An investigation of evanescent wave excitation of fluorescence using optical fibres
Potter, Colin E
(1990)
An investigation of evanescent wave excitation of fluorescence using optical fibres.
Master of Science thesis, Dublin City University.
A study of fluorescence excited by the evanescent
wave (E.W.) of guided radiation in an optical fibre is
reported. E.W. excitation of fluorescence is important
because of its application in novel optical sensors for
biomedical and chemical parameters.
An experimental system whose design is based on the
theory of evanescent wave (E.W.) excitation of
fluorescence is described. Several chemical immobilisation
techniques for the attaching of fluorescent dye molecules
onto the surface of an unclad optical fibre core were
investigated and were found to be unsatisfactory. These
techniques when examined using evanescent wave excitation
lacked consistency with regard to their optical emission
spectra, peak wavelength and intensity of fluorescence.
A novel technique to coat an unclad optical fibre
core surface with a porous glass coating (a Sol-gel)
which was doped with fluorescent dye was investigated and
found to have potential in the area of optical fibre
sensors. Fluorescent dyes such as fluorescein, fluorescein
isothyocyanate and rhodamine 6G were used as initial
dopants within the Sol-gel matrix. Using the technique of
evanescent wave excitation the fluorescent dyes were found
to exhibit emission spectra comparable to that of bulk
excitation.
A pH probe was constructed using a fluorescein-doped
Sol-gel coating around a short length (90mm) of unclad
optical fibre. It was found to have a pH sensitivity in
the range of pH2 to pH7 and a response time of
approximately 5s.
Metadata
Item Type:
Thesis (Master of Science)
Date of Award:
1990
Refereed:
No
Supervisor(s):
Ruddy, Vincent and MacCraith, Brian
Uncontrolled Keywords:
Fluorescence; Optical fibres; EW excitation; Optical sensors