Chapter: Fiber optics and Laser instruments : Industrial Applications of Laser
Laser for Measurement of Length
Laser for Measurement of Length
The large
coherence length and high output intensity coupled with a low divergence
enables the laser t find applications in precision length measurements, using
interfermetric techniques. Here the laser beam is split into two parts, and
they are made to interfere after transversing two different paths. One of the
beam emerging from the beam splitter is reflected by a fixed reflector and the
other by a cube corner reflector. The two reflected beam interfere to produce
either constructive or destructive interference.
As the
reflecting surface is moved one would get alternatively constructive and
destructive interference which can be detected with the help of a photo
detector. Since the change from a constructive to a constructive and
destructive interference corresponds to a change of a distance of half a wave
length. One can measure the distance transverse by the surface on which the
reflector is mounted by counting the number of fringes which have crossed the
photo detector.
Accuracies
upto 0.1µm can be obtained by using such a technique. This technique is used
can be obtained by using such a technique. This technique is used for accurate
positioning of aircraft components
On a
machine tool, for calibration and testing of testing of machine tools, for
comparision with standards
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