Laser technology, which continues to advance in efficiency, compactness, and usefulness, and has made a tremendous impact on military strategy, is celebrating its 50th birthday this year.
Fi fty years ago, American physicist Theodore Maiman, then working at Hughes Aircra ft Co., invented the first laser based on ruby lasing medium. The principle was first described by Albert Einstein in 1917, but it wasn't realized until 1960 when Maiman stimulated a ruby rod by means of high-energy flashes of light. Today, Hughes is part of Raytheon Company, but the work on lasers continues, with Maiman's "torch" carried by several protgs who joined Hughes in 1979: Dan Nieuwsma, Senior Principal Physicist for the Optics & Laser Engineering Department in Raytheon Space & Airborne Systems (SAS), and Bob Byren, Principal Engineering Fellow and the Technology Area Director for electro-optical, infrared, and laser technology for Raytheon's SAS business.
Byren, who holds an M.S.E.E. from Stanford University, earned an early education on laser technology during a four-year tour of duty as a reserve officer for the United States Air Force, serving as an electro-optical warfare Project Engineer and Executive Assistant to the Chief of the Electronic Warfare Division in what eventually became the Air Force Research Laboratory (AFRL). He le ft with the rank of Captain to join Hughes. Nieuwsma also started at Hughes in 1979 fresh from graduate school at Washington State University, where his work focused on studying the effects of physical damage from ruby lasers. The two became part of the "second generation" of engineers at Hughes to work on laser technology.
They note that although some might associate military laser technology with high-energy weapons, much of the development done at Hughes/Raytheon has been in the area of sensing and detection (see figure), with Hughes an early innovator in laser radar systems.
One of the early laser product successes for Hughes was the first military-quali fied laser range finder for the M60A2 battle tank. "Eventually, we made a system for the M1 as well," says Nieuwsma, noting that the company has delivered over 20,000 laser range finders over the years for different battle tanks.
By 1968, the military became interested in applying lasers for homing munitions, using a target designator laser to send a string of coded pulses at a target so that a missile or a bomb with an appropriate seeker could home in on the re flected laser pulses from that target. "Th e key was that they could hit the target very accurately, and not the things around it," offers Byren. The war in Vietnam created a strong demand for laser target designation, with the technology being applied in Southeast Asia by 1972. Nieuwsma tells the story of the Thanh Hoa Bridge on the Song Ma River in Vietnam, and how it was a target that refused to fall. " There were 873 aerial sorties against this bridge, without ever taking it out," he recalls. "In May of 1972, the first mission was conducted with laser designators and laser homing munitions, to accurately pinpoint the bridge. For the first time, they managed to take it out," he explains.
Portability has been an important design requirement for military laser systems, especially with the military push for reduced size, weight, and power (SWAP). Techniques such as diode pumping have raised laser efficiency and helped shrink the size of "man-portable" systems. Nieuwsma compares a system that was 11 lbs. in 1979 to a current prototype at about 2.5 lbs., designed for the same mission. His design was the first military-quali fied diode-pumped laser, the laser target designator and range finder for the F/A-18 Super Hornet.
Byren points out that there is still room for improvement in laser technology: "We started with ruby lasing medium, and there has been much improvement in solid-state media. One of the more efficient of the solid-state lasers was the neodymium (Nd)-YAG laser, which was the basis for all the laser designators and range finders in that era." Hughes also developed high-power chemical lasers and had breakthroughs in gas lasers.
The future of military laser technology is bright. Nieuwsma explains that "We are working to advance the state of the art in lasers, to make them more compact and efficient so that every soldier on the battlefield can have their own targeting laser. That is the bulk of the lasers that we have supplied, supplying nearly 50,000 military lasers over the last 50 years. We continue to deliver 2000 to 3000 military lasers every year to support both US and friendly foreign forces."