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MIT invented slightly ominous lasers that transmit whispers you can only hear



The new technology, developed by Lincoln's Massachusetts Institute of Technology, uses laser light to excite the humidity in the air around the target's ear, resulting in a quiet whisper of a few meters of personal message.

"Our system can be used remotely to broadcast information directly to someone's ear," says the head of the MIT team and physicist Charles M. Wynn.

Probably we do not need to count potential apps for such devices, ranging from military applications to targeted ads.

Pretty much where environmental noise is a problem – or the headphones are inappropriate – a laser whisper can do this.

In case you worry about a "laser in your ear", the developers promise it is harmless.

"This is the first system that uses lasers that are completely safe for the eyes and skin to locate a beep to a particular person in any environment."

The technology that channels the sound in a narrow field has existed for decades.

Most use speakers to amplify sound waves or to channel ultrasound in a small area. Although useful for keeping the volume relatively limited, they require the listener to be at a relatively short distance from the source. "That's why the team has turned from speakers to lasers.

The heart of MIT's new technology is a 1

.9 micrometer tall laser. Thanks to the principle called photoacoustic effect, the water vapor in the air absorbs the emissions of the laser, which results in vibration of the sound frequency. "It can work even in relatively dry conditions because there is almost always a little water in." We found that we do not need plenty of water if we use a wavelength of the laser that is very highly absorbed by the water. This is the key because stronger absorption leads to more

The team tests two methods of transmitting sound. The first simply changes the laser amplitude through a continuous wave modulator, creating vibrations that can be taken from a 2.5 meter (8 feet) microphone.

Forwards and backwards with the velocity of sound in so-called dynamic photoacoustic spectroscopy, which effectively creates stronger waves by stirring more water particles. Salonberger.

"The traditional photoacoustic method provides sound with greater accuracy, while laser sweeping provides sound with louder sound." Any closer, and the laser will be too high. Everyone further down and the frequency falls below the audacity.

Although it's only tested with a volume of 60 decibels (the level of a normal conversation) a few meters, the researchers believe they can now increase the distance and volume now

. "We hope this will eventually become in commercial technology, "says Sullenberger.

This means that in the future someone can potentially emit rumors of your ear from significant distances … something that is light.

This study is published in OSA Publishing .


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