MIRROR balls鈥攖hink John Travolta鈥攈ave inspired an idea for
improving the way computers communicate over a wireless office network.
Local networks that use infrared beams run into problems when people walk
into the beam and cut the link鈥攁 big problem in crowded offices.
Channel-surfing couch potatoes have a similar problem when someone gets in the
way of their TV remote control.
The frustration could soon be over thanks to a device called a chaos mirror,
invented at the Advanced Telecommunications Research Institute (ATR) in Kyoto,
Japan. This distant cousin of the mirror ball splits a narrow incoming beam into
a widely spread array of reflected beams, vastly increasing the chances of the
beam finding the intended receiver.
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Some infrared networks already use simple mirrors on the ceiling to reflect
infrared network signals, but a single reflected beam may still miss its target.
Others use specular reflection off the rough surface of the ceiling, but this
absorbs energy and weakens the beam.
The chaos mirror is different. It consists of a box enclosing seven highly
reflective surfaces: three flat and four curved. As an infrared beam bounces
around inside the box, it is split into many separate beams that emerge at a
variety of angles. Researchers at ATR say that 80 per cent of the beams entering
the box are reflected no more than 20 times and that 88 per cent of the incident
energy is reflected.
The performance of the chaos mirror is further improved by moving the
incident beam in a narrow arc, so that its extended reflections cover an even
wider area. Researchers say that by moving the beam in a 0.2-degree arc, a
50-centimetre-wide chaos mirror can achieve complete coverage of an office.
ATR鈥檚 development comes as infrared networking systems are growing in
capability. The computer industry鈥檚 Infrared Data Association (IrDA) is
considering boosting the speed of infrared wireless networking systems to 16
megabits per second鈥攆our times the current speed possible for
computer-to-computer infrared data transfers.
But even these new 16-megabit-per-second systems will only be able to connect
to computers鈥攐r peripherals such as printers鈥攖hat are 1 metre away
or less, at an angle of no more than 15掳 from the infrared transmitter.
IrDA鈥檚 plan is to increase both the range and degree of coverage possible: one
plan calls for reception equipment to be boosted to 180掳 coverage at a
10-metre range. It is in such wide-angle systems that the chaos mirror is most
likely to be used.
鈥淏ut there are a number of other applications for this technology,鈥� says
Peter Davis, a senior researcher on the ATR laboratory team that developed the
mirror. Industrial robots often need to scan an object with a laser beam in
order to analyse what is in front of it鈥攂ut currently they need motors to
move the scanning mirrors that move the beam. 鈥淥ne chaos mirror could replace
these,鈥� says Davis. 鈥淚f you have fewer moving parts you鈥檒l have fewer breakdowns
and maintenance problems.鈥�
