title: Multiwavelength phase unwrapping and aberration correction using depth filtered digital holography.
abstract: In this Letter, we present a new approach to processing data from a standard spectral domain optical coherence tomography (OCT) system using depth filtered digital holography (DFDH). Intensity-based OCT processing has an axial resolution of the order of a few micrometers. When the phase information is used to obtain optical path length differences, subwavelength accuracy can be achieved, but this limits the resolvable step heights to half of the wavelength of the system. Thus there is a metrology gap between phase- and intensity-based methods. Our concept addresses this metrology gap by combining DFHD with multiwavelength phase unwrapping. Additionally, the measurements are corrected for aberrations. Here, we present proof of concept measurements of a structured semiconductor sample.
authors.forename: Volker
authors.initials: V
authors.lastname: Jaedicke
authors.forename: Sebastian
authors.initials: S
authors.lastname: Goebel
authors.forename: Nektarios
authors.initials: N
authors.lastname: Koukourakis
authors.forename: Nils C
authors.initials: NC
authors.lastname: Gerhardt
authors.forename: Hubert
authors.initials: H
authors.lastname: Welp
authors.forename: Martin R
authors.initials: MR
authors.lastname: Hofmann