nm, by using the hard X-ray scanning microscope at PETRA III. The ALS is also home to the world's first soft x-ray microscope designed for biological and biomedical research. This new instrument, XM-2 was designed and built by scientists from the National Center for X-ray Tomography. XM-2 is capable of producing 3-dimensional tomograms of cells. Liquid-metal-anode X-ray source Extremely high-intensity sources of 9.25 keV X-rays (gallium K-alpha line) for X-ray phase-contrast microscopy, from a focal spot about 10 um x 10 um, may be obtained with an X-ray source which uses a liquid metal galinstan anode. This was demonstrated in 2003. The metal flows from a nozzle downward at a high speed and the high intensity electron source is focused upon it. The rapid flow of metal carries current, but the physical flow prevents a great deal of anode heating (due to forced-convective heat removal), and the high boiling point of galinstan inhibits vaporization of the anode. The technique has been used to image mouse brain in three dimensions at a voxel size of about one cubic micrometer. Detection devices Scanning transmission Sources of soft X-rays suitable for microscopy, such as synchrotron radiation sources, have fairly low brightness of the required wavelengths, so an alternative method of image formation is scanning transmission soft X-ray microscopy. Here the X-rays are focused to a point, and the sample is mechanically scanned through the produced focal spot. At each point the transmitted X-rays are recorded using a detector such as a proportional counter or an avalanche photodiode. This type of scanning transmission X-ray microscope (STXM) was first developed by researchers at Stony Brook University and was employed at the National Synchrotron Light Source at Brookhaven National Laboratory. Resolution The resolution of X-ray microscopy lies between that of the optical microscope and the electron microscope. It has an advantage over conventional electron microscopy is that it can view biological samples in their natural state. Electron microscopy is widely used to obtain images with nanometer to sub-Angstrom level resolution but the relatively thick living cell cannot be observed as the sample has to be chemically fixed, dehydrated, embedded in resin, then sliced ultra thin. However, it should be mentioned that cryo-electron microscopy allows the observation of biological specimens in their hydrated natural state, albeit embedded in water ice. Until now, resolutions of 30 nanometer are possible using the Fresnel zone plate lens which forms the