Unknown Material Analysis in Less Than A Second Man Portable LIBS A Tool for First Responders in...
Transcript of Unknown Material Analysis in Less Than A Second Man Portable LIBS A Tool for First Responders in...
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
What is LIBS?
Nd-Yag Laser
LIBS3000
Spectrometer
Computer -
Standard PC
Analyze
One 7 ns laser pulse
15,000 K plasma, much hotter than the sun’s surface but for only 20 microseconds
Identify < 0.5 sec
0.000000007 seconds
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– 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
• 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
Hand-held probe contains laser, joystick for control, and focus optics
Microplasma/ LIBS Event
Backpack contains broadband high-resolution spectrometer, laser power supply, computer, and battery
MP-LIBS
• First responder in Full Class A protection Suit
• MP-LIBS should be inside suit
MP-LIBS Outside Backpack
Argon Bottle
for
Special targets
LIBS3000-gh spectrometer
Computer with cell phone and wireless network
How do we identify complex substances?
LIBS Spectrum
We have stored the 2-dimensional barcode of items of interest!
Position
Amplitude
ultraviolet Blue Green Red Infrared
Position
Amplitude
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
BGBTSugarSaltCreamer
1.000.590.490.470.46
What else are we doing?30 + meter long distance LIBS