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Earthquake Detector Using the Michelson Interferometer
The Mid-South Annual Engineering and Sciences Conference
MAESC 2006
Memphis, Tennessee
Haoyan Bill Lan
March 31, 2006
Every Day
Deep underground
America's most destructive earthquakes since
the turn of the 20th century:
Last Decade
People Are at Risk
Researches need to be done
there are 70,000 buildings in state of
California alone that could sustain major
quake damage
Experts predict there will be a major
earthquake in state of California before
year 2024
For those who lives there
It would be nice….
If……
Earthquake Detector Prototype
Optical Power Meter
Analog to Digital Interface
and LED Displays
Michelson Interferometer
UP3 Board with a
Cyclone Microprocessor
Project Concept
Michelson
Interferometer
Light
Intensity
Measuring
Device
Analog to
digital
interface
Major part of the project
Central processing unit UP3 board
(Quartus II)
Alarm System
and back up
power supply
4 Digits
7-Segment
LED Display
Screen Matrix for Different Needs
3D View of an Interferometer
Sensor of Light Intensity Measuring Device
Bright Fringe
Mirror#2 Stationary
Dark Fringe
Beam Splitter
He Ne Laser Beam Generator
Dispersion Lens
Move Mirror#1 to cause the fringe movement
HowMirror#2
does
it
work?
Stationary
Mirror#1 Moving
Bright Fringe
Dark Fringe
Sensor of Optical Power Meter
Dial for Moving Mirror
Movement of Mirror#1 generates fringe movement
Need fringes number to calculate the
wavelength
Fringe movements not be counted using
naked eyes
The sinusoidal wave has a frequency
approx. at 100Hz
The way to measure the spectral of the light
is
2d

n
where d is the distance M1 has been moved
and n is the number of the fringes and
Lambda is the wavelength of the laser beam.
How does this work?
a single tap on the table will cause
rapid movement of the fringes
this property can be used to detect a
potential earthquake
Sinusoidal wave from the optical power meter
Offset Voltage
Output wave form goes into the UP3 board
Design of an Analog to Digital Interface
Adjustable offset voltage
TTL output
Project Concept
Michelson
Interferometer
Light
Intensity
Measuring
Device
Analog to
digital
interface
Major part of the project
Central processing unit UP3 board
(Quartus II)
Alarm System
and back up
power supply
4 Digits
7-Segment
LED Display
Altera UP3 board is setup in the lab
Microprocessor is Programmed
via a PC
Input from Analog
to Digital Interface
Output to 4-digits
Displays
Circuit Design using Quartus
Output of the Unit
Digit
Input from Analog
to Digital Interface
Output of the
Hundredth Digit
Output of the Tenth
Digit
Output of the
Thousandth Digit
Decade Counter
Decoder
Input
A 74143 chip
LED Digit Displays
7-Seg LED Display
Prototype Testing
Simulate an
earthquake
Tester tap table
with his/her finger
Since
Lambda for a He-Ne laser beam is 632nm
For each fringes (n=1), we are moving
Theoretically we are detecting vibration on
1/3um scale
Put 1/3um into a prospective scale
Human hair avg. 65um in Diameter
Vibration of
1/3 of this Scale
Prototype Estimated Cost
Interferometer $700
Light intensity detector $150
Quartus II and software $300
Other parts and hardware $50
Total cost $1200
Estimated Production Cost
Interferometer $100
Light intensity detector $50
Burn-in Chips $10
Other parts and hardware $50
Total cost ~$210
Instead of the $300 UP3 Board
References
http://www.3dimagery.com/3dmichelson.ht
ml
http://www.latimes.com/business/la-mequake8sep08,0,3035306.story
http://www.altera.com/education/univ/stud
ents/unv-students.html
http://www.space.com/scienceastronomy/a
stronomy/interferometry_101.html
Questions And Comments?
Prototype Testing Continues
Simulation of a fire disaster has been conducted
as well
A pressure changing device has been used