Wednesday, 18 July 2018

Surface structures easily revealed

As it is known, revealing the surface structure of minerals and fossils can be done by making an ultra-thin section or an acetate peel. An ultra-thin section is a thin slice of a mineral or fossil mounted on a glass slide and viewed under a microscope. Preparing thin sections produces excellently detailed images, but the techniques are relatively difficult and can require expensive equipment. Making acetate peels is much easier and much cheaper.

Acetate peels are made by polishing a surface, etching it with acid to give it some relief, and then chemically melting a piece of acetate film onto that surface with the aid of acetone. The acetate film is then pulled off the surface and is examined under a microscope. In essence, the acetate film preserves a fingerprint of the structure of the surface to be studied. Other surfaces can also be examined, such as metals, botanical objects, archaeological items etc., whereby polishing and etching is not always desirable. 

On the the images shown in this article, a negative imprint of a small section of the surface of a fingertip is displayed in bright- and in darkfield. The presentation of the surface details on these microscopic images can be enhanced by the application of video, based on 3D models made by photo stacking.

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