A quantum camera can take images using light that has never actually illuminated the subject. It could be useful for imaging particularly fragile tissues and materials.
Conventional cameras capture the light that bounces off objects to create images. Consequently, dimly lit objects that are only in contact with a few light particles end up blurry. Xiaosong Ma at Nanjing University in China and his colleagues have now built a device that can utilise light that doesn’t ever touch the object.
Their device is a maze of lenses, mirrors and crystals arranged on a table so that light is produced at one of its ends and detected at the other. They tested it on a small plate embossed with three letters that was placed between two of the mirrors. Instead of using natural light or a camera flash, the researchers hit one of the device’s crystals with a laser beam, which made it emit pairs of light particles. These travelled through the maze but never touched the object.
Some of the particles took a path with a fork in the road that could have led them to the lettered plate but they went the the other way instead. However, thanks to quirks of quantum physics, the mere possibility of this alternate route was enough to encode something about the object into the properties of the light particles. At the end of the maze, the light hit a detector that recorded those properties, then a computer used them to generate the final image of the three letters.
“Quantum physics is often counter-intuitive to our daily experience, but here that helps us go beyond conventional imaging,” says Ma. The new method may be useful for studying objects like fragile living cells whose structures change when bombarded with light, he says.
Radosław Łapkiewicz at the University of Warsaw in Poland says that it could also be helpful for imaging materials that react to one kind of light, like infrared, but not another, like visible light. However, in the current design photons sometimes manage to touch the object, so it could still be improved, he says.
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