Good job bringing this to light. People won't realise how huge the problem is and municipalities are woefully ill equipped to...
Agreed; mining can never be sustainable, but then how do you get the metals to make all the things you need in the course of...
Very good piece.
TREMENDOUS advances in computer
technology have been the order of the
day in the last decade. The machines
have become faster, more robust and
capable of handling much more data
than before (Science, Vol 269).
For instance, the latest Intel 80586
chip (Pentium) works at almost 100
MHZ, compared to the last generation of
80486 chips which were running at
about half that speed. Advances in display, networking and data storage technology have made today's machines
extremely versatile. While a few years
ago, magnetic hard disks had a capacity
of about 20 megabytes (or 20 million
bytes, a byte being an unit of information), today disks of 540 megabytes are
ubiquitous. Even more impressive has
been the development of optical CD-ROM
(compact disc-read only memory) drives, used to store software and data upto
640 megabytes in a compact disc.
Impressive though these advances
are in data storage, they are still not
enough. Programmes, databases and
applications are being developed which
require much more data storage
capacity. The CD-ROM or a magnetic
hard disk stores a single unit of information on an area of about one millionth
of a square metre. The challenge has
been to reduce the size in which the
memory stores the ififormation and
allows access to it at a high speed.
Recently some groups - working
separately at IBM Almaden Research
Center, Stanford University and Sony
Corporation - have reported combin-
ing high resolution optical microscopes
and high speed magnetic drives to make
the bits as small as 300 nanometres (I
nano-metre is a billionth of a metre).
The groups have reported
gne ic that these high density storage devices also allow data
retrieval (reading and writing'of data on the disk) at 8
milliorl bits per second, faster than a CD-ROM.
Conventional magnetic drives write
by using a magnetic head over a film.
The magnetic field changes rapidly and
the small region of the film gets magnetized. The IBM team used a variation of
this technique with the help of a specially designed optical microscope. This
microscope uses the solid immersionlens which focuses light from an infra
red laser to a point on the lens bottom.
While most of the light is reflected
back, some of it tunnels through upto
150 nanometres from the lens. This light
can be used to heat a small spot on a
magneto-optic disk. When the spot cools, it can take the magnetic orientation of the field of the magnetizing head.
This transition can then be read by a
laser because the magnetic orientation
changes the polarisation of the laser
light reflected from the surface.
However, speed is a problem. The
method used in,the past had the disk
spinning on an air cushion at 420 revolutions per minute, allowing the head to
stay close to it. This could achieve data
density 4 times higher than before, but
the access speed was low. The trouble
was that spinning the disk faster than
this pushed the head further than 150
nanometres from the surface.
The Stanford team used a different
technique. They reshaped the lens to
allow' more light from the laser and thus
could move the head further from the
disk. As a result, they could achieve
speeds upto 8 million bits per second.
They also enhanced the data density by
using a green laser which has a shorter
wavvlength and can thus make a smaller
spot on the disk.
But that is not all. IBM and other
teams are also working on other microscopes to increase the density and speed
of data storage devices. One of the
promising technologic3 uses the atomic
force microscope which has extremely
tiny tips (about 10 nanometres) and
thus can be used to make much smaller
bits. The holdup here again is speed,
with the best technology only giving
about 1.2 million bits per second.
Researchers are trying novel methods to
increase this but it may be some time
before they are successful.
The data storage market is worth
about us $40 billion worldwide., And
this is providing the incentive to most
big hardware manufacturers. As computer applications become more sophisticated, the software used will become
bigger and need faster access; powerful
microscopes, therefore, might hold the
field in future data storage technology.