Earthquake Detector Using the Michelson InterferometerEarthquake Detector Using the Michelson Interferometer

The Mid-South Annual Engineering and Sciences ConferenceThe Mid-South Annual Engineering and Sciences ConferenceMAESC 2006MAESC 2006

Memphis, TennesseeMemphis, Tennessee

Haoyan Bill LanHaoyan Bill Lan

March 31, 2006March 31, 2006

Deep undergroundEvery Day

America's most destructive earthquakes since America's most destructive earthquakes since

the turn of the 20th century:the turn of the 20th century:

Last Decade

People Are at RiskPeople Are at RiskResearches need to be done Researches need to be done

there are there are 70,00070,000 buildings in state of buildings in state of California alone that could sustain major California alone that could sustain major quake damage quake damage

Experts predict there will be a major Experts predict there will be a major earthquake in state of California earthquake in state of California before before year 2024 year 2024

For those who lives thereFor those who lives there

It would be nice….It would be nice….

If……If……

Earthquake Detector PrototypeEarthquake Detector Prototype

Michelson Interferometer

Optical Power Meter

Analog to Digital Interfaceand LED Displays

UP3 Board with aCyclone Microprocessor

Project Concept 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 Digits7-Segment LED Display

Screen Matrix for Different NeedsScreen Matrix for Different Needs

3D View of an Interferometer3D View of an Interferometer

Sensor of Light Intensity Measuring Device

Move Mirror#1 to cause the fringe movement

He Ne Laser Beam Generator

Beam Splitter

Mirror#2 Stationary

Bright Fringe

Dark Fringe

Dispersion Lens

How does it work?How does it work?Mirror#2 Stationary

Mirror#1 Moving

Bright Fringe

Dark Fringe

Sensor of Optical Power Meter

Movement of Mirror#1 generates fringe movement

Dial for Moving Mirror

Need fringes number to calculate the Need fringes number to calculate the wavelength wavelength

Fringe movements not be counted using Fringe movements not be counted using naked eyesnaked eyes

The sinusoidal wave has a frequency The sinusoidal wave has a frequency approx. at 100Hzapprox. at 100Hz

The way to measure the spectral of the light The way to measure the spectral of the light is is

where d is the distance M1 has been moved where d is the distance M1 has been moved and n is the number of the fringes and and n is the number of the fringes and Lambda is the wavelength of the laser beam. Lambda is the wavelength of the laser beam.

n

d

2

How does this work?How does this work?

a single tap on the table will cause a single tap on the table will cause rapid movement of the fringes rapid movement of the fringes

this property can be used to this property can be used to detect a detect a potential earthquakepotential earthquake

Sinusoidal wave from the optical power meter

Output wave form goes into the UP3 board

Offset Voltage

Design of an Analog to Digital InterfaceDesign of an Analog to Digital Interface

Adjustable offset voltage

TTL output

Project Concept 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 Digits7-Segment LED Display

Altera UP3 board is setup in the labAltera UP3 board is setup in the lab

Output to 4-digits Displays

Input from Analogto Digital Interface

Microprocessor is Programmed via a PC

Circuit Design using QuartusCircuit Design using Quartus

Input from Analogto Digital Interface

Output of the UnitDigit

Output of the TenthDigit

Output of the Hundredth Digit

Output of the Thousandth Digit

A 74143 chipA 74143 chip

Input

Decade Counter

Decoder

LED Digit DisplaysLED Digit Displays7-Seg LED Display

Prototype TestingPrototype Testing

Simulate an Simulate an earthquakeearthquake

Tester tap table Tester tap table with his/her fingerwith his/her finger

SinceSince

Lambda for a He-Ne laser beam is 632nmLambda for a He-Ne laser beam is 632nmFor each fringes (n=1), we are movingFor each fringes (n=1), we are moving

Theoretically we are detecting vibration on Theoretically we are detecting vibration on 1/3um scale 1/3um scale

Put 1/3um into a prospective scalePut 1/3um into a prospective scale

Vibration of1/3 of this Scale

Human hair avg. 65um in Diameter

Prototype Estimated CostPrototype Estimated Cost

Interferometer $700Interferometer $700

Light intensity detector $150Light intensity detector $150

Quartus II and software $300Quartus II and software $300

Other parts and hardware $50Other parts and hardware $50

Total cost $1200Total cost $1200

Estimated Production CostEstimated Production Cost

Interferometer $100Interferometer $100

Light intensity detector $50Light intensity detector $50

Burn-in Chips $10 Burn-in Chips $10

Other parts and hardware $50Other parts and hardware $50

Total cost ~$210Total cost ~$210

Instead of the $300 UP3 Board

ReferencesReferences

http://www.3dimagery.com/http://www.3dimagery.com/3dmichelson.html3dmichelson.html

http://www.latimes.com/business/la-me-http://www.latimes.com/business/la-me-quake8sep08,0,3035306.storyquake8sep08,0,3035306.story

http://www.altera.com/education/univ/http://www.altera.com/education/univ/students/unv-students.htmlstudents/unv-students.html

http://www.space.com/scienceastronomy/http://www.space.com/scienceastronomy/astronomy/interferometry_101.htmlastronomy/interferometry_101.html

Questions And Comments?Questions And Comments?

Prototype Testing ContinuesPrototype Testing Continues

Simulation of a Simulation of a fire disasterfire disaster has been conducted has been conducted as wellas well

A pressure changing device has been usedA pressure changing device has been used