Thesis (M.Sc.) - Cairo University - National Institute of Laser Enhanced Sciences - Department of Laser Sciences and Interactions

An experimental study of some selected fluorescent dyes has been carried out for the development of fluorescence based fiber optic temperature sensor. Fluorescent dyes like: Fluorescein (F) and two of its derivatives [allyl Fluorescein (DA-F) and diallyl Fluorescein (DA-F)] are solidified in glycidyl methacrylate (GMA) polymer matrix. These two Fluorescein derivatives were investigated in order to study the influence of substituted groups on Fluorescein dye sensitivity for temperature changes. The concentration of the dyes in the used polymer is 5x10⁻³ M. The dye-polymer discs have been investigated separately before being integrated in a fiber optic system in order to determine their sensitivities in the temperature ranges from 10K to 300K and from 297K to 370K. The dye-polymer disc is excited by Argon-ion laser (488 nm, 50 mW) and the fluorescence intensity is measured using lock-in technique. Below room temperature (F) dye in (GMA) polymer shows very weak sensitivity towards temperature changes in the range from 10K up to 297K. The fitting curve therefore gave a polynomial equation of second degree with R2 value of 0.6758. For (AF) dye in (GMA) polymer its fluorescence exhibits temperature tendency for decreasing slightly while the dye is warmed up from 40K to 245K. The calibration curve fits a linear equation with an R² value of 0.9795. Also, the (DA-F) dye in (GMA) shows good sensitivity in the range from 49K to 300K. Its calibration curve fits with an exponential equation with R² value of 0.9385

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