Some defects only generate dark field
optical information, while others only
produce bright field effects. To
complicate life, many defects exhibit both
bright field and dark field effects.
Therefore, to reliably detect and classify
the range of defects, present in most high
quality unit operations, the inspection
system must capture all the defect bright
field and dark field optical information |
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Dark Field Optics are Critical!
In general, for high value-added
operations, the importance of dark field increases as rejectable
defect size
decreases (tighter quality standards).
Both bright field and dark field
capabilities are normally required. An
example of a scratch is shown below:
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Micro-Scratches on Display Film
dark field
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Repeating Roll Mark on Coated Film
dark field
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Scratches in Display Film
dark field
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Coating Wave
dark field
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