10 July 2008
Philippe Hébert loves his job as an optical engineer at CNES. Hi-fidelity music is another of his passions. One day, while listening to his hi-fi, he noticed that on replaying the same piece of music on a CD immediately it sounded clearer the 2nd time. This got him thinking and he turned his attention to the laser beam in his CD player. He soon worked out what was happening: the 1st pass of the beam was cleaning tiny particles of dust away from the track, making decryption on the 2nd pass much clearer.
Next, Philippe Hébert attempted to reproduce the phenomenon using space-related technologies. “In space (but not only in space), the lenses used in remote-sensing instruments like those on the SPOT satellites are cleaned by ultraviolet rays to remove dust,” he explains. So he decided to insert some small UV diodes he had to hand inside his CD player.
After some fine tuning, he got the result he was looking for. “I first pointed the UV diode straight at the track, but I got better results when it was aimed just in front of it,” says Hébert. The UV rays trained on the surface of the CD clear away dust from the track ahead of the laser beam, thus improving the sound quality.
6 small magnets
But that’s not all: to refine his device, Philippe Hébert reckoned he needed to capture dust to stop it getting on the surrounding electronic circuits. “When dust particles, which carry a natural electric charge, collect on electronic circuits they create interference,” he explains. “So I inserted 6 small magnets and two electrically charged plates inside my CD player to trap them.”
Consisting of a UV diode, 2 copper plates, 6 magnets and a household battery, Philippe Hébert’s invention costs no more than €5. “We’ve just filed the patent. Obviously, the device is adaptable to new Blu-Ray technologies and professional optical data storage systems.” And when CNES’s inventor is asked what drove him to do it, he has a simple answer: “It was fun!”