22 August 1997 Help is at hand for sound archivists around the world in charge of large collections of old records and antique phonograph cylinders that are too worn out or damaged to play on conventional decks. The new stylus is a short length of standard optical fibre which is thicker than a traditional diamond stylus or phonograph needle. The fibre touches the walls of a record's V-shaped spiral groove above the paths worn by mechanical styli during countless playings and is thus able to play the music, songs, sound effects and speech previously trapped in damaged and broken surfaces. Laser light shines down the fibre and reflects off its angled end onto a position detector. As the record turns, the groove make the optical stylus vibrate.
Vibrations move the beam back and forth across the detector.
Electronics then interpret these movements as sound. Some of the signals from the detector control an electric motor that keeps the optical stylus on track, even when parts of the record are missing. The new device can play monophonic or stereophonic recordings. Jurge Poliak, Laboratoire de Metrologie, Ecole Polytechnique Federale Lausanne, Switzerland.