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The role of laser systems in modern life
Today, in the era of new technologies, it is very hard to imagine human life without the use of laser systems. Fiber lasers became an integral part of modern equipment and society as a whole. The fields of their application continue to enlarge and include not only physics, medicine, and other natural sciences, but also security.
Recently, a group of researchers from Massachusetts has developed a laser system-based technique of transmitting different audio signals and even recorded speech at a conversational volume to a person without any receiver equipment. The principle of the laser module device operation is based on the photoacoustic effect.
How the technology works
It is possible to transmit sound selectively due to the use of water vapor in the air, with the aim of light absorption and then the creation of a sound. The use of the laser system device is not limited to only wet conditions, but it is ideal for relatively dry conditions because the air always has a little amount of water, especially around people.
Also, the researchers found that it is not required to have a lot of water due to a laser wavelength that is highly absorbed by water. The stronger absorption leads to more sound. The laser system device creates an audio signal that is heard at a certain distance from the transmitter, enabling it to be localized to a certain person.
Basis of the development
The basis for the laser module development was a method called dynamic photoacoustic spectroscopy for chemical detection because sweeping a laser beam at the speed of sound could make chemical detection more precise. The main particularity of the method is that the audio signal can only be heard at a certain distance from the transmitter.
It means that an individual can get the message rather than a group of people crossing the light from the laser beam. The researchers confirm that there is a possibility of transmitting the message to multiple individuals. They also demonstrated the transmitting distance that is more than 2.5 meters away at 60 decibels using the laser system sweeping technique. In the future, the distance could be longer.
Accuracy and advantages of the method
The conventional photoacoustic technique provides sound with higher accuracy, whereas the laser beam sweeping provides sound with louder audio. The possibility of transmitting highly targeted audio signals over the air is considered to be quite useful for warning individuals of a dangerous situation, for example, during terrorist attacks. It is the first system that uses laser systems that are totally safe for the eyes and skin to localize an audible signal to a particular person.