A salt grain size camera

Researchers at Princeton University and Washington have successfully developed a small-scale camera that can be compared to a grain of salt. Nevertheless, it can take pictures of hundreds of thousands of times the quality of a large device.

This miniature camera is widely used in medicine to make less invasive medical oscillations or to give more advanced senses to microbots. A small machine capable of taking quality photos … the challenge seems classic, but not yet fully resolved. In fact, it presents scientists with major problems affecting the basic laws of optics.

In “traditional” cameras, optical components, such as lenses, are assembled to collect light in a scene and adjust its refraction until a stable image is obtained. If these lenses are only present, it already imposes a certain size. Second limit, focal length. The distance between the optical lens and the sensor of the camera is called the focal length. It can be large or small, but it can not be reduced indefinitely, otherwise we get an image with many color variations.

Metaserphs to change optics

To overcome these size limitations, a team of scientists used so-called “metasurface”. Metasurfaces, accordingly CNRS Description File, They ” Introduces abrupt changes in the optical path, phase, amplitude and / or polarity along the thickness of the array wavelength, to avoid long scattering of optical elements (…) made of nanoparticles. “In other words,” playing “with the wavelength of light is not the same, so it allows scientists to partially eliminate the limitations mentioned above.

Definitely, the device will take the form of millions of tiny optical “antennas”, each of which is individually configured. These antennas all process at different wavelengths, thus sending back a synchronous image like the camera at the end of the journey.

However, using metaserfaces alone is not enough to create a small camera. In fact, this is not the first such attempt. As it stands, this method causes a lot of optical problems, and there are a lot of distortions and discolorations in the image obtained from previous attempts in this area, which were difficult to use.

An image reconstruction algorithm

To improve the image, Princeton scientists worked on the ups and downs of filmmaking. Upstream, it is a question of performing the complex task of configuring each of the millions of optical antennas individually. In fact, because of their number, but also because of the complexity of their interactions with light, the challenge remains significant. One of the researchers, Shane Colburn, developed a computer model capable of automating their adjustment with sufficient precision to accurately upgrade antennas.

The “bottom line” of the film’s production was that scientists used a reconstruction method. This neuro-nano-optical network is capable of identifying image defects and correcting them according to “learned” data, making it possible to obtain the desired quality. ” Although our design size is 550,000 times smaller, we demonstrate image quality comparable to a bulky six-element commercial lens. , They congratulate each other Their statement.

In addition, the material used, such as silicon nitride and glass, is compatible with the production methods of standard semiconductors used for computer chips. In other words, scientists claim that large-scale production is possible at a lower cost than conventional camera lenses. They are still trying to improve their invention to allow for the detection of objects or the perception of certain elements. Additional skills that can prove useful in the fields of medicine and robotics. Meanwhile, they already imagine that their invention will completely change the way they design objects. What if any surface turns into a camera?

Source: Princeton University