LASERS: Lasers have come a long way since Albert Einstein first established their use and applications in 1917 in the publication Zur Quantentheorie der Strahlung (On the Quantum Theory of Radiation). In the context of lasers, there is an assumption that they have to do with visibly manifested things, essentially things that we can see and perceive to be physically alternated in some way, which is not surprising because lasers have to do with light as they are devices which emit light through optical amplification. Hence, the original acronym of laser (“light amplification by stimulated emission of radiation”). Let us forget this assumption with the latest developments in laser-tech coming from Massachusetts Institute of Technology (MIT). While the news is serious, recent headlines make it seem as if this technology has suddenly appeared in a groundbreaking form, which as you shall find out is misleading. Namely, the story is this: MIT scientists have figured out a way of using a laser to transmit audio, ranging from music to speech. That first assumption that was mentioned earlier? Forget it, lasers as it turns out, can be used for audible means.
This is a potential breakthrough for audio and communication: Imagine standing in a room and you want to transmit some sort of sound, be it a tiny whisper or a song. Without receiver equipment and using lasers and a bit of moisture, this is now possible. MIT have figured out a way to be able to whisper in your ear without the surroundings even hearing what is said all because of the photoacoustsic effect – in this case an invisible laser interacts with its environment and the moisture around it for you to pick up a signal that only “tickles in your ear”. The first question raised here is obvious: is it safe? Upon reading this, many would perhaps draw the connection of lasers used in laser eye surgery (LASIK) and would assume that this laser could be damaging in some way or another. We don’t even see the radiofrequency radiation (radio waves) being emitted of cell phones and yet some people refrain from using cell phones because of this fear of the unknown. In this case, the researchers claim that their technology is completely harmless, and now they hope to commercialize it. However, what does this really mean for the community of science and technology? Is this completely new? Yes and no. To understand the implications of what this means, it’s best to read a segment from the official press release (paraphrased from Science Alert)
“It is the first system that uses lasers that are completely safe for the eyes and skin, in order to send an audio signal to a specific person in any environment,” says research team leader Charles M. Wynn to Science Alert.
MIT’s Lincoln Laboratory is where the magic has happened once again and the laboratory now believes that their solution is unique. They utilize the photoacoustic effect, which means that matter that absorbs light can be caused to produce sound waves. With a 1.9 micron thulium laser, the researchers made water vapor vibrate with an audible frequency. At the first tests with a regular modulator, one could capture the sound with a microphone at a distance of 2.5 meters away. This is not some sort of stereotypical laser sound effect reminiscent of the Star Wars films. This is a reality that can be broken down even further: there are several ways of working with technology to generate sound at a specific point with laser. The Massachusetts Institute of Technology claims that they can whisper a message into the ear of a person many meters away without hearing the surroundings. This entails that the technology could be used in places where the environment has disturbing sounds. A noisy classroom? A Sunday fish market? How about a warzone? Recent geopolitical commentators suggest that we have been in a new Cold War since 2008, can this be used in the military? The conspiracy-minded have even made similar connections to subliminal advertising and how inaudible sounds have been used in marketing slogans and campaigns. Lasers. Sounds. Let’s be real: it’s an astonishing breakthrough.
No one else hears the message…
The researchers used what is known as the photoacoustic effect which occurs when a material forms sound waves after absorbing light (Geek.com) In this case, researchers used water vapor in the air to make up light and create sound. But you need to be standing in a rainstorm or sitting at the bottom of a pool for the technique to work. “This can work under relatively dry conditions as there is almost always some water in the air, not least around people,” says Wynn. The photoacoustic spectroscopy means that the sound can only be perceived at a certain distance, but it also means that one can send messages to a specific individual who is inaudible to the surroundings. The researchers mentioned the potential commercialization, but what’s interesting and perhaps more frightening is application in the military as was mentioned above. This is where this new breakthrough falls behind in its sense of novelty as headlines claiming that this is the first time something like this is brought to the surface is misleading.
The US military was earlier in its findings than MIT, and they are currently investing in greater distances than just a short room. Last year, the Joint Non-Lethal Weapons Program showed a clip where they generated sound and light using laser. They have named their concept Laser-Induced Plasma Effect. A powerful laser transforms the air molecules into a plasma ball and it is then manipulated by a second nanolaser. The result in the movie clip was an unpleasant crackling sound with elements that could possibly be interpreted as voice-like – but the Pentagon thought in 2018 that within three years it will be possible to project a clear voice at great distances. The armed forces have managed to create plasma balls at a distance of three miles. This begs the question: could this be used to send subliminal messages during election periods and changing peoples’ votes? This opens up a new level of debate in yet another thrilling area of tech. Will we see a larger number of the population claiming they are hearing voices? The voice of the laser – a voice that we may hear more about in the coming years.
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