Present times offer us optical media with capacities varying from hundreds of MB to tens of GB, and hard-drives got well-beyond 100 Gb in capacity. But the media called Hyper CD-ROM canaccomodate up to 10 TB (terabytes) of data, this means no less than 10,000 GB!
The disc itself has a diameter equal to that of a regular CD-ROM and a width of 10 mm; this last value isn't a regular one for optical media, but that is the secret: the information recording can be done over all the three dimensions, by using what is scientifically called volumetric data burning. The "classic" burners use only two media dimensions for recording the information and the DVDs can contain two information surfaces on the same side. The new HyperCD has no less that 10,000 information layers (mentioning that these layers are in fact in-depth planar surfaces of the disc) and every one of them can store about 1 GB of data. The layer is made out of a fluorescent substance, which by itself has the property of emitting, in the presence of an optical ray, another optical ray but of another wavelength. This substance is distributed within the physical support, which is in fact a vitro-ceramic material with very high mechano-thermal resistance, in order to offer a great data reliability: data can be safely kept for a period of several millenia, and high tolerance (this disc can even be sank in melted crude-iron without damaging the data, according to inventor's statements).
Constructively speaking, the reading/writing unit is twice higher than an ordinary one, because the technique for using these multilayer discs requires an optical block much more complex then in case of a regular CD/DVD. this supplementar optical device consist of a co-focalizer (some kind of a microscope), which concentrates the laser ray emmited by a laser device to a certain depth within the disc, this way being added the third coordinate dimension, not mentioning the classic track/sector point. The second function of the co-focal microscope consist in filtering the optical information so only the information coming from the desired depth could be sent to the reading device. In the focus point, due to the exitation of the fluorescent substance, a powerful enough optical emmision can be provided, so that it can be used for reading the data after reversely passing through the co-focal microscope. Producing a different wavelength is essential so that filtering possible ray reflections would not interfere with the optical data-carrier (the needed optical ray itself). The reading device is basically a photographic cell which is activated by the light intensity, no matter its wavelength. This simplified device requires previous color separation, which is done by using a di-chromatic mirror. This is in fact a piece of filtering glass which permits passing an optical ray with a wavelength of 532 nm (nanometers) and possible ray reflections but redirects fluorescent radiaton (with a wavelength of 610 nm) to the reading device. The co-focal microscope is situated between the mirror and the disc, in order to guide the laser ray and selecting the desired layer depth. The disc rotation mechanism and the head-positioning motor are built the same as those of a traditional CD unit.

Here's the translated interview with professor Eugen Pavel, the inventor of the HyperCD:

We've discussed with Mr. Eugen Pavel about several aspects concerning this invention and its current developing stage.
Chip: Infos about the HyperCD technology appeared first in 2000. What stage is the project currently in?
E.P.: The theorethical part was finalized in 1998, but the general study covers all my activity in time. I've built the experimental prototype which was first presented in 1999 at the EUREKA Expo in Bruxelles, among other such expositions. The commercial prototype, with full functionality and prepared for mass production is very close to being finalized.
Chip: What does this invention mean and how much of it has been conceived in Romania?
E.P.: The research for this project is 100% personal, so is the support for experiments. this invention is pure Romanian and has been internationally accepted through legalizing over 40 patents and inventor's brevets, covering all domains, from the substances included in the disc creation, to the device itself.
Chip: In the general specifications, which can be found at http://www.dntb.ro/users/frdbuc/hyper-cdrom we've learned that the transfer speed is of about 3 MB per second. In these conditions, reading an entire disc could take tens of days.
E.P.: This speed is obtained in laborator conditions, and will be increased for commercial products. The disc's spinning speed can be greatly increased way beyond the actual CD spinning speeds, because of its composition. Its mechanical properties are way superior to those of the actual CD materials. Beyond that, its capacity can be increased 100 times theoretically, reaching a limit of 1 Petabyte (1000 Terabytes).
Chip: Are there any contracts with a producer for mass-producing such discs?
E.P.: I have had discussions with several companies, but I'd rather not specify names, because discussions are not final yet.
Chip: Can you provide a sum as a possible price for end-user technology?
E.P.: The HyperCD unit would cost around $ 1000, and a 10,000 Gb disc would reach about $ 300. There will be a "light" version of the disc, with a width of 1.2 mm which will cost $ 30 and would store about 200 GB of data.
Chip: How long would it take for the HyperCD Unit to be largely available on the stores' shelves?
E.P.: One year, at most!
Chip: We cannot be other than happy of such news. Thank you!