Final answer:
The two writable Blu-ray disc formats are BD-R and BD-RE, utilizing a blue laser light to achieve higher data density compared to CDs. The blue laser's shorter wavelength allows for smaller pits and more information on a Blu-ray disc. Higher resolution and close-packed data storage are made possible by the use of a blue laser with a numerical aperture of 0.95.
Step-by-step explanation:
The two writable formats for Blu-ray discs are BD-R (Blu-ray Disc Recordable) and BD-RE (Blu-ray Disc Rewritable). BD-R discs allow users to write data to the disc once, whereas BD-RE discs enable users to erase and rewrite data multiple times. These formats make use of a blue laser with a short wavelength, which allows for higher data density than the longer-wavelength red laser used in CDs and DVDs. The blue laser light has a wavelength of 405 nm and is used because it has the capability to read and write smaller pits, which translates to more information being stored on a Blu-ray disc compared to a CD.
To understand how a Blu-ray player can read more information than a CD player, it is useful to know that the resolution of a player is a function of the laser's wavelength and the numerical aperture of the system. Using the given resolution formula, Resolution = 0.60(2/NA), with NA representing the numerical aperture, we can compute that the 405-nm laser in a Blu-ray system with NA = 0.95 allows for very closely packed data storage. This is why Blu-ray discs can hold significantly more data than CDs or DVDs.