Brent D. Johnson, Senior News Editor
F-15E fighter aircraft control sophisticated systems such as advanced radar, tactical navigation, high-frequency communications and weapons. System designers organize the information that inundates the pilot by creating graphical displays such as off-board ones with digitized, color-coded information.
Organic LED technology enables a small, bright display in a pilot's helmet.
A team from eMagin, Eastman Kodak and Honeywell created an organic LED display that fits into helmet-mounted systems such as those planned for the Strike Helmet 21.
Dean Kocian, chief engineer of the US Air Force Armstrong Laboratory's Helmet-Mounted System Technologies Div., said that he experimented with liquid crystal and electroluminescent microdisplay technologies but that they posed design integration problems. Miniature cathode-ray tubes offered another, more traditional option, but they had voltage, size, power, color and resolution problems in a helmet application, he said. The organic LED, on the other hand, "had everything," he said.
Whereas the cathode-ray tube provides a luminous efficiency of ~0.1 lm/W, the organic LED's efficiency approaches 10 lm/W. The organic LED also can deliver 29,000 fl at 27 V for transparent display applications that use only a small portion of the display surface. This allows a pilot to view the display while looking into the horizon or when the sun reflects off clouds.
The organic LED's lambertian emission allows designers to interface it with low f-number optics common in military helmet displays. Another benefit is that organic LED displays operate through temperatures from -77 to 143 °C. Liquid crystal displays require heaters at low temperatures and have been known to pop during pressure changes, Kocian said.
"I see this as having potential for being a ubiquitous display technology," he said.