Researchers at Utrecht University and at TU Wien (Vienna) create special light waves that can penetrate even opaque materials as if the material was not even there.
Why is sugar not transparent? Because light that penetrates a piece of sugar is scattered, altered and deflected in a highly complicated way. However, as a research team from TU Wien (Vienna) and Utrecht University (Netherlands) has now been able to show, there is a class of very special light waves for which this does not apply: for any specific disordered medium – such as the sugar cube you may just have put in your coffee – tailor-made light beams can be constructed that are practically not changed by this medium, but only attenuated. The light beam penetrates the medium, and a light pattern arrives on the other side that has the same shape as if the medium were not there at all.
This idea of “scattering-invariant modes of light” can also be used to specifically examine the interior of objects. The results have now been published in the journal Nature Photonics.
An astronomical number of possible wave forms
The waves on a turbulent water surface can take on an infinite number of different shapes – and in a similar way, light waves can also be made in countless different forms. “Each of these light wave patterns is changed and deflected in a very specific way when you send it through a disordered medium,” explains Prof. Stefan Rotter from the Institute of Theoretical Physics at TU Wien.
Together with his team, Stefan Rotter is developing mathematical methods to describe such light scattering effects. The expertise to produce and characterize such complex light fields was contributed by the team around Prof. Allard Mosk at Utrecht University. “As a light-scattering medium, we used a layer of zinc oxide – an opaque, white powder of completely randomly arranged nanoparticles,” explains Allard Mosk, the head of the experimental research group.
First, you have to characterize this layer precisely. You shine very specific light signals through the zinc oxide powder and measure how they arrive at the detector behind it. From this, you can then conclude how any other wave is changed by this medium – in particular, you can calculate specifically which wave pattern is changed by this zinc oxide layer exactly as if wave scattering was entirely absent in this layer.
“As we were able to show, there is a very special class of light waves – the so-called scattering-invariant light modes, which produce exactly the same wave pattern at the detector, regardless of whether the light wave was only sent through air or whether it had to penetrate the complicated zinc oxide layer,” says Stefan Rotter. “In the experiment, we see that the zinc oxide actually does not change the shape of these light waves at all – they just get a little weaker overall,” explains Allard Mosk.
A stellar constellation at the light detector
As special and rare as these scattering-invariant light modes may be, with the theoretically unlimited number of possible light waves, one can still find many of them. And if you combine several of these scattering-invariant light modes in the right way, you get a scattering-invariant waveform again.
“In this way, at least within certain limits, you are quite free to choose which image you want to send through the object without interference,” says Jeroen Bosch, who worked on the experiment as a Ph.D. student. “For the experiment, we chose a constellation as an example: The Big Dipper. And indeed, it was possible to determine a scattering-invariant wave that sends an image of the Big Dipper to the detector, regardless of whether the light wave is scattered by the zinc oxide layer or not. To the detector, the light beam looks almost the same in both cases.”
A look inside the cell
This method of finding light patterns that penetrate an object largely undisturbed could also be used for imaging procedures. “In hospitals, X-rays are used to look inside the body – they have a shorter wavelength and can therefore penetrate our skin. But the way a light wave penetrates an object depends not only on the wavelength, but also on the waveform,” says Matthias Kühmayer, who works as a Ph.D. student on computer simulations of wave propagation. “If you want to focus light inside an object at certain points, then our method opens up completely new possibilities. We were able to show that using our approach the light distribution inside the zinc oxide layer can also be specifically controlled.” This could be interesting for biological experiments, for example, where you want to introduce light at very specific points in order to look deep inside cells.
What the joint publication of the scientists from the Netherlands and Austria shows already is how important international cooperation between theory and experiment is for achieving progress in this area of research.
Reference: “Scattering invariant modes of light in complex media” by Pritam Pai, Jeroen Bosch, Matthias Kühmayer, Stefan Rotter and Allard P. Mosk, 8 April 2021, Nature Photonics.
