A Photomultiplier Tube (PMT) based optical fiber Raman sensor was developed for online
monitoring of nitrogen/oxygen concentration ratios in gaseous mixtures. The sensor employed a frequency
doubled 532 nm continuous wave (CW) Nd:YAG laser and a modified In-Photonics fiber optic state-of-art
miniaturized Raman Probe. The gaseous mixture was enclosed in a high pressure cell and subjected to
varying degrees of pressure. Raman signal of gaseous nitrogen and oxygen were first analyzed with a
miniature spectrometer. The detection system was then replacing by a Labview interfaced PMT module for
fast data acquisition and real time monitoring of relative Raman signals of nitrogen and oxygen.
Instrumentation features and sensor performances with different detection systems (i.e. spectrometer and
PMT) is presented in the paper.
A novel fiber optic prototype sensor based on Raman spectroscopy for qualitative and quantitative monitoring of various chemicals in the sample was developed. The sensor employs a high power 670nm laser diode as an excitation light source and a specially designed fiber optic Raman probe with launching and collecting fibers. Raman signal was collected by six optical fibers; filtered, and then fed to the spectrometer through another optical fiber bundle. The uniqueness of the sensor lies in its compact and stable design configuration, that includes carefully aligned optical components, viz. laser diode, filter holder, and miniature spectrometer. Developed sensor is immune to ambient light fluctuation and offers a cost effective solution for probing several species in harsh environment. Various issues like system fabrication, optimization, functional stability, signal/noise ratio, repeatibility etc are well addressed and presented in this paper.
An optical fiber sensor is being developed for diagnosis of human breast cancer cell lines. The sensor exploits laser-induced fluorescence spectroscopy in conjugation with fiber optics. The main advantage of fluorescence detection compared to absorption measurements is the greater achievable sensitivity due to the fact that the fluorescence signal has a very low background. However, an accurate and sensitive method for the diagnosis of cancer cell lines is quit challenging. The sensitivity and accuracy of LIF technique can be improved by optimizing the sensor configuration. In this work, the spectral characteristics of the fluorescence, which was induced by frequency tripled Nd:YAG laser operating at 355nm are recorded from two different type of human breast cancer cell line. Effects of various influential experimental parameters and configuration were investigated in order to optimize the sensor performance. The sensor with optimum configuration enables to differentiate two types of cancerous cell lines with a maximum achievable fluorescence spectral contrast. A unique data processing technique has been developed to analyze the recorded data for cell lines identification and differentiation.