Fibre optics aluminium

Ahmad M., Narayanaswamy R., Fibre Optic Reflectance Sensor for the Determination of Aluminium (III) in Aqueous Environment, Anal. Chim. Acta 1994 291 255-260. 

Charge recombination luminescence was measured in a set-up described in detail elsewhere (75). Stoichiometric mixtures of DGEBF and DDM in aluminium pans were taken to the cure tenq)erature at 15 G/min and cured isothermally under nitrogen in a chamber covered by a quartz window. The sanq>le was intermittently irradiated with a Kulzer Duralex UV-3(X) fibre optic wand for 60 s. After each irradiation the shutter of the photomultiplier was opened with a delay of 5 s, and the initial intensity of emitted light, 7o, was recorded. 

Figure 4. Experimental set-up for in vitro and in vivo measurements of the collimated light transmittance and the reflectance spectra 1 - optical fibre 2 — aluminium jacket 3 — neutral filters 4 -tissue sample 5 - immersion solution 6 — 0.5 mm pinhole 7 — cuvette.

Consequently, mirror optics are more common, in particular in the mid-IR. The mirrors used are usually aluminium- or gold-coated flat or curved substrates. While near-IR mirrors are usually protected by thin SiO-layers, in the mid-IR unprotected mirrors have to be used. Disadvantages of mirror optics are the elevated space consumption and the higher prices in comparison to refractive optics, especially comparing non-standard mirrors against non-standard lens. In total, mirror optics are so preferable to fibres and refractive optics, at least in the mid-IR, that in some technical applications they are used to replace waveguides to transport IR radiation between source, sensor head and spectrometer. 

In this configuration, both ends of the fibres were coupled to a LASER source the 178 optical fibres were gathered into a metallic coupling element of 2.7 mm. Furthermore, aluminium foil was applied at the back of the diffuser in order to improve the radiation emission. 

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