Why Are Movie Discs Called Blu-ray?

April 26, 2024

Blu ray icon

The major 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, allowing manufacturers to pack more data on a disc that is the same size as 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, then 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 are 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:

A Blu-ray 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 when the HD DVD also came out in 2006. 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 trivia books, and editor of Fact World and the Knowledge Stew sister site on Medium, our ad-free subscription sites. I hope you learn many new things here that add to your knowledge.

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