Integrated Laser Sensor (ILS) for Remote Surface Analysis: Application for Detecting Explosives in Fingerprints

Abstract

Here, we describe an innovative Integrated Laser Sensor (ILS) that combines four spectroscopic techniques and two vision systems into a unique, transportable device. The instrument performs Raman and Laser-Induced Fluorescence (LIF) spectroscopy excited at 355 nm and Laser-Induced Breakdown Spectroscopy (LIBS) excited at 1064 nm, and it also detects Laser Scattering (LS) from the target under illumination at 650 nm. The combination of these techniques supplies information about: material change from one scanning point to another, the presence of surface contaminants, the molecular and elemental composition of top target layers. Switching between the spectroscopic techniques and the laser wavelengths is fully automatic. The instrument is equipped with an autofocus and it performs scanning with a chosen grid density over an interactively-selected target area. Alternative to the spectroscopic measurements, it is possible to switch the instrument to a high magnification target viewing. The working distances tested until now are between 8.5 and 30 m. The instrument is self-powered and remotely controlled via wireless communication. The ILS has been fully developed at ENEA for security applications and it was successfully tested in two outdoor campaigns where an automatic recognition of areas containing explosives in traces had been implemented. The strategies for the identification of nitro-compounds placed on various substrates as fingerprints and the results obtained at a working distance of 10 m are discussed in the following.

Identification of microplastic fibres released from COVID-19 test swabs with Raman imaging

“…For example, the Raman peak heights can act as the weighting factors towards merge [ 24 ]. Taking PA as an example, we can set the weighting factors to be 0.07, 0.13, 0.14, 0.24, 0.19 for the images mapped at ~ 1050 cm −1 , ~ 1130 cm −1 , ~ 1300 cm −1 , ~ 1450 cm −1 and ~ 1630 cm −1 , respectively.…”

Wavefront-enhanced laser-induced breakdown spectroscopy (WELIBS) utilizing a crystalline silicon wafer for a flat-top IR laser beam

“…In addition, other approaches relevant to the target, e.g., nanoenhanced laser-induced breakdown spectroscopy (NELIBS), are challenging to apply in numerous cases. For example, in remote LIBS measurements, the target is not only distant 10,11 but may also be in a hostile environment. 12 Besides, the addition of layers of nanoparticles onto the object's surfaces is prohibited in the case of cultural heritage and art.…”

“…, nano-enhanced laser-induced breakdown spectroscopy (NELIBS), are challenging to apply in numerous cases. For example, in remote LIBS measurements, the target is not only distant 10,11 but may also be in a hostile environment. 12…”

A confocal-controlled Raman-LIBS hybrid microscope with high stability and spatial resolution

“…4,5 It has been reported that the complementary information provided by these two methods allows the identication of unknown terrestrial and extraterrestrial minerals. [6][7][8][9][10] Geology and space exploration further require the instrument to be used in situ and comprehensive analysis. Therefore, a dual spectroscopic platform, which is a hybrid between Raman and LIBS, is highly demanded.…”