In this Letter, a novel concept based on superresolution technique that enables the measurement of high gradient and deep topography objects using digital holographic (DH) microscopy is introduced. The major problem of DH systems is limited NA that prohibits the metrological characterization of object features of high frequencies. The proposed technique has the ability to extend spatial frequency spectrum of the measured topography by applying multidirectional plane wave illumination, which is experimentally realized with a grating. The technique recovers sample topography from the set of object waves with different object spectra that are converted into a set of topographies by using an algorithm which takes into account refraction. Application of this novel approach is experimentally validated by characterization of high gradient topography objects with maximum angle of tangent 65°.
© 2013 Optical Society of America
Original Manuscript: February 20, 2013
Revised Manuscript: April 29, 2013
Manuscript Accepted: May 2, 2013
Published: May 23, 2013
Vol. 8, Iss. 7 Virtual Journal for Biomedical Optics
Kamil Liżewski, Tomasz Kozacki, and Julianna Kostencka, "Digital holographic microscope for measurement of high gradient deep topography object based on superresolution concept," Opt. Lett. 38, 1878-1880 (2013)