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Kris Merkel, co-leader of the S2 CHIP project in the MSU Spectrum Lab. (Stephen Hunts photo)

Group rethinks radar with lasers and crystals

By Annette Trinity-Stevens

Depending on whom you ask, radar either fought World War II or it won it.

Though a war hero, radar didn't begin in the 1940s. The key concepts came along some decades earlier, and the first idea for implementation centered on helping ships avoid obstacles like the iceberg that tragically sank the Titanic.

Like many influential technologies, radar has a long line of inventors beginning, perhaps, with Heinrich Hertz, a German scientist who first studied radio waves in the 1880s. Likewise, it's an invention with a lot of stories. Here's a recent one that can be told from Montana.

Cooked at 4000 degrees


MSU Spectrum Lab director Randy Babbitt holds the crystal that's at the heart of the proposed new radar technology. (Stephen Hunts photo)

Randy Babbitt holds in his hand what looks like a piece of glass. Clear and inauspicious, the crystal about the size of a fingernail was sliced off a much larger crystal that was grown in about 14 days from molten powders heated to 4000 degrees Fahrenheit.

The crystal gives no clues as to what it might be used for. You could make it into a necklace or hang it from your rearview mirror or add it to a collection of odd minerals and chunks of pyrite.

Instead, Babbitt, a professor of physics and head of the Spectrum Lab at Montana State University-Bozeman, and a team of other scientists plan to make it the brain of an advanced type of radar.

They're working with Scientific Materials Corporation, which made the crystal. Now the Bozeman company has a $16-million, 5-year contract from the U.S. Army Space and Missile Defense Command. The project, funded by the Missile Defense Agency, seeks to build around the crystal a host of electronics and other components. In the end, Scientific Materials envisions marketing a radar component that offers much higher resolution information than available in today's systems. Likely customers include the military for reconnaissance, ships and missile targeting. Air traffic controllers are potential users as well.

Echo and shift

Radar technology relies on two simple concepts. The first is echo. The other is Doppler shift. Radio waves are pulsed from a transmitter, bounce off a distant object and echo back into the "ear" of a radar antenna. By measuring how long it takes for the echo to return as well as the Doppler shift, or compression, of those radio waves, the radar system figures out how far away the object is as well as how fast it's moving.


MSU contributors to the S2 CHIP technology include (top, from left) Zack Cole, Randy Babbitt, Yongchen Sun, Mark Ivey and Todd Harris; (bottom, from left) Kris Merkel, Krishna Rupavatharam, Dennis Bacon and Kevin Repasky. (Stephen Hunts photo)

Scientists from several countries were contemplating radar systems in the opening decades of the 20th century, but it was the British, worried about Germany's military buildup in the 1930s, who pushed ahead, wrote Robert Buderi in "The Invention that Changed the World." (Interestingly, the British briefly entertained the idea of using radio waves as a death ray, but calculations quickly showed that it would be easier to detect an enemy pilot with radio waves than to blow him up with them.)

By 1940, England had surrounded herself with a series of radar units called "Chain Home" that successfully warned when the German Luftwaffe was on its way.

Radar systems became more sophisticated as the war went on, with several American scientists playing key roles. Today, a form of radar automatically opens the door at the grocery store. Meteorologists use radar to predict weather. Police officers catch speeders with it, and air traffic controllers use it to track planes. In the military, radar systems guide weapons and warn of enemies. In the kitchen, microwave ovens have at their core an invention that first belonged to radar.

Millions of colors

The Montana invention is called the S2 CHIP. S2 means spatial spectral. CHIP stands for coherent holographic integrating processor. But don't worry about remembering that.

At the heart of S2 CHIP technology is the crystal that can "see" millions of colors of light, each bearing information. What's more, the crystal can remember patterns of light and can process what's different about them.

So the proposed processor would work like this: As with today's radar, a signal goes out toward a distant object. At the same time, the signal is encoded onto a laser beam and shone on the crystal as multiple colors. When the return radar signal or echo comes back, it, too, is encoded onto a laser beam and sent to the crystal as multiple colors.

The crystal now has received the same light pattern twice, only the return pattern-the one that bounced off the distant object-is attenuated, or weaker. The crystal is smart enough to analyze the time delay between the two patterns and to measure any color shift between them. In other words, as with today's radar, the crystal can tell how far away the approaching object is and how fast it's traveling.

But because the crystal has so much more processing power than current electronics, the crystal could also tell a radar operator details about the shape of the plane, such as the distance between its nose, wing and tail.

Current radar systems have to ignore lots of pulses bouncing back from the distant object that might be nanoseconds apart. Well, maybe not ignore-they don't even know they're there. But the crystal-with the help of lasers and other inventions-has the resolution to know those pulses are there. Plus, it has the processing power to do something with them. It can help a radar operator distinguish between different types of planes, which would be darn handy if a plane lacks a transponder to identify itself.

A prototype in three years

The beauty of S2 CHIP technology is its ability to do its intense processing of echoes and Doppler shifts, and then download that information to conventional, off-the-shelf, robust and reliable low-bandwidth electronics. If the crystal had to hand off its information to high-bandwidth electronics, well, there wouldn't be a story here yet. "High bandwidth electronics exist," said Randy Equall, director of research technology at Scientific Materials, "but those electronics are very expensive or lack the performance capabilities required for advanced missile defense radar systems."


Scientific Materials President Ralph Hutcheson (left) and Director of Research Technology Randy Equall show a crystal in the company's crystal growth room. (Stephen Hunts photo)

The project funded by the Missile Defense Agency is for Scientific Materials, MSU-Bozeman and the University of Colorado to engineer the crystal, lasers, cooling system and other necessary components into a rack of electronics that, as Babbitt puts it, "doesn't need a Ph.D. to operate it."

The team plans to have a lab model done in two years, a prototype in three and a plan to commercialize in five. Scientific Materials will hire more employees but isn't sure yet how many. About six MSU patents have been filed on elements of the technology.

Even so, the scientists emphasize that many of the S2 components already existed.

"The odds in 1995 of commercializing this technology was 1 in 10,000," said Scientific Materials President Ralph Hutcheson. "The odds today are better than 1 in 10 because of all the new developments that have occurred, both in Montana and elsewhere."

The Montana contributions include the crystal, the lasers that "talk" to the crystal, and how the crystal processes information. In fact, Babbitt said that the field to which the S2 CHIP belongs might have died altogether some years ago if Hutcheson hadn't started making high-quality and affordable experimental crystals at his Bozeman company. No one else in the world was providing this essential service.

Mention this to Hutcheson, a modest man, and he fidgets with his tie without saying anything. Just another side note, one supposes, in the ongoing story of radar.

Contributions to the S2 CHIP technology came from scientists in the Spectrum Lab and physics department at MSU; the University of Colorado and at Scientific Materials. The Montana Board of Research and Commercialization Technology has contributed to the project by funding some of the work of MSU scientists. Other funding has come from the Air Force Office of Scientific Research, the Ballistic Missile Defense Organization, the National Science Foundation and the Defense Advanced Research Project Agency (DARPA). The MSU Spectrum Lab was funded initially with appropriations from NASA and the Department of Defense through the efforts of Montana Sen. Conrad Burns.



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Research Notes | Faculty and Student Awards | Research Expenditures for Fiscal Year 2003

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