Transcript Man Portable LIBS, A Tool for First Responders in Homeland

Unknown Material Analysis in Less
Than A Second
Man Portable LIBS
A Tool for First Responders in Homeland Defense
Roy A. Walters, Ph.D. PE
Vice President, Research and Development
Ocean Optics, Inc.
Winter Park, Florida
[email protected]
What is
LIBS?
NdYag
Laser
One 7 ns laser pulse
0.000000007
seconds
15,000 K plasma, much
hotter than the sun’s
surface but for only 20
microseconds
LIBS3000
Computer -
Spectrometer
Standard PC
Analyze
Identify
< 0.5 sec
Who is a First Responder?
• Fire Department, Police, Public Health
• Specifically - an organization of specially trained people
serving a single city or a region
• Includes
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Haz-Mat team
Swat team
Medical emergency team
etc.
What does the First Responder want an
instrument to do?
• Find out what “it” is and not have to touch it or get
very close
• If “it” isn’t pure material, find out what other
things might be in it
Where and how does it have to work?
• Rain, snow, night, bright sunlight, hot days
• Portable with hours of time between battery
charges
• Must be light and easy to carry
• Must be reliable
• Must give immediate answers
What do we need to identify?
Not so nasty stuff
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Sodium hydroxide
Sodium carbonate
Adipic Acid
Aluminum Sulfate hydrate
Ammonium Nitrate
Urea
Terephthalic Acid
1,2-propanediol (aka propylene glycol)
viscous and non-flammable Acetic acid
carbon black
potassium carbonate (pot ash)
Titanium dioxide
Arsenic
oxidebarium carbonate (for barium metal)
Cadmium
chromium
Lead
Mercury
Nickel
Zinc
sodium fluoride
Etc.
• There are 70 or so of
these
Bad Materials
• Explosives or their residues and IEDs
– Stable (RDX, TNT, C4, etc) LIBS does not explode them
– Unstable (London event)
– Explosive or corrosive gasses
• Biological materials (bacillus spores)
• Poisons
• Drugs
MP-LIBS A full laboratory High-Resolution
Broadband LIBS system in a portable backpack
Head’s-up display
Backpack contains
broadband highresolution
spectrometer, laser
power supply,
computer, and battery
Hand-held probe contains
laser, joystick for control,
and focus optics
Microplasma/
LIBS Event
MP-LIBS
• First responder in Full
Class A protection Suit
• MP-LIBS should be
inside suit
MP-LIBS Outside Backpack
LIBS3000-gh
spectrometer
Computer with cell
phone and wireless
network
Argon Bottle
for
Special targets
How do we identify complex substances?
LIBS
Spectrum
We have stored the 2-dimensional barcode of
items of interest!
Position
Position
Amplitude
Amplitude
ultraviolet
Blue
Green
Red
Infrared
Mathematics
• Correlation
– Checks everything in the catalog, tells you what
is closest and grades it, 1.0 being perfect, 0.0
being no correlation
– 2 types
• Linear – all peak heights count according to how
high they are
• Rank – Big peaks count more than little ones
What else do we do?
• PCA - a type of analysis
• PPA - Primary peak analysis
– What’s missing from the closest matches, or
what is additional
• PPC - Peak picking correlation
– Get rid of the junk between the big peaks
Then What?
• It’s time to vote to determine the winner
• An example, pick the 10 highest scorers and for each calculate
• Score = 0.2 x (Rank Correlation) + 0.3 x (Linear Correlation) +
0.2 x PCA + 0.1 x PPA + 0.2 x (Peak Pick Correlation)
Then display the top 5 matching items and
their scores
BG
BT
Sugar
Salt
Creamer
1.00
0.59
0.49
0.47
0.46
What else are we doing?
30 + meter long distance LIBS