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Medicine Technology

Visible Light 'X-Ray' Sees Through Solid Objects 122

Posted by samzenpus
from the I'm-looking-through-you dept.
disco_tracy writes "Some day we may not need X-rays to see inside people, thanks to a new way to decipher light that passes through opaque surfaces. Normally visible light becomes too scattered to detect after passing through opaque surfaces. But scientists in France have developed a way to reconstruct images from light passing through such surfaces by deciphering just how the material makes the light scatter. In the short term the research will help improve the strength of telecommunications signals and fiber optics cables, but years from now the technology could supplement or even replace traditional ultrasounds for baby imaging and X-rays for weapons detection at airports."
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Visible Light 'X-Ray' Sees Through Solid Objects

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  • This is a double edged sword. I see good uses, then I see this used to try to execute search warrants, saying that anything in someone's domicile is in "plain view".

    Of course the voyeurs will also love opaque viewing technology too.

    • especially the ones that work in the TSA and homeland security. Yet another way for them to perv out on the job.
      • Que the Emperor and his new clothes?

    • by Amorymeltzer (1213818) on Wednesday October 06, 2010 @06:00PM (#33817510)

      Not likely (in the US at least). Kyllo V United States [go.com] established that using IR to peer into a home requires a warrant, and that's a pretty strong precedent. A key issue of the case was that using IR didn't even need to penetrate the house (it just "recorded" what was being emitted) and yet was STILL not allowed without a warrant. Anything that "peers in" will be just as illegal.

      • by gstoddart (321705) on Wednesday October 06, 2010 @07:13PM (#33818306) Homepage

        Anything that "peers in" will be just as illegal.

        Nowadays, "illegal" doesn't mean you can't do it -- it's just not admissable in court.

        You can get your last dollar they still do it, but then need to come up with a pretense for anything involving the courts.

        Remember, they can now slap a GPS device onto your car with absolutely no court oversight. Just imagine all of the illegal things they do and cover with sealed court proceedings.

        • by PitaBred (632671)

          NSLs. "We thought he was a terrorist your honor, but all we found was some pot"

        • Re: (Score:3, Insightful)

          by Agripa (139780)

          Nowadays, "illegal" doesn't mean you can't do it -- it's just not admissable in court.

          You can get your last dollar they still do it, but then need to come up with a pretense for anything involving the courts.

          For the moment at least, a 4th amendment violation is still a 4th amendment violation even if they do not bother admitting any evidence they find into court. The court sanction of inadmissibility of evidence does not mean law enforcement is free to search and seize when they do not plan on admitting ev

          • by gstoddart (321705)

            The secret court proceedings and administrative actions are more insidious to my mind.

            Agreed 100% with this and all of your other points.

            I've just developed a fairly cynical and cranky point of view that says they're doing far more illegal stuff than we know of, doing it every day, and essentially don't care since they can do it with impunity.

            Sometimes, the dystopian present seems so damned depressing that it is hard to believe in those constitutional/legal freedoms anymore. :-P

      • Anything that "peers in"

        What if it pees in? That OK?

      • by N1AK (864906)

        A key issue of the case was that using IR didn't even need to penetrate the house (it just "recorded" what was being emitted)

        Fortunately the court realised the stupidity of the argument. When I look through your window part of my body or conscious doesn't travel within your house, my eyes use the visible light spectrum emissions that travel from the property.

        Clearly most people think of private as being unavailable to the human senses of people on public ground. If I phone my neighbour I want that to be

      • to think that US law enforcement still follows such an arcane principal as 'the law'
      • One expects the hidden 3D image reconstruction process to improve with multiple image capture sources at different angles:

        This would imply that public surveillance cameras could be used in a "phased-array" configuration to provide data for hidden 3D image reconstruction, unless the photons are routed around the target volume using metamaterial fabrics.

