Researchers at Tennessee’s Oak Ridge National Laboratory have developed a two-laser system that will enable scientists to identify biological and chemical agents from a distance.
The researchers from the University of Alberta, University of Tennessee, Knoxville and Oak Ridge National Laboratory have authored the paper “Pump-probe photothermal spectroscopy using quantum cascade lasers” which has been published in the Journal of Physics D: Applied Physics.
The researchers have detailed the process wherein a quantum cascade laser has been used to strike or pump a target while a second laser was used to monitor the thermal response of the material. The photothermal measurements derived using the pump-probe photothermal spectroscopy allows for rapid evaluation of compounds such as organophosphate pesticide, polystyrene and cellulose.
A researcher at the Oak Ridge National Laboratory’s Nanoscale Science and Devices division, Dr. Ali Passian stated that the approach used by the scientists enables the second probe laser to extract information that allows the researchers to determine the composition of the chemicals. The second laser provides a stable and robust readout approach which is independent of the settings of the first pump laser.
A return signal carries data of the molecules that need to be determined. The approach, although comparable to LiDAR and radar sensing techniques, is different in certain ways. Dr. Passian explained that the photothermal spectroscopy configuration ensures that the probe and pump beans are almost parallel. In the technique employed by the scientists, beam reflectometry is used as the return signal which minimizes the dependency on wavelength-dependent IR-based telescopes, detectors and cameras.
The two-laser system can be applied to develop potential applications for the military, forensics, medicine, quality control and airport security.