How does Blu Ray work?
Answers:
In language of how the data is compressed on the disk? Or how it is read? While current optical disc technologies such as DVD, DVD¡ÀR, DVD¡ÀRW, and DVD-RAM rely on a red laser to read and write facts, the new format uses a blue-violet laser instead, hence the first name Blu-ray. Despite the different type of lasers used, Blu-ray products can easily be made backwards compatible near CDs and DVDs through the use of a BD/DVD/CD compatible optical pickup unit. The benefit of using a blue-violet laser (405nm) is that it have a shorter wavelength than a red laser (650nm), which makes it possible to focus the laser spot beside even greater precision. This allows data to be stuffed more tightly and stored in smaller amount space, so it's possible to fit more data on the disc even though it's impossible to tell apart size as a CD/DVD. This together with the alteration of numerical aperture to 0.85 is what enables Blu-ray Discs to hold 25GB/50GB.
Almost equal as a DVD, except the laser that reads it is MUCH smaller, and is blue, thats why it's call Blu-Ray.
im not a techie and cant awnswer you 100% so i found some info that will bring up to date you what you need to know...
http://blue-ray-dvd.blogspot.com/