Most insects have compound eyes that consist of hundreds to thousands of visual receptor units called ommatidia. Because of these, insects tend to react very quickly to any kind of movement around them.
Researchers from Tianjin University in China have created a compound eye, inspired by biology as it looks and works like the ones that insects have. This, as they report in Optics Letters, would help them and other scientists understand how insects see, or even sense, things around them so that they can react with such high speed.
To make the eye, they had to produce 169 microlenses on its surface through single-point diamond turning-a machining process where diamond moves linearly to cut into shape the material while it rotates. With each microlens having two millimeters in diameter, a component that measures about 20 millimeters could "see" or detect objects at a 90-degree angle. This 90-degree field of view of each microlens overlapped with the ones next to it, just like how the ommatidia do for insects.
In addition, because of its shape, the researchers had to place a light guide between the curved compound lens and a flat image detector. This light guide served to overcome the difference in shape, while it also allowed uniformity in the absorption and refraction of light from different angles. Again, this feature was inspired by nature as one of the researchers, Le Song, explained. "This uniform light-receiving ability of our bio-inspired compound eye is more similar to biological compound eyes and better imitates the biological mechanism than previous attempts at replicating a compound eye."
To test their device, the researchers looked at its efficiency with 3D trajectory. They first added grids to let the microlenses pinpoint location. Then, they put LED light sources at various locations with known distances and angles respective of the eye. After this, they calculated for the 3D location of the LED lights as a function of location and intensity. With this, they found that their compound eye was able to provide the 3D location of the LED lights at a fast rate but with less accuracy at greater distances. This could be a theoretical explanation to why most insects are considered near-sighted.
The researchers suggested a number of applications for the development. One would be to aid entomologists in the study of visual systems of insects, like theorized above. Another would be in robotics, where the compound eye would be useful in the prompt detection of lightweight objects and systems. The researchers were also planning to incorporate the system and its algorithm into integrated circuits of certain devices and autonomous vehicles.
