Scientists build full-colour camera the “size of a grain of salt”

By Alex Hughes

Published: Wednesday, 08 December 2021 at 12:00 am

Ever wanted to live out your very own Innerspace experience? This camera that’s roughly the size of a grain of salt could one day find itself working its way around your digestive system, to give doctors a clearer picture of your health.

Built by researchers at Princeton University and the University of Washington, the camera is able to pump out clear, full-coloured images equivalent to what you would see from a camera 500,000 times the size!

To build a working camera at this scale, the scientists had to completely reimagine the tech that you would find inside a camera. “In order to shrink down the size of the camera you really have to look at the optical system” said Felix Heide, the study’s senior author.

“If you look at the remaining pieces of a camera, that being the sensor and the electronics, they have already been miniaturised over the last decade quite substantially so we can already build ultra-small sensors. The optical systems haven’t really been designed very differently since the days of Gauss.”

Instead of the usual array of curved glass pieces used in most camera optics – which we know as lenses – this tiny device makes use of nanotechnology known as metasurfaces, cramming in an incredible 1.6 million cylindrical posts onto a surface just half a millimetre wide. With this surface being so small, it comes as no surprise that these posts are absolutely tiny, roughly the size of the human immunodeficiency virus (HIV).

These posts effectively channel incoming light towards a sensor, a bit like antennae. An artificial intelligence then makes sense of the pattern of light hitting the surface of the sensor. In the past ultracompact lenses have produced blurry images, with a small field of view and a limited colour spectrum. But Heide’s team were able to train a machine-learning algorithm in simulations to create a clear picture from the data collected.