@conference {scholz1996, title = {In-situ determination of cell concentration in bioreactors with a new depth-from-focus technique}, booktitle = {Proc.\ Optical 3-D Measurement Techniques IV, Zurich, Sept. 29 - Oct. 2, 1997}, year = {1996}, pages = {392--399}, author = {Thomas Scholz and Bernd J{\"a}hne and H. Suhr and G. Wehnert and P. Geissler and K. Schneider} } @conference {geissler1995b, title = {Depth-from-Focus Verfahren zur absoluten Gr{\"o}{\ss}en- und Konzentrationsbestimmung kleiner Teilchen}, booktitle = {Bildverarbeitung{\textquoteright}95 - Forschen, Entwickeln, Anwenden}, year = {1995}, pages = {365--380}, publisher = {Technische Akademie Esslingen}, organization = {Technische Akademie Esslingen}, doi = {10.5281/zenodo.14710}, author = {Peter Gei{\ss}ler and Thomas Scholz and Bernd J{\"a}hne and Schmidt, C. and H. Suhr and G. Wehnert}, editor = {Ahlers, R. -J.} } @conference {scholz1995a, title = {In situ determination of cell concentration in bioreactors with a new depth from focus technique}, booktitle = {Computer Analysis of Images and Patterns}, volume = {970}, year = {1995}, pages = {392--399}, publisher = {Springer}, organization = {Springer}, abstract = {A new depth-from-focus technique is introduced that requires only a single image to determine the distance of simple shaped objects from the focal plane. The technique has been applied to evaluate the concentration of cells in a bioreactor during a fermentation process. Since the low-intensity fluorescent light gathered by a light-amplifying camera results in images of low signal-to-noise ratio, an adaptive smoothing filter is used. A sharpness criterion derived from bandpass decomposition of the image in a Laplacian pyramid is used to define a virtual measuring volume. In this volume, process parameters such as cell concentration, cell size and intensity of cell fluorescence are evaluated. The technique is also suitable for other types of simple objects.}, doi = {10.1007/3-540-60268-2_321}, author = {Thomas Scholz and Bernd J{\"a}hne and H. Suhr and G. Wehnert and P. Geissler and K. Schneider} } @article {suhr1995a, title = {In-situ microscopy for on-line characterization of cell-populations in bioreactors, including concentration measurements by depth from focus}, journal = {Biotechnology and Bioengineering}, volume = {47}, year = {1995}, pages = {106--116}, abstract = {A new technique is presented which allows the use of a front-end sensor head for in situ and on-line characterization of cell concentration and cell size during fermentation. An epifluorescence microscope is mounted in a port of a bioreactor viewing directly into the agitated broth. Still images from cells are generated using pulsed illumination. They are directly visualized on a monitor and used for automatic image analysis. The cell concentration and morphological information are determined by counting and evaluating the cell images with respect to their depth from focus characteristic. An in situ microscope was successfully tested during yeast fermentations and yielded results which correlated well with results from a hemocytometer.}, doi = {10.1002/bit.260470113}, author = {H. Suhr and G. Wehnert and K. Schneider and C. Bittner and Thomas Scholz and Peter Gei{\ss}ler and Bernd J{\"a}hne and T. Scheper} } @conference {scholz1994, title = {A new depth from focus technique for in situ determination of cell concentration in bioreactors}, booktitle = {Proc. 16. DAGM-Symposium Mustererkennung}, year = {1994}, pages = {145--150}, doi = {10.5281/zenodo.14888}, author = {Thomas Scholz and Bernd J{\"a}hne and H. Suhr and G. Wehnert and Peter Gei{\ss}ler and K. Schneider} }