Coherence effects in applications of frequency and time domain full field optical coherence tomography to optical metrology Academic Article uri icon

abstract

  • The interplay of spatial versus temporal coherence in the context of full field optical coherence tomography (OCT) for optical metrology applications is investigated both theoretically and experimentally using the Linnik and the Mirau interference microscopes. It is shown that multiple interference effects have a little influence on the thin film thickness measurement when the coherence length is much smaller than the layers thickness. When high numerical apertures used it is possible to rely on the longitudinal spatial coherence and work with narrow spectral band thus improving the measurement accuracy. This is particularly important as it avoids taking the dispersion relations into account. For frequency domain (FD) operation we have shown that using objectives with low numerical aperture (NA) up to 0.3 it is still possible to use FD-OCT with high accuracy. For large NA …

publication date

  • January 1, 2009