Rami Arieli: "The
Laser Adventure" Section 9.1.1 page 1
9.1.1 Accurate measurements (Distance,
Movement, Interferometry).
Since laser radiation is electromagnetic
radiation, traveling at the speed of light,
very accurate measurements can be performed with lasers.
Because of its high speed (the speed of light (c) is the ultimate
speed …), measurements of high speed moving objects is not a problem,
and the information is available in (almost) real time.
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Interferometric measurements (which
gives the highest resolution known today) are described in chapter
10.
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Range-finder for military
applications is described in chapter 9.3.1. Based on the same principles
for measuring distances, industrial measuring devices have been developed.
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Chapter 7 explains
the low divergence of laser beams, which allows us to
send laser beam over very long distances.
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Measurement of the distance from
Earth to the moon:
One of the known precise measurements with a laser was measuring the
distance from Earth to the moon. The astronauts who landed on the surface
of the Moon left there a corner
cube (a system of three perpendicular mirrors that reflect
light in the same direction where it came from).
A pulsed laser beam was sent from Earth to the moon and was reflected
from this corner cube back to Earth.
The travel time of the pulse was recorded.
From the known speed of light (c) the distance was calculated, with
accuracy of tens of centimeters (!).