Blu-ray disc is the next generation optical disc format that can hold 25 or 50 gigabytes of data, allowing for high definition video and extra features. It uses a blue-violet laser with a wavelength of 405nm to read incredibly small pits that are half the size of DVDs. Blu-ray discs are more durable than DVDs due to their protective hard coating and single layer structure, and have faster data transfer rates and seek times due to their greater density and smaller beam size.

4. HISTORY 1 st GENERATION : Compact Disc (CD):-- 650/700MB It is with us for over 20 yrs. Wavelength of laser which reads data: 780nm Color of laser: Red 2nd GENERATION : Digital versatile disc (DVD):-- 4.7GB It offers high quality sound and video than CD. Wavelength of laser which reads data: 650nm Color of laser: Red

16. Comparison in Beam size

17. CD vs. DVD vs. HD-DVD vs. Blu-ray Disc

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