How do Blu-ray discs store more data than DVDs?
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laser
Basic laser components.
Blu-ray discs store significantly more data than DVDs primarily due to the type of laser used to read the information.
While both formats store data in tiny pits arranged in a spiral track on a 120-mm disc, they utilize different light wavelengths:
- DVDs: Use a red laser with a wavelength of 635 or 650 nanometres.
- Blu-ray: Uses a blue-violet laser with a much shorter wavelength of 405 nanometres.
Because the blue-violet laser has a shorter wavelength, it can resolve smaller pits and read tracks that are more tightly wound and closely spaced than those on a DVD. This increased precision allows a single-layer Blu-ray disc to hold 25 gigabytes of data, compared to the 4.7 gigabytes typically held by a single-layer DVD.12