Insect inspires vision system

An insect-inspired imaging device could give guided missile-tracking systems a panoramic 120º field of vision, and be used in other areas, such as civilian security and keyhole surgery.

The new technology, from BAE Systems’ Advanced Technology Centre in Essex, takes inspiration from the compound eyes of the Xenos peckii, a parasitic insect that lives inside wasps.

Each lens of the parasite’s eye produces an individual inverted image of a scene. These images are then meshed together to form a single large image in its brain.

Leslie Lacock, executive scientist at BAE Systems, said his research team was able to recreate this with nine lenses — each about the size of mobile phone camera lens — arranged on a curved surface. Each lens captures an inverted image of a scene, and a software programme reverts the images and stitches them together to give a clear, wide-angled panorama.

The research into the technology was funded by an MoD programme designed to reduce the size and weight of imaging equipment used in a variety of military applications, such as missile tracking systems and night vision equipment.

‘When you look at a conventional camera most of its size and weight is due to the glass — the actual optics,’ said Lacock. ‘So when we were thinking of ways to miniaturise we looked at insects because obviously they have very miniaturised optics in their eyes and they have very capable performance.’

Lacock said the compound eyes of insects can sometimes contain hundreds of thousands of little lenses. ‘Obviously we didn’t want to go to that level of complexity,’ he said. ‘When we looked at the requirements we needed for these types of cameras in a military application we wanted to still maintain a high level of resolution and sensitivity. So we didn’t want to have lenses too small.’

The Xenos peckii has 50 lenses per eye compared to 700 lenses in the eye of a fruit fly. However, each lens is 15 times larger.

Lacock said many current small military optical imaging devices can only achieve about a 20º field of vision — this means that the camera would have to be attached to a mechanical mount and swivelled around to film wide areas.

‘If you can get away with just having a camera that stares in all directions simultaneously then that’s another piece of hardware you can remove,’ he said.

One of the main challenges for the researchers dealt with the curved surface on which the lenses are placed. Images acquired from these various angles could not simply be relayed to a conventional flat video sensor. ‘A lot of those images would be out of focus and distorted,’ said Lacock.

The team therefore developed a faceted and polished fibreoptic face plate that could process the images before they hit the sensor.

‘The plate has millions of fibreoptics fused together,’ explained Lacock. ‘If you image a scene on to one side of this plate, the light from it will channel through the fibreoptics through one face to the other.

‘This is a fairly well known component, but we made the plate into a prism so it can take images from angles and relay them at angles down on to another surface, which is a flat sensor.’

The new device could be used to not only give missile-tracking systems a wider view, but could also be integrated into night vision equipment for troops.

‘It would be a big benefit because soldiers have to wear this equipment, and any reduction in the size and weight would probably be most welcome,’ said Lacock.

Away from the military arena, the device could be used to track down criminal activity on town and city streets. Lacock envisages CCTV cameras that could survey panoramas of crowded public spaces without any of the usual ‘black spots’ or out-of-view areas.

The multiple lenses could also zoom in on certain areas of a scene without affecting the rest of the image on the screen.

‘With the advancements of mobile phone-type zoom lenses, you could imagine that each one of those lenses could be a zoom,’ said Lacock. ‘You can currently do this digitally, but you obviously lose resolution.’

Other areas for the technology include the medical field, where it could be used for keyhole surgery. This would require the researchers to shrink their system — which can currently be held in the palm of your hand — even smaller.

‘We would need to make the lenses smaller, but normally when this happens they collect less light so obviously you need to bear that in mind when you are designing these very small systems,’ said Lacock.

He added that now they have demonstrated their first camera with 120º field of vision, they could theoretically design one with an even greater field.

‘There is no real sort of limitations, but it will be difficult to have something more than 180º,’ he said. ‘We think that 120º is a reasonable step change for now.’

Siobhan Wagner