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HOLOGRAPHIC DATA STORAGE. Contents. Introduction. Magnetic and conventional optical data storage technologies are approaching physical limits beyond which individual bits may be too small or too difficult to store.
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Introduction • Magnetic and conventional optical data storage technologies are approaching physical limits beyond which individual bits may be too small or too difficult to store. • Holographic data storage is an approach of storing information throughout the volume of a medium—not just on its surface. • With the rapidly increasing demand for increased storage capacity in a smaller space, this technology offers an economy in price.
Features • Next – Next generation Technology • 1 HVD = 5800 CDs = 830 DVDs = 160 Blu-ray • Media type : Ultra-high density optical disc • Encoding : MPEG-2, MPEG-4 AVC (H.264), and VC-1 • Capacity theoretically up to 3.9 TB • Developed by HSD Forum • Usage : Data Storage, : High-defination video and the possibility of Ultra-high defination video • permits over 10 Kbits of data to be read and written in parallel with a single flash
What Is Hologram ? A hologram is a recording of the optical interference pattern that forms at the intersection of two coherent optical beams • Signal beam • Reference beam on the holographic medium.
Types of Holograms • Transmission Hologram • Can be used to store data • Uses coherent light • Reflection Hologram • The kind you find on credit cards • Uses white light
Holography vs Photography • Black and white photograph • Intensity • Color photograph • Intensity and wavelength • Hologram • Intensity, phase, and sometimes wavelength
Qualitative Explanation of Storage Reference beam Object image Resultant pattern Stored in film
Qualitative Explanation of Reconstruction Reference beam Stored in film Reflection
Spatial Light Modulator(SDM) • Translates electronic data (0’s and 1’s) into optical pattern of light and dark pixcels • Data is arranged in an array similar to a checker board of usually 1 million bits • By varying the angle of the reference beam ,wavelength or media position, many holograms can be stored in the same volume of storage material
HVD Technology • HVD uses a technology called ‘collinear technology’ • Two Laser rays one blue-green and one red are used • The role of blue-green laser is to read the data encoded the form of laser interference fringes from the holographic layer • The red laser serves the purpose of a reference beam and also to read the servo info from the aluminum layer
Read only HVD Read\Write HVD • supports some irreversible photochemical reaction triggered by the bright regions of the optical interference pattern • Material diffuses from darker to brighter regions so that short monomer chains can bind together to form long molecular chains • uses inorganic photorefractive crystals • Electrons get photo-excited at the bright fringes, diffuse or drift and are re-trapped at a dark fringe • Trapped charge can be rearranged by later illumination, so it is possible to erase recorded holograms
Current State of Technology • Storage and Cost • CD-ROM: 783 MB to 1.3 GB – 10 cents • DVD+DL: 5 GB to 30 GB - $3 • Blu-Ray DL: 25 GB to 50 GB - $30 • InPhase Tapestry: 300 GB - $250 • Hard disk: 1 TB - $300 • HVD (future): 4 TB
Current State of Technology • Tansfer rates and Recordable Player Approx Cost • CD-ROM 52x: ~ 5 MB/second --$200 • DVD 16x: ~ 20 MB/s --$ 2000 • InPhase Tapestry: 20 MB/sec • Blu-Ray and HDDVD: ~ 30 MB/sec --$2000 • 7200 rpm Hard disk: 80 MB/sec • HVD: 1 GB/sec --$3000
Interesting Facts • It has been estimated that books in the U.S. Library of Congress, the largest library in the world, could be stored on 6 HVD’s • The pictures of every landmass on Earth – like the one shown in Google Earth can be stored on two HVD’s • With MPEG4 ASP encoding , a HVD can hold anywhere in between 4,600 to 11,900 hours of video, which is enough for non-stop Playing for a year