Three-dimensional Images of Biological Cells


Using a technique similar to that of medical tomography, it is now possible to obtain layered three-dimensional images of biological cells or even semiconductor devices.

The task of analyzing the internal structure of biological cells is a relatively complex affair. When using an electron microscope, the whole cells first have to be fixed, followed by the time-consuming task of preparing the individual slices. The surface of the slices can then be analyzed at high resolution, one slice at a time. The procedure is much less laborious when using an X-ray microscope.
Immediately after cryo-fixing of the whole cells, it is possible to obtain 3-dimensional images with a resolution of 20 nanometers (at current standards). The technique is rather similar to that of medical tomography (CAT scanning). X-ray microscopes can also be used in semiconductor electronics to examine current-carrying circuits at high resolution. This allows defects to be detected and visualized in working electronic devices.

To achieve the comparatively high resolution of 20 nanometers that distinguishes X-ray microscopy from basic light microscopy, a short- wavelength source in the soft X-ray range is required. Furthermore, the appropriate short exposure times call for the presence of a high photon flux. To date, the usual way of generating the necessary photon flow has involved the use of an electron storage ring. Such facilities are only available in a limited number of major research centers, and can only be used on-site, which makes it difficult for many users to take advantage of them.

The Fraunhofer Institute for Laser Technology has now developed a compact, integrated light source/collector lens system that enables powerful X-ray microscopes to be built on a laboratory scale. The volume of the resulting X-ray microscope does not exceed 2 cubic metres. This permits it to be installed wherever it is needed.

COMPAMED.de; Source: Fraunhofer Institute for Laser Technology