Bright field, front light illumination

In bright field, front light illumination, light reflected by a flat surface is collected by the optics. This is the most common situation, in which non-flat features (e.g. defects, scratches etc.) can scatter light outside the maximum acceptance angle of the lens, showing dark characteristics on a bright background (the bright field - see pictures.

Bright field, front light can be produced by LED barlights or ringlights, depending on the system symmetry. In both cases LED light can be direct or diffused by a medium (sometimes the latter is to prefer to avoid uneven illumination on reflective surfaces).

Front bright field illumination scheme.
Front bright field illumination scheme.
Ringlight (a) and barlight (b) geometry.
Ringlight (a) and barlight (b) geometry.
Engraved sample with front bright field illumination
Image of engraved sample with front brigth field illumination (ringlight).
Metal coin with front bright field illumination (ringlight).
Image of a metal coin (featuring embossed parts) with front bright field illumination (ringlight).
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