As discussed here, two teams are developing optical cloaks that could be used to make small spaces on walls or floors–spaces that could contain microphones, among other objects–appear invisible by changing the angle at which light bounces off the bump, making the bump appear flat.
One team from Berkeley etched holes into a thin layer of silicon nitride deposited on porous glass to hide a small bump. The size of the hole determined the angle of refraction. Although they used polarized light in their test, the researchers claimed it was not necessary, meaning their technology could be used in other fields, such as increasing the efficiency of solar energy devices.
Researchers at the Singapore-MIT Alliance for Research and Technology used polarized light to similar effect earlier this year to cover up a bump 2mm high. But their device used calcite crystals, which have refractive properties that depend on the direction of the polarized light’s electric field. Although the Singapore-MIT device only used polarized light, the cloak was reportedly “about 10,000 times bigger than the Berkeley cloak, and also…more than 10,000 times cheaper.”
The article supposes that a tiny microphone could be hidden under the cloak. What else could you hide under such a cloak? What if you could create an invisible dead drop? There would have to be some prior communication about where to find it, of course, but a small microdot (or nanodot?) under a cloak might be a great option–and harder to spot if you had to make a drop while under surveillance.
I would think cameras are not an option because the cloak’s material would distort the recorded images. But what if some light passed through the cloak, and the camera’s software could compensate and record images? How would you use invisible cameras? Would you use them in tandem with more visible cameras to lull wrongdoers into a false sense of security? Might undercover cops use them instead of a traditional “wire”?
If surveillance is a cat-and-mouse game between the watchers and the watched, how could you counter these cloaks or the devices hidden underneath, given you might not be entirely sure they are present? First, you need some way to detect the cloaks. I wonder if it would be easier to try to detect what is hidden under the cloak (heat signal, data transmission, signal interference, etc.). Second, you need some way to counter the cloaks or the device (or some way to use the cloak to screw up the concealed device). Perhaps some engineers can weigh in on this one though. I’m out of my depth.
What do you think of these cloaks? How would your security or law enforcement personnel use them in your story? How would your criminal/spy defeat them?
P.S. if you want information on “dazzle” techniques used to defeat facial recognition software, you can see a brief description on another one of my posts here.