Transcript Laser interferometer

Laser interferometer
Su-Jin Kim, GNU
& Xiaoyu Ding
Xiaoyu Ding
Laser Interferometer
•
•
•
•
What’s laser interferometer?
The principle of standard interferometer
Types of interferometers
Applications
Xiaoyu Ding
What’s a Laser Interferometer
• Laser Interferometer:
– the instrument used for high precision
measurements (distance, angles…. etc.)
– it uses interferometry as the basis for
measurement.
– it uses the very small, stable and accurately
defined wavelength of laser as a unit of measure.
Xiaoyu Ding
Physics Review
• Diffraction
Diffraction is a sure
sign that whatever is
passing through the
hole is a wave.
Diffraction of Water Waves
Xiaoyu Ding
Physics Review
• Diffraction of Light
Light, just like a water
wave, does spread out
behind a hole is the hole
is sufficiently small.
Light is a electromagnetic
wave.
Diffraction of light Wave
Xiaoyu Ding
Physics Review
• A Double-Slit Interference Experiment
Color
pattern
Visible light
Interference of Light
Xiaoyu Ding
Principle of Michelson Interferometer
• Albert Michelson (1852~1931)
– the first American scientist to receive
a Nobel prize, invented the optical
interferometer.
– The Michelson interferometer has
been widely used for over a century
to make precise measurements of
wavelengths and distances.
Albert Michelson
Xiaoyu Ding
Principle of Michelson Interferometer
• Michelson Interferometer
1) Separation
2) Recombination
3) Interference
A Michelson Interferometer for use on an optical table
Xiaoyu Ding
Principle of Michelson Interferometer
• Analyzing Michelson Interferometer
– The central spot in the fringe pattern alternates
between bright and dark when Mirror M2 moves.
If we can know the spacing distance
of M2 between two sequent central
bright spots and the number of
central bright spots appeared, then
we can calculate how long M2 moved.
λ/4 -> bright to dark
Photograph of the interference fringes
produced by a Michelson interferometer.
He Ne
• 632.8 nm wave length is used.
Xiaoyu Ding
Applications
• Measurement of Distance
–
–
–
–
1) frequency stabilized He-Ne laser tube
2) combination of beam-splitter and retroreflector
3) a moving retroreflector
4) detection electronics
Aerotech’s LZR3000 Series Laser Interferometer System
Xiaoyu Ding
Applications
• Other Applications
– Measure angles, flatness, straightness, velocity
and vibrations, etc.
Rearrangements
of the light paths
Xiaoyu Ding
Resolution
• XL-80 Laser Measurement System
Xiaoyu Ding
References
•
•
•
•
•
http://www.aerotech.com/products/engref/intexe.html
http://www.renishaw.com/en/interferometry-explained--7854
http://en.wikipedia.org/wiki/Michelson_interferometer
http://en.wikipedia.org/wiki/Interferometry
PHYSICS FOR SCIENTISTS AND ENGINEERS, Randall D. Knight, 2003.
Laser interferometer
Su-Jin Kim
Gyeongsang National University
Linear Distance Measurement
The positioning accuracy is measured by
comparing the position value displayed by
machine with the actual position.
Rectangularity Measurement
Measurement of the rectangularity between the
x-axis and z-axis.
Straightness Measurements
Straightness and parallelism measurements with
moving board up to 20 mm.
Reference
• http://www.youtube.com/watch?v=VyePASErr
5Q Theory
Renishaw
• http://www.youtube.com/watch?v=41Auhp1R
TP0