Imagine sitting down to dinner with the group of friends, when a laser tickles the water molecules inside your ears. You need to get home right away, your older child shouts.
“You need to get home right away,” your older child shouts. The younger one has fallen and cut their knee and might need stitches.
You stand up, excuse yourself, and make for the exit. Your friends have no idea why but assume you heard a message inaudible to the rest of them in the noisy room, transmitted into your ear by laser light.
These are things future scientists at MIT imagined when they developed a laser system. This system is to send sound across a room using laser light.
Their method is not the first to transmit sound waves in using lasers. But it is loudest. They have described their machine in a paper published on Jan 25 in the journal Optics Letters. This machine depends on wiggling a laser back and forth across the water molecules in the air by someone`s ear. That wiggling motion jolts the molecules and produces sound waves.
This doesn’t need much water
This can work even in dry conditions because there is almost always a little water in the air. Especially around people. As per research team leader Charles Wynn “We found that we don’t need a lot of water if we use a laser wavelength. It is very strongly absorbed by water. This was a key because the stronger absorption leads to more sound.
Other methods are still under development. They noted that they produce clearer sounds. There are methods like switching a laser on and off really fast to jiggle the water molecules. But those methods don’t make sounds as loud as a wiggling method. Researchers call it “sweeping” instead of wiggling. The main point of all this is to send messages to individuals in a crowd without blasting them over loudspeakers.
Ability of system
The ability to send highly targeted audio signals over the air could be used to communicate across noisy rooms. It can be used to warn individuals of a dangerous situation such as an active shooter. In the paper, the researchers said that some laser-sound techniques are under development by the military.
One thing that we should be clear with is that the underlying concept here isn’t very new. As per Alexander Graham Bell, who invented the first practical telephone has patented a device back in 1880. Which he did along with a partner named Charles Sumner Tainter that transmitted sounds via light.
Bell and Tainter`s Photophone-transmitter
The Bell and Tainter`s photophone-transmitter was a purposed instrument for controlling a radiant beam. Also to impart to it a varying character whereby in falling on an appropriate receiving-instrument the said beam may be made to produce sound.
Wiggle light over some material and sound should emerge. There are key differences, obviously, in the modern MIT system are that the receiver material is just ambient water vapor. That light is a precision laser. But the underlying concept is the same.
the researchers are going to try it outdoors and longer range. This will be the next step of MIT.