Data which is collected needs to be stored. But the laws of nature are such that all media of recorded data will decay. Gone are the days of files and papers which are very cumbersome, difficult to retrieve and even more difficult to preserve. In the digital age of today, data is recorded in digital media. With the passage of time, phenomenal developments and improvements have been made with storage media.
The earliest storage discs were based on the Laser Disc technology; the first prototypes of the compact media were then produced by Philips and Sony. Compact Discs (CDs), Digital Video Discs (DVDs), High Definition DVDs and Blu-ray all fall in this category of optical media.
CDs: Laser Disc technology enabled the birth of the compact disc. Philips and Sony were the first to release the CD technology in the latter half of the 1970s. These were used initially to record and play just music. But they evolved as storage for data as the CD-ROM. Then they made rewritable (CD-RW) and advanced further as Video Compact Discs (VCDs). The CDs replaced the cassettes and were superior to them because they could copy music free of the defects which occurred due to compression.
DVDs: DVDs are sometimes referred to as Digital Versatile Discs. DVDs are efficient because they are able to hold files which are several gigabytes and are so large like movie films. DVD-RW discs are capable of read and write operations. DVDs were first developed in 1995 by Philips, Sony, Toshiba and Panasonic. Distributors of home entertainment and movies switched to DVDs from VHS tapes for its durability and interactivity. 650 nm wavelength of laser diode light is used for DVDs while CDs use 780 nm. This has helped in increasing the storage capacity of DVDs. At first, DVDs were used for data backup as to help transport data, but now the use has expanded to audio recording and also recording of videos. Another innovation is the dual-layer recording of the double layer recording. This enables the DVD discs to store a much larger amount of data even up to 8.5 gigabytes.
HD DVDs and Blu-Ray: High Definition or High Density DVDs, known as HD DVD, was an improvement on the standard DVD. It was meant to be a high density format of optical disc to be used for storing high definition video and data. Toshiba was the generator of this form of storage device. The HD REC used a blue laser having a shorter wavelength. So it was able to store 3.2 times more data for every layer as compared to the DVD discs. Now the HD DVD was able to store 15 GB per layer as opposed to the 4.7 GB for every layer of the regular DVD discs.
Ultra Density Optical (UDO): and the DVR Blue was used together for making rewritable discs which were then reborn as the Blu-Ray disc in Feb 2002. The other optical discs use a red laser for recording and reading data. But the Blu-Ray uses a blue violet laser and thus got its name, Blu-Ray. This blue violet laser has a 450 nm wavelength that is shorter than the 650 nm wavelength red laser. The laser spot in the Blu-Ray is focused with greater precision allowing it to pack data more tightly and in a lesser space. This is also helped by the change in the numerical aperture to 0.85. And recently, Pioneer has further increased the storage capacity of a single disc to 500 GB by making it record on 20 layers!
Despite the increasing use of MP3 players and USB storage drives, the future of compact disk media is still prosperous. According to a leading digital media company, disk storage will continue to rise for the foreseeable future.