Laser scanned CD

In reading the Compact disks (and DVDs, and blu-rays too) the disk moves while the laser beam stays (comparatively) still. At the time the compact disk was introduced, this was the only thing possible from mechanical and optical considerations.

However, the advances in technology have made other arrangements possible. There are advantages to be gained in holding the disk still, and moving the laser beam, by the use of scanning mirrors, to follow the circular data track. Since the mirrors used for deflecting the laser beam do not have to be removed, they can be engineered to move fast. So reading speeds will not be limited by the maximum rotatinal speed of the disk.

The disadvantage is the need for long - throw optics, ie, the laser and the surface of the disk are at a comparatively long distance. This will necessiate higher quality optical components in order to maintain focus across the travel of the beam. But since the disk is being held still there are no rotational components of defocusing as with a rotating disk.

And the track need not be circular any longer - the LSCD drive will need to read the traditionally recorded disks and so will need to scan such disks in the traditional manner. But in making a fresh recording, on a virgin disk, any convoluted non-crossing space-filling pattern can be used. It will be able to record on a scrap of CDR of any shape.

Perhaps this will bring back the ye olden golden years of yore when messages were exchanged in microdots under the postage stamps stuck on to otherwise inocuous letters.