What is Blu-ray?
Blue Laser
Blu-ray discs (BD) get their
name from a combination
of the words blue and
optical ray. The format was
developed by the Blu-ray
Discs Association (BDA),
which is made up of a
group of leading consumer
electronics, major fi lm studios
and PC companies, including our
parent company, Mitsubishi Kagaku Media. Verbatim, as a
subsidiary of MKM, has therefore, fi rst hand access to the
latest in Blu-ray technology.
The Blu-ray disc’s higher storage capacity is enabled
by a blue laser that has a shorter wavelength than the
standard red laser used in CD (780nm) and DVD (650nm)
technology. Blu-ray disc utilises a blue laser with a
wavelength of only 405nm combined with a strong lens
system with a numerical aperture of 0.85. This results in a
ultra-small laser spot which allows writing smaller data pits
which increases the amount of data on the disc. Due to the
small data entry spot on the disc surface hard coating is
needed on Blu-ray discs.
How a BD Disc Works
Red Laser (DVD)
technology
Blu-ray (BD-R/RE)
technology
Data
Laser
Disc Label
Minimum pit length = 0.15μm Track pitch = 0.32μm Capacity = 25GB
Data
Polycarbonate Layer 1
Recording Layer
Refl ective Layer
Polycarbonate Layer 2
Disc Label
Minimum pit length = 0.4μm Track pitch = 0.74μm Capacity = 4.7GB
Hardcoat Layer
Cover Layer
Protective Layer
Recording Layer
Protective Layer
Refl ective Layer
Polycarbonate Layer
