US 11,867,618 B2
Systems and methods using active FTIR spectroscopy for detection of chemical targets
Derryck Telford Reid, Edinburgh (GB); and Oguzhan Kara, Jena (DE)
Assigned to Heriot-Watt University, Edinburgh (GB)
Appl. No. 17/606,568
Filed by Heriot-Watt University, Edinburgh (GB)
PCT Filed Apr. 17, 2020, PCT No. PCT/GB2020/050969
§ 371(c)(1), (2) Date Oct. 26, 2021,
PCT Pub. No. WO2020/217046, PCT Pub. Date Oct. 29, 2020.
Claims priority of application No. 1905848 (GB), filed on Apr. 26, 2019.
Prior Publication US 2022/0205904 A1, Jun. 30, 2022
Int. Cl. G01N 21/3504 (2014.01); G01J 3/02 (2006.01); G01J 3/453 (2006.01); G01N 21/3563 (2014.01); G01N 21/3577 (2014.01); G01N 21/17 (2006.01); G01N 21/35 (2014.01)
CPC G01N 21/3504 (2013.01) [G01J 3/0208 (2013.01); G01J 3/4535 (2013.01); G01N 21/3563 (2013.01); G01N 21/3577 (2013.01); G01N 2021/1793 (2013.01); G01N 2021/3595 (2013.01)] 24 Claims
OG exemplary drawing
 
1. An active FTIR spectroscopy system for quantitative measurements of concentrations of chemical targets in an open-path measuring arrangement, the system comprising:
an illumination source comprising an optical parametric oscillator configured to generate broadband IR light,
a calibration source configured to generate calibration light,
a scanning interferometer arranged to
synchronously receive each of the broadband IR light and the calibration light, and
then modulate each of the received broadband IR light and calibration light over a scanning period,
with the received calibration light being configured to deduce optical path differences introduced by the scanning interferometer over the scanning period for each of the modulated broadband IR light and the modulated calibration light,
a launch system for illuminating the chemical targets with the modulated broadband IR light,
a collector system for receiving broadband IR light spectrally-modulated by the chemical targets,
wherein the launch system is configured so that an optical axis of a launching path is substantially co-aligned with an optical axis of the collector system,
a detector system for detecting and then recording interference fringes generated by the spectrally-modulated broadband IR light and by the modulated calibration light,
a computer processor, and
a non-transitory computer readable medium encoded with a computer program,
wherein the computer program comprises instructions stored therein for causing the computer processor to perform a plurality of functions to simultaneously compute concentrations of each of the chemical targets from spectra of the recorded interference fringes generated by the spectrally-modulated broadband IR light and by the modulated calibration light;
wherein the computer processor is configured to extract an effective illumination spectrum of infrared light illuminating the chemical targets and using the effective illumination spectrum to simultaneously compute the concentrations of each of the chemical targets.