Using Lasers to Play Old-Fashioned Records

May 3, 2005 — -- Remember phonographs and record albums?

The introduction of smaller, scratch-resistant audio compact discs has made such analog music formats obscure if not obsolete. But with an estimated 30 billion platters of vinyl still in the hands of audiophiles, collectors and die-hard music fans today, old-fashioned records haven't exactly faded away.

And now a small Japanese company called ELP believes it can bring old school albums a new spin at life -- thanks in part, to CD technology itself.

Since 1989 -- just six years after the development of CD players -- ELP has been developing and fine-tuning its Laser Turntable. As the name implies, it's a record album player that replaces the traditional turntable stylus with a group of five high-tech lasers.

How the technology works is deceptively simple and similar to the basic operation of common audio CD players.

Two pairs of lasers shine on the album's microscopic track, or the "groove" cut into the album's surface by a diamond-tipped stylus during the recording process. One pair of lasers measures the minute variations embedded in the groove's walls -- the part that would cause a tradition phonograph's needle to vibrate and re-create the sound recorded on the album. The other pair of lasers tracks the groove's "land," or the two "shoulders" that straddle the groove, marking the surface of the album. A separate laser shines onto the album's surface itself so the other lasers always maintain a precise distance above the album.

As the turntable spins the record, optical sensors detect the laser reflections from the grooves' walls. The measured variations create an electronic signal similar to that produced by a phonograph needle vibrating within the groove. Scratches on the surface of the album, which can produce annoying popping sounds and skips in the music, are generally ignored.

Audio distortions typically produced from even slightly "warped" records is also eliminated since the tracking laser ensures that the other lasers consistently remain at an optimal distance for pick-up by the optical sensors.