Optical phase measurements on biological cells

The mapping of morphological and physiological states of cellular and subce llular objects gains increasing importance in bioanalytics. Recent experime nts have shown that the distribution of the phase shift of a monochromatic optical wave experience passing through a cell is closely related to the mo rphology as well as to the current metabolic activity of the cell. Since me asurements of phase shift distributions can be performed without any cell d amage, as it usually happens due to staining and/or long-term preparation p rocesses, and have the potential of being carried out time-resolved, they m ay open a new window for the observation of dynamic intercellular metabolic processes. This article presents phase measurements on different cell type s using a laser phase microscope and correlates the results with the metabo lic state of the cells. Furthermore a new approach for phase measurements w ill be introduced. This approach is based on the tomographic reconstruction of the Wigner distribution function of the beam passing the cell and can b e realized by a very simple setup. Besides, it may allow time-resolved meas urements.