Gyroscopes
have been used for over 150 years for a number of purposes.
An important contribution by gyroscopes is in the area of
navigation, because they are able to remain in a stable
orientation. On ships, for example, they continued to point
north, while the ship carrying them continually changed
direction. This made them more reliable than magnetic compasses
that were used to navigate for hundreds of years. In space
applications, gyroscopes are also used for precision guidance
as well as tests of fundamental physics
Currently,
two practical gyros exist:
- Mechanical
gyroscopes - with a mechanical spinning body
- Optical
gyroscopes - a fiber gyro and laser gyro, based on laser
interferometry
Currently
under development are:
- Atomic
gyroscopes - that use wave property of matters, interferometry.
- Superfliud
gyroscopes - using cryogenic liquid helium, interferometry
The
Interferometric gyro is based on the Sagnac effect, which
is proportional to the energy of the interfering particles.
Compared to a similar optical gyro, an atomic gyroscope
would have 10 billion times higher sensitivity. This atomic
gyro technology is being developed to support future space
missions. The new capability would be particularly helpful
in deep space automated navigation, in precision guidance
such as telescope pointing and in observations of fundamental
physics tests.
The
atomic gyroscope relies on the peculiar quantum-mechanical
wave property of all matters. Otherwise it works in principle
the same way as optical gyroscopes. Atomic waveguides (that
correspond to fiber in optics) will be developed to confine
the atom wave and form the necessary interferometric loop.
When they are working, atomic gyros send laser-cooled atoms
along these atom wave-guides in the loop. This beam of atoms
is split into two arms of a loop and recombined. A detectable
shift in the distance around the sides of the loop results
if there is the slightest rotation of the atomic gyroscope.
An
interesting part of this concept to explain is that the
waveguide splits individual atom wave packets into two pieces,
which travel two paths at the same time. In other words,
part of the atom is traveling one direction around the loop
while the other part of the same atom goes the other way
around the loop. One atom is, essentially, in two places
at once. This is the essence of particle-wave duality in
quantum mechanics.
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