Author, Katherine Heathwood
Designation, BBC World Service
Published 4 minutes ago
Reading Time: 8 minutes
Percy Shaw was returning home on a foggy night in 1933 when he saw a light on the roadside and suddenly stopped.
It is being said that it was a cat. The light of the car's headlights fell on the cat and its eyes reflected that light straight back towards them.
Percy's great niece Glenda Shaw told the BBC's 'Witness History' podcast in 2022: "It was a coincidence. He saw something that reflected the light and he was forced to stop. When he saw it he realized he was on the wrong side of the road. If he had gone straight ahead he would have fallen into a ditch."
That incident not only saved his life, but is also believed to have inspired Shaw to invent the reflective studs used in road markings. In Britain these are commonly called 'cat's eyes'.
By the time Shaw died in 1976, approximately 15 million Cats Eyes had been made. These studs and their variations are still used today on roads around the world.
According to his elder niece, Shaw had no connection with science.
He said, "He had no knowledge about physics, reflection of light etc. He understood it on his own."
Although his design was not based directly on the structure of a cat's eye, Shaw tried to mimic the reflection of light seen that night. For this he used small glass bullets.
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How do cats' eyes 'shine'?
However, real cat eyes glow in the dark because there is a reflective layer of tissue behind the retina called the 'tapetum lucidum'.
Bridey Foote, veterinary ophthalmologist and clinical associate professor at the University of Tennessee, says that this is a special structure, which is not present in humans.
'Tapetum Lucidum' means 'shiny layer' in Latin.
This reflective layer turns the cat's eye into a kind of mirror. This improves his vision even in low light and helps him hunt at night.
This allows the eye to recapture light that would normally escape the eye.
"Whenever a beam of light does not hit a photoreceptor, it is considered a lost beam of light," says Foot.
But in the part of the eye where there is 'tapetum lucidum', this light bounces back and can reach another photoreceptor.
Foot says, "Because of this, when there is less light at night, the pupil dilates a lot. This is why it seems that a lot of light is coming back from the eye."
Due to this, some part of the 'reflective layer' also goes out of the eye.
The color of this glow visible in the cat's eyes can vary. It can range from orange and yellow to green. It depends on the pigments present in their tissue.
But this reflective layer is not present only in cats. For this reason, you may also see the eyes of other animals glowing in the dark.
"All animals, including dogs, cats, horses and cattle, have a tapetum," says Foote.
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Decades after Shaw's invention, modern engineers are developing high-tech camera technology taking inspiration from the structure of the cat's eye.
These cameras can be used in robots, drones and driverless vehicles.
Young Min Song, a professor of electrical engineering at the Korea Advanced Institute of Science and Technology in South Korea, wanted to create a camera that could work in different types of lighting and recognize objects even in crowded environments.
For this, he first tried to copy the 'tapetum lucidum' present in the cat's eye.
In the true cat's eye it is composed of cells that contain rod-shaped crystals of riboflavin and zinc. These crystals reflect light.
Song explains that recreating this nanostructure through chemical engineering proved to be very difficult.
So his team instead created an artificial reflector by placing a layer of reflective silver behind the image sensor.
This increased the camera's ability to absorb visible light by 52 percent.
After this, Song noticed another specialty of the cat's eye. In bright light his pupil becomes like a thin, vertical slit.
Research shows that this can help cats judge distance. Because of this, they can identify prey hidden among the surrounding dense vegetation.
Song thought that if he could create a camera inspired by the cat's eye with a vertical pupil, it could help in removing the useless or scattered background of the surrounding area. After this you can see anything clearly.
Modern computer vision systems can already distinguish objects in such busy or cluttered scenes. Just like the portrait mode of a smartphone blurs the background behind a person.
But doing this often requires a lot of computing power. Song's idea was to develop some of this capability inside the camera itself.
For this, he shaped the camera's aperture like the vertical pupil of a cat's eye. Aperture is the hole in the camera lens through which light reaches its sensor.
To test this idea, Song's team photographed objects with a background filled with objects.
For this he used both a normal round aperture and a vertically shaped aperture.
In the picture taken through the round aperture, both the object and the scattered background behind it were clearly visible. But the object appeared much clearer in the picture taken with a vertically shaped aperture.
At present the aperture has to be changed manually. Like a cat's eye, it does not automatically change according to the level of light. Song says that he wants to solve this problem in the future.
Can the eyes of other animals also help?
In addition to the camera inspired by the cat's eye, Song and his colleagues have also created several cameras inspired by the eyes of other animals.
He believes that hundreds of such designs can be prepared by taking inspiration from nature.
While at the University of Illinois Urbana-Champaign in 2013, he built a camera inspired by the eye of a fly.
Song says about this, "Flies have bulging eyes and they can see in every direction simultaneously."
"This camera has a very large field of view and can identify objects very quickly," he says. According to him, these properties make it useful for use in robotic drones.
His lab has created another camera, which has been inspired by the eye of a hawk.
This camera captures a clear and large image of the central area of its field of view, while recording the larger surrounding area in lower resolution.
"You can think about which animal might be best suited for a particular task," says Song.
Song says, "They have a total of eight eyes... on the front, on both sides, and even on the back. They can see in every direction. Also, with the help of the front eyes, they can determine the exact distance of an object with just one eye."
He explains that the retina of these spiders is in several layers one above the other. For this reason, she can estimate the distance very accurately and can make very precise jumps without missing her target.
Song says most modern camera systems today, like your phone's camera, largely mimic the human eye. But cameras inspired by animals' ability to see could be used for specific tasks, "in robots, industry, drones or any next-generation robotic system."
We used AI to translate this article, which was originally written in English. A BBC journalist checked this translation before publication. Learn more about how we're using AI.
