Why Are Movie Discs Called Blu-ray?

May 15, 2016


The latest innovation for digital video and sound for movies at home came about with the introduction of the Blu-ray disc and the release of the first movies on Blu-ray in 2006. But why are these discs called Blu-ray?

The answer has to do with the laser that is used. They’re simply called Blu-ray because a blue laser (actually blue-violet laser) is used to read and write data as opposed to an infrared or red laser that is used for CDs and DVDs. “Ray” is used because it is an optical ray. Why is the color of the laser so important for what these discs can do? A blue laser uses a tighter wavelength than its red counterpart, thus allowing manufacturers to pack more data on a disc that is the same size of a DVD. While a DVD has its data sandwiched between layers on the disc, the Blu-ray disc has its data closer to the surface.  This allows it to be read using a smaller beam where the pits of data on the disc are much smaller than on a DVD.

If the Blu-ray’s name is based on the use of a blue laser than why isn’t it called, “Blue-ray”? There’s a simple explanation for that. The “e” was intentionally left out by the Blu-ray Disc Association, the group of companies that developed the format, so the name could be trademarked. A common word like “Blue” cannot be trademarked.

Here’s some other facts about Blu-ray that you might want to learn in case anyone asks, or if you just want to sound knowledgeable in the subject:

Blu-ray discs single-layer disc can hold 25 GB of data, and a double-layer disc can hold 50 GB. A DVD, by comparison, can only hold about 4.7 GB of information.

A Blu-ray can hold more than 2 hours of HD video on a single layer disc, while on a double-layer disc it can have around 4.5 hours of HD video.

There was a competitor to Blu-ray with the HD DVD in 2006 when they both came out. The Blu-ray format won out when movie studios moved to Blu-ray in 2008.

The correct abbreviation for Blu-ray is BD, not BR.

How about another blue related tech question to top things off? Try this one out. Learn why Bluetooth is called Bluetooth.

Sources: Blu-ray.com, How Stuff Works, Sony, USA Today

About the author 

Daniel Ganninger - The writer, editor, and chief lackey of Knowledge Stew, the author of the Knowledge Stew line of great trivia books, and editor of Fact World and the Knowledge Stew sister site on Medium. I hope you find things here to annoy those around you with your new found knowledge.

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