holographical memory systems have been around for X . They offer far more memory capacity thanCDsandDVDs– even " next - multiplication " DVDs likeBlu - ray– and their transfer rates pass on formal discs in the dust . So why have n’t we all been usingholographic memoryfor years now ?
There are several hurdle that have been holding holographical storage back from the realm of mass consumption , including price and complexity . Until now , the system have required a cost - prohibitive level of precision in manufacturing . But recent changes have made the holographic versatile disc ( HVD ) develop by Optware a viable option for consumer .
In this clause , we ’ll find out how the HVD works , how it has improved upon premature method of holographical reposition and how it stacks up to Blu - ray and HD - DVD .
Basics of Holographic Memory
The first measure in understanding holographical memory is to understand what " holographic " substance . Holography is a method acting of recording form of light to produce a three - dimensional object . The recorded design of light are called ahologram .
The process of create a hologram begins with a focused beam of light – a laser beam . Thislaser beamissplitinto two freestanding ray : areference beam , which persist unaltered throughout much of the process , and aninformation beam , which pass through an image . When luminousness take on an image , its composition changes ( see How Light go to learn about this unconscious process ) . In a sense , once the entropy radio beam find an image , it carries that image in its waveforms . When these two beams intersect , it create a pattern oflight interference . If you commemorate this practice of light interference – for example , in a photosensitive polymer layer of a disc – you are basically immortalize the unaccented pattern of the image .
To call back the data store in a holograph , you shine the reference beam directly onto the holograph . When it reflects off the hologram , it holds the light pattern of the double stored there . You then send thisreconstruction beamto a CMOS sensor to recreate the original image .
Most of us think of hologram as stack away the range of an objective , like the Death Star pictured above . The holographic computer memory systems we ’re discussing here use holograms to store digital rather of analog information , but it ’s the same construct . alternatively of the information beam receive a pattern of light that represents the Death Star , it take on a shape of light and dreary area that interpret ones and nothing .
HVD offers several advantages over traditional store applied science . HVDs can ultimately storemore than 1 terabyte(TB ) of information – that ’s 200 times more than a individual - sided DVD and 20 times more than a current double - sided Blu - ray . This is part due to HVDs storing holograms inoverlapping form , while a DVD basically lay in bits of information side - by - side . HVDs also expend a thick recording layer than videodisc – an HVD storage information in almost the intact volume of the disc , instead of just a exclusive , thin bed .
The other major boost over conventional computer memory system is HVD ’s transfer of training rate of up to1 gigabyte ( GB ) per second– that ’s 40 times degraded than DVD . An HVD stores and retrieve an entire varlet of data point , approximately 60,000 bits of information , in one pulse of light , while a videodisk stores and retrieves one moment of data in one pulsation of light .
Now that we have intercourse the assumption at work in HVD technology , let ’s take a tone at the social structure of the Optware phonograph record .
The Holographic Versatile Disc
Holographic memory has been around for more than 40 old age , but several characteristics made it difficult to implement in a consumer market . First off , most of these systems send the reference beam and the information beam into the transcription medium on dissimilar Axis . This requires highly complex optic systems to line them up at the exact point at which they ask to intersect . Another drawback has to do with mutual exclusiveness with current storage media : Traditionally , holographic storage system contained no servo data , because the beam carrying it could interfere with the holography operation . Also , former holographical memory discs have been notably thicker than CDs and DVDs .
Optware has implemented some changes in its HVD that could make it a better fit for the consumer market . In the HVD system , the optical maser beam travel in the same bloc and strike the recording culture medium at the same slant , which Optware phone thecollinear method . harmonise to Optware , this method requires a less complex system of optic , enabling a smaller optical pickup arm that is more suitable to consumer use of goods and services .
HVD also includesservo data . The servosystem beam in the HVD system is at a wavelength that does not photosensitize the polymer recording spiritualist . In the HVD test organization , the servomechanism data point is carried in a red ( 650 - nm wavelength ) laser . The sizing and thickness of an HVD is also compatible with CDs and videodisc .
The structure of the disc places a thick transcription layer between two substratum and incorporates a dichroic mirror that reflect the blue - green light carry the holography data but allows the reddened luminosity to travel by through for forgather servomechanism info .
Because Optware ’s HVD organization is currently in the late stages of enquiry and development , arrant proficient entropy is unavailable for public consumption . But in the next surgical incision , we ’ll discuss a simplified variant of the system that enshroud the major view of HVD .
The HVD System: Writing Data
A simplified HVD organization consists of the following main part :
The process of write entropy onto an HVD begins with encoding the information intobinary datato be stored in theSLM . These data are turned into ones and zeroes represented as opaque or semitransparent orbit on a " page " – this page is the image that theinformation beamis belong to pass through .
Once the page of data point is make , the next step is to fire alaser beaminto abeam splitterto produce two identical shaft . One of the beam is directed away from the SLM – this beam becomes thereference beam . The other beam of light is organise toward the SLM and becomes theinformation balance beam . When the entropy beam passes through the SLM , portions of the Inner Light are deflect by the unintelligible orbit of the Sir Frederick Handley Page , and portion cash in one’s chips through the semitransparent field . In this path , the information ray express the image once it exit through the SLM .
When the character beam and the info beam rejoin on the same axis , they create a pattern of tripping interference – theholography information . This joint beam carries the interference practice to thephotopolymer discand stores it there as a hologram .
A memory system is n’t very useful if you ca n’t get at the data you ’ve stored . In the next section , we ’ll find out how the HVD data - retrieval system works .
The HVD System: Reading Data
To read the data from an HVD , you ask to recollect the unclouded pattern stored in the hologram .
In the HVD read system , the laser externalize a abstemious electron beam onto the holograph – a light beam that is identical to thereference beam(Read System 1 in the image above ) . The holograph diffracts this beam grant to the specific pattern of Light Within disturbance it ’s storing . The resulting light hearten the image of the page datum that make the light - interference convention in the first place . When this beam of brightness level – thereconstruction beam– bounces back off the disc ( Read System 2 ) , it travels to theCMOS sensor . The CMOS sensor then reproduces the page data .
Now let ’s take a expression at how HVD compares to other next - coevals depot medium .
How HVD Compares
While HVD is attempting to revolutionize data point storage , other discs are endeavor to ameliorate upon current systems . Two such discs are Blu - ray and HD - DVD , deemed the next - generation of digital storage . Both work up upon current DVD technology to increase repositing capacity . All three of these technologies are aiming for thehigh - definition videomarket , where focal ratio and capacity count . So how does HVD stack up ?
Because HVD is still in the later stages of growth , nothing is compose in stone ; but you ’ve likely noticed that the projected basic Leontyne Price for an HVD is a bit steep . An initial price of about $ 120 per disc will probably be a with child obstacle to consumers . However , this damage might not be so unsurmountable to businesses , which are HVD developer ' initial butt audience . Optware and its challenger will commercialise HVD ’s depot electrical capacity and transfer f number as idealistic for archival diligence , with commercial systems uncommitted as soon as recent 2006 . Consumer devices could hit the market around 2010 .
For more entropy on HVD and relate topics , see out the link on the next varlet .
