About 400 million years before eyeglasses were invented, the extinct trilobites already had much better ones built into them. Not only could the sea creature see things both up close and far away, it could also see both distances in focus at the same time, an ability unthinkable by the human eye and most video and photo cameras.
Until now. Inspired by the eyes of those prehistoric trilobites, a new camera prototype can simultaneously focus on two points anywhere between three centimeters and almost two kilometers away, as reported by the creators of the invention in the prestigious scientific publication Nature Communications .
Focus both far and near
To mimic the ability of trilobites, the team built a metalens, a type of flat lens made up of millions of rectangular nanopillars of different sizes arranged like rows of buildings in a city plan. Nanopillars act as obstacles that deflect light in different ways depending on their shape, size and arrangement. The researchers arranged the pillars so that some light traveled through one part of the lens and some light traveled through another, creating two different focal points.
To use the device in a light field camera, the team built an array of identical Metalenses that could capture thousands of tiny images. When combined, the result is an image that is in focus near and far , but blurry in between. The fuzzy bits are then sharpened by machine learning software that removes pixels and blurriness, ultimately resulting in a sharp image.
Greater depth and quality
Achieving a large depth of field can help the software collect information to improve the quality of subsequent photos. Standard images do not contain information about distances to objects in the photo, but 3D images do. So the more depth information that can be gathered, the better.
The focus of this new camera based on the eyes of trilobites is not the only way to increase the range of visual acuity. Other cameras using less sophisticated methods have achieved a similar depth of field, although they have never achieved simultaneous near and far focus. Conventional cameras typically contain a series of tiny glass lenses of three different types that work together, with each type designed to focus light from a particular distance, but never simultaneously.
The trilobite camera also uses a series of lenses, but all lenses are the same, each capable of doing all the depth-of-focus work on its own, helping to achieve slightly higher resolution than using different types of glass.
Nature Communications (study).