        Rapid adoption of hidden 3D image reconstruction technology could result in a commercial demand for metamaterial fabrics to provide pedestrians with rel
    • by sjames (1099)

      Fortunately, so far the courts support a view that enhancements like IR don't count as plain view. Hopefully that will continue here.

    • Re: (Score:3, Insightful)

      by Mr. Freeman (933986)
      "This is a double edged sword."

      As is every single piece of technology that ever has, and ever will be, invented. Any progress in any field of study has both benevolent and malevolent purposes. Fire is used for cooking, also for arson. The wheel is used to transport goods, also make off with stolen goods. The hammer helps build things, and bash skulls in. Etc.

      This new visible light "x-ray" can be used for spying or legitimate medical purposes.

      The trick is to ensure that those in power do not abuse this
      • by tombeard (126886)

        I like your conclusion.

        I suggest that personal information become a new IP. Who you are when and where you are with whomever doing whatever should be property of the individual. Other people may have that same IP, but they may not store it, aggregate it, track or sell it. The information belongs to the subject. This is completely opposite of current thinking, but current thinking leads to unworkable situations. You own your own information and no one else can keep or aggregate it, except as you expressly al

      • by stor (146442)

        > As is every single piece of technology that ever has, and ever will be, invented.

        Indeed! As Louis CK says, "Even a single-edged sword is a double-edged sword"

        -Stor

  • by MrEricSir (398214) on Wednesday October 06, 2010 @05:35PM (#33817164) Homepage

    This will make the "xray" threads on /b/ waaay more interesting.

  • This is a pretty cool idea, but it will probably not take the place of x-rays. X-ray is cheap, easy, accurate, and relatively harmless (in small doses).

    This sounds expensive, requires a large amount of processing capability, isn't very portable, and relies on light actually passing through the object. For some applications this may be useful, but for the vast majority of imaging tasks that require visualizing the internals of an object, x-rays will be the better solution.

    Now, an x-ray scanner that didn't re

    • Re: (Score:3, Funny)

      by eleuthero (812560)
      But don't you realize that everything is interconnected? Even if a bomb is totally obscured by thirty tons of rice around it in a packing crate, it will be detectable by taking a visible-light picture of the period in U.S.A. on the side of the separately packaged delivery manifest. This is the great thing about technology, it is always bringing us ever closer to a world where the primary question on our lips should be, "Do you know where your towel is?"
    • by c6gunner (950153)

      These durned new ow-toe-mo-beals sound like the bees knees, but they will never take the place of good ol' "Lightning" over here. He might fart a lot and throw me once in a while, but he's cheap, easy, accurate, and relatively harmless. These sound expensive, require all sorts of factories, they break down all the time, and rely on someone to bring oil from who-knows-where just to get them to move. In some cases they may be useful, but for the majority of your traveling needs, horses are clearly the way

    • by mcgrew (92797) *

      Now, an x-ray scanner that didn't require film plates. That would be good!

      New X-ray machines have been digital for years now. Film is almost obsolete.

  • Visible? Opaque? (Score:5, Insightful)

    by Gothmolly (148874) on Wednesday October 06, 2010 @05:36PM (#33817172)

    How does visible light make its way through an opaque object?

    • Re: (Score:3, Informative)

      by piemonkey (1628149)

      How does visible light make its way through an opaque object?

      I know you aren't supposed to read TFA, but ""It's like putting a flashlight behind your hand," said Sylvain Gigan... "You cannot see an image, but you can still see a faint glow.""

      • by msauve (701917) on Wednesday October 06, 2010 @05:44PM (#33817302)
        No. Reading is useless without understanding. The OP was correct in asking. Your hand is not opaque [wikipedia.org], it is translucent.
        • by sjames (1099)

          Yes, but so are most things if the light is bright enough or the detector sensitive enough.

          • by delt0r (999393)
            Not really. 1mm of just about any pure metal will not transmit any visible wavelengths till the light source is powerful enough to vaporize it.
      • by blincoln (592401) on Wednesday October 06, 2010 @05:56PM (#33817462) Homepage Journal

        I know you aren't supposed to read TFA, but "'It's like putting a flashlight behind your hand,' said Sylvain Gigan... 'You cannot see an image, but you can still see a faint glow.'"

