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Sound Metrics Corporation
15029 Bothell Way NE, Suite 100
Lake Forest Park, WA 98155
Based in Lake Forest Park, Washington, Sound Metrics Corporation designs and manufactures imaging sonars that deliver the clearest, most detailed video images in their class. The company’s line of products can be deployed from vessels, ROVs (remotely operated vehicles), AUVs (autonomous underwater vehicles) and by divers.
In 1999, the U.S. Navy asked engineers at the Applied Physics Lab, University of Washington, to develop a tool capable of identifying swimming intruders in cloudy or dark water. With very detailed image quality and fast frame rates, the imaging sonar the researchers created delivered near video-like data, enough to capture the behavior of highly dynamic objects. Requests for other applications soon followed and in 2002 the research team founded Sound Metrics Corp.
Seeing with sound
Sound Metrics imaging sonars transmit sound pulses and convert the returning echoes into digital images, much like a medical ultrasound sonogram. The advantage is that they can “see” what’s going on through dark or turbid (cloudy) water in zero visibility conditions.
Why use sound in the first place? Sound wavelengths in water are about 2,000 times longer than those of visible light. Because of its longer wavelengths, sound can go around suspended particles that would otherwise block and scatter light waves. Light can’t penetrate very far in these conditions, making optical systems (like underwater cameras) ineffective. Also, optical images lack the range information found in sonar images.
The performance of an imaging sonar—from the distance at which they can detect an object, to the clarity of the image, to the number of images they can display per second—are determined by a number of specifications, most notably the operating frequency, acoustic beamwidth and processing power and time to form an image. Sound Metrics sonars use acoustic lens technology which forms beams instantaneously using zero power.
Generally speaking, a lower frequency increases the distance at which an image can be captured. A higher frequency and a smaller beamwidth used to map an object will deliver clearer images. The depth at which the sonar is deployed has no direct effect on how clearly an imaging sonar can capture a target.
Phone: 206 364 1441