Alakai Defense Systems has created a standoff explosive detection sensor called the Check Point Explosives Detection
System for use at military check points. The system is designed to find trace level explosive residues from a standoff
distance to thwart the transport and use of illegal homemade explosives, precursors and related contraband. Because of
its standoff nature, this instrument could offer benefits to those searching for explosives, since it removes the searcher
from harm's way if a detonation occurs. A short description of the instrument, improvements to the system over the past
year, and a brief overview of recent testing are presented here.
In order to stop the transportation of materials used for IED manufacture, a standoff checkpoint explosives detection
system (CPEDS) has recently been fabricated. The system incorporates multi-wavelength Raman spectroscopy and laser
induced breakdown spectroscopy (LIBS) modalities with a LIBS enhancement technique called TEPS to be added later
into a single unit for trace detection of explosives at military checkpoints. Newly developed spectrometers and other
required sensors all integrated with a custom graphical user interface for producing simplified, real-time detection results
are also included in the system. All equipment is housed in a military ruggedized shelter for potential deployment intheater
for signature collection. Laboratory and performance data, as well as the construction of the CPEDS system and
its potential deployment capabilities, will be presented in the current work.
Recent progress has been made on an explosive laser standoff detection system called TREDS-2 constructed from COTS
components. The TREDS-2 system utilizes combination of Laser Induced Breakdown (LIBS), Townsend Effect Plasma
Spectroscopy (TEPS) and Raman spectroscopy techniques with chemometric algorithms to detect hazardous materials.
Extension of the detection capability of the TREDS-2 system on the real-time point detection of chemical, biological,
radioactive, and nuclear threats has been tested and presented in this report.
System performance of surface detection of a variety of CBRNE materials is shown. An overview of improvements to
the explosives detection capabilities is given first. Challenges to sensing some specific CBRN threats are then discussed,
along with the initial testing of TREDS-2 on CBRN surrogates on a limited number of surfaces. Signal processing using
chemometric algorithms are shown as a demonstration of the system's capabilities. A path forward for using the specific
technologies is also provided, as well as a discussion of the advantages that each technology brings to the CBRNE
The present work focuses on a new variant of double pulse laser induced breakdown spectroscopy (DP-LIBS) called
Townsend effect plasma spectroscopy (TEPS) for standoff applications. In the TEPS technique, the atomic and
molecular emission lines are enhanced by a factor on the order of 25 to 300 times over LIBS, depending upon the
emission lines observed. As a result, it is possible to extend the range of laser induced plasma techniques beyond LIBS
and DP-LIBS for the detection of CBRNE materials at distances of several meters.
A fully integrated UV Townsend Effect Plasma Spectroscopy (TEPS)-Raman Explosive Detection System (TREDS-2)
system has been constructed for use of standoff detection. A single 266nm Q-Switched Nd:YAG laser was used for
Raman excitation and TEPS plasma ignition. A nearly simultaneous 10.6μm CO<sub>2</sub> laser was employed for the signal
enhancement in the TEPS measurements. TEPS and Raman spectra have been measured for a wide variety of energetic
samples on several different substrates. Chemometric techniques are presented for analysis and differentiation between
benign and energetic samples. Since these techniques are orthogonal, data fusion algorithms can be applied to enhance
the results. The results of the TEPS and Raman techniques along with their algorithms are discussed and presented.
We have used a simultaneous 10.6 micron CO<sub>2</sub> laser pulse to enhance the Laser Induced
Breakdown Spectroscopy (LIBS) emission from a 1.064 micron Nd:YAG laser induced plasma on a hard
target. The enhancement factor was found to be one or two orders of magnitude, depending upon the
emission lines observed and the target composition. The output energy of the 5 ns Nd:YAG laser pulse
was about 50 mJ and was focused to a 1 mm diameter spot to produce breakdown. The CO<sub>2</sub> laser pulse
(100 ns spike, 5 microsec tail) had a similar energy density on target (0.06 J/mm<sup>2</sup>). Timing overlap of the
two laser pulses within 1 microsecond was important for enhancement to be observed.
Enhancement of neutral atomic emission was usually on the order of
5-20X, while enhancement of
ionized species tended to be higher, 10-200X. We attribute the increase in both the atmospheric
components and the +1 and +2 ionic emission to heating of the Nd:YAG plasma by the coincident CO<sub>2</sub>
laser. Such inverse bremsstrahlung absorption of CO<sub>2</sub> laser radiation by the free electrons of plasma is well
known. We are conducting additional studies to better quantify the effects of laser beam mode, pulse-to-pulse
jitter, temporal pulse shaping, and optimization of these parameters for different LIBS target
A Deep-UV LIBS system has been constructed for the standoff detection of Explosives, and potentially Chemical,
Biological, Radiological, and Nuclear (CBRN) substances. A Q-Switched Nd:YAG Laser operating in at 266nm was
used for excitation of the LIBS plasma and future Raman excitation. This plasma was enhanced by the means of a nearly
simultaneous CO<sub>2</sub> laser which results in a method referred to as Townsend Effect Plasma Spectroscopy (TEPS). Spectra
covering the range of 240-800nm at standoff distances are presented. The classical emission lines (i.e. C, N, O, H, etc)
of the energetic samples were observed and a peak ratio technique was used to differentiate between benign and
energetic samples of interest.