Billionaire Roman Abramovich shouldn't rely on an anti-paparazzi laser shield to protect his privacy on board his new super-yacht: it probably won't work on most digital SLRs or any film snappers.

In a write-up of Abramovich's £725 million Eclipse boat, The Sunday Times revealed that the Chelsea boss had invested in a system that "fires a focused beam of light at camera's CCDs, disrupting its ability to record a digital image."

However, researchers at Georgia Tech university in the USA who developed a very similar system in 2006 warned that it would be unable to protect against the digital SLRs used by most news photographers.

News flash

Professor Gregory Abowd's system used off-the-shelf equipment - camera-mounted sensors, lighting equipment, a projector and a computer - to scan for, find and neutralise digital cameras. The system worked by looking for the reflectivity and shape of the CCD sensors used in some digital cameras.

It worked on the principle that CCDs are retroreflective - they reflect light directly back at its source, like road signs. This allows a laser to scan for them, detect its own reflection and increase the power to effectively blind the sensor momentarily.

However, the Georgia Tech system was designed to work in a dark cinema, seeking out would-be pirates filming movies on domestic video cameras, where the CCD sensor is exposed many times a second. How effective it would be in bright sunlight is less clear. "The biggest problem is making sure we don't get false positives from, say, a large shiny earring," said a researcher on the project, Jay Summet.

Summet also warned that such camera-neutralising tech may never work against single lens reflex cameras, which use a folding mirror that masks the CCD except when a photo is actually being taken. Moreover, anti-digital techniques don't work on conventional film cameras because they have no image sensor. Also, many modern SLRs now use CMOS rather CCD sensors.

Still, Abramovich shouldn't feel too hard done by. The 557-foot Eclipse still boasts a mini submarine, two helipads and a missile defence system...