Infrared sensors and other electro-optical sensing devices for aerospace and defense applications have come a long way in the past few decades, and over the next several years will see major technological breakthroughs in sensitivity, resolution, and overall ability to help military forces see through fog, smoke, dust, and the darkness of night.
The two most widely used electro-optical sensors for military and aerospace applications involve infrared (IR) and light amplification sensor technology. IR sensors, for example, primarily detect heat signatures, while light-amplification sensors -- such as night-vision goggles -- amplify available light thousands of times to make nighttime scenes look like daylight.
Infrared sensors, on the one hand, are making big improvements in resolution and in the ability to function reliably either without external cooling, or with less cooling than hitherto has been necessary.
Light-amplification sensors, on the other hand, continue to squeeze more performance out of conventional light-amplification tube technology, and to convert the sensor's analog signal to digital to align the technology for use in network-centric operations on the digital battlefield.
For both technologies, however, one trend is clear -- the growing use of multispectral electro-optical sensing that blends inputs from several different sensors to capitalize on the best capabilities of each technology for a growing number of applications in hand-held devices, as well as unmanned vehicles.
"We are seeing a trend to fused solutions, ranging from shortwave IR, plus longwave IR, as well as fusing light amplification and thermal imaging," explains Chris Wright, senior vice president of business development for the DRS Technologies RSTA group in Palm Bay, Fla., which specializes in IR sensors. RSTA stands for reconnaissance, surveillance, and target acquisition.
Combining the best aspects of several different electro-optical sensors has many advantages, but works best when the given sensor combination is suited to specific applications.
Light-amplification sensors, for example, are good at watching broad areas at night, but might fall short in detecting a motionless person under cover of foliage. Combine this sensor with a longwave IR thermal imager, however, and the person standing still behind a bush will come out clearly. Better yet, include a shortwave IR sensor, and the facial features of the person behind the bush become recognizable.
Searching for heat sources with a longwave IR sensor, such as people, machinery, and vehicles, is a relatively easy trick, yet these sensors cannot see through windows in buildings and vehicles; to do that requires either a light-amplification sensor or shortwave IR. For challenges in seeing through fog, mist, dust, or smoke in daylight, shortwave IR often is the best solution.
"The soldier wants to have as complete situational awareness as possible, and he wants all the information he can," says Less Hodges, business development manager for U.S. government sales the ITT Geospatial Systems Night Vision and Imaging segment in Roanoke, Va., which specializes in light-amplification technologies for night-vision goggles and other night-vision optics.
"Based on DOD [U.S. Department of Defense] desires, the push for us is into multispectral sensing with two or more channels in a digital platform," Hodges says. "Visible light amplification, near-infrared, and thermal spectrum imaging are the ones getting the most fielding time."
As far as IR sensors are concerned, major trends in cooled and uncooled sensor technologies involve putting increasing numbers of pixels on sensing arrays. "In the cooled area, we are in the 10-micron pixel size, and are moving to five microns in about five years time," says DRS's Wright. "This can provide either twice as many pixels in the same detector for enhanced resolution, or the same number of pixels in a smaller detector."
In light amplification, experts are making incremental improvements in tube technology such that the blooming from ambient light sources that once was the bane of night-vision goggles has virtually disappeared, says ITT's Hodges.
Driving these technological improvements are a growing number of aerospace and defense applications that require ever-smaller sensors with ever-more capability, such as hand-held sensors, and tiny sensor payloads for unmanned aerial vehicles (UAVs).
"You read about the drones in Afghanistan and Pakistan, but at all levels, you're seeing airborne platforms in a variety of sizes really taking off in terms of how many are being used and the capabilities they have," says David Strong, vice president of market for the government systems division of FLIR Systems Inc. in Wilsonville, Ore.
"One of the key factors are the sizes of sensors that can go onto UAV platforms of various sizes, from the Predator and even to the hand-launched kinds of UAVs that are being used in great numbers now," Strong says. "A great deal of work in technology development is to have multisensor packages for a variety of applications."
Infrared and other optical sensor suppliers
Axsys Technologies -- a division of General Dynamics
Rocky Hill, Conn.
www.axsys.com
BAE Systems Electronics, Intelligence & Support
Nashua, N.H.
www.eis.na.baesystems.com
DRS Technologies RSTA
Palm Bay, Fla.
www.drs.com
FLIR Systems Inc.
Wilsonville, Ore.
www.flir.com
Lockheed Martin Missiles and Fire Control
Orlando, Fla.
www.lockheedmartin.com/mfc
ITT Geospatial Systems Night Vision and Imaging
Roanoke, Va.
www.nightvision.com
ITT Geospatial Systems
Rochester, N.Y.
www.ssd.itt.com
Kollsman, an Elbit Systems of America company
Merrimack, N.H.
www.kollsman.com
L-3 Infrared Products
Dallas
www.l-3com.com
OASYS Technology
Manchester, N.H.
www.oasys-technology.com
Premier Electronics Ltd
Hoddesdon, England
www.premierelect.co.uk
Princeton Lightwave
Cranbury, N.J.
www.princetonlightwave.com
Raytheon Vision Systems (RVS)
Goleta, Calif.
www.raytheon.com
Sagem
Paris
www.sagem-ds.com
Sensors Unlimited Inc.
Princeton, N.J.
www.sensorsinc.com
Sofradir
Chatenay-Malabry, France
www.sofradir.com
Stanford Photonics Inc.
Palo Alto, Calif.
www.stanfordphotonics.com
