3D Printed Acoustic Holograms: Totally Cool, Not Totally Useless

If you wave your hand under the water’s surface, you get a pattern of ripples on the surface shortly thereafter. Now imagine working that backwards: you want to produce particular ripples on the surface, so how do you wiggle around the water molecules underneath?

That’s the project that a crew from the University of Navarre in Spain Max Planck Institute for Intelligent Systems undertook. Working backwards from the desired surface waves to the excitation underwater is “just” a matter of math and physics. The question is then how to produce the right, incredibly irregular, wavefront. The researchers’ answer was 3D printing.

The idea is that, by creating the desired ripples on the water’s surface, the researchers will be able to move things around. We’ve actually seen this done before in air by [mikeselectricstuff], and a more sophisticated version from the University of Navarre in Spain uses multiple ultrasonic transducers and enables researchers to move tiny objects around in mid-air.

What’s cool about the work done underwater by the Navarre Max Planck Institute group is that all they’re doing is printing out a 3D surface and wiggling it up and down to make the waves. The resulting surface wave patterns are limited in comparison to the active systems, but the apparatus is so much simpler that it ought to be useful for hackers with 3D printers. Let the era of novelty pond hacking begin!

13 thoughts on “3D Printed Acoustic Holograms: Totally Cool, Not Totally Useless

  1. Reading the article I’d say that this was done by “a team from the Max Planck Institute for Intelligent Systems, in Germany”. I understand the Navarre team in Spain did the air version of this using multiple transducers.

  2. There are a large number of “minor” complications, e.g. boundary reflections. The figure clearly does NOT show the surface of the water. It shows a time averaged surface. The give away is the color amplitude scale. So this is NOT what you would see looking at the water. This sort of stuff is why I quit reading the IEEE Spectrum website. Too many authors with exceedingly narrow knowledge breathlessly reporting things ridiculously wrong. I don’t know what the original research is intended to accomplish, but the Spectrum article is crap. The assertions made are quite simply silly as was pointed out in a few of the Spectrum comments. The major flaw in this approach is you do not get an impulse image. What you get is the image convolved with the motion of the transducer carrying the 3D printed interference pattern. The only reason they got an image at all is that they time averaged all the surface ripples so that they cancelled.

    As for the science and mathematics, this is stock and trade for the oil industry which runs hundreds of thousands if not millions of computers 24×7 doing the calculations. Individual imaging runs will use 50,000 nodes for a week. In short, this has been around a very long time in a variety of forms with a variety of applications. Kidney stone treatments being a common one. Rumor is that multiple USAF radars can blow out the receiver front ends on a hostile aircraft using the same basic idea.

    BTW Not meant to beat up in Elliot whose writing I respect. He just got suckered by bad writing and sloppy editing at IEEE Spectrum.

    1. If you click through to the page on Nature with the figures from the article, it does show both floating objects being attracted to the (anti?)nodes of the constructive interference pattern generated. It’s just the dove figure that doesn’t have a “that’s unambiguously real” picture associated.

    2. But I should know better! I usually like to read the original papers when I can, and here I didn’t.

      That said, if all they’re doing is trying to move little spheres (for instance) around on the surface of the water, and hold them in the image of Picasso’s dove for whatever obvious scientific purpose, all they need is a time-averaged surface, right? If the frequency of the wiggles are high enough, then the inertia of the little spheres should behave like they’re doing time-averaging as well, and settle in nicely to their average valleys.

      And all _that_ said, I’m waaaay out of my depth on this one. What’s the application in industry? Are you talking oil prospecting? Or are they moving stuff around using surface waves?

      1. Yeah you should have read the actual paper, then you’d know Reg was talking out of his ass and that Fig. 3b does in fact show an “Oblique angle photograph of the crests formed by the hologram in f–h“.

        And for anyone wishing to do something similar to this work on a DIY level I suggest that you start with an array of transducers each driven by a signal generator where you have amplitude and phase control, then using genetic algorithm methods and feedback from open CV code processing the image of the light (caustics) passing through the resulting waves you will be able to have a solution converge on a reasonably optimal configuration to produce whatever image you desire. For extra fun do it with a clear UV setting resin and hit it with the UV once you have established the standing waves.

        Reg you are a yahoo, and completely useless.

  3. Hello, i think this is fantastic!!!!
    I Have been doing some research on Cymatics, frequency and energy behaviour, specialy the efect of wave frequency on matter. I also Have been studyingi about the ancient symbols of past civilizations where they print their wisdom on extraordinary patterns And also that talks allot about their technologies And knowledge. Im working on a proyect reggarding sound And geometrical patterns as a form of art and technology development which i have to say is way beyond our time to understand how it works And how can we use it And where to use it.
    Please i Will appreciate if you keep me posted on further information reggarding frequency waves technology And Cymatics. Thanks for sharing.

  4. Once again, i Have to mention the japanese Dr. Emito Masaru who made several experiments with frequencies like sound, labels, thoughts, words, pictures And even prayers from tibetan monks. Watching amazing results on water And the efect of all these kinds of frequencies And the efect this has on water, by freezing it And watching it under the microscope amazing water christals with wonderful shapes all different as a result of the exposure of frequencies. Ofcourse there was also the non Beautiful ones which they where expose to more negative frequencies.
    It is quiet interesting all his work on water christals.
    So based on his work And in combination with Cymatics there is a huge field of study And work reggarding this topic And i think the wave 3D printing is such a good idea, Just imagine the possibilities using frequencies that could help to Heal people or restore cells from cancer. Or Just print What your thoughts are in a geometrical pattern or even physical.

    Consider the information And once again, Thanks for sharing.

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