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Optical microscopy


Optical microscopy is an essential component of scientific investigation methods. It provides basic information about the spatial structure of solids. Microscopic examination serves to describe the properties and states of materials qualitatively and quantitatively by determining the proportions and local distribution of the individual phases in order to clarify the relationships between physical properties and chemical composition.


In principle, any material can be examined by light microscopy. For the optical characterization of metal, ceramics, slag, rock or organic materials, suitable preparations such as ground sections, thin sections or thin sections must be prepared. Translucent materials can be examined in transmitted light, opaque and reflective materials in incident light. As the shape, colour and reflectivity of the individual structural constituents are structure-dependent, it is relatively easy to differentiate between individual phases by changing the illumination arrangement (bright field, dark field, polarised light, etc.) and to identify them. With the help of digital image processing, quantitative microstructural analyses can be carried out (e.g. size, volume fractions).

Fig. 1: Transmitted light microscope image of a copper slag under polarised conditions (crossed polarisers).
Fig. 2: Microstructure of a recrystallised tin bronze developed with Klemm III colour etching under bright field conditions (incident light).


Interaction of electromagnetic waves (light) with a solid.

Fig. 3: Optical microscope Axioskop 40 A Pol , as it is used at the CEZA for microscopic examinatio (Photo: CEZA).


The resolving power is determined by the wavelength of the light. It is not possible to determine the chemical composition with a light microscope.

Sample properties

Solids, undisturbed solid sample of at least 1 mm3 to cm3 (depending on material and problem).