One of the most spectacular technologies that we have seen in science fiction films, but have not yet been able to bring to life - holograms. However, British and Japanese scientists were able to bring the future closer: their device uses ultrasound to create tangible color volumetric images.
The secret of the "Multimodal acoustic trap display" (MATD) is simple: it is hidden in the name itself - acoustic traps. The essence of the phenomenon is that sound waves, configured in a certain way, can hold a fairly light object in the air. Just as areas of debris or foam that do not float away are formed along a coast with a complex geometry at the intersection of incoming and reflected waves, acoustic air vibrations form "traps."
MATD consists of two arrays of 15x15 ultrasonic transducers located above and below the imaging region. They direct waves towards each other and "catch" an almost weightless plastic ball with a diameter of several millimeters. The projector uses a series of acoustic traps to move it very quickly through the air. The speed reaches 8.75 m / s vertically and 3.75 meters per second horizontally. In a limited volume, this allows the ball to flicker so that the human eye does not have time to track it.
Several sensors and light emitters are located around the imaging area between the emitters. Sensors track the position of the ball, and LEDs illuminate it from different sides at the right time. So he gets the desired color and becomes visible, and accordingly forms an image. Of course, a digital camera can only capture the result at long exposure, but in any case, this is a breakthrough device.
A projector can simultaneously interact with several objects, and not all of them must necessarily form an image. For example, if you put your hand into the area of the hologram, the emitters will help you feel the wind blowing from the flapping of the butterfly's wings or give tactile feedback. Moreover, the hologram can produce sounds audible to a person, which further adds to the realism of the three-dimensional picture.
Undoubtedly, the technology requires a lot of improvements and is not one hundred percent original. Acoustic traps have previously been used to move objects in the air, as well as to form volumetric images. But engineers and scientists from Sussex managed to implement several functions in one device at once, which have been found for so long in the cinema, but never in life. All previously created holographic projectors were either pseudo-three-dimensional displays, or formed a picture with lasers in a special environment.
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Author: Vasily Parfenov