HOLOGRAPHIC VERSATILE DISC. Outline. What is HVD? Collinear Holography. Basic structure How it work? Compare with other devices. Advantages/Disadvantages Conclusion. What is HVD ?.
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Outline • What is HVD? • Collinear Holography. • Basic structure • How it work? • Compare with other devices. • Advantages/Disadvantages • Conclusion
What is HVD ? • Holographic Versatile Disc (HVD) is an optical disc technology which would hold up to 3.9 terabytes (TB) of information. • It employs a technique known as collinear holography.
Collinear Holography • In collinear holography there are two type of laser beam. Red beam(Information beam) Green beam(Refrence beam) • This two beams are collimated in a single beam. • The green laser reads data encoded as laser interference fringes from holographic layer near the top of the disc.
while the red laser is used as the reference beam and to read servo information from a regular CD-style aluminum layer near the bottom. • A dichroic mirror layer between the holographic data and the servo data reflects the green laser while letting the red laser pass through.
Basic structure • It has similar to CD-DVD structure. It is differs to use laser beams & its pulse speed. • The Components are like … blue or green laser(532 nmwl), red laser ,beam splitter, mirrors special lights modulator(SLM), C-MOS sensor ,photo polymer recording medium.
How it works? • Current optical storage saves one bit per pulse & the HVD hopes to improve this efficiency with capability of around 60,000 bits/pulse. • Truncated cone shape that has 200 micrometer diameter at the bottom & 500 micrometer diameter at top.
Data-SLM-Binary • Data is created to fire laser beam into the beam splitter to produce 2 beam. 1.Reference beam ( Directed to away from the SLM). 2.Information beam ( Direct toward – the SLM ).
The 0’s & 1’s data pages are translated into the pixel of the special light modulator that either block or tr- ansmit light. • A memory system isn't very useful if you can't access the data you've stored.
Advantages • HVD have the capacity to hold up to 3.9 terabytes (TB) of information, which is approximately 5,500 times the capacity of a CD-ROM,830 times the capacity of a DVD,160 times the capacity of single-layer Blu-ray Discs, and about 4 times the capacity of the largest computer hard drives as of 2007.
The HVD also has a transfer rate of 1 Gbit/s (128 MB/s). • It has been estimated that the books in the U.S. Library of Congress, one of the largest libraries in the world, would contain a total of about 20 terabytes if scanned in text format. Not including images from the books, the content could be stored with capacity to spare on six 3.9 TB discs.
Using MPEG4 ASP encoding, a 3.9 TB HVD could hold 4,600–11,900 hours of video—just over one year of uninterrupted video at usual encoding rates. • Using typical satellite radio encoding (CT-aacPlus at 40 kbit/s), a 3.9 TB HVD could hold over 26.5 years of uninterrupted stereo audio.
Disadvantages • Holography memory has been around for more than 40 years but several characteristic made it difficult to implement , now progras of HVD make it easy to implement. • It is not available in market.
References Ashley, J. et al. “Holographic Data Storage” IBM Journal of Research and Development, Vol 44, No 3, 2000, pp 341-368 Ferri, Vic. “Holographic Video Storage” TechTrax, http://pubs.logicalexpressions.com/Pub0009/LPMArticle.asp?ID=118 Orlov, Sergei S. et al. “High-transfer-rate high-capacity holographic disk data-storage system” Applied Optics, Vol 43, No 25, Sept. 1 2004, pp 4902-4914 Psaltis, Demitri and Mok, Fai. “Holographic Memories” Scientific American, Nov. 1995, pp 70-76 Schwartz, Karen D. “HVD: Coming to a Storage Device Near You” eWeek, Feb. 3, 2005, http://www.eweek.com/article2/0,1759,1759907,00.asp “Blue laser media offers terabytes on a disc” Mar. 12, 2004. http://www.ferret.com.au/articles/49/0c01d949.asp “Ecma International creates TC44 to standardize Holographic Information Storage systems” http://www.ecma-international.org/news/TC44_PR_Jan2005.htm “Holographic Disk is Quickly Searchable” Laser Focus World, Feb. 2003, p 17 “Holographic Storage Takes a Step Toward Viability” Photonics Technology World Oct. 1998 http://www.photonics.com/spectra/tech/XQ/ASP/techid.422/QX/read.htm “Technology” http://www.optware.co.jp/english/tech.htm