Mathematical Model of a Laser-Induced Fluorescence Fiber-Optic Sensor Head for Trace Detection of Pollutants in Soil

The efficiency evaluation and optimization of various geometric and material aspects for a fiber-optic sensor head (optrode) are described. For the efficiency evaluation, a mathematical model has been developed and implemented as a computer program. The model allows the variation of several parameters such as diameter and numerical aperture of the optical fibers, their position and orientation in space, and the optical characteristics, as well as the orientation and size of other optical elements used. Peculiarities in manufacture such as oblique polishing of fibers are also taken into consideration. The model was used for the development of a UV laser fluorometer for trace detection of aromatic pollutants in soil. With the other parameters kept constant, the influence of two parameters at a time was calculated and is visualized in a contour plot. A series of such plots is presented, showing how crucial it is to carefully choose the material and geometric properties of an optrode.

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