Firefighters could also make use of multiple frequencies at once, each color-coded on a display, says Agarwal. Hot spots detected at one frequency could be displayed as red; infrared light emitted by human bodies could be displayed as blue; and the critical temperature of flammable liquids could be yet another color. The areas on screen that are not at these specific frequencies would appear as mixtures of these colors – this is, in fact, precisely how digital cameras produce full-color images.
With future developments in materials it could be possible to sense wider ranges of frequencies. Agarwal says this might be especially useful for helicopter pilots. In one scenario, a detector material might be tuned to respond to all the visible frequencies. Its output would be displayed in a grayscale, creating a black-and-white image of the visible scene. On top of this background could be overlaid red images indicating the location of people, and other colors for identifying different types of vehicles.
By dramatically cutting the cost of such a system, the new technology could make high-quality infrared detection widely available for nonmilitary applications. These could include detecting bruised apples on an assembly line, surveying dark areas with security cameras, and monitoring industrial machines for overheating. Automaker BMW already offers cars with infrared systems that help drivers see at night, alerting them to animals or people beyond the beam of a car’s headlights. The new, inexpensive device might improve the quality of such a system and make it more widely available.
Agarwal declines to reveal the exact composition of the materials used, although she says they’re not new. The materials weren’t used in the past for this application because researchers believed they wouldn’t produce a clear signal. “People thought the signal-to-noise ratio would be horrible, so there’s no point in researching these materials,” she says.
While a prototype device for detecting narrow frequency ranges for early military applications could be ready within a year, Agarwal says other applications will require further materials developments to extend the frequency range of the detectors while maintaining a clear signal, and therefore could be several years away.