Millenniata

M-DISC Stores Information for Ages

The recording process in the M-DISC requires more energy and much higher temperatures than ordinary optical discs to create a permanent change in the more stable materials used. The nano-structured composite layer within the M-DISC employs materials that are chemically stable and heat-resistant to hundreds of degrees. The level of laser energy employed to write an ordinary DVD or CD cannot successfully write to these materials. Only the focused application of intense laser energy (about 5X higher than used for ordinary DVD-Rs) can alter these materials to record digital data. As shown conceptually in Figure 1, the bits are written by physically altering the recording layer where the higher-powered laser strikes it, leaving permanent voids or holes.  These small holes in the recording layer create a less reflective or dark region and capture the data. While the data-recording results — light and dark spaces — are the same for both the organic dye and the M-DISC, data recorded as a string of tangible holes is a much more robust and stable structure than other data recording mechanisms available today.

Materials Make the Difference

Materials were specifically chosen to ensure that stored information would stay intact in the harshest storage conditions. As a result, the materials, how they function, and the production methods used to manufacture the M-DISC, are substantially different than what is commonly found in optical discs. The M-DISC basic construction is a molded polycarbonate substrate, data layer, adhesive layer, and the top polycarbonate substrate. The very foundation begins with layers that are molecularly bonded together to form a unitary structure.

The M-DISC Construction

The beginning layer of the M-DISC is made of a polycarbonate substrate and the data layer with several atomically thick layers of inorganic materials, chosen for their stability. These layers are molecularly bonded to one another and to the polycarbonate substrate. The resulting data layer is “rock-hard” and prevents oxidation. The adhesive is then coated across the entire data layer. The adhesive was chosen based on its strong bonding properties and its ability to inhibit both oxidation and corrosion. The final polycarbonate substrate is then applied and the adhesive is cured with UV light. The materials that make up the M-DISC have shown they will keep the integrity of the digital information written on them after exposure to high heat, humidity, and natural sunlight (for more information go to http://www.millenniata.com/orphan/china_lake_summary/).

The Millennial Composite Layer

The M-DISC data layer performs the functions of both the reflective layer and the recording layer simultaneously. The combination of these materials forms a one-dimensional, nanostructured composite material that must be deposited in specific thicknesses and in the proper sequence to provide the desired optical properties. Sufficient reflectivity is required to enable the disc to be read in a standard disc drive.  The M-DISC read specification is based on the DVD+RW specification and requires a reflectivity of from 22% to 28%. 

Absorption is also important because these composite materials must absorb sufficient energy from the writing laser to record the data.  Insufficient absorption would mean laser energy was wasted and too much laser power would be required.  Too much absorption would mean that the reflectivity would be too low and the disc would not play properly in standard DVD drives.  Reflectivity and absorption are just two of the many technical issues that must be balanced properly to create a workable data storage technology. The semi-transparent appearance of the M-DISC is the final result of balancing all the different technical issues to produce a data layer that captures digital data permanently while using the laser power efficiently and meeting the DVD+RW read-back specifications of standard DVD drives.