Digital holography enables a multifocus quantitative phase microscopy for the investigation of reflective surfaces and for marker-free live cell imaging. For digital holographic long-term investigations of living cells an automated (subsequent) robust and reliable numerical focus adjustment is of particular importance. Four numerical methods for the determination of the optimal focus position in the numerical reconstruction and propagation of the complex object waves of pure phase objects are characterized, compared, and adapted to the requirements of digital holographic microscopy. Results from investigations of an engineered surface and human pancreas tumor cells demonstrate the applicability of Fourier-weighting- and gradient-operator-based methods for robust and reliable automated subsequent numerical digital holographic focusing.
© 2008 Optical Society of America
Original Manuscript: November 2, 2007
Revised Manuscript: February 29, 2008
Manuscript Accepted: March 13, 2008
Published: April 22, 2008
Vol. 3, Iss. 8 Virtual Journal for Biomedical Optics
Patrik Langehanenberg, Björn Kemper, Dieter Dirksen, and Gert von Bally, "Autofocusing in digital holographic phase contrast microscopy on pure phase objects for live cell imaging," Appl. Opt. 47, D176-D182 (2008)