        I think it would help if TFA included an actual example image, and not just a photo of someone holding their hand up behind a shower screen and a note to the effect that the actual technology might produce images sort of like that one.

        • Re: (Score:2, Informative)

          by erichill (583191)
          The actual "FA" is here [arxiv.org], with images. Gigan, et al. say, "opaque materials."
        • by wringles (12507)

          ... and not just a photo of someone holding their hand up behind a shower screen ...

          That picture looks suspiciously like the poster of this movie [imdb.com].

    • Re: (Score:3, Insightful)

      That's exactly what I thought. It's a poor choice of words, in my opinion. Opaque by definition means that it blocks light from passing through it, but I just figured it was some kind of quantum mechanical thing, just like all the other physics I don't understand.
      • Re: (Score:3, Insightful)

        by jd (1658)

        I guess the first question is whether something can be truly opaque (zero light travels through) or whether all things are translucent if you've a sensitive enough detector.

        Assuming that there are genuinely opaque objects, are there enough objects that are translucent (though not to the unaided eye) to make this technique interesting?

        My guess is that almost everything will be translucent, though not everything. If the gaps between atoms is on the scale of the wavelength of light, then the atoms will act as

        • Re: (Score:3, Informative)

          by JesseMcDonald (536341)

          Thanks to quantum tunneling nothing is ever completely opaque. A particle's path from A to B doesn't necessarily have to pass through all the points in between. Some tiny fraction of the photons will always act as though the object isn't even there.

          • by delt0r (999393)
            Tunneling is exponential in nature. If you get say 1 in 10 photons through a 1um think piece of material. Then you only get a 1 in 100 with 2um thick.

            Now lets assume that the thickness is now 1mm. Now just one photon in 1x10^1000 gets through.

            Now lets assume we have a red laser (700nm) that has a power output of the sun (3.846×10^26 W). Thats 1.3x10^45 photons per second. After waiting 1000 billion years, thats still only 4.5x10^55 photons. So none get through. You could use all the energy in th
            • I did say that it would be a tiny fraction. The GP's definition of "opaque" was as follows:

              In order to be truly opaque, two criteria must be met - every photon has to intersect a particle and for every such intersection, the particle has to be able to absorb the photon.

              To me, that means that no photons can ever get through. Tunneling is a matter of probabilities, so one might get through, even if the odds are overwhelmingly against it.

              • by delt0r (999393)
                Not a single photon even after 100s of times the age of the universe is not a "tiny fraction" by any stretch of the imagination. Its none.

                The *size* of a photon in the visible region is much larger than an atom. Blue light is in the 400nm range while an atoms radius is in the 0.1nm range. So a photon intersects many atoms.. often all at once.
                • The *size* of a photon in the visible region is much larger than an atom. Blue light is in the 400nm range while an atoms radius is in the 0.1nm range. So a photon intersects many atoms.. often all at once.

                  What you say about blue light (400nm) is its wavelength, not the size of the photon itself. Size and wavelength are separate properties. I could be wrong, of course (I am not particularly familiar with quantum mechanics and such).

        • by ceoyoyo (59147)

          There's a difference between a photon every once in a while making it through and having enough to form an image. There are likely a lot of objects that you simply can't form a reasonable image through without using enough light to vaporize them.

          • by jd (1658)

            You are correct, but there you get into the muddy waters of whether you mean "enough to form an image" even in theory (ie: regardless of technological constraints) or whether it's constrained to some specific level of technology. The theory option then depends on how complete the theory is (you can only extrapolate so far before any theory breaks down) and whether there even is much in the way of theory when it comes to photons passing through matter.

