The ellipsoidal and stalk-eye structures of the crabs enable them to see in three dimensions and in all directions.
To protect themselves from attacks on wide-open tidal flats and to interact and communicate with their mates, they have evolved to gaze at practically everything at once.
Biomimetic cameras aren’t exactly a new invention
In Nature in 2013, a wide field of vision (FoV) camera that resembled an insect’s compound eyes was described, and in 2020, a wide FoV camera that resembled a fish eye appeared.
Although these cameras can cover a lot of ground at once, it is structurally challenging to go beyond 180 degrees. More recently, however, commercial solutions with 360-degree FoV have entered the market.
These, on the other hand, can be hard to use because they need to combine images from two or more cameras.
To increase the field of view, you also need an optical system with a complicated setup, that distorts the image.
Because it’s hard to keep your concentration up in different places, like in the air and underwater, you need to pay attention to the calling crab.
For this reason, the researchers concluded, the crab served as a good subject.
During tests, a dolphin, an airplane, a submarine, a fish, and a ship were shown on the artificial vision system from different distances and angles.
The team ran multi-laser spot imagining tests, and the synthetic images agreed with the simulation. They placed the apparatus in a container of water and lowered it halfway to reach its depth.
This study was funded by the National Research Foundation of Korea, the GIST-MIT Research Collaboration grant that was given out by the GIST in 2022, and the Institute for Basic Science.
“Biological visual systems have inspired the development of various artificial visual systems including those based on human eyes (terrestrial environment), insect eyes (terrestrial environment) and fish eyes (aquatic environment). However, attempts to develop systems for both terrestrial and aquatic environments remain limited, and bioinspired electronic eyes are restricted in their maximum field of view to a hemispherical field of view (around 180°).Here we report the development of an amphibious artificial vision system with a panoramic visual field inspired by the functional and anatomical structure of the compound eyes of a fiddler crab. We integrate a microlens array with a graded refractive index and a flexible comb-shaped silicon photodiode array on a spherical structure. The microlenses have a flat surface and maintain their focal length regardless of changes in the external refractive index between air and water exhibiting an extremely wide field of view covering almost the entire spherical geometry. We illustrate the capabilities of our system via optical simulations and imaging demonstrations in both air and water.”