DOI: 10.1038/s41566-021-00789-9
20 Comments
It’s similar to something called “Photomic Lensing”; similar to the effect produced when “discrete” LASER-sourced light passes around a sphere. That a material-specific light source would “pass through” said material is not magic. What are atoms but field coherent “spheres”? By “attenuation” I presume is meant a shift toward the long-wave end of the Spectrum. GREAT SCIENCE. What of APPLICATION? LOL I can see one of my boyhood wishes met. Remember (you are OLD if you do) those MAGICAL Glasses that promised the method and means to see through Woman’s clothing? The ones advertised on the back cover of comic books? We would have to fine-tune the manipulation of “scattering-invariant modes of light, but it’s feasible… Women beware! You’ll soon have nothing to hide. 👀 In the interim, let’s Science the Hell out it, Guys… 🤔 Bless our pointed little heads. 👼
Very curious about the use of this technology in firearm detection.
It seems impossible to divorce gun ownership from American society, so scientific discovery appears to be our only hope for greater public safety.
Here’s a spoon…
While the article and one of the researchers used the word “opaque,” I strongly suspect that what is meant is “transluscent.” Truly opaque substances have a refractive index composed of a real component (n) that is equivalent to what is usually called the index of refraction, and a mathematically imaginary component (ik) that is a measure of the absorption. Truly opaque substances tend to have high reflectivity and a metallic luster. Zinc oxide doesn’t fit that description. Furthermore, all oxides that I have measured have had negligible absorption (k).
Having a bit of a laugh with the title being self-contradictory. The ‘material’ is no longer opaque if the light penetrates it, nor is the beam ‘indestructible’. Yes, I am oversimplifying a lot. I get it. ((Chuckels))… 😉
Seems like there is a national defense opportunity to be explored here, similar to a cloaking device. Some form of reverse engineering?
Ahhh gun control, a method to take exactly what protects you from the same entity that it is designed to protect you from. What would you use if not a firearm to protect yourself from an already technologically superior military?
The police will probably have a new way of busting crack houses. In the future. The police could get a search warrant and used this new technology to see what is in the house before they entered the house. Which could save lives.
Why are we always worried about saving lives? There are over 7 billion people on this planet. The last thing we should be worried about is saving lives!
Yeah great comments guys are smarter than me but I can still understand them! This also sounds very similar to how spy technology can pick up the sound of audio by watching the flickering of waves from a lightbulb; very innovative
I would use this to defend myself if they take away my guns
In the event that houses are made from powdered materials and not solidified compounds, this may become useful in preemptive home invasion. But I don’t see that as a prominent building solution in the coming future.
Wouldn’t a good application of this be medical imagine specifically mammography? I know they spoke of cell imaging in the article but if it is scalable enough it could be a great option for optical mammography. This area of imaging can be tricky and sometimes very difficult depending on the patient’s morphology. If it is scalable it could maybe be more discerning and less expensive not to mention non-ionizing. I only say less expensive because if a woman has dense, fibrous, or otherwise challenging breast makeup I believe am MRI is what is called for, and they can be quite expensive.
Would it be theoretically possible / feasible to use this approach instead of or with muons to “look” at the chambers discovered in an egyptian pyramid that I learned about in another article?
Now amp up the beam strength to burn through thick material, condense the light into a small portable device, add said device to a 3d model Star Wars blaster, and BAM! Or should I say PEW! There you go, laser blasters for all!!!!!
How is this different than T-Ray?
Does this mean you could possibly use it as a lazer weapon?
Seems to me that the ability to “to focus light inside an object at certain points” sounds like the panacea for both good (I.e. 3D data storage), as well as for evil (i.e. insideous weapons).
This could possibly assist me in my three year ongoing quest to combine the green screen with energy to allow ghost to manifest using a high powered Laser beam spread out and its radiation I also have multiple lenses and outside as well as in use them to create Art in real time as large as the background is.
This began as a failed hologram missing one piece.
Note illumiRoddy on YT were I use a laundrymat I am convinced I have discovered a portal to another dimension as well although Einstien may refer to it as a glimpse into the future.
(Round room water coming down)
Note Wish catalog just referred to the laser matrix caps as “ghost finders.” I am blown away by the videos I shoot here do this skeptics take my video
Into frames .
This is the science behind superman’s “x-ray vision”