Researchers at the Department of Energy's Oak Ridge National Laboratory have developed a two-laser system that can detect chemicals from a distance.
Ali Passian and his associates presented a technique in the Journal of Physics publication. The technique is based on a quantum cascade laser that can strike or ‘pump’ a target, whereas another laser will monitor the material's response that results from temperature-induced changes, thereby enabling the detection of chemicals and biological agents.
According to Passian, one of the two lasers will act as a pump, while the other will serve as a probe. The second laser acquires information, eliminating the need for a weak return signal. It serves as a strong and reliable readout approach, without using the pump laser settings.
Just like radar and lidar sensing techniques, this approach utilizes a return signal in order to transmit information of the molecules to be detected.
Passian added that initially the photothermal spectroscopy configuration is used, with parallel pump and probe beams. The probe beam reflectometry serves as the return signal in standoff applications, without using detectors, cameras, and telescopes.
Passian and co-author Rubye Farahi said that this effort will contribute to developments in standoff detectors that can be used widely in the fields of airport security, quality control, medicine, forensics, and military. In addition, the measurements resulting from the technique will support hyperspectral imaging.
Passian further added that photothermal spectroscopy-based cell-by-cell measurement was used for this observation. Hyperspectral imaging provides topographical information in addition to high-resolution chemical information.
Source: http://www.ornl.gov/