An Introduction to Blu-Ray Disc:
Until recently, optical disc technologies such as DVD, DVD±R, DVD±RW, and DVD-RAM relied on a red laser to read and write data. The new technology Blu-Ray format uses a blue-violet laser, which explains the name Blu-ray.
Blu-ray drives can also be made backwards compatible with CDs and DVDs through the use of a BD/DVD/CD compatible optical pickup unit.
A blue-violet laser (405nm) has a shorter wavelength than a red laser (650nm); this makes it possible to focus the laser with even greater accuracy. This will allow data to be packed more tightly, so it's possible to squeeze more data on the disc even though it's the same size as a CD/DVD. This together with the change of numerical aperture to 0.85 enables Blu-ray discs to hold 25GB/50GB.
Blu-ray media is structurally different from DVD media. The Blu-ray disc consists of a single 1.1 mm thick polycarbonate substrate with a 0.1 mm thick cover layer on the bottom side of the disc, while the DVD disc is made of two 0.6 mm thick substrates. In both cases, two substrates are bonded together by a UV-cured resin adhesive:
DVD vs. Blu-ray disc structure
The larger 25 GB and 50 GB storage capacity of the Blu-ray disc is due to the higher density of pits and tracks on the disc. Unlike previous optical discs, Blu-ray uses a shorter-wavelength, tighter-focused violet laser to read and write pits that are about three times smaller than pits used in DVDs:
CD, DVD and Blu-ray laser beam color and size
CD, DVD and Blu-ray pits and tracks as seen by a scanning electron microscope
Blu-ray disc surface mapped by an atomic force microscope
Blu-Ray Reading Performance:
Here we will look at how the Pioneer BDR-205BK performs when reading Blu-Ray discs.
The Pioneer BDR-205BK read our SL BD-ROM at a speed of 8X.
The Pioneer BDR-205BK read our DL BD-ROM at a speed of 8X.
BD-R SL Video
The Pioneer BDR-205BK reader had no problem reading our SL BD-R Video disc at its rated speed of 8X.
BD-R SL Data
The Pioneer BDR-205BK reader had no problem reading our BD-R SL Data disc at its rated speed of 8X. (Special thank to nikoneko Ya! for supplying us with this media)
The Pioneer BDR-205BK did a great job of reading our BD-RE disc at its rated speed of 8X. (Special thank to nikoneko Ya! for supplying us with this media)
The Pioneer BDR-205BK was only able to read our TDK BD-R DL at a maximum speed of 8X.
The Pioneer BDR-205BK did a great job of reading our BD-RE Dual Layer disc at its rated speed of 6X.
Moving on to next page you can read about Blu-ray Writing Performance...