Fiber optic probes are designed, developed and
fabricated in the laboratories for remote fluorescence
spectroscopic studies in various fields such as investigation of
tissues, environmental monitoring, and analysis of samples in
hostile environment. Optimized probe design is very much
important for efficient transport and collection of photons,
which ultimately helps in quantifying resultant emission and
understanding light-matter interaction. Instead of the
conventional ray optics, Monte Carlo technique has been used to
optimize the design of fiber optic probes, comprising only of
flat tipped fibers with and without focusing lenses, for remote
fluorescence measurement in three different types of target
media having different optical properties. Typical probe
geometry consists of one excitation fiber surrounded by a ring
of collection fibers. The effects of fiber parameters like fiber
diameter, numerical aperture, core-clad ratio, arrangement of
collection fibers around the excitation fiber and dead space
between them, and optical properties of the medium on the
performance of probes have been analysed and compared with the
results of previous observations, wherever the data are
available. The results show a significant difference between the
collected emission with and without consideration of dead space,
which plays a very significant role in probe design and is
dependent on the number of collection fibers in the geometry,
relative dimension of collection and excitation fibers and
separation between the two. Introduction of a convex lens in the
probe increases the amount of fluorescence signal for a given
probe arrangement.
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