Fluorescent Multilayer Disc (FMD) was an optical disc

Optical disc

In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...

 format developed by Constellation 3D

Constellation 3D

Constellation 3D was a company developing a new optical medium, the Fluorescent Multilayer Disc and Card .The company was shut down following a failure to receive a committed investment by a Swiss based investor and the unavailability of other financial sources...

 that uses fluorescent

Fluorescence

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...

, rather than reflective

Reflection (physics)

Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...

 materials to store data. Reflective disc formats (such as CD and DVD

DVD

A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

) have a practical limitation of about two layers, primarily due to interference, scatter, and inter-layer cross talk. However, the use of fluorescence allowed FMDs to operate according to the principles of 3D optical data storage

3D optical data storage

3D optical data storage is the term given to any form of optical data storage in which information can be recorded and/or read with three dimensional resolution ....

 and have up to 100 data layers.