Anyone who has seen Star Wars will be familiar with the concept of optical hologram-a 3D image floating in mid-air-although the technology in real life is far less advanced than that depicted on the screen.
Hologram is actually a record of 3D light field, and a copy of the original can be projected under sufficient light. (The term hologram can refer to the recording medium and the generated projection. The concept of hologram can be applied to sound waves to produce sound wave holograms, although according to the scientists who developed this new method, this research field is still very new. 10 future technology "Star Trek" fans really want to see it.
The previous methods required complex loudspeaker arrays and control electronics. But now, researchers have demonstrated how to use walls made of complex plastic bricks to bend the sound waves emitted by a single speaker into complex three-dimensional shapes.
It is a computer rendering of sound waves, which propagate through a series of acoustic metamaterials and are shaped into a pattern, just like a letter passing through a one-foot array. This pattern is invisible and can only be heard. Steve said, "What we have shown is that you can create a very complex sound field from a very simple sound source with carefully designed and manufactured structures. ? Cuomo said,
"It's like a hologram. You put it in front of a beam of light, and then it's "a more complex sound field," says Cummer, a professor of electrical and computer engineering at Duke University in North Carolina, so it doesn't need any additional sources-it's just a supplement to any sources you already have, and it's relatively easy to manufacture, "he told Live Science.
Building "brick" brick is a kind of so-called metamaterial, a family of materials with special engineering microstructure, which leads to unusual properties that have not been found in essence. The research team designed 12 different types of bricks, which can effectively slow down sound waves at different speeds.
These bricks are made by traditional 3D printers and used as pixels of holograms. The improved optical hologram design algorithm is used to determine the structure of the brick needed to reproduce the required three-dimensional sound field.
In a paper published in Science Report on October 4th, 654381KLOC-0, the researchers described how to make a 256-pixel hologram by this method, and transform the uniform sound and fluctuating sound waves into the sound field in the form of letter A. Scientists made another hologram as a holographic lens by focusing the sound energy on several circular points with different sizes.
Cuomo stressed that this research is exploratory at this stage. However, Bai Yang, a doctoral student in Cummer Lab and the first author of the paper, said that this method has obvious advantages over the previous method of relying on loudspeaker array.
"Other methods consume a lot of electricity; They need quite complicated control circuits and electronic equipment, "Xie told Life Science, because the system is more complicated, it is often more unstable. With our method, once you create a hologram, it will last for a long time, be very stable and consume no electricity.
Xie added that a potential application of this technology is audio speakers. He said that the commercialization office of the university is actively looking for industrial partners to help develop this technology.
"Speakers can not only transmit frequency and tone information, but also provide spatial information." If you play cello suite on iPhone, it sounds like speakers are playing cello suite. One potential application is that we can use holograms to reconstruct a better acoustic scene, where your feeling of sound space information is more realistic.
Peer Fischer, a physical chemist at Max Planck Institute for Intelligent Systems in Stuttgart, Germany, was not involved in this research, but he said that this new method seems promising. His team recently produced acoustic holograms from ultrasonic waves using specially designed 3D printed plastic blocks.
"This is especially promising for long-wave and low-frequency acoustics, because it makes the elements of holograms very compact," he told field science. Their method will bring exciting possibilities in forming sound fields.
However, researchers also hope to adjust their methods to manipulate ultrasound. Cummer said that the wavelength of ultrasonic wave is much shorter, so this means reducing the brick to its current size of 1%.
Cummer and his colleagues collaborated with scientists at the Massachusetts Institute of Technology to create an early version of millimeter-scale bricks with smaller internal features.
Researchers believe that this may lead to better ultrasonic imaging equipment.
The current system uses sensor arrays (basically speakers) to generate precisely controlled sound waves, but the stick needs to be connected to a large machine to adapt to the complex control system. Professor Xie said that the system using this method can be more compact.
Some start-ups are also studying the use of ultrasound to wirelessly charge mobile phones. Professor Xie said that their method can greatly simplify the control methods of these systems.
This is an original article about life science.