Longer arm for the law

The military and police could increase surveillance camera reach by five times using a UK astronomy team’s method of reducing the Earth’s atmospheric distortion in images of distant galaxies.

Atmospheric turbulence like wind or heat can cause long-distance images to smear, shudder and blur, such as astronomical pictures taken from Earth-based telescopes. To prevent this, a University of Cambridge team has been using a processing method called ‘Lucky Imaging’ to pick out the sharper moments from the turbulence to combine to create Hubble-quality pictures.

But atmospheric turbulence is also a problem for long-distance surveillance, so the team is applying the technique to improving existing cameras used in crime and terrorism prevention, said Dr. Craig Mackay of the university’s Institute of Astronomy. ‘You can’t read the name on a ship from the coastline before it comes into territorial waters and you can’t recognise a face at the perimeter of an airport from the central buildings,’ he said.

The researchers aim to go five times sharper than today’s surveillance cameras, which can only achieve about 3in resolution at a distance of a mile, for example.

The key to this is research into a high-speed surveillance camera, that grabs sharper moments in an image that are least affected by atmospheric turbulence and combines them to give a much higher resolution image then would be possible simply by adding together all the images irrespective of their quality.

‘The resolution you get at a long distance is an average of the turbulence. But every now and then the fluctuations get quite a lot better,’ said Mackay. ‘Our device looks for those moments and grabs them. By selecting these moments of sharpness and replacing the lower quality cells you can improve the image quite markedly.’

At the heart of the camera is a high-speed Charged-Coupled Device detector with no readout noise provided by E2V Technologies, said Mackay.

The team will have a working prototype in the next few months, as part of a £250,000, three-year EPSRC-funded project. ‘The catch is that you have to run the camera fast enough to freeze atmospheric turbulence, at around 100 frames per second,’ he said. ‘That’s quite a bit higher than TV camera frame rate.’

The researchers presented their project at the Royal Society’s recent Advanced Technologies in Crime Prevention and Detection conference.

Also at the conference, a UK company revealed a quicker method to spot explosive detonators in airport baggage screening.

Glenealy International’s ‘Beagle’ camera processes x-rays to filter out unwanted metal objects and pick out detonators.Glenealy director David Bilcliffe said that too much focus is put on spotting just explosive material during screening. ‘A detonator is a crucial part of a bomb – without it there are zero consequences.’ But he said that the human eye can miss a detonator in the average five seconds taken to screen baggage.