What are Blu-Ray Discs?

Blu-ray discs are media devices that are most commonly used to archive and store high definition video content. They often look like standard CDs or DVDs at first glance, and they work in basically the same way. The biggest differences are their storage capacity and how they’re read by players and other receiving devices. In most cases these discs need their own dedicated players that read the discs with a blue laser rather than a standard red laser. Content producers often like releasing films and gaming content with this sort of high-powered technology because of all that it allows them to do: images can be sharper and more realistic, and more special features can be included.

Disc technology has been a popular way to store music and video files for decades. The first optical discs available to consumers were the large video laser discs that were marketed during the early 1970s. By the 1980s the familiar compact disc, or CD, became available. One compact disc was able to hold about 700 megabytes (MB) of data. The first CDs were used for audio albums, then grew to also hold some video and image content — supplemental material from musicians like music videos, for instance, or digital animation as for video games or gaming consoles.

In the 1990s, digital video disc (DVD) technology became popular and ultimately became mainstream in many markets by the early 2000s. DVDs look just like a CD on the outside but are able to hold much more data. In general, one DVD has the storage capacity for one standard-length movie and, depending on the specifics, can usually also hold some bonus material.

Blu-ray is the next iteration on the optical disc timeline. It was established to hold a feature-length movie in high-definition television (HDTV) format. Such movies are displayed in significantly higher resolution and therefore they require much more storage space. A disc usually holds about 27 gigabytes (GB) of information, which is about 40 times the amount of data that a standard CD can hold and at least 10 times the storage of a regular DVD.

Aside from storage concerns, the fundamental difference between these and older CDs and DVDs is the laser that is used to read the discs. Blu-ray machines use a blue laser instead of the red lasers that are used to read earlier discs. Blue lasers have a shorter wavelength, usually about 450 nanometers, than do red lasers, which usually measure in around 650 nanometers. As such, the beam can be focused on a much smaller area. Practically speaking, this means that producers and content developers can put much more data on a single disc.

The blue laser also means that these discs are not readable on standard CD and DVD players and readers, though. In almost all cases consumers must buy a dedicated device in order to show these sorts of features. Putting one of these discs in a standard CD or DVD drive will usually result in an error message.

Many blue laser drives are what’s known as backward-compatible, however, which means that they are able to read more standard CDs and DVDs. Many feature an additional red laser, or they have the capability of switching between red and blue as needed for the disc. In part this is because manufacturers have realized that consumers who already own a lot of content in older formats may not be willing to repurchase everything in HD just for a better viewing experience, and this might be a hindrance to them buying new content in that format, too. By marketing players able to play both new and old discs, distributors hope to actually encourage more sales. Most scholars and researchers think that the growth of Blu-ray will parallel the increasing popularity of HDTV and overtake legacy systems at some point in the not too distant future.

The most popular use of this technology is movies and feature-length film projects, though serial television shows are often packaged and stored on these discs, too. They are also increasingly used to store video gaming content as they can create a more realistic virtual setting for players.