USA — Army researchers explore laser detection techniques

ADELPHI, Md. — As the need for chem­i­cal, bio­log­i­cal and explo­sive detec­tion becomes more rel­e­vant in today’s world, the U.S. Army Research Lab­o­ra­to­ry is lead­ing the effort in laser-induced break­down spec­troscopy, which is capa­ble of high­ly advanced mate­ri­als analy­sis.

ARL's Advanced Weapons Concepts Branch
Dr. Andrzej Miziolek and his col­lab­o­ra­tors in ARL’s Advanced Weapons Con­cepts Branch are lead­ing the effort on stand­off detec­tion per­tain­ing to trace amounts of haz­ardous mate­ri­als using the LIBS tech­nol­o­gy. The work of his team has lead to greater detec­tion and iden­ti­fi­ca­tion of CBRNE. Miziolek has co-authored over 80 jour­nal arti­cles and pub­lished three books.
Pho­to cred­it U.S. Army Pho­to
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The tech­nol­o­gy has shown sig­nif­i­cant advance­ments since its incep­tion in the 1980’s. Today, LIBS tech­nol­o­gy is used for mul­ti­ple pur­pos­es, includ­ing the 2011 mis­sion to Mars, detec­tion of chem­i­cal, bio­log­i­cal, radi­o­log­i­cal, nuclear, and explo­sive mate­r­i­al, and mate­ri­als match­ing in foren­sic cas­es.

Dr. Andrzej Miziolek and his col­lab­o­ra­tors in ARL’s Advanced Weapons Con­cepts Branch are at the fore­front of stand­off detec­tion per­tain­ing to trace amounts of haz­ardous mate­ri­als using the LIBS tech­nol­o­gy. Their work is an impor­tant exam­ple of apply­ing spec­troscopy to dif­fi­cult prob­lems in chem­i­cal analy­sis.

“One of the many rea­sons LIBS is so suc­cess­ful is because it com­bines laser abla­tion with sam­ple exci­ta­tion, all in a sin­gle laser shot,” said Miziolek. “We have the capa­bil­i­ty to remove nanograms of mate­r­i­al from the sur­face, whether the mate­r­i­al is bulk or a residue. The resul­tant microplas­ma emits light which is ana­lyzed by a spec­trom­e­ter.

ARL has led the evo­lu­tion of a new gen­er­a­tion of LIBS where we com­bine sin­gle shot spec­trum cap­ture with advanced sig­nal pro­cess­ing to iden­ti­fy the mate­r­i­al,” he added. “Thus, we ana­lyze each spec­trum on the fly, rather than aver­age many spec­tra. We have one shot to get it right — once the residue is gone, it is gone.”

In 2000, ARL worked with Ocean Optics Inc. to devel­op a new capa­bil­i­ty — a broad­band high res­o­lu­tion spec­trom­e­ter which became com­mer­cial in 2003. This new spec­trom­e­ter allows the LIBS sys­tem to be sen­si­tive to all chem­i­cal ele­ments in the peri­od­ic table, as long as their con­cen­tra­tion is parts-per-mil­lion or high­er with­in the sam­ple. This makes LIBS a very gen­er­al tool for mate­ri­als analy­sis, both benign and haz­ardous.

Accord­ing to Miziolek, the LIBS sys­tem has the abil­i­ty to detect all five of the threats in CBRNE, as long as the laser hits the mate­ri­als direct­ly. “As recent­ly as a decade ago, very few peo­ple would have expect­ed that LIBS, which is fun­da­men­tal­ly an ele­men­tal analy­sis tech­nol­o­gy, would be able to iden­ti­fy unknowns of bio­log­i­cal ori­gin, let alone to be able to dif­fer­en­ti­ate between path­o­gen­ic and non-path­o­gen­ic strains of the same bac­teri­um,” he not­ed.

While com­mer­cial­iz­ing this tech­nol­o­gy for field appli­ca­tions is a slow process in the U.S., LIBS has grown sub­stan­tial­ly in Europe. Miziolek serves as a sub­ject mat­ter expert in “stand-off LIBS” in many areas local­ly and world-wide. A recent advance was his efforts in get­ting LIBS accept­ed to the Stan­dard­ized Equip­ment List, which is an impor­tant step in trans­fer­ring tech­nol­o­gy from lab to user through the com­mer­cial­iza­tion process.

The ARL LIBS group includes Drs. Frank DeLu­cia, Chase Mun­son, and Jen­nifer Got­tfried, all of whom have been instru­men­tal in gen­er­at­ing the data which shows con­sis­tent ana­lyt­i­cal suc­cess of 95 per­cent true pos­i­tives. They have also pio­neered the use of advanced chemo­met­rics, and their work has been adopt­ed by many oth­er LIBS lab­o­ra­to­ries world-wide.

“The best is yet to come with LIBS,” not­ed Miziolek, “with the antic­i­pat­ed com­mer­cial­iza­tion of rugged and user-friend­ly field devices in many dif­fer­ent form fac­tors includ­ing stand­off, close-con­tact, robot­ic-mount­ed and under­wa­ter sys­tems”.

The attrib­ut­es of LIBS are com­pelling, includ­ing real-time analy­sis, no sam­ple prepa­ra­tion, high sen­si­tiv­i­ty and high speci­fici­ty. The recent devel­op­ment of real-time sig­nal pro­cess­ing soft­ware has made one-sec­ond analy­sis a real­i­ty.

Source:
Army Research Lab­o­ra­to­ry Pub­lic Affairs br/> U.S. Depart­ment of Defense
Office of the Assis­tant Sec­re­tary of Defense (Pub­lic Affairs)