11-04-2011, 03:37 PM
Prsented By
Sapna lahoti
[attachment=12026]
Holographic Versatile Disc
INTRODUCTION
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 paterns 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
• 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.
THE HVD System: Writing Data
• 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
• Photopolymer recording medium
• RECORDING DATA
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.
STORAGE PATTERN
• Comparision
Advantages
• High Storage capacity of 3.9 terabyte(TB) enables user to store large amount of data.
• 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.
The transfer rate of HVD is up to 1 gigabyte (GB) per second which is 40 times faster than DVD .
An HVD stores and retrieves an entire page of data, approximately 60,000 bits of information, in one pulse of light, while a DVD stores and retrieves one bit of data in one pulse of light.
Disadvantages
• Manufacturing cost HDSS is very high and there is a lack of availability of resources which are needed to produce HDSS.
• However, all the holograms appear dimmer because their patterns must share the material's finite dynamic range.
• You would be unable to locate the data if there’s an error of even a thousandth of an inch.-
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.
Sapna lahoti
[attachment=12026]
Holographic Versatile Disc
INTRODUCTION
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 paterns 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
• 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.
THE HVD System: Writing Data
• 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
• Photopolymer recording medium
• RECORDING DATA
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.
STORAGE PATTERN
• Comparision
Advantages
• High Storage capacity of 3.9 terabyte(TB) enables user to store large amount of data.
• 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.
The transfer rate of HVD is up to 1 gigabyte (GB) per second which is 40 times faster than DVD .
An HVD stores and retrieves an entire page of data, approximately 60,000 bits of information, in one pulse of light, while a DVD stores and retrieves one bit of data in one pulse of light.
Disadvantages
• Manufacturing cost HDSS is very high and there is a lack of availability of resources which are needed to produce HDSS.
• However, all the holograms appear dimmer because their patterns must share the material's finite dynamic range.
• You would be unable to locate the data if there’s an error of even a thousandth of an inch.-
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.
