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InPhase Announces 300GB Holographic Discs
turboflux writes "After rolling out prototype holographic drives last year, ExtremeTech reports that InPhase has announced they intend to ship drives to commercial customers in 2006. InPhase originally intended on shipping the 200GB version of their media this year. Another article on Engadget mentions that 1TB discs will be available in 2009."
Maybe you didn't read the article properly? The linked article states that "the recording material is 1.5 mm thick and is sandwiched between two 130 mm diameter transmissive plastic substrates". So from my take on this, it seems that they have a plate-like object (possibly see-thru... I can imagine GREAT case-modding...) that is VERY THIN. I could even imagine that perhaps several of these could eventually be sandwiched together into a sort of cube to create massive amounts of storage. You would have several thin read/write "heads" that would read the "plates" on each side of them. They say the timeframe for R/W media is 2-3 years. Exciting!
Ads? What ads?
that seems kind low
That is because
Second-generation rewriteable products are due in 2007 or 2008, Murphy said
Releasing 1.5 TB disks would satisfy the storage market immediately. They first get people interested in the 'low density' variant, then those people will become greedy again for the higher density versions in 2007 or 2008.
Stachel
It's sort of the same, but then again not really. From InPhase's website:
Light from a single laser beam is split into two beams, the signal beam (which carries the data) and the reference beam. The hologram is formed where these two beams intersect in the recording medium.
The process for encoding data onto the signal beam is accomplished by a device called a spatial light modulator (SLM). The SLM translates the electronic data of 0's and 1's into an optical "checkerboard" pattern of light and dark pixels. The data is arranged in an array or page of around a million bits. The exact number of bits is determined by the pixel count of the SLM.
At the point of intersection of the reference beam and the data carrying signal beam, the hologram is recorded in the light sensitive storage medium. A chemical reaction occurs in the medium when the bright elements of the signal beam intersect the reference beam, causing the hologram stored. By varying the reference beam angle, wavelength, or media position many different holograms can be recorded in the same volume of material.
"This does not seem to be holographic in the sense we are expecting."
What sense were you expecting? A normal holographic image does precisely that, chemical reactions induced by light, it's the same basic principle as normal photography. The difference is that you use lasers (coherent phase background), and increase resolution to the point that you can store not just amplitude but relative phase information of the wavefront.
The full wave front of light, including the relative phase is sufficient to recreate the entire wave, including all "3D information". This is known in physics as Huygen's Principle: http://en.wikipedia.org/wiki/Huygens_principle
No, *you* got it wrong. They do not state the transfer rate anywhere in the article. They never say that the "one million bits at a time" is "per second". They are simply saying that the mechanism can read 1 million bits at the same time in a single operation, in the same way that a digitial camera CCD "reads" 5 megapixels worth of data at the same time (it uses similar technology to read the holographic information).
The article states that the "200-GB drive, the HDS-200R, would ship this year with a 20-Mbyte transfer rate". I assume the transfer rate will be roughly the same on the 300GB drive and not miracously increase to 1GB per second just because of a minor upgrade in data density.
If the capacity is kind of "low" by holographic memory standards, it might be because this medium doesn't use any other kind of multiplexing beside spatial multiplexing.
Basically, what we have here is a disc with several "holographic bits", scattered across the disc just like a regular compact disc. The main difference here is that when you read an holographic bit with the reconstruction beam, you get a full page of data (here, a 1024x1024 image - hence 1 Mbit).
What is interesting with holographic memory is that when you use thick layers of holographic materials you can also multiplex the data using the angle of the reconstruction beam, or its wavelength. That means that you can hit the same area on the disc with the reconstruction beam at a different angle, and get a different page of data. Or use a different laser beam, and get again another page of data.
Of course, this process seriously complexifies the hardware that must be used to read an hoographic medium, but it is the key to reach tremendous densities with the holographic technique.
What is interesting here is that FillFactory designs CMOS-APS detectors instead of the more traditional CCD imagers.
APS stands for Active Pixel Sensor: basically the main difference with CCD's is that you get the line and row selection transistors, and an amplification transistor built in every pixel. That means you don't have to transfer the charge from pixel to pixel over the whole matrix as in CCDs: you can directly address the detector matrix as you would do on RAM.
The main drawback is that these selection and amplification units take room on the silicium, and therefore prevent the whole surface of a pixel to be sensitive to light. This is what is called the fill factor : the amount of a pixel which is effectively capturing light.
FillFactory (now owned by Cypress Semiconductors) have promising patents related to increasing the fill factor - hence their name.
For WORM applications, this is not that big a deal. However, for R/W applications, some serious file system and virtual memory redesign is needed.
Not to worry - these holo drives wear out quickly with repeated rewriting just like CD-RW, so they are not providing paging space anytime soon. But it is fun to think about.