I have more than 15 years in the Optical field.  I first started working with Optical Technology in 1988 when storage was on 12 inch Write Once-Read Many or WORM optical platters with 1.0 GB standard storage (CAV format) and 1.6 GB maximum storage (CLV format) on each 12 inch surface.  Double sided media produced 2.0 to 3.2 GB per platter.  The second generation of optical technology resulted in that capacity being doubled to 4.0 to 6.4 GB per platter. and a 200KBS transfer rate.  Around this time 5¼ inch Magneto Optical drives were introduced at 594 to 650 MB per disk or 297 to 325 MB per side.  This product line introduced rewrite capability to optical.

Libraries or "jukeboxes"  were also developed to handle 1 or 2 drives and up to 50 platters.  Later versions of the libraries added expansion capability for up to 4 or 5 drives and 110 to 150 platters.  Shortly after 5¼ drives were introduced, libraries for that format drive holding from 10 or 20 platters up to 500 or even 1000 platters were added to product lines.  16 to 32 drives were not uncommon in the larger systems.

Today's DVD products generally store 4.7 GB per side and may store up to 9.4 GB if both sides are recorded or on one side if it is recorded in two layers.  Two layer recording is made possible because the DVD recording surface is transparent allowing for a drive to select a focus level embedded below the top layer of the media.  The first layer of information is written on the surface and the second layer of information is written at a level below the surface where the data written on the surface will not interfere with the deeper write and read operations.

More to come!

Much more to come!!