Utilization of fiber loop ring down technique for sensing applications

Yolalmaz, Alim
Fiber loop ring down (FLRD) spectroscopy is based on multiple interaction of laser light with sample/analyte. It is evolved from cavity ring down spectrometer with addition of optical fiber. Measurement accuracy rises with multiple interactions and this enhances the minimum detection limit compared to other spectrometers using single pass interaction such as FTIR, UV-VIS spectrometer. The other advantages of this technique are its insensitivity to laser fluctuation and detector performance. In this study, three FLRD set-ups were constructed with two laser sources at 800 and 1534 nm. Sensor regions were designed with two interaction methods as transmission and scattering and optimization for measurement parameters and probe structure were performed. The spectrometers’ parameters were examined with chemicals such as ethanol, acetone, toluene, acetylene gas, nitrogen gas. The response of the spectrometers to sample/analyte were investigated and limitations were discussed. Finally, the performance of the spectrometers was compared with the literature. 


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Fiber loop ring down (FLRD) spectroscopy is a sensitive spectroscopic technique that is based on absorption and it is convenient for trace chemical detection. Different FLRD systems are being improved in order to increase their sensitivity. In FLRD spectroscopy, detection of a sample is done by measuring of a leaking light at each trip within an optical cavity. Intensity of leaking light has an exponential decay where it is reduced by absorption of sample and scattering of light. In this project, two FLRD s...
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Fiber loop ring down spectrometer optical based sensor for trace chemical detection
Yolalmaz, Alim; Esentürk, Okan; Danışman, Mehmet Fatih; Hanifehpour, Farhad (2016-04-11)
Fiber loop ring down (FLRD) is a time domain multi-functional sensing, characterization, detection technique. FLRD technique is used to sense temperature, pressure, strain, biological cells, refractive index, and chemical species. FLRD has high accuracy, high selectivity, ability of remote control and rapid response. In this project, two FLRD spectrometers working at 800 nm (figure 1) and 1535 nm (figure 2) were set up for sensing different chemical analytes like C2H2, CO2, Ar, N2, DMSO, DMF, H2O, C2H6O, C3...
Citation Formats
A. Yolalmaz, “Utilization of fiber loop ring down technique for sensing applications,” M.S. - Master of Science, Middle East Technical University, 2017.