text: In addition to the academic research, several companies have been set up to commercialize 3D optical data storage and some large corporations have also shown an interest in the technology. However, it is not yet clear whether the technology will succeed in the market in the presence of competition from other quarters such as hard drives, flash storage, and holographic storage.
  *Call/Recall was founded in 1987 on the basis of Peter Rentzepis' research. Using two–photon recording (at 25 Mbit/s with 6.5 ps, 7 nJ, 532 nm pulses), one–photon readout (with 635 nm), and a high NA (1.0) immersion lens, they have stored 1 TB as 200 layers in a 1.2 mm thick disk. They aim to improve capacity to >5 TB and data rates to up to 250 Mbit/s within a year, by developing new materials as well as high-powered pulsed blue laser diodes.
  *Mempile are developing a commercial system with the name TeraDisc. In March 2007, they demonstrated the recording and readback of 100 layers of information on a 0.6 mm thick disc, as well as low crosstalk, high sensitivity, and thermodynamic stability. They intend to release a red-laser 0.6-1.0 TB consumer product in 2010, and have a roadmap to a 5 TB blue-laser product.
  *Constellation 3D developed the Fluorescent Multilayer Disc at the end of the 1990s, which was a ROM disk, manufactured layer by layer. The company failed in 2002, but the intellectual property (IP) was acquired by D-Data Inc., who are attempting to introduce it as the Digital Multilayer Disk (DMD).
  *Storex Technologies has been set up to develop 3D media based on fluorescent photosensitive glasses and glass-ceramic materials. The technology derives from the patents of the Romanian scientist Eugen Pavel, who is also the founder and CEO of the company. At ODS2010 conference were presented results regarding readout by two non-fluorescence methods of a Petabyte Optical Disc.
  *Landauer Inc. are developing a media based on resonant two-photon absorption in a sapphire single crystal substrate. In May 2007, they showed the recording of 20 layers of data using 2 nJ of laser energy (405 nm) for each mark. The reading rate is limited to 10 Mbit/s because of the fluorescence lifetime.
  *Colossal Storage aim to develop a 3D holographic optical storage technology based on photon-induced electric field poling using a far UV laser to obtain large improvements over current data capacity and transfer rates, but as yet they have not presented any experimental research or feasibility study.
  *Microholas operates out of the University of Berlin, under the leadership of Prof Susanna Orlic, and has achieved the recording of up to 75 layers of microholographic data, separated by 4.5 micrometres, and suggesting a data density of 10 GB per layer.
  *3DCD Technology Pty. Ltd. is a university spin-off set up to develop 3D optical storage technology based on materials identified by Daniel Day and Min Gu.
  *Several large technology companies such as Fuji, Ricoh, and Matsushita have applied for patents on two–photon-responsive materials for applications including 3D optical data storage, however they have not given any indication that they are developing full data storage solutions.