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Measurement of refractive index of single microparticles

Gregor Knoener·Simon Parkin·Timo A. Nieminen·Norman R. Heckenberg·Halina Rubinsztein-Dunlop
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Abstract

The refractive index of single microparticles is derived from precise measurement and rigorous modeling of the stiffness of a laser trap. We demonstrate the method for particles of four different materials with diameters from 1.6 to 5.2 microns and achieve an accuracy of better than 1%. The method greatly contributes as a new characterization technique because it works best under conditions (small particle size, polydispersion) where other methods, such as absorption spectroscopy, start to fail. Particles need not be transferred to a particular fluid, which prevents particle degradation or alteration common in index matching techniques. Our results also show that advanced modeling of laser traps accurately reproduces experimental reality.

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Gregor Knoener, Simon Parkin, Timo A. Nieminen, Norman R. Heckenberg, Halina Rubinsztein-Dunlop. 2006-10-12. Measurement of refractive index of single microparticles. https://doi.org/10.1103/physrevlett.97.157402

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