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

Wednesday, 4 July 2018

Muscovite under polarization microscope

Muscovite has an anisotropic crystal structure, with two optical axis and a negative optical sign. The images and video taken with a polarization microscope with crossed polarizers and the Bertrand lens in place, are showing interference images (without lambda filter) in the plane perpendicular to the bisector between the two optical axes.To obtain these images, a thin slice of muscovite was split off from the crystal and taken for examination. Light entering this slice of crystal, produces the typical interference images for this type of crystal.

Click here for more information about Muscovite Mineral.

Monday, 2 July 2018

Basics of Light Microscopy: Incident Light Microscopy for opaque samples (I)

A closer look on Incident Light Microscopy reveals a new and noticeable fact. In a compound microscope for opaque samples, the objective plays two roles. First, like in a Transmitted light setup the objective is part of the imaging process. Quality and performance of the objective are essential elements to get reliable and “close-to-truth” results. 

Secondly, the objective additionally is part of the illumination system. Light from the lamp house passes the illumination axis and is deflected by a 45° orientated semi-transparent mirror. Sent through the objective, the light is reflected by the sample surface and brings back sample information to the eyepieces/camera. For a beginner it is difficult to accept that both illumination and imaging processes do not interfere visually.