Phase Imaging of Human Cells Using Digital Holographic Microscopy

Digital holographic microscopy (DHM) is a 3D method for imaging cells without using labels. It gives detailed information about cell shape and behavior. This study has explored two applications of 3D phase imaging. Firstly, an image was made of an out-of-focus mono chromatically illuminated cheek cell with a conventional light field microscope. The resulting Fresnel diffraction pattern associated with the cell images has been numerically refocused at various positions. The images show details of the organelles. the changing shape of the cell nucleus and the chromosomes within it. Secondly, a simple in-line DHM system used phase imaging to analyze cancer cells. The system uses a 532nm laser, 10x and 40x microscope lenses, and a CCD camera to achieve clear phase images with 250nm resolution and 23. 63x magnification. The system was used to view both the growth of cancer cells (SMMC-7721) and in a subsequent test the ability of fluorouracil, an anti-cancer drug, to destroy them. The DHM data displayed cell changes over at 24-hour intervals over a 24-96-hours period. Holographic Amplitude images show the shape of the cell and its nucleus, while phase images gave 3D cell structural details.