The short wavelength of X-rays enables microscopy with high resolutions (~30 nm) exactly between optical microscopy (> 200 nm) and scanning electron microscopy (~1-2 nm). Modern X-ray microscopes achieve spatial resolutions of less than 10 nm, theoretically limited only by the objective optics. The high penetration depth of X-rays compared to electrons also makes studies of thick (10 µm) aqueous samples possible, making this technique an ideal tool for the study of cells and organic tissue.
Together with the Max-Born-Institute, the Berlin Laboratory for Innovative X-ray Technologies (BLiX) is operating a prototype full-field water window laboratory X-ray microscope based on a plasma source induced by a high-power laser.
The BLiX X-ray microscope is operated with a highly brilliant laser plasma source at an emission wavelength of 2.48 nm in the spectral range of the water window. The high natural absorption contrast between carbon and oxygen in this spectral range allows the study of the internal structure of biological samples in their natural aqueous environment. The penetration depth of the radiation is up to 10 micrometers in water at this wavelength. The sample is exposed with a multilayer condensing mirror. By using zone plates as imaging optics, a spatial resolution of a few 10 nm can be achieved in this spectral range. The microscopy chamber integrated in the demonstrator allows high-resolution tomography on snap-frozen samples. The application area of the laboratory X-ray microscope is biomedical research.
With the laboratory X-ray microscope, fundamental developments of the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy have been transferred to the application laboratory BLiX.
The following publications are suitable to get an overview: