Reflected Darkfield Illumination Under the Microscope

Reflected Darkfield Illumination and Environmental Particles

Reflected darkfield illumination is necessary for the analysis of environmental particles because many of those particles are opaque. Their morphology, texture, and reflectivity in reflected light is critical to their identification and characterization. This must be used simultaneously with various forms of transmitted polarized light in order to full characterized the particles.

Reflectivity of Environmental Particles

The Three particles below were all photographed at the same time with the same exposure and illumination. The first particle is a magnetite sphere. The second particle is a fungal spore, Nigrospora. It has a reflectivty of less than 1% in the 1.515 refractive index mounting medium that all of these particles are in. The last particle is a magnetite sphere with large crystal domains that result in more scattered light. The pattern of the ring shows regions of light and dark as a result.