Transcript Document
SPSA / SIPR Conference 2010 Remote Chemical Detection by Tunable Lasers : Potential applications in Threat Detection and Forensics Dr Graeme Malcolm Acknowledgements •Co-authors: • G.T. Maker, B.Miller & G. Robertson, M Squared Lasers Ltd • M.H. Dunn and D.J.M Stothard, University of St. Andrews, UK •Co-workers : • C.R Howle, A McIntosh, L.Lee and C.Dyer • Defence Science and Technology Laboratory (DSTL), Porton Down, UK • Work supported by: • DSTL, MoD, Royal Society of Edinburgh, Scottish Enterprise. Overview •Active IR hyperspectral sensing concept •Source requirements •Source & imaging system •Results •Threat Detection and Forensic Applications •Conclusion and Summary Introduction •Problem: real-time detection & imaging of threat materials at safe distances • CWAs, BWAs, IEDs, TICs • Ideally detect many agents with one device • ‘Safe’ distance typically ten(s) metres IED Threat Typical Explosives Mass (TNT Equivalent) Building Evacuation Distance Pipe Bomb 2.3 kg (5 lbs) 21 m (70 ft) Suicide Belt 4.5 kg (10 lbs) 27 m (90 ft) LPG Tank 9 kg (20 lbs) 48 m (160 ft) Ref: US Army, National Ground Intelligence Center, IED Safe Standoff Distances www.m2lasers.com Stand-off Concept •Threat Detection Concept •M Squared Current Capability •CWA Sensing Confidential - Feb ‘09 Application Requirements: IR Threat Signatures •Typical absorption wavelengths of molecular bonds in common organic molecules •4000 •C C •C N •N H •O H•3200 •X-H attached to hetero-atoms •4000 •2.5 •2800 •C-H •3000 •3.3 •2300 •2100 •C O •C N •C C •1800 •1500•cm-1 •Double s •Triples •2000 •5.0 •Singles •cm-1 •1000 •10 •µm www.m2lasers.com Active IR Hyperspectral Remote Sensing- Concept •Use strong absorptions of target molecules or compounds in the IR waveband •Illuminate scene with IR light of high spectral purity to coincide with absorption features • Collect back-scattered light •Target molecule/compound in path of beam will absorb and reduce backscatter • Negative Contrast Imaging •Tunable IR source • Different absorption features measured and spectroscopic identification possible Spectroscopic survey of line strengths of in the 3-5µm infrared region Line Strength (cm/molecule) 10 10 CO2 -17 -18 HCN C2H2 10 -19 10 -20 HCI C2H6 OH NH3 C2H4 CH3CI 10 -21 10 -22 H2CO CO HBr GeH4 C2N2 NO2 H2 O 3. 5 O3 HI H2S BTEX 3.0 N2O PH3 CH4 OCS SO2 4.0 Wavelength (µm) 4.5 5.0 Source Requirements •Sensitivity & specificity require sources with: • • • • High power & brightness (for range, high SNR) Broad wavelength tuning (cover many species) Suitable linewidth (selectivity) High efficiency and compactness (portability) •Lack of suitable IR illuminators has hindered adoption of active IR hyperspectral sensing Novel IR Illuminator - Firefly-IR •OPO = broad tuning, dual NIR & MWIR outputs •Intracavity OPO = high efficiency •Integrated pump = compact •Designed for field use: • Maintenance-free design • Instrument Control by Ethernet • InvarianT™ alignment-free mounts 36 x 21 x 7cm (L x W X H) Firefly-IR: Performance Characteristics •Tuning ranges: Typical Tuning Curve - MWIR Output, Broadband Pump • 1.4 - 1.8 µm (>300 mW) Signal Idler • 2.8 - 4.6 µm (>120 mW) PPLN •Pulse repetition rate: • Up to 300 kHz (Optional étalons) QS Nd:YV04 •Pulse width: pump • < 10 ns (FWHM) •Linewidth: • < 6 cm-1 (no étalons) • < 2 cm-1 (signal étalon) M2 < 1.4 at 3.3µm Firefly-IR + Scanner: Imaging Raster : Backscatter Absorption Gas Imaging for Gases Galvanometer mirror From Firefly-IR CaF2 Lens MCT Detector Active Reflectance / Absorption Imaging of Liquids/Solids Video-Rate Imaging of Gases Normal video: gas is invisible What Firefly saw – methane gas Firefly-IR + Scanner: Imaging Applications Demonstration of gas imaging and false colour concentration measurement with Firefly-IR using differential absorption Firefly-IR + Scanner: Concentration Resolution & range •Sensitive CH4 monitoring • Detection to <35 ppm.m • Real-time imaging Identification of Liquids Spectral fingerprinting of liquids : various mineral oils Identification of Liquids II •Spectroscopic & spatial negative contrast imaging of mineral oils – with differential analysis Z ~1.2 m Imaging Threat Simulants: Forensics : Attempted to remove CWA simulant but still detectable •Z ~1.2 m www.m2lasers.com Applications in Threat Detection / Forensics •Identifying threats • Security & venue protection • Counter Terrorism screening •Decontamination • Identifying effective decontamination requirements •Triage • Understanding nature of attack substance •Forensic Investigation • Ability to investigate a scene remotely and chemically map evidence. THz Imaging for Drug Detection •The Importance of Terahertz: •New spectroscopic area important for molecular identification •Like X-rays but non-ionising – • not dangerous •Drug detection and Identification •Leveraging pharmaceuticals non-destructive testing / analysis •THz Spectral Fingerprinting •Ecstasy •Aspirin •Meth Summary •Demonstrated active IR spatial/spectral detection of gases and liquids • Gases down to 10ppm.m at >10m • Liquids down to 20ul at 10m • Solids down to ng of residue •Novel laser sources provides new capabilities for threat agent imaging with potential applications in: • Detection of CWAs and Explosive Materials • Counter-terrorism and forensic investigation • Drug detection and analysis •[email protected]