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| Reflected light – Darkfield (DF) |
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This method is ideal for the inspection of surfaces.
The light coming from the reflected-light illuminator is directed downwards towards the objective (4) via a mirror step assembly (2) and a mirror with an oval hole (3). Having passed the outer sleeve of the objective, it hits a ring-shaped concave mirror which directs the light rays for grazing incidence on the sample surface (5). If the object were a perfect mirror, no light would be reflected into the objective and the image would remain dark. Existing structures, however, direct light towards the objective and become brightly visible against a dark background.
Important: open the luminous-field and aperture diaphragms so that the light beam will illuminate the mirror assembly (2)!
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| In reflected-light brightfield, the fine structures in the iron casting are difficult to see. | Only in reflected-light darkfield they are clearly visible in the surface. |
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