Researchers at the University of Washington and the University of Princeton have developed a camera that is the size of a grain of salt. The meta surface is studded with 1.6 million cylindrical posts and can be used to make a computer chip. Credit: the university
Micro-sized cameras have the potential to spot problems in the human body and enable sense for super-small robots, but past approaches captured fuzzy, distorted images with limited fields of view.
The researchers at the University of Washington and the University of Princeton have overcome these obstacles with an ultracompact camera. The researchers reported in a paper that the new system can produce crisp, full-color images on par with a conventional compound camera lens 500,000 times larger in volume.
The camera's hardware and computational processing were combined to enable the system to be used with medical robots to diagnose and treat diseases, and to improve image quality for other robots with size and weight constraints. A lot of cameras could be used to turn surfaces into cameras.
The new optical system uses a meta surface, which can be made like a computer chip, to bend light rays into focus. The meta surface is half a millimeter wide and studded with 1.6 million cylindrical posts.
Each post has a unique geometry and functions like an optical antenna. The entire optical wavefront needs to be shaped correctly if the design of each post is to be changed. The posts' interactions with light combine to produce the highest-quality images and widest field of view for a full-color metasurface camera developed to date.
The integrated design of the optical surface and the signal processing algorithms that produce the image was a key innovation in the camera's creation. Felix Heide, the study's senior author and an assistant professor of computer science at Princeton, said that this boosted the camera's performance in natural light conditions, in contrast to previous metasurface cameras that required the pure laser light of a laboratory or other ideal conditions to produce high-
The researchers compared the images produced with their system to the results of previous metasurface cameras, as well as images captured by a conventional compound that uses a series of six Refractive lens. The images of the small camera were similar to those of the traditional lens setup, which is more than half a million times larger.
Other ultracompact meta surface lens have suffered from image distortions, small fields of view, and limited ability to capture the full spectrum of visible light.
"It's been a challenge to design and set up these little microstructures to do what you want," said a computer science student who co-led the study. It's not clear how to design millions of little microstructures in an optimal way for capturing large field of view images.
Micro-sized cameras captured fuzzy, distorted images with limited fields of view. A new system called neural nano-optics can produce crisp, full-color images on par with a conventional compound camera lens. Credit: the university
The co-lead author created a simulation to automate testing of different configurations. This type of simulation can use a lot of memory and time because of the number of antennas. He created a model to approximate the metasurfaces' image production capabilities.
Colburn is now an assistant professor at the University of Washington Department of Electrical & Computer Engineering, where he was a student. He directs system design at Tunoptix, a Seattle-based company. Arka Majumdar is an associate professor at the University of Washington and a coauthor of the study.
The metasurfaces are made from a glass-like material that is compatible with standard manufacturing methods used for computer chips, meaning that a given meta surface design could be easily mass-produced.
"Although the approach to optical design is not new, this is the first system that uses a surface optical technology in the front end and neural-based processing in the back," said Joseph Mait, a consultant at Mait-Optik and a former senior researcher and chief scientist at the
The Herculean task of designing the size, shape and location of the meta's million features and the parameters of the post-detection processing is being completed by the published work.
Heide and his colleagues are trying to add more computational abilities to the camera. They would like to add capabilities for object detection and other sensors that are relevant for medicine and robotics.
Heide envisions using ultracompact imagers to create "surfaces as sensors." If we could turn individual surfaces into cameras that have high resolution, you wouldn't need three cameras on the back of your phone anymore, but the whole back of your phone would become one giant camera. He said that they can think of different ways to build devices.
Nature Communications has more information on Neural nano-optics for high-quality thin lens images. There is a DOI of 10.1038/s41467-021-26443-0.
Nature Communications is a journal.
The camera was shrunk to the size of a salt grain by researchers.
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