Low-coherence interferometry and absolute distance measurement system are exploited for the high speed 3-D inspection of complex patterns on products of large area. In terms of low-coherence interferometry, emphasis is on configuring an optimum optical hardware design to deal with large complex patterns up to a few hundreds micrometers of height. For the absolute distance measurement, the optical frequency generator which emits single optical frequency with 10⁻¹² relative uncertainty referenced to the time/frequency standard is developed. The overall performance is demonstrated by measuring metal bumps fabricated on film-coated substrates and measuring an absolute distance of ~1 meter with 20 ㎚ uncertainty.
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