We report our research on the development of optical fiber trace gas sensors for environmental applications. A novel optical fiber sensor for monitoring acetylene (C2H2) gases is described. Through studying the measure theory, we use the Beer-Lambert law to monitor the gas. And after analyzing the C2H2 spectrum, we select Distributed Feedback Laser Diode (DFB LD) as light source. Comparing many kinds’ sensor detection head, the gas absorbing cell with tail fiber can have good coupling with optical fiber and improve the coupling stability. In the data processing system, signals are distilled by lock-in amplifiers and then harmonic measure technology processes that distilled faint signals. After the all, the electronic signals are transmitted into computer to process, alarm and display. We design the instrument who can remote and on-line measuring acetylene. Through theory analysis and system experiment, the design of the system is practicable, and has a better precision and some apply foreground.
Fiber coherent bundles used in various instruments must provide for high quality image transfer. The primary defects, degrading the image quality, include the presence of broken fibers, which lead to troublesome dark dots in the view field, and so-called `grey' fibers (fibers have a partially reduced light transmission in the bundle). Both lead to a degradation of the local resolution capability of fiber-optic systems and to viewer discomfort who works with instruments in which these bundles are used. Such defects can be evaluated by the parameter-defect ratio, which is defined as amount ratio of defect fibers to total fibers. This paper describes a system designed for an objective and automatic evaluation of the defect ratio of fiber coherent bundles by a new method involving the image process.