Hardware Autopsy
r & d BREAKING DOWN TECH —PRESENT AND FUTURE
The laser beam is directed at a spinning
disc, which has a polycarbonate layer stamped
with pits (surface areas without pits are called
lands). The polycarbonate layer is backed by
a refl ective metal (aluminum, typically). As the
disc spins beneath the laser, the light passes
through the polycarbonate layer and bounces
off the aluminum layer. Inside the drive,
an optical pickup measures the difference
between the pits and lands to create the binary
ones and zeroes used to encode music, video,
and other types of data.
DVDs pack more data into the same area
by rendering the pits and lands smaller and
closer together; DVD drives use lasers that
emit light with a shorter wavelength, 650nm,
projected through a lens with a higher numeri-
cal aperture: 0.65. The pits and lands on Blu-
ray and HD DVD discs are even smaller and
more tightly packed than those on DVDs —
players that read these discs use blue lasers
that emit light with a 405nm wavelength. One
reason Blu-ray delivers more storage capacity
than HD DVD, despite both using blue lasers,
is that Blu-ray devices use a numerical aper-
ture of 0.85, compared to HD DVD’s 0.65.PRINTER APPLICATIONS
Next to optical drives, lasers are most com-
monly found in printers. And like optical drives,
laser printers utilize lasers that emit light in
wavelengths ranging from 650nm to 780nm
(with higher-powered models using lasers with
shorter wavelengths).
The laser is focused on a rotating drum
inside the printer, which is coated with photo-
conductive material. The drum initially receives
a positive electrical charge from either a
charged roller or a corona wire. The laser then
emits a pulse of light for each dot that is to
be printed, which discharges that area of the
drum. Once this pattern of dots is created for
the entire image on the page, the printer coats
the drum with positively charged toner. The
toner “sticks” to the discharged areas of the
drum and is repelled by the areas that remain
positively charged.
A sheet of paper (which the corona wire
has endowed with a negative charge) is then
rolled over the drum. Since the negative
charge on the paper is stronger than the one
on the drum, the paper pulls the toner away
from the drum. The paper then passes through
a fuser, which melts the toner and bonds it
with the fi bers in the paper.
More powerful lasers may be capable of
cutting through steel, and the Department
of Defense has made no secret of its efforts
to weaponize laser technology, but the vast
majority of lasers are used in peaceful applica-
tions such as these.HOLIDAY 2007 MAXIMUMPC 77
White Paper: How Lasers Function
Any requests? What hardware—new or old—would you like to see go under
Maximum PC’s autopsy knife? Email your suggestions to [email protected].Gaming Mouse
We’ve autopsied mice before, but we were especially interested to see if there’s
anything inside a high-end gaming mouse that separates it from a more traditional
mouse. Aside from a fancy-pants laser sensor, there wasn’t much inside this rodent
that’s different from what’s inside a typical beige OEM mouse.mouse. Aside from a fancy-pants laser sensor, there wasn’t much inside this rodent
that’s different from what’s inside a typical beige OEM mouse.TEFLON
MOUSE FEET
These superslick pads
on the bottom of the
mouse (not visible
here) ensure that it will
glide with ease across
any surface. While
they’re not quite fric-
tionless, good mouse
feet make moving
quickly effortless and
will help you lay waste
to your opponents.CMOS SENSOR
The secret of the laser mouse, this Agilent sensor
detects minute changes in the surface beneath
its camera at a rate of 5.8MP/s. This, combined
with the laser that illuminates the area below the
mouse, lets laser mice track on surfaces that nor-
mal optical mice don’t work with.INFRARED LASER
The infrared laser illuminates the area
directly beneath the sensor. By using
laser light instead of simple LEDs, the
mouse is more sensitive and works on
reflective surfaces that would confound a
traditional optical mouse.BUTTON
Each button on the mouse’s chas-
sis is physically connected to a but-
ton housing just like this one. These
buttons can stand up to repeated
rapid clicking—ensuring that your
mouse will continue functioning for
a very long time.WEIGHT HARNESS
This particular mouse includes a top-mounted weight sys-
tem, which allows you to adjust the mouse’s mass. The
weight cartridge clicks into this mount, letting you quickly
and easily adjust the mouse’s weight.