Optimising the image contrast of conventional and confocal optical microscopes imaging finite sized spherical gold scatterers

OPT COMMUN 155 (4-6): 335-341 OCT 15 1998 Torok P, Higdon PD, Juskaitis R, et al.

We examine the optimum conditions for conventional and confocal microscopes imaging finite sized spherical scatterers.We extend the Mie scattering theory to be applicable to a focused field illumination produced by high aperture lenses. Wefind that the relationship between the scattered intensity, illuminating wavelength and scatterer radius is more complicatedthan intuitively assumed. We present the numerical results for the practically available immunogold particle size range anddemonstrate the signal optimisation for commonly used illumination wavelengths. We also establish that the largestcommercially available immunogold particle, which is 100 nm in diameter, can legitimately be used to map the point spreadfunction of both conventional and confocal microscopes.

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