Roman Abramovich's latest extravagance, Eclipse, probably so-called because it's almost big enough to block out the sun, is the world's largest mega-yacht. Measuring 557ft long, it boasts two swimming pools, two helipads and an onboard missile defence system. And, just in case any missiles do get through, it comes complete with an escape pod: its own submarine. Its most curious feature, however, defends it against an altogether more insidious weapon: the prying eyes of the paparazzi.

The boat's anti-paparazzi system, described in several reports as a "laser shield", is a little less science fiction than it sounds. The lasers – beams of infrared light – are used to detect the electronic light sensors that digital cameras use instead of film. The camera is then targeted with a focused beam of bright light that disrupts the potential photo, making any shots unusable. It's not so much a space-age Star Wars laser shield, then, as a big budget version of shining a torch in someone's face.

A similar technology is already available to all in the form of an anti-paparazzi purse, devised by New York University student Adam Harvey, which detects the flash of a camera and responds with a bright flash of its own, cloaking the intended target in a blob of white light. Nigel Atherton, editor of What Digital Camera, explains, "You couldn't stop them taking a picture but you could ruin the picture." Eclipse's anti-paparazzi defence grid, he suspects, "is essentially a large-scale version of that."

What makes Eclipse's system special is that it can detect any digital camera, whether it's using a flash or not, and before the first shot. But Abramovich's shield still has a serious weakness: it can't possibly detect the presence of an old-fashioned analogue or mechanical camera.

So for £724m, he's got himself a boat that digital-camera-wielding paparazzi can't photograph, say, falling over outside a nightclub at 3am. It's a shame really. That's exactly the sort of memory you'd want to capture.