Digital-holographic metrology enables quantitative phase contrast microscopy of
reflective and (partially) transparent samples. In this way, new application
fields are opened up for nondestructive investigations of technical samples as
well as for marker-free and time-resolved analysis of cell biological processes.
Studies on long-term biological processes require permanent focus position
readjustment to maintain an optimum image quality. Digital holographic
microscopy permits subsequent numerical focusing by variation of the propagation
distance. Here, the determination of the optimal propagation distance for a
sharply focused image is of particular importance. At the Laboratory of
Biophysics image definition quantification algorithms were adapted to the
requirements of digital holographic microscopy. In order to obtain robust and
reliable algorithms, the object-dependent optical absorption properties were
taken into consideration.
Automatic focus tracking is demonstrated on investigations with digital
holographic microscopy on both technical amplitude objects and cytological pure
© 2007 SPIE