood or other device for bona fide medical reasons upon the advice of a licensed physician or osteopath and carrying on his person an affidavit from the physician or osteopath specifying the medical necessity for wearing the device and the date on which the wearing of the device will no longer be necessary and providing a brief description of the device. The violation of any provisions of this section shall constitute a Class 6 felony.
I've had enough abrasive sigs. Kittens are cute and fuzzy.
Were you aware that if you were to shine a laser off a window that you could take the mathematical computations and produce a very high quality recording? They dont even have to bug a room now, they can shine a laser at it. So, yeah, lasers have lots of uses.
I don't relish the idea of being watched in public anymore than the next person. But, I doubt using technology to observe people in public places is an invasion of privacy. (Private bathrooms are another matter.) Public seems to me the antithesis of private.
In principle, how is this different than getting a glance from a cop on the beat? Yes, you can see the cop, and you probably won't see the cameras. But, so long as notice is given that an area is under surveillance, the legalities are probably handled.
Another precedent: Police checking for speeders. They watch us; odds are we don't see them.
-- Slashdot: When Public Access TV Says "No"
In most countries (US, Europe...), the law says that you can take pictures in public places, but selling them or broadcasting them is something else entirely: anyone who can recognise himself on a picture can oppose its use. 'Recognisable' must be taken in a very broad sense, for instance if you take a picture of Big Ben at 2:13 on a given day and there's one tiny person at the bottom, that person will be able to say: 'it was me waiting there at that time', then you need that person's permission.
This means that whenever you take a picture with someone in it, you should have them sign a 'limited time use' form (unlimited has no value).
So the person who takes the picture owns it, but the person on it can oppose its use. This means that if you take a picture in a crowd and a dork goes: "Hey you! You can't take my picture, gimme that film !", he has no right to ask you for the film, although all you can do with the pic is look at it at home.
That doesn't help the current argument much though.
Non-Linux Penguins ?
It was Debt of Honor, which is indeed by Clancy. The aircraft in question was a Japanese 767-AWACS bird, and the light was essentially a high-powered spotlight; Clancy described it as having a beam width of 40 feet at a mile's distance, and being bright enough to read a newspaper at the same distance. And yes, it was shined into the cockpit on short final, causing a crash. IIRC, John Clark and Ding Chavez executed the mission.
Moderate drunk! It's more fun that way!
Most of the replies to this post are misguided in their understanding of acceptable use. In the US at least, if you take a picture of a person on the street regardless of whether they are recognizable you can use the image without permission for "editorial" purposes (art or journalism). You can even sell the picture as an illustration. You cannot use or sell the image for commercial purposes (for example to promote a product). If you don't believe me pick up a copy of the national enquirer. Do you really think Oprah authorizes all those fat photos?
I was looking for these earlier today - not for jamming Big Brother, but for use in a display of color-change gem materials. Most gem materials change fine under fluorescent light, but some work better between 395 and 400nm, which these LEDs will cover admirably.
Lemon curry?
So, you really want ultraviolet. Just barely into that range will work.
Try here for high-powered short-wave UV LEDs.
Lemon curry?
I'm sorry, but this is bull. If supermarket scanners were capable of such damage, do you really think they would be allowed? No bloody way. I'm not sure which kind of scanner you are talking about, hand scanner of the kind built into the table, but there is no way it burned you. Absolute puppycock. The only possible way such a thing could have happened is if you'd been mucking about inside one of the large scanners and got beamed. Even then it's very, very, very unlikely. Don't believe me? Go tell your story on alt.laser where many a professional laserist & optical engineer hang out. They'll tell you the same story. In fact someone recently posted a comment along those lines, you'd have loved the response. I can scan a 5watt laser across your eye and you'd be totally fine. In fact, I used to do it routinely as part of laser shows. It's based on power density and exposure. A beam that held in your eye would burn cannot if it is in motion at sufficient speed.
And contrary to your assertion that any movement "will cause the eye to move" -- people have a natural tendency to look directly AT a bright point of light.
Not so. If you notice something you tend to look at it. But if you look towards a bright light (or have on projected at you) then your "Blink Response" takes over. You actually turn away and/or blink. Try it, flash a camera bulb at someone not expecting it. They'll avert their eyes.
Also you must consider the movement of the bodies... just try holding a laser pointer still on one spot at any distance. I guarantee you that it will move about no matter how hard you try to hold it still. The natural twitches in your hand will magnify the further you try to project that beam. Add in any movements of the person being beamed (be it of the body or of the eye itself) and you have a huge range of motion.
If you don't think this is a hazard, try it on yourself first. Remember not to stare into laser beam with remaining eye.
I have. I guess you missed that part of my original post. I used to routinely work with high power lasers (5-7 watts typically), both Pulsed and CW. Even a 5 watt CW laser is safe to scan across an audience, as long as the beam remains in motion. I wouldn't point a static beam of that power at anyone though.
You quote a standard, old, industry joke. That doesn't mean a pointer will do it.
As to the "you are here" nonsense, the beam from a laser is itself invisible. It is only made visible by passing thru something reflective, like clouds, fog, or smoke.
Not quite. The beam isn't "invisible" so much as it's just not aiming into your eye. Since the beam travels in a very straight line, there are no photons being directed away from this path and into your eye. Something must deflect the photons towards you. This is why haze is a favorite.
But guess what, high humidity can give enough air born particles of water to help diffract the beam. As can engine exhaust from, say, that theoretical helicopter. (BTW, I used that example for a reason - it happened)
Additionally take into account the fact that in order to see a laser beam it must enough photons have to be deflected towards your eye. Thus a laser will appear much brighter to someone looking towards the source, than to the person holding the source. Why? For the person holding the source photons must be reflected back the way they came. To someone looking towards the laser they only need to be diverted a few degrees.
Also, since we are talking about pointing it towards someone's eye, their eye is very near the beam - photons need only be deflected slightly from their original path to enter the eye. Not so for the person holding the laser, they require a much greater change in direction.
This is also why a laser appears dimmest when viewed at right angles - the photons must be deflected at a right angle to it's original path to be seen. This is the least likely angle of reflection.
Unfortunately it is people such as you who are responsible for the ridiculous draconian laws of the CDRH in regards to the use of lasers. The US is the only country in the world where audience scanning is illegal. The variance laws are also way out there. It's a shame, done correctly a laser show is a beautiful thing.
"They do not preach that their god will rouse them, a little before the Nuts work loose." Kipling, 'The Sons of Martha'