Double laser spectroscopy can deliver more data say researchers

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Chemicals and biological agents could be rapidly identified from a distance by zapping them with a quantum cascade laser and then analysing the target’s response with a second laser, according to researchers at the US government’s Department of Energy Oak Ridge National Laboratory (ORNL).

Called photothermal spectroscopy, this technique that the researchers have developed uses probe beam reflectometry, which minimises the need for wavelength-dependent expensive infrared components such as cameras, telescopes and detectors. This proof of principle success could lead to advances in standoff detectors with potential applications in quality control, forensics, airport security, medicine and the military.

‘With two lasers, one serves as the pump and the other is the probe,’ said Ali Passian, a member of ORNL's measurement science and systems engineering division. ‘The novel aspect to our approach is that the second laser extracts information [and] provides a robust and stable readout approach independent of the pump laser settings.’

This new type of hyperspectral imaging is expected to provide high-resolution chemical information as well as topographical data.