[ad_1]
Researchers have shown that a laser can transmit an audible message to a person without any type of receiver equipment. The ability to send highly targeted audio signals by air could be used to communicate through noisy rooms or warn individuals of a dangerous situation such as an active shooter.
In Optics Letters of the Optical Society (OSA), researchers at the Lincoln Laboratory at the Mbadachusetts Institute of Technology say they use two different laser-based methods to transmit sounds, music, and speech in a conversational volume.
"Our system can be used at a distance to transmit information directly to the ear," said Charles M. Wynn, head of the research team. "This is the first system that uses totally safe lasers for the eyes and skin to locate a sound signal to a particular person, regardless of the context."
Create sound from the air
The new approaches are based on the photoacoustic effect, which occurs when a material forms sound waves after absorbing light. In this case, the researchers used the water vapor contained in the air to absorb the light and create a sound.
"It can work even in relatively dry conditions, because there is almost always a little water in the air, especially around people," Wynn said. "We found that we did not need a lot of water if we used a laser wavelength very strongly absorbed by water. This was essential because the stronger absorption leads to more of her ".
One of the new methods of sound transmission comes from a technique called dynamic photoacoustic spectroscopy (DPAS), which researchers have previously developed for chemical detection. In previous work, they discovered that scanning or scanning a laser beam at the speed of sound could improve the detection of chemicals.
"The speed of sound is a very special speed to work on," said Ryan M. Sullenberger, the newspaper's first author. In this new article, we show that scanning a laser beam at the speed of sound at a wavelength absorbed by water can be used as an effective way to create a sound. "
For the DPAS approach, researchers are changing the length of laser scans to encode different frequencies, or sound pitches, in light. A unique aspect of this laser scanning technique is that the signal can only be heard at a distance from the transmitter. This means that a message could be sent to a person rather than to everyone pbading through the beam of light. It also opens the possibility of targeting a message to several people.
Laboratory tests
In the laboratory, researchers have shown that a commercially available equipment could transmit sound to a person at a distance of more than 2.5 meters to 60 decibels using the laser scanning technique. They believe the system could easily be extended to longer distances. They also tested a traditional photoacoustic method that does not require laser scanning and encodes the audio message by modulating the power of the laser beam.
"There are tradeoffs between the two techniques," said Sullenberger. "The traditional photoacoustic method provides a sound of greater fidelity, while laser scanning provides sound with a more powerful sound."
Researchers then plan to demonstrate outdoor methods at longer distances. "We hope this will eventually become a commercial technology," said Sullenberger. "There are many exciting possibilities and we want to develop communication technologies in a useful way."
Research report: "Photoacoustic communications: emission of sound signals by absorption of light by atmospheric H2O"
Related Links
The optical company
New Space Technologies – Applications and Research
|
We need your help. The SpaceDaily information network continues to grow, but revenues have never been more difficult to maintain. With the rise of ad blockers and Facebook, our traditional revenue streams via quality advertising on the network continue to decline. And unlike so many other news sites, we do not have a paywall – with these usernames and boring pbadwords. Our press coverage takes time and effort to publish 365 days a year. If you feel that our news sites are useful and useful, then consider becoming a regular supporter or contributing for the moment. |
||
|
SpaceDaily Contributor $ 5 billed once credit card or paypal |
 |
SpaceDaily Monthly Supporter $ 5 billed per month paypal only |
Raytheon signs a contract with Elbit Systems for a two-color laser system
Washington (UPI) January 4, 2019
Raytheon won a contract with Elbit Systems of America for the two-color laser system, part of the surveillance system embedded in a military aircraft.
The financial terms of the agreement were not disclosed in a press release published on the Elbit Systems website, but the US subsidiary of the Israeli company announced that the contract would be concluded in 2019. The two-color laser system serves the multispectral targeting system, Elbit Systems says.
The system, also known as TCLS, has a size, a weight … read more
[ad_2]
Source link