            • by ceoyoyo (59147)

              We can do a little better than theory. If you assume you can perfectly account for the scattering that happens when photons go through the subject you're basically left with a regular imaging problem. You've got some sort of detector, probably a CCD, and you've got photons hitting it. Your detector has such and such a quantum efficiency, and is subject to a certain amount of noise from various sources. Even if you postulate a perfect detector, at any temperature above absolute zero it's still going to b

              • by jd (1658)

                Ok, that works. We can remove the technology-dependence by describing it in the abstract. If you have a signal, you will have noise. We can then circumvent the question of the type of noise and the conditions surrounding it. If the noise conceals the signal, you will not be able to detect the signal.

                Now, we can apply a bit of theory to this. If we treat each possible path from the object to the detector as a continuous-time analog channel and the presence/absence of some count of photons of a given frequenc

                • by ceoyoyo (59147)

                  There's an easier way, which is commonly used: averaging.

                  You don't actually have to change the light frequency. Since the noise is random, simply imaging N times and averaging the result will give you a sqrt(N) improvement in SNR. Astrophotographers do this when they stack multiple images, and it's also used in MRI scans when you acquire the same image multiple times and average.

                  A continuous version just involves imaging longer. A standard digital camera will leave it's shutter (electronic or mechanical)

                  • by jd (1658)

                    Yeah, long baselines work. I was working on the assumption that at any given frequency there will be gaps in what you can know because of absorption so by changing frequency you can change what gaps there are. (Since you can't tell in a noisy signal whether the gap is due to noise swamping the data or there really being a gap.)

                    As for hamburgers, I think that anything moving would prefer something more substantial [icanhascheezburger.com]. :)

      • by turing_m (1030530)

        Opaque by definition means that it blocks light from passing through it, but I just figured it was some kind of quantum mechanical thing, just like all the other physics I don't understand.

        So in other words, quantum mechanics is opaque to you. Or at best, translucent.

    • Re: (Score:3, Funny)

      by noidentity (188756)

      How does visible light make its way through an opaque object?

      Simple, on exit from the opaque object, the light has turned invisible. This new device can see the invisible light.

    • by rolfwind (528248)

      Ever put a powerful flashlight against your fingertips?

    • Re:Visible? Opaque? (Score:5, Informative)

      by seeker_1us (1203072) on Wednesday October 06, 2010 @07:14PM (#33818314)
      It's called Ballistic light [wikipedia.org].

      The idea is that you send light against an opaque medium, the photons getting blocked or scattered is a statistical process. Some of them, simply as a matter of probability, "sneak through" in a straight line.

      To get around the low probability, you use a strong light source, modulate it (if you modulate the light, you can pick it out with a tuning circuit, so that you can screen out background light), and then average over a long period of time.

      Eventually, you get enough ballistic photons through that you can map out an image.

      • Re: (Score:3, Funny)

        by edjs (1043612)

        It's called Ballistic light [wikipedia.org].

        Eventually, you get enough ballistic photons through that you can map out an image.

        And if you get the light strong enough, you resolve the opacity issue permanently, once the smoke clears.

      • Re:Visible? Opaque? (Score:4, Informative)

        by radtea (464814) on Thursday October 07, 2010 @09:22AM (#33823568)

        Eventually, you get enough ballistic photons through that you can map out an image.

        Physicists don't actually use terms like "opaque" very often. We are more likely to talk about material that is "highly absorbing" or "highly scattering". The human body contains lots of both.

        One area where people have tried to apply this is in optical mamography: women's breasts are primarily fatty tissue that is highly scattering but very weakly absorbing, so you get a surprisingly large fraction of transmitted light. You have to do a huge amount of processing to deconvolve the scattering kernel, but when I worked in the area in the late '90's it was getting close to useful.

        For people reading this who are female or who have wives or girlfreinds willing to go along, go into a dark room and hold a flashlight under your (partner's) breast. You'll be amazed by the amount of veinous structure and whatnot you can see. Squeeze the breast flat to get more detail. Insert joke here about how now you're in a dark room with a woman who has at least one breast exposed so you know what comes next...

        Very athletic women with smaller breasts may not see much: the chest muscles are highly absorbing and any any photon that scatters into them is lost.

        High-speed computation is making visible light a more useful medium of detection all the time, and the work described in TFA is an interesting step along the way.

      • by delt0r (999393)
        For many materials nothing ever effectively sneaks through at least in the visible region.

        See my other post: http://tech.slashdot.org/comments.pl?sid=1811066&cid=33824520 [slashdot.org]
    • by ceoyoyo (59147) on Wednesday October 06, 2010 @08:28PM (#33818950)

      It just so happens that your object here is only MOSTLY opaque. There's a big difference between mostly opaque and all opaque. Mostly opaque is slightly transparent. With all opaque, well, with all opaque there's usually only one thing you can do.

    • There are very few opaque objects, people are translucent. A small percentage of photons manages to pass through without hitting anything which will stop them. Both intensity and frequency (color) deliver information.

      BTW: there's some prior art on this, Dr Jerry Tiemann had proof of concept going prior to 1993, at GE's Corporate Research Center. GE Medical Systems declined to fund development. I believe he was using an algorithm developed by Dr Glen Row for transforming fan beam data to parallel beam, to pr

  • by Anonymous Coward

    I say why stop at x-rays. Gamma rays are too good for them.

  • opaque:
          1. Impervious to the rays of light; not transparent; as, an opaque substance.
    Translucent:
        1. Transmitting light but causing sufficient diffusion to prevent perception of distinct images.

    If an object is opaque there is no "light passing through such surfaces" that can be deciphered. It is call opacity but opaque means 0 light pass through.

  • Amazing! A friend of mine has done his Ph.D. in exactly this field. He was shining a beam of light right THROUGH an opaque sheet of material (paper, I think) already a few years ago, and published about it in 2008. I think it's pretty much the same idea, from what I understand of it (but keep in mind, I chose the evil path of Business instead of Science, so I have no brain).

    Anyway; on his page [ivovellekoop.nl] there's a much better explanation, with cute pictures and all that, of the same idea.

    • Amazing! A friend of mine has done his Ph.D. in exactly this field. He was shining a beam of light right THROUGH an opaque sheet of material (paper, I think) already a few years ago, and published about it in 2008. I think it's pretty much the same idea, from what I understand of it (but keep in mind, I chose the evil path of Business instead of Science, so I have no brain).

      Anyway; on his page [ivovellekoop.nl] there's a much better explanation, with cute pictures and all that, of the same idea.

      Thanks, I thought I read some journal articles about this a year or two ago.

    • by toQDuj (806112)

      Yes, the scattering of light has been investigated for almost 100 years now, so not much new in this except that they managed to deconvolute the spread function of the white paint from the image and retrieve the original projection.

  • I've had this idea for a while now that low-heat, very bright LEDs are available as light sources: 1. take an existing CAT scanner: Xray source, detector, mounting system (with the rotating arm) and image processing software. 2. replace the Xray source with a bank of LEDs 3. replace the Xray detector (a scintillation screen? whatever it is) with a CCD 4. start scanning Obviously there's a whole bunch of experimentation needed to calibrate diffusion due to different types of tissue/bone/marshmallow but th
    • by c6gunner (950153)

      5. Replace melted patient with new patient.
      6. Fix broken chair and write reminder to buy restraints for next patient.
      7. Demand ONE HUNDRED BEEEELION dollars.
      8. Profit!

    • by ceoyoyo (59147)

      I think you'd find that in order to get enough photons through your head, for example, in some sort of reasonable time, you'd need to use a very high power light. Probably high enough power that it would tend to vaporize your subjects.

      These guys can (sort of) reconstruct an image from scattered light. That doesn't address the problem of convincing enough light to measure to go through in the first place.

      • but what about for thinner body parts, like hands or feet? A quick scanner for those might still be useful for replacing the need for xrays in some situations. It might be possible to have the light sent to include positioning information (for example, send a string instead of a single pulse) and correlate where it was seen with where it was sent from.
        • by ceoyoyo (59147)

          I think that's what they're getting at.

