Holographic Microscopy Techniques for Multifocus Phase Imaging of Living Cells - Biomedical Optical Phase Microscopy and Nanoscopy - page 92

CHAPTER 6
Holographic Microscopy Techniques
for Multifocus Phase Imaging of
Living Cells

Bj¨rn Kemper 1 , Patrik Langehanenberg 1 , Andreas Bauwens 2

1

Center for Biomedical Optics and Photonics, University of Muenster, Muenster, Germany
2

Institute of Hygiene, University of Muenster, Muenster, Germany

Editor: Natan T. Shaked

6.1 Introduction

In cancer research and in the investigations of infection and inflammation processes, the
analysis of dynamic processes such as temporal changes of the cell morphology and the
concentration of intracellular substances is of particular interest. Here, the imaging of living
single cells with light microscopy can give new insights into cell motility, biomechanical
properties on cellular or subcellular level, and the response of cells to drugs and toxins. On
a molecular level, live cell imaging aspects have been addressed widely by using a variety
of fluorescence microscopy techniques (see Refs. [1 3] and references therein). The
specificity of fluorescence signals is high due to a large number of available dyes, specific
autofluorescence mechanisms, fluorescence life-time imaging, and a wide experience with
the techniques. However, there still remain challenges in the application of these methods
for live cell imaging as fluorescence staining is often toxic, restricted to specific subcellular
structures, or limited to chemically fixated samples. Thus, in addition to research activities
on the improvement of labeling techniques, label-free methods for quantitative cell imaging
have been developed. To make use of the high accuracy of diffraction and interferometry-
based metrology, the activities of a growing number of research groups focus on techniques
for quantitative phase imaging. Quantitative phase imaging provides label-free data with
low demands on light exposure and high data acquisition rates. In deference to the
above-mentioned fluorescence techniques, such methods detect changes in the optical path
length (OPL) that are caused by the specimen under investigation.