28-07-2011, 11:00 AM
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INTRODUCTION
With its omnipresent computer all connected via internet information age has lead an explosion of information available to users. With the decreasing cost of storing data and increasing storage capacity with a same small device foot print have been key enablers of this revolution. While the current storage need are being met the storage technologies must continue in order to keep pace with a rapidly increasing demand.
However both magnetic and conventional optical data storage technologies, where individual bits are stored as distinct magnetic or optical changes in the surface of recording medium, are approaching physical limits beyond which individual bits are too small or too difficult to store. Storing information through the volume of the medium not on its surface offers an intriguing high capacity alternative. Holographic data storage is a volumetric approach, which has made recent progress towards practicality with the appearance of lower cost enabling technologies.
Hence the holographic memory has become a great white whale of
technology research.
CONCEPT OF HOLOGRAPHIC MEMORY
Holography is a technique which allows recording and playback of 3- dimensional image. The is called a hologram unlike other 3-dimenssional “picture” hologram provide hologram provide what is called “parallax”. Parallax allows the viewer to move back and forth up and down and see different perspective – as if the object were actually there.
In Holography, the aim is to record complete wave field (both
amplitude and phase) as it is intercepted by recording medium the record in
plane may not even be an image plane. The scattered or reflected light by object is intercepted by the recording medium and recorded completely in spite of the fact that the detector is insensitive to the phase difference among the various part of the optical field
In holography, interference between the object wave and reference
wave is formed and recorded on a holographic material. The record known as hologram (whole record) captures the complete wave which can be viewed at the later time by illuminating the hologram with an appropriate light beam.
To this day holography continues to provide the most accurate depiction of 3-D image in the world.
HISTORICAL ROOTS
Dr. Dennis Gabor is known as the father of holography. In year 1947, Dr. Gobor a Hungerian Physicist given the idea of holography at the imperial college of
London in1971 Dr. Gabor received a noble prize in physics for holography. His theory was originally meant to increase the resolving power of electronic microscvope and towards that he used light of beam instead of electronic beam and this resulted in the first hologram ever made.
In 1960s, two engineers from the University of Michigon, Emmitt Lerth and Juris Upatlipks, developed a new device that produce a 3-D image of an object
Polaroid scientist Peter J. Vann Heerdern proposed the idea of holographic
storage in the early 1960s and decade later scientist at RCA laboratories
demonstrated the holographic storage technology by recording 500 holograms in an iron doped lithium niobate crystal and 550 holograms of high resolution
images in a light sensitive polymer material
However, the development of holographic data storage was put on holed for several years because of the absence of cheap parts of the advancement in magnetic and semiconductor memories.
In recent years IBM and lucent Bell labs are actively involve\d in creating a
successful holographic storage medium as a result of which it has become
possible to store 1000 GB of data in a small cube.
WHAT IS HOLOGRAM ?
The word Hologram is derived from Greek word “Holos” meaning ‘Whole’ and “GRAM” meaning ‘Message’. Older English dictionaries define a hologram as a document (such as a last will and testament) hand written by the person whose signature is attached. A hologram is often described as a 3-D picture.
While a photograph has an actual physical image, a hologram contains
information about size, shape, brightness and contrast of object being recorded .This information is stored in a very microscopic and complex pattern of
interference. The interference pattern is made possible by the properties of light generated by a LASER.
In order to record the whole pattern, the light used must be highly directional and must be one of one color. Such light is called coherent. Because the light from a LASER is one color and leaves the LASER with one wave in perfect one step
with all others, it is perfect for making hologram.
When we shine a light on the hologram the information that is stored as an
interference pattern takes the incoming light and re-creates the original optical wave front that was reflected off the object hence the eyes and brain now
perceives the object as being in front of us once again.
INTRODUCTION
With its omnipresent computer all connected via internet information age has lead an explosion of information available to users. With the decreasing cost of storing data and increasing storage capacity with a same small device foot print have been key enablers of this revolution. While the current storage need are being met the storage technologies must continue in order to keep pace with a rapidly increasing demand.
However both magnetic and conventional optical data storage technologies, where individual bits are stored as distinct magnetic or optical changes in the surface of recording medium, are approaching physical limits beyond which individual bits are too small or too difficult to store. Storing information through the volume of the medium not on its surface offers an intriguing high capacity alternative. Holographic data storage is a volumetric approach, which has made recent progress towards practicality with the appearance of lower cost enabling technologies.
Hence the holographic memory has become a great white whale of
technology research.
CONCEPT OF HOLOGRAPHIC MEMORY
Holography is a technique which allows recording and playback of 3- dimensional image. The is called a hologram unlike other 3-dimenssional “picture” hologram provide hologram provide what is called “parallax”. Parallax allows the viewer to move back and forth up and down and see different perspective – as if the object were actually there.
In Holography, the aim is to record complete wave field (both
amplitude and phase) as it is intercepted by recording medium the record in
plane may not even be an image plane. The scattered or reflected light by object is intercepted by the recording medium and recorded completely in spite of the fact that the detector is insensitive to the phase difference among the various part of the optical field
In holography, interference between the object wave and reference
wave is formed and recorded on a holographic material. The record known as hologram (whole record) captures the complete wave which can be viewed at the later time by illuminating the hologram with an appropriate light beam.
To this day holography continues to provide the most accurate depiction of 3-D image in the world.
HISTORICAL ROOTS
Dr. Dennis Gabor is known as the father of holography. In year 1947, Dr. Gobor a Hungerian Physicist given the idea of holography at the imperial college of
London in1971 Dr. Gabor received a noble prize in physics for holography. His theory was originally meant to increase the resolving power of electronic microscvope and towards that he used light of beam instead of electronic beam and this resulted in the first hologram ever made.
In 1960s, two engineers from the University of Michigon, Emmitt Lerth and Juris Upatlipks, developed a new device that produce a 3-D image of an object
Polaroid scientist Peter J. Vann Heerdern proposed the idea of holographic
storage in the early 1960s and decade later scientist at RCA laboratories
demonstrated the holographic storage technology by recording 500 holograms in an iron doped lithium niobate crystal and 550 holograms of high resolution
images in a light sensitive polymer material
However, the development of holographic data storage was put on holed for several years because of the absence of cheap parts of the advancement in magnetic and semiconductor memories.
In recent years IBM and lucent Bell labs are actively involve\d in creating a
successful holographic storage medium as a result of which it has become
possible to store 1000 GB of data in a small cube.
WHAT IS HOLOGRAM ?
The word Hologram is derived from Greek word “Holos” meaning ‘Whole’ and “GRAM” meaning ‘Message’. Older English dictionaries define a hologram as a document (such as a last will and testament) hand written by the person whose signature is attached. A hologram is often described as a 3-D picture.
While a photograph has an actual physical image, a hologram contains
information about size, shape, brightness and contrast of object being recorded .This information is stored in a very microscopic and complex pattern of
interference. The interference pattern is made possible by the properties of light generated by a LASER.
In order to record the whole pattern, the light used must be highly directional and must be one of one color. Such light is called coherent. Because the light from a LASER is one color and leaves the LASER with one wave in perfect one step
with all others, it is perfect for making hologram.
When we shine a light on the hologram the information that is stored as an
interference pattern takes the incoming light and re-creates the original optical wave front that was reflected off the object hence the eyes and brain now
perceives the object as being in front of us once again.