          It might work on hands, if they manage to reconstruct better images. If you try and do CT you're going to get a lot of artifacts from the bones though.

  • ... see anything more than the silhouette of what is being concealed by the "opaque" surface though? While in many cases, a silhouette could well provide enough for a lot of different purposes, I don't think it's quite what I'd consider really "seeing" something.
  • 1) We see reflected and refracted light, otherwise we would see darkness.
    2) An opaque object means that light bounces from it, therefore see the opaqur object and we can't see what's in the other side.
    3) if the best analogy they could have come up with is a hand with a potent source of light that allows to see the blurry hints of bones and veins of our hand, it is translucency not opacity.

    It makes sense to recompose scattered light with algorithms, but it doesn't make sense if they insist calling it "see

  • ...years from now the technology could supplement or even replace traditional ultrasounds for baby imaging...

    Ultrasound is for listening to sounds inside the body, such as the faint heartbeat of an unborn human. Imaging is accomplished by Sonogram.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      Ultrasound is for listening to sounds inside the body, such as the faint heartbeat of an unborn human.

      No it isn't. Ultrasound is ultrasonic, by definition. (Higher frequency than normal sound.) Ultrasound is often used for imaging; the resulting images are called sonograms. Ultrasound can detect heartbeats through movement (Doppler shifting the ultrasound waves). It's not for listening to normal sound waves originating from inside the body. That's just a stethoscope (or fancier variant thereof).

    • by ceoyoyo (59147) on Wednesday October 06, 2010 @08:53PM (#33819172)

      A sonogram is the image produced by an ultrasound machine. Ultrasound imaging is called "ultrasonography."

      Listening to sounds within the body is called auscultation.

      • by ndege (12658)

        mod parent up. grandparent is wrong.

      • Listening to sounds within the body is called auscultation.

        Unless you're not listening to the noises themselves directly with a stethoscope (= auscultation), but listening to artificial reconstruction of noises produced by a machine.

        When it's not practical to stick a stethoscope on it (like the heart of a *un*born baby), you can use Doppler effect to detect motion of the blood. This is then either shown with colours superimposed over the regular US-picture, or (after Fourrier transformation) on a frequency/time/intensity graph, or can be converted to audible freque

        • by ceoyoyo (59147)

          True, although you might say that listening to a fetal heartbeat with a doppler ultrasound is like listening to the sound a car makes by feeding the output of a radar gun into a speaker.

          The conversion of doppler us to audio is a small part of one us modality though. Even if you accept that you're actually listening to sounds, it's not true that "ultrasound is for listening to sounds inside the body" NOT imaging.

          • The conversion of doppler us to audio is a small part of one us modality though.

            (Nowadays. Before miniaturization of digital processing, sound-only Doppler where the only small and hand-carried devices. I had met old Internal Medicine professors who only trust their antiquated sound-only portable device for some exams).

            Even if you accept that you're actually listening to sounds, it's not true that "ultrasound is for listening to sounds inside the body" NOT imaging.

            Yeah, you're right. I was just nit picking on the fact that you can use it to listen to heartbeats when a normal auscultation isn't practical.

            But basically yes, to go back to your metaphor :

            like listening to the sound a car makes by feeding the output of a radar gun into a speaker

            Ultrasound is mostly used for imaging, just like radar guns' main usage is measur

  • To a google truck near you.

  • Pretty sure those assholes with the halogen headlights can see through several meters of solid rock pretty easily.

    • Halogen headlights are the normal ones. The problem is when people put xenon bulbs in their halogen housings.
  • ISTR seeing footage of nuke tests where the flash is so bright pretty much everything in front becomes see through. Well, until it becomes vapour.
  • Is this another application of the Wiener filter?

    http://en.wikipedia.org/wiki/Wiener_filter [wikipedia.org]

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