Remote measuring system for infrared spectral features using hollow fiber probe

Infrared probes composed of different hollow fibers were designed, fabricated, and optimized according to their transmission properties. Remote measuring system using the probe was set up with a Fourier Transform Infrared Spectrometer (FTIR). The experimental results showed that the transmission efficiency reached 17.6% when tapered fiber is used as the receiving fiber in the probe. Infrared spectral features were measured for films such as polycarbonate (PC) and Poly vinylidene fluoride (PVDF), as well as liquid-phase films such as ethanol and toluene. Quantitative measurements were carried out for the mixed liquid of ethanol and toluene using the characteristic absorption peak of toluene at the wavenumber of 1605cm-1. A number of mixed liquid with various concentrations ranging from 5% to 50% were made to build the quantitative model and evaluate the effect of the measurement. The results showed that RMSEP was 3.356 and the correlation coefficient was 0.9200. The system can be used in remote measuring of spectral features for solid and liquid phase films.