Environmental Tapelift Sample
This is an image of particles collected outside a home using 3M Scotch Brand Magic tape. This home was near a wildfire. With reflected light the red fire retardant particles amid the natural minerals, tire wear, pollen, and charred wood can be easily identified.
Definition/Function:
Oblique illumination produces a shadow effect on the transparent particles which gives them greater contrast against the background. It results in higher resolution for features at right angles to the beam and slightly lower resolution for features oriented closer to the direction of the beam.
Off crossed circular polarized light makes the birefringent particles easy to detect without having to rotate the stage because with circular polarized light there are no extinction positions. moving one of the polarizers off by a few degrees results in a brighter background so that the outline of the particles is easier to see.
Reflected darkfield illumination is a form of illumination where the light impinges on the sample at an angle greater than that collected by the objective. The objective can only collect the reflected light that is scattered or that is reflected by an object or parts of the object that are not parallel to the plane of the stage.
