Download A day in the life of a Laser scientist

A day in the life of a laser scientist
Dr Helen Pask
Macquarie University Vice-Chancellor’s Innovation Fellow,
Department of Physics and Engineering,
Macquarie University, NSW 2109, Australia
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Purpose of my talk
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Celebrate the 50th anniversary of the laser
Highlight the prominence of lasers in our lives
Science/Physics/Lasers is fun
Finding the answers to problems is fun
“You guys” will develop new applications for
lasers that I can’t even imagine – in the next
50 years
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Overview
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What’s a laser?
Properties of laser light
Famous lasers, including the first laser
My job and a few projects I am working on
– Multiwavelength lasers for treating retinal diseases
– Remote sensing of water temperature
– Terahertz lasers
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What’s a laser – Light Amplification by
Stimulated Emission of Radiation
Means of excitation: eg.
flashlamp, laser, sun,
electrical current, chemical
reaction
Before amplification – laser
photon incident on excited ion.
After amplification – de-excited
ion and two laser photons.
Laser gain medium:
Gas: CO2, N2
Liquid: dye
Solid: Nd:YAG, ruby, diamond, jelly
Mirrors trap laser
photons in the cavity,
and a laser beam is
output through the
end mirror
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Basic Properties of Laser Light
Laser Light has some distinctive features compared
to other light sources
Monochromatic – laser light has very narrow
spectral range ( ie very pure colour) due to the
discrete energy levels in the excited atoms or ions
which make up the laser medium
High directionality - laser light has very low
divergence, a consequence of the many passes
between mirrors and the amplification process
Coherence - laser light waves (photons) have the
same phase, due to the nature of the light
amplification process. This gives rise to laser
“speckle”.
www.adaptiveoptics.org
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Some famous lasers… the first laser
• 50 years ago, on May 16th
1960, Theodore Maiman
demonstrated the first laser.
It was a ruby laser, pumped
by a pulse of light from
helical flashlamp.
Photo courtesy of HRL
Laboratories, LLC
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Big and Small Lasers
The world's largest laser was completed in 2009, designed to create a nuclear
reaction like the one at the centre of the sun. 192 laser beams will be focused
on a tiny target at the centre of an enormous spherical target chamber, creating
temperatures of up to 100 million degrees. This building which houses the
laser is the size of a football stadium. It is the National Ignition Facility (NIF)
at the Lawrence Livermore National Laboratory in California.
Somewhat more modest is the
diode laser in a CD player
Lawrence Livermore National
Security, LLC, and Lawrence
Livermore National Laboratory
www.explainthatstuff.com
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How lasers impact on our lives
Lasers are there:
– When we go shopping
– When we watch movies
– Log on to the internet
– Talk on the phone
http://www.laserfest.org/lasers/innovations.cfm
Lasers have revolutionised:
• Manufacturing
• Medicine
• Defence
• Science
Credit: Trumf
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My Job – Laser Physicist/Optical Engineer
• Working with Industry – understanding what applications people
have for lasers, then figuring out how to make a laser that will
make the application work as well as possible. (CSIRO, laser
manufacturers, medical companies and DSTO (Defence
Science and Technology Organisation)
• Inventing stuff and entrepeneurship: We invented a new type of
laser and in 2004 formed a company to commercialise it.
• Commercialising research: Finding ways for some of the great
research that we do at Macquarie to be taken up by companies
and ultimately benefit our community.
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Project 1: Wavelength-selectable lasers
• We have demonstrated a unique laser system in which the laser output
can be efficiently channelled “on-demand” into several visible wavelengths
• There are many applications where the ability to get several wavelengths
from a laser source is highly valued
• Ophthalmology is one of these.
• The invention has been patented and licensed.
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Step 1: Making yellow lasers for retinal
photocoagulation
This yellow laser is being developed
by my colleagues and I with
companies in Adelaide and Brazil. It
will be used for laser eye surgery of
the retina.
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Wavelength-selectable lasers for
ophthalmology
• Funded jointly by the ARC (Australian Research Council)
and Opto Global (an Australian ophthalmic company)
• Ideally, a retinal surgeon should choose his/her laser
wavelength to best suit the procedure and the particular
patent. Our laser is designed to offer this flexibility
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So how do we do it?
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Multi wavelength Raman laser
Up to 20% of the diode pump light is
converted to green or yellow
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Project 2: Remote sensing of water
temperature (LIDAR = Light Detection and Ranging)
A new laser project I have just
started will try to determine the
temperature of the sea and inland
waterways as a function of depth.
This could help predict ocean
currents, monitor climate change
and to understand algal blooms and
salinity.
Lasers are used to measure water
depth along the coast of Australia
(http://www.navy.gov.au)
(http://www/physics.ucsd.edu)
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Raman Spectroscopy for remote-sensing
- water temperature depth profiling Raman
shiftRaman Effect. When
C.V. Raman is the father
of the
green
light is scattered
by water,components
a substance,ata small (1
Superposition
of
5
Gaussian
-1
in3225,
106) fraction
is found
have
different
3425, 3520,
3612
anda 3060
cmfrequency (red).
www.aps.org
30000
25000
This “lumpy” spectrum can
be analysed to give
information about the
temperature and salinity of
the water sample.
Raman signal
20000
15000
10000
5000
0
2500
3000
3500
4000
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Some questions we need to answer
In principle, we can apply this method using
land, sea or air-based platforms. If sucessful,
• it will provide inputs for hydrologic modelling
of water circulation along coast lines and in
inland waterways.
• Monitoring environmental conditions that
trigger algal blooms
www.oceandatacenter.ucsc.edu
• Assessing environmental health of waterways
But first, we need to understand:
• How the optical properties of the water impact on the
accuracy of temperature measurement?
• How the optical properties (absorption, scattering,
transmission, fluorescence) depend on the sample
environment (eg fresh/salt, clear/turbid, high/low organics)
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Project 3: Terahertz Lasers – “the last
frontier of the electromagnetic spectrum”
THZ Applications: personnel
screening, substance
identification, explosives
detection, military, medical,
biological, pharmaceutical
THz radiation:
•non-destructive, non-ionising
(cf x-rays)
•Penetrates fabric, packaging,
skin (<1mm), but not metal or
water.
Many applications, but
serious lack of practical
sources.
Credit: Teraview
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Addressing the Terahertz problem
1. Start with the most robust, well-established
technology - Solid-State Nd lasers.
2. Developing new methods for frequency
conversion to the THz spectral region
3. So far, so good. Watch this space!
THz output
diode
pump
Nd:YAG
MgO:LiNbO3
Q-switch
HR mirrors to resonate fundamental (1064nm)
HR mirrors to resonate Stokes (~1070-1075nm)
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Getting Here
Maths, Physics and Chemistry at High School
Science at University – a bit of everything including kayaking,
bushwalking, ski-touring…..
Honours year in Physics – physics of gas discharges
PhD project on laser Physics
Postdoctoral work in UK – optical fibre lasers and amplifiers
UK to Australia in a small steel yacht
ARC Fellowship at Macquarie (5years)
Completed NSW Enterprise workshop
Since 2006, Vice Chancellor’s Innovation Fellow.
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Some highlights of my job
• Light is fantastic and amazing to work with!
• I never get bored with my job
• Many opportunities to be imaginative, creative and innovative
• Good balance of independence and teamwork
• Travel and living overseas
• Working with scientists around the world (UK, Japan, Brazil, China)
• Started up a laser company
• Pretty good salary
• Career + family
A career in science is an opportunity to
“do something worthwhile” and perhaps
“make the world a better place”
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LaserFest Sydney –
16th May 2010 till 16th May 2011.
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