Blu-ray Technology and Its Future
Student, Masters in Computer Science
Blu-ray technology is very modern technology to store huge amount of data and there is, no doubt, that Blu-ray Disk (BD) will replace other previously using storage devices like CDs and DVDs. A Blue-ray disk can store data from 25 GB to 50 GB, which is more than 5 times larger than the storage of DVD disks. There are some modifications of in mechanism of storing and reading the data in the Blu-ray technology so that it is capable of storing very large amount of data.
Blu-ray disc was developed by the Blu-ray Disc Association, a group representing makers of consumer electronics, computer hardware and motion pictures. Although Blu-ray disk specification was officially announced in Feb 2002, it had started to market from the year 2006 and it is gaining popularity in high definition television (HDTV) video format and processing the video data for presentation purpose. The standard BD can store 25 GB in single layer and up to 50 GB in dual layer and we can get mini BDs which can store up to 7.8 GB and 15.6GB in dual layer. The further enhancement of Blu-ray technology is going on, and in future there is possibility of multilayer Blu-ray disks more than 100 layers which can store up to hundreds of terabytes!
There is one prominent difference in the Blu-ray technology and other disk technologies. The older disk technologies use red laser light to read the data stored in the disk, however, the Blu-ray disks use blue violet laser light (so it is called Blu-ray). Since, the wavelength of blue ray (405nm) is less than red light (650nm), the laser spot can focus with greater precision which allows data to be packed more tightly and stored in less space. So, it is possible to store more data than the same sized DVDs and CDs. And Blu-ray technology is backward compatible means it can read both the DVD and CD formats just like a DVD reader can also read CD data. [IBRAHIM (2007)]
The Blu-ray technology has adopted its success by changing the disk layer specifications. Since, the disks have more and more compressed data, so the cover layer of the Blu-ray disks is significantly decreased up to 100 µm and numerical aperture (NA) value of objective lens increased to 0.85. Since the transparency of the plastic disk material decrease when the wavelength is decreased below than 400nm, so we should be careful so that the wavelength of the laser beam does not decrease below 400nm because even the temperature change may cause the wavelength change of the laser beam. However, a 400 nm GaN(Gallium Nitride) laser, which has been currently used to read BDs, seems to have a wavelength with a very small temperature dependency.
Blu-ray uses phase change film as a recording media. The phase change film can be divided into two types: 1) GST type 2) Eutectic type. The former GST (Ge Sb Te stoichiometrical composition) type is used for DVD RAM and the second one is used for CD-RW, DVD-RW. The recording of blue ray supports both the above mentioned recording types. [Blue-ray Disc Founders (2004)].
Interestingly, the structure of Blu ray dual disk is different to that of the DVD dual layer disk. In DVD, the rear and the front layers are formed separately on two substrates and, the substrates are attached one on the top of another with a UV-hardening resin adhesive. In contrast to this, in BD, the rear layer consisting of multi-layered films is formed on a 1.1 mm thick polycarbonate substrate with a guide groove for tracking, and then the 25µm thick spacer layer made of resin is formed. The front layer is formed on it and finally the 75 µm thick layer is formed.
Future of Blu-ray
The future of Blu-ray technology is very high and demanding. Like, nowadays, just like DVDs are replacing the use of CDs, the similar condition that BDs will be replacing today’s DVDs demands, although it will take some time to completely replace the use of DVDs. Similarly, modifications and new researches, like Blue-ray 3D, are going on this technology to make it more robust and stable.[Wikipedia (2010)].Not only this, BDs can also be used to provide huge programs to the customers and provide the updates to save the network bandwidth. The prominent possibility of further enhancement includes the concept of multilayer disc technology, in which many companies are thinking of the possibilities of increasing as much layers as possible so that we can get as much disk space as possible.
Thus, Blu-ray technology has introduced revolution in the field of disc technology and media storage. It has some drawbacks, like other technologies. Since it is very new technology, so purchase of Blue-ray devices is expensive. I think after some time production will be more, then the cost will reduced drastically, and in terms of space, it will be far cheaper than DVDs.
I would like to thank Mr. Ivan Christoff and Mrs.Yunyun for their valuable advice in writing this report. Again, I am thankful to my friend Mr. Hari Prasad for assisting me by reviewing my report.
- IBRAHIM, K.F. (2007). Newness guide to Television & Video Technology.4th Edition.Pages:412-425. Jordan Hill, Oxford OX2 8DP, UK:Elsevier.978-075068-165-0
- Blu-ray Disc Founders. (2004). White Paper Blu-ray Disc Formats [available at http://www.blu-raydisc.com/en/Technical/TechnicalWhitePapers/general_bluraydiscformat-15263.pdf] [accessed on 2010/09/23]
- Wikipedia.(2010).Blu-ray Disc[available at http://en.wikipedia.org/wiki/Blu-ray] [accessed on 2010/09/30]
(Assignment: Advanced Computer Studies in Sweden, I/I/I)