The first three parts of this series explored the different types of Blu-ray drives for use in computers (and some game systems).  We looked at the basic Blu-ray disk readers (BD-ROM), that were capable of playing Blu-ray discs, and probably also capable of reading data recorded onto Blu-ray discs.  We also looked at the ‘combo’ drives that not only had the ability to read Blu-ray discs, but also could record DVDs and CDs.

Next, we looked at the Blu-ray Disc recorders (BD-R) drives.  These drives could read and write data onto single layer (25 GB capacity) and double layer (50 GB capacity) media.  An important aspect to the capability of recording data onto Blu-ray media was that you can store large amounts of data (and, of course, not just data, but audio, video, and other content) onto a single disc.  Of course, a BD-R drive could also read and write to DVD and CD media, making a BD-R drive a useful replacement for the older DVD-R (DVD-R and DVD+R) drives — and immensely important if you want to get the most amount of data onto the fewest number of discs.

Part Three took the story a bit further, introducing the Erasable or Re-Writable capabilities (BD-RW, BD-RE).  Erasability (or re-writability) provided the option for reusing a disk many times.  We suggested a few applications where the extra cost of erasable media (when compared to the write-once, BD-R, media) made sense.  BD-RE is available in single layer (25GB) or in double layer (50GB) versions and, as would be expected, the double layer media costs more than the single layer.   However, if you need the capability of storing, and re-writing 50 GB on a disc, the extra cost would be well worth paying.   (Imagine, for example, that you’re editing a large video–and you make frequent changes to the video.  You use one disc for each change, and distribute multiple copies of each disc for review and comment.  Every few hours, you generate another disc with some new changes.  The oldest of the discs is of little value – so it’s returned, erased, and new data is written onto the now empty disc.  In such a scenario, where reuse of a disc makes sense, having the ability to erase and re-record onto media is very attractive).

Now, in Part Four of this series, we’ll look at a new format that promises 128 GB of storage (100 GB rewritable) on one disc.  The format, called BDXL, was proposed by the Blu-ray Disc Association.  It takes the idea of Blu-ray recordable to whole new levels.

You’ll recall that Blu-ray media is now available in single or double layer.   Each layer is capable of storing up to 25 GB of data.  This proposed standard uses as many as four layers for the rewritable media.  Thus, as 25GB for layer, as much as 100 GB of data can be stored, erased, and stored again on a BDXL disc.

Record-only media is being stretched even further, under BDXL.  For compatibility with the rewritable, a four layer version of BD-R is being offered, with the BDXL  recordable disc capable of storing up to 100 GB of data.  The proposed specification pushes this to a total of 128 GB of storage.

These capabilities will require new hardware.  The current drives feature a laser that is capable of writing to and reading from two media layers on the disc.  The drives that support BDXL must be able to write to four (and maybe five in the case of the 128GB disc) distinct layers.  This may mean that more laser power is required to get through the first layers; it may mean that a new laser is required that can reliably produce a beam of light at a wavelength that is precise enough to read or write each distinct layer.

As with all optical disc technologies in the past – this one won’t be much different in its production and pricing curve — limited numbers of prototypes will be available first – at extremely high prices.  Production units will follow, and with the high capacities being offered, these may initially be bought and targeted to industrial users (movie studios, medical imaging, other large producers and keepers of data), and later, as production increases, will eventually make their way down to the consumer.  As time goes by–if the technology exists to actually be able to produce these drives and media in quantity — drives supporting BDXL will eventually drop in price as production increases.

Another disc format, aimed more at the consumers than at the industrial user, is the IH-BD (Intra-Hybrid Blu-ray Disc) that was also proposed early this march.  But more about the IB-HD in Part Five….coming soon.