RSS Feeds

Earth Science

Space Science

Life Science

Fields of Scientific Study

Nanotechnology

Cancer

Definitions of The Fields of Scientific Study

Lasers Generate Underwater Sound

September 08, 2009

Scientists at the Naval Research Laboratory are developing a new technology for use in underwater acoustics. The new technology uses flashes of laser light to remotely create underwater sound. The new acoustic source has the potential to expand and improve both Naval and commercial underwater acoustic applications, including undersea communications, navigation, and acoustic imaging. Dr. Ted Jones, a physicist in the Plasma Physics Division, is leading a team of researchers from the Plasma Physics, Acoustics, and Marine Geosciences Divisions in developing this acoustic source.

Efficient conversion of light into sound can be achieved by concentrating the light sufficiently to ionize a small amount of water, which then absorbs laser energy and superheats. The result is a small explosion of steam, which can generate a 220 decibel pulse of sound. Optical properties of water can be manipulated with very intense laser light to act like a focusing lens, allowing nonlinear self-focusing (NSF) to take place. In addition, the slightly different colors of the laser, which travel at different speeds in water due to group velocity dispersion (GVD), can be arranged so that the pulse also compresses in time as it travels through water, further concentrating the light. By using a combination of GVD and NSF, controlled underwater compression of optical pulses can be attained.

The driving laser pulse has the ability to travel through both air and water, so that a compact laser on either an underwater or airborne platform can be used for remote acoustic generation. Since GVD and NSF effects are much stronger in water than air, a properly tailored laser has the ability to travel many hundreds of meters through air, remaining relatively unchanged, then quickly compress upon entry into the water. Atmospheric laser propagation is useful for applications where airborne lasers produce underwater acoustic signals without any required hardware in the water, such as undersea communications from aircraft.

Also, commercially available, high-repetition-rate pulsed lasers, steered by a rapidly movable mirror, can generate arbitrary arrays of phased acoustic sources. On a compact underwater platform with an acoustic receiver, such a setup can rapidly generate oblique-angle acoustic scattering data, for imaging and identifying underwater objects. This would be a significant addition to traditional direct backscattering acoustic data.

Naval Research Laboratory

Related Underwater Sound Current Events and Underwater Sound News Articles

NJIT professor's research suggests changes in underwater data communications
An NJIT professor, who has discovered new communication channels in underwater environments and invented a technique to communicate data through these channels, will be honored later this month by the New Jersey Inventors Hall of Fame.

How is that whale listening?
Researchers from San Diego State University and the University of California have been using computer models to mimic the effects of underwater noise on an unusual whale species and have discovered a new pathway for sound entering the head and ears.

More Underwater Sound Current Events and Underwater Sound News Articles

	Principles of Underwater Sound 3rd Edition by Robert J. Urick (Author)
	Drowning Underwater - Horror Sound Effect Ultimate Horror Sounds (Primary Contributor)
	Escape to Nature, Vol. 2: Underwater Peace Starring: Various Artists Relaxation is guaranteed while watching the new DVD series ESCAPE TO NATURE. The soothing tranquility of the underwater world is featured on Volume 2, UNDERWATER PEACE. Become one with the elements and find instant relaxation at a great price.
	Clark Synthesis AQ339 Aquasonic Underwater Speaker by Tactile Sound Tactile Sound has been the leader in design and production of tactile transducers for over 10 years. Their unique products are designed to provide the best possible sensory experience, and take music and movie listening to another level. Utilizing the latest in engineering and materials, their products have continually improved into a complete line of one-of-a-kind transducers. Whether you are constructing a home theater, building a garden sound system, or adding sound to your swimming pool, Tactile Sound has a product that can enhance your experience. This underwater speaker is designed to be submurged into a pool, providing sound for training and recreating. Its non-permanent installation allows the transducer to be positioned anywhere in a pool, and it can be easily moved or removed...
	Salmon Underwater, Clayoquot Sound, Vancouver Island National Geographic Collection Photographic Poster Print by Joel Sartore, 40x30 by Art.com Art.com is the world's largest retailer of art prints, posters, photographs, and framed artwork. With our huge selection of over 400,000 prints, you'll easily find the perfect piece for your home, office, or classroom. Our art is printed on quality paper. When you order framed artwork, the piece is built by our team of in-house professionals. Visit our Amazon store today at www.amazon.com/artdotcom to find Special Offers and search for products based on 'Artist Name' and 'Subject Categories' such as Movie, Music, Vintage, TV, Children, Travel, Kitchen, Museum Art, Animals, Floral, Motivational, and Sports. Art.com is dedicated to providing you with high quality products and service by offering you 100% satisfaction guaranteed. We ship internationally to over 80 countries. Decorate your...
	An Introduction to Underwater Acoustics by Xavier Lurton (Author) Presented in a clear and concise way as an introductory text and practical handbook, the book provides the basic physical phenomena governing underwater acoustical waves, propagation, reflection, target backscattering and noise. It covers the general features of sonar systems, transducers and arrays, signal processing and performance evaluation. It provides an overview of today's applications, presenting the working principles of the various systems.
	Underwater Kona [VHS] Directed By: Judy Brown JB Productions creates unique MPEG-2 underwater videos on CD-ROM specifically for playback on MS Windows-based computer systems. Not VHS, not DVD, these videos will not play on standalone players. Any computer 2 years old or newer can play these CDs from either the CD or DVD drive. Underwater Kona is the first title released in this format. Turtles groomed by yellow tangs, free-swimming eels, manta rays cruising overhead, an octopus peeking out from behind a coral head - all common scenes in the waters off the coast of Kailua - Kona on the Big Island, Hawaii. Relax to the ebb and flow of underwater life accompanied by soothing audio tracks licensed from Sugo Music.
	Deep Voyage by Aris Multimedia Entertainment, Inc. Explore another dimension of still and uncharted waters! The tranquil vistas of the deep open up to show you a universe of beauty and terror...Come Join us!
	Underwater; waves roll overhead, bubbles foaming and gurgling to the surface. Dolphins communicate in the murky depths. Our World's Sounds (Primary Contributor)
	Underwater Acoustics: An Introduction (Springer Praxis Books / Geophysical Sciences) by Xavier Lurton (Author) Sound waves are the only practical means of remote investigation of the sea and its bottom and transmission in seawater. Underwater acoustics has become one of the major technologies used in the exploration and exploitation of the oceans for scientific, industrial, or military/naval purposes. It is widely employed in the fields of ocean engineering, seafloor mapping, defence, oceanography, navigation, and fisheries. Dr Xavier Lurton is a renowned specialist in underwater acoustics. He has worked in this field as a scientist, engineer, project manager and teacher since 1981 and has participated in many scientific projects, systems developments and at-sea cruises. In the second edition of his book, Dr Lurton provides an updated and extended introduction to underwater acoustics,...