Fibre optics reflectance

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

Yao et al. [26] combined spectro-electrochemistry at grazing incidence angle with EQCM to study copper deposition from ammonial solutions. They also reported the use of a bifurcated fibre optic reflection spectro-electrochemical cell combined with an EQCM for the study of poly-naph-thylamine film growth on platinum from acetonitrile solutions. 

Measurement of surface scattering from opaque surfaces (44) has been made with a fibre-optic reflectance probe, for determination of demineralization of tooth enamel, milk-fat content and the whiteness of the eyeball. A reference fibre optic probe on a white BaS04 calibrated surface provides a differential measurement. 

Fibre optics reflectance spectroscopy (FORS) is a powerful and non-destructive method for the analysis of works of art [46]. 

Figure 5. Single-point IR sensor head layouts a transmission probe with fibre coupling b transflectance probe with variable pathlength and single fibre coupling c (diffuse) reflection probe with single illumination fibre and collection fibre bundle d two-reflection ATR probe with fibre-optic coupling e multi-reflection ATR probe (DiComp -type) f ATR fibre...

M. Blanco, J. Coello, H. Iturriaga, S. Maspoch, C. Pezuela and E. Russo, Control analysis of a pharmaceutical preparation by near-infrared reflectance spectroscopy a comparative study of a spinning module and fibre optic probe, Anal. Chim. Acta, 298, 183-191 (1994). 

Reeves, J.B. Ill and McCarty, G.W. (2001) Quantitative analysis of agricultural soils using near infrared reflectance spectroscopy and a fibre-optic probe. Journal of Near Infrared Spectroscopy 9, 25-34. 

Fibre optic-based flow-through optical biosensors The dramatic advances in fibre optic development in die last decade have promoted construction of sensors where radiation, whether emitted, transmitted or reflected, is conducted fi-om the sample to the detection system. The wide variety of available optical waveguide types (solid rods, hollow cylinders, micro-planar geometries) has been used with varying success in sensor development. 

Detergency is about the theory and practice of the removal of foreign material from solids by surface-active substances. This definition excludes pure mechanical cleaning. Also a pure chemical cleaning, e.g., by solvation of the foreign material, is not considered. In textiles oily substances usually attach to the fibres (animal fats, fatty acids, hydrocarbons, etc.). Also dust, soot, and other solid particles have to be removed in a washing process. In order to test the effectiveness of a surfactant, textiles are often polluted with standard dirt mixtures and cleaned with a standard washing procedure (launderometer). Often cleanliness is measured on the basis of optical reflectivity of white textiles. 

Gonzalez-Martin, I., Hemandez-Hierro, J. M., Vivar-Quintana, A., Revilla, I., and Gonzalez-Perez, C. (2009). The application of near infrared spectroscopy technology and a remote reflectance fibre-optic probe for the determination of peptides in cheeses (cow s, ewe s, and goa t s) with different ripening times. Food Chem. 114,1564—1569. 

Figure 3.31 Fibre-optic-coupled insertion transmittance and diffuse reflectance probes. (Courtesy of Axiom Analytical Inc., www.goaxiom.com)...

Figure 3.34 Internal reflection and acceptance angle in a fibre-optic cable.

The maximum input acceptance angle for a fibre-optic cable is determined by the critical angle for total internal reflection, which is given by Snell s law. 

Also, for parallel multichannel devices, the source image can be divided, and injected simultaneously into a number (for example up to eight) of output fibres. Alternatively for more demanding diffuse reflectance or diffuse transmission applications with much lower optical throughput the whole source image dimension can be used, but injected into micro- or macro-bundle fibre optics. 

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