We report on a prototype Laser Induced Breakdown Spectroscopy (LIBS) Deminers' Probe used to identify
underground objects. We have built a prototype, and are in the process of developing a more advanced LIBS
based Deminer' s Probe used to prod objects underground, and then sense them by creating a micro-plasma
plume of the surface material and analyzing the spectrum of the emitted light to identify the object. It is
expected that the Deminer will be able to eliminate many false positives, which consume most of the
SARA Fiber-Optics coupled LIBS system consists in a probe that can be inserted into the ground to provide a
path for both the laser beam to the target, and for the micro-plasma plume fluorescence from the target to a
spectrometer or spectrometers for analysis.
The probe is closely modeled after the conventional Deminers' probe, resembling a saber. We have
demonstrated that this simple system is capable of producing remarkably different spectra from different
materials. Our next steps are to add a number of features to the Deminers' Probe. These include: a new
optical configuration to increase the irradiance and fluence created by the pulsed laser at the target, a multiple
channel fluorescence reception system that can increase the amount of light delivered to the spectrometers, a
fluidic system to clear the detritus away from the probe tip, and a complete operational/control and readout
system for the Deminer to use.
Mine-lane tests are planned to be performed in the later part of 2009, or shortly thereafter.
The "ColorDazl" is a device designed to be used for testing eye and sensor dazzling, at modest range, in a
package that can be carried, and with a projector that could be mounted to a lethal weapon (or if desired, to
another type of non-lethal device such as a "stinger"). The Tri-Laser Module (TLM) is a completely self
contained subsystem of the device containing functional 3 color (RGV) laser sources. The laser beams are
transmitted to the projector by an optical fiber. A 2" or larger diameter projector produces an eye-safe beam
throughout its range, yet one of sufficient Irradiance or Illuminance to potentially dazzle sensors, and the
unaided eye at ranges between 20' and 200' under night-time or twilight conditions.
The TLM is a single pulse laser source, which can be fired every few seconds, with computer controls which
keep it eye-safe at the exit aperture, and throughout the range. The output is adjustable with varying power
levels and varying pulse duration of the three colors, allowing a flickering output. The system is operated
from a LapTop computer which controls the total power, and pulse lengths of each individual laser, so that the
total power is below 500 mW, and the energy per pulse for all 3 beams is kept below 30 mJ per pulse. This
mode of operation ensures that the device is a Class 3b source as determined by ANSI Z136 classification, and
is therefore free from the limitations of Class 4 which include key lock, emission delay, audible warning, etc.
With simple refinements to the ColorDazl laser controller software and new projector and receiver
combinations currently being considered, a higher power dazzler could be designed in the near future that
will be effective and relatively safe under brighter ambient lighting and longer range conditions.
We have performed analysis of the requirements for an optical dazzler, designed and built a three-wavelength source with a baseline beam projector, and a Smart Beam Projector that can point the beam, and adjust the laser power for a particular target. The source is based on diode lasers, and diode pumped lasers in the Red, Green and Violet ranges of wavelengths. Each laser can be independent adjusted in output power, and pulse duration. The beams are combined using optical fibers, and the source fits in a 1/4 cubic foot Pelican Box, and can run off a battery for field testing. The baseline beam projector can be mounted to a rifle or pistol. The Smart beam projector is designed for laboratory testing at this time. The operation of the prototype system will allow a variety of combinations of laser power, and pulse length to give a varying spatial and temporal profile of illumination. The system is to be tested by the Army for effectiveness. A next generation of dazzler is under construction that will allow microprocessor control of pulse power and duration, increasing the variety of illumination spatial and temporal patterns and more fully utilizing the Smart beam projector capabilities.
We have developed an accurate simulation program to predict the performance of flashlamp- pumped Titanium Sapphire (TiS) lasers. The program has been benchmarked to several experimental lasers with energy outputs from 0.1 to 1.0 Joules per pulse. The results for lasers operating in both long-pulse and Q-switched modes agree with experimental results to within 20%. We have used this program to explore energy scaling of TiS laser oscillators from 1.0 to 10.0 Joules using realistic values for lamp pulse energy loading and TiS material Figure-of- Merit (FOM). We present here results of this energy scaling as explicit functions of laser rod diameter, length, doping level, Figure of Merit, use of dye converters, pump pulse length and number of lamps. The results indicate that with proper lamp coupling, via reflectors, etc., lasers with pulse energies greater than 10 Joules are possible with electrical-to-output efficiency greater than 1%.