If it’s over-the-top crazy to swat a fly with a sledgehammer, what are we to say of vaporizing one with a laser?
How about: good riddance. We need new weapons for the war on bugs, particularly disease-bearing mosquitoes, which are quick to evolve resistance to poisons and are hardly fazed by traps that lure them to their deaths. That’s because there are just too many of the little bloodsuckers out there, particularly in the malarial regions of Africa.
After years in the blue-sky area of speculative inquiry, the laser bug zapper took its first solid step toward commercialization last week, when Intellectual Ventures, the patent-holding giant, announced that it had licensed the manufacturing of the system to Lighting Science Group of Melbourne, Florida, a maker of LEDs.
The idea itself was the brainchild of Jordin Kare, a laser specialist and onetime anti-missile defense researcher, who five years ago described a prototype in IEEE Spectrum. He tells Spectrum he no longer has much to do with the technology but is gratified that Intellectual Ventures was moving forward with it.
The point of such a laser system is not to kill vast numbers of bugs but merely to fence them out of a particular patch, says Maurizio Vecchione, a senior vice president at Intellectual Ventures.
“Think of the mosquitoes in an area as an infinite reservoir,” Vecchione says. “A photonic fence is a radically different way of thinking of this problem: Now we have a realistic way of creating a mosquito-free area. Malaria has been eradicated in many areas not by eliminating every mosquito but by reducing the biting rate--if we could take wet-season biting rate to a dry-season level, we could make a major dent in that community’s malaria incidence.”
Villages and hospital clinics in Africa are one obvious market. Deserts swarming with sand flies--a problem for the U.S. military in its deployments in the Middle East--are another.
So what does it take to zap a mosquito with a laser? First you must find it and track it, a job that must be done very carefully because the beam is just 2 to 6 millimeters wide--“a tiny firehose,” says Arty Makagon, an electrical engineer who’s leading the research effort.
The ideal range is between 25 and 100 meters: not so far away that you can’t hit the bug and not so close that you can’t steer the beam to it quickly. “Sometimes what matters is to get the beam from here to there before the mosquito goes away,” Makagon says.
It’s possible to use the same system to track and kill, but it’s easier to use two--an infrared beam to track and a 3-watt, 532-nanometer-wavelength green laser to kill. Because the killer beam blinds the system, it’s pulsed for just 25 milliseconds. That may not vaporize the beastie, but it’s enough hurt render it hors de combat.
“We cooked the bug with a lot lower power than we had thought possible,” Makagon says.
The problem with green light is that people can trace it to its source and perhaps steal it--a problem whenever the photonic fence is to be deployed in a low-income area. That leaves invisible infrared light, which the mosquito’s body doesn’t absorb so well. But that doesn’t seem to matter much.
“We did a bunch of experiments with a 1-micron beam, and we expected the effect to be an order of magnitude worse, but no,” Makagon says. “We needed 12 W, less than half an order of magnitude less. Maybe that’s the desirable way to go.”
Stand-alone systems would use batteries to store up power gathered by solar panels. Though the odd mosquito wouldn’t strain things, a large buzzing swarm would require a bit of energy-conserving finesse. One way to economize on power is by using the tracking laser to count the frequency of the wing beats and thus tell the sex of the mosquito. The harmless males would get a pass; the blood-thirsty females would get fried.
Right now, Makagon and his colleagues are working purely within the confines of a lab. He strenuously rejects the suggestion that he might have succumbed to the urge to try it out in someone’s backyard.