[attachment=7427]

---

This article is presented by:
Ranjit Kamal

---

Holographic Versatile Disc

CONTENTS

What is HVD ?
Holographic Versatile Disc Structure
Working Principal
HVD Write System
HVD Read System
How HVD compares Others ?
Advantages
HVD Alliance
HVD Forum
Conclusion
References

What is HVD ?

An HVD is an advanced optical disk that’s presently in the development stage. Polaroid scientist J van Heerden was the first to come up with the idea for holographic three-dimensional storage in 1960.
Holographic Versatile Disc (HVD) is an optical disc
technology still in the research stage which would hold up to 3.9 terabytes (TB) of information .
The first step in understanding holographic memory is to understand what "holographic" means.
Holography : Holography is a method of recording patterns of light to produce a three-dimensional object.
Hologram : The recorded patterns of light are called a hologram

HVD Structure
Green writing/reading laser (532 nm)
Red positioning/addressing laser (650 nm)
Hologram (data)
Polycarbon layer
Photopolymeric layer (data-containing layer)
Distance layers
Dichotic layer (reflecting green light)
Aluminium reflective layer (reflecting red light)
Working Principle
HVD uses a technology called 'collinear holography,' in which two laser rays, one blue-green and one red, are collimated into a single beam..

The blue-green laser reads data encoded as laser interference fringes from a 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 aluminium layer near the bottom.

Servo information is used to monitor the position of the read head over the disc, similar to the head, track, and sector information on a conventional hard disk drive.


 HVD Write System
A simplified HVD system consists of the following main components:
Blue or green laser (532-nm wavelength in the test system)
Beam splitter/merger
Mirrors
Spatial light modulator (SLM)
CMOS sensor
Polymer recording medium


HVD Read System
To read the data from an HVD, you need to retrieve the light
pattern stored in the hologram.
In the HVD read system, the laser projects a light beam onto the hologram -- a light beam -- a light beam that is identical to the reference beam.
The hologram diffracts this beam according to the specific pattern of light interference it's storing.
The resulting light recreates the image of the page data that established the light-interference pattern in the first place. When this beam of light -- the reconstruction beam -- bounces back off the disc it travels to the CMOS sensor that reproduces the page data.


. How HVD compares Others ?
Advantages
High Storage capacity of 3.9 terabyte(TB) enables user to store large amount of data.
Records high-definition television (HDTV) without any quality loss.
Records one program while watching another on the disc.
Edit or reorder programs recorded on the disc.
Automatically search for an empty space on the disc to avoid recording over a program.

HVD Alliance
The HVD Forum
The HVD FORUM (formerly the HVD Alliance) is a coalition of corporations purposed to provide an industry forum for testing and technical discussion of all aspects of HVD design & manufacturing.

Alps Electric Corporation, Ltd.
Optware Corporation
CMC Magnetics Corporation
Dainippon Ink and Chemicals, Inc. (DIC)
EMTEC International (subsidiary of the MPO Group)
Fuji Photo Film Company, Ltd.
Konica Minolta Holdings, Inc.
LiteOn Technology Corporation
Mitsubishi Kagaku Media Company, Ltd. (MKM)

Conclusion
HVD will soon replace previous DVDs.
It is currently supported by more than 170 of the world's leading consumer electronics, personal computer, recording media, video game and music companies.
The format also has broad support from the major movie studios as a successor to today's DVD format.
Holographic Versatile Disc already has the backing of seven out of eight leading Hollywood studios. It will soon be able to enjoy a growing range of film entertainment with unsurpassed Full HD pictures and cinema-quality multi-channel sound.
References
http://tech-faqhvd.shtml.
http://electronics.howstuffworkshvd.html
http://en.wikipediawiki/Holographic_Versatile_Disc
http://eweekarticle2/0,1759,1759907,00.asp
http://newsGroup-aims-to-drastically-up-disc-storage/2100-1041_3-5562599.html