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In this paper, we have designed a U-bent fiber optic sensor based on evanescent wave absorption for iron detection and quantification in the iron tablet. A detailed investigation of the impact of the bend-induced material deformation on the refractive index losses, numerical aperture, light propagation inside core and absorption coefficient has been presented. The experiment results of the developed sensor demonstrate the sensor sensitivity as 0.0316 O. D/ppm with a linear regression coefficient (R2) of 98.1%. [ABSTRACT FROM AUTHOR]

High-power lasers typically form a multidisciplinary technological area laced with innumerable challenges in its realization as a practical system. The prime amongst them are infrared gas laser sources, such as carbon dioxide gas dynamic laser, hydrogen fluoride, deuterium fluoride laser, and chemical oxygen iodine laser. Each of these laser systems is associated with a unique as well as complex active medium environment involving intense interaction between lasing and pumping species under specific gas dynamic conditions. The parameters viz., specie concentration of the lasing, pumping mediums and other by-products, medium homogeneity, individual constituent gas flow rate, pressure and temperature at critical locations, and cavity Mach number are very crucial in determining the output of the gas laser system. It is essential to determine these parameters nonintrusively, with necessary precision so as to optimize these lasers especially in case of large-scale systems. Thus, the focus of this paper is to review and discuss the existing applicable optical detection methodologies ranging from the more established methods, such as optical absorption/emission spectroscopy, to very contemporary, such as Raman spectroscopy, cavity ring down spectroscopy, laser-induced fluorescence/planer laser-induced fluorescence, and so on, which are relevant for the diagnostic needs of gas lasers. [ABSTRACT FROM PUBLISHER]

This paper focuses on the implementation of various diagnostics for optimizing chemical oxygen iodine laser. This paper also dwells on the measurement methodologies and instrumentation employed in these diagnostic systems. The prime diagnostics are for the measurement of vital species in form of iodine, singlet oxygen, and chlorine. Iodine concentration measurement (absorption at \lambda = 499\ \nm), chlorine utilization (absorption at \lambda = 330\ \nm), and singlet oxygen yield (emission at \lambda = 1.27\ \mu\m) have been implemented based on optical absorption/emission principle. Furthermore, online Mach number determination, which is critical for supersonic gas flows, laser pulse detection (at \lambda = 1315\ \nm), and flow rate measurement and control over wide range, have been carried out. A dedicated diagnostics and data acquisition system (DDAS) customized for parameter monitoring have been developed. The developed DDAS also serves the purpose of precise operation sequencing and parameter control. It is a 168-channel personal-computer-based system with customized interface electronics employing Visual C++ programming language with user-friendly graphical user interfaces. A detailed uncertainty analysis of various critical parameters has been also presented. [ABSTRACT FROM AUTHOR]