Imaging the Pore Structure of Geomaterials

TLDR

Laser scanning confocal microscopy can image the pore structure of geologic materials in three dimensions at a 200‑nanometer resolution. The technique fills voids with fluorochrome‑doped epoxy, slices sub‑micron optical sections from polished samples, stacks them into 3‑D reconstructions, and is also applicable to other brittle solids such as ceramics. Applying the technique to rocks with 1–20 % porosity reveals the geometric complexity of their pore space.

Abstract

Laser scanning confocal microscopy can be used to image the pore structure of geologic materials in three dimensions at a resolution of 200 nanometers. The technique involves impregnation of the void space with an epoxy doped with a fluorochrome whose fluorescent wavelength matches the excitation wavelength. Optical sections with a thickness of less than 1 micrometer can be sliced from thick polished sections and combined to produce three-dimensional reconstructions. Application of the technique to rocks with porosities from 1 to 20 percent reveals the geometric complexity of the pore space. The technique can also be applied to other brittle solids such as ceramics.