Phase contrast studies of biological specimens with the x-ray microscope at BESSY (invited)

Abstract

The transmission x-ray microscope at the BESSY storage ring is being used for investigations in the fields of biology, biophysics, medicine, colloid chemistry, and soil sciences. The system has been instrumented for phase contrast studies with the possibility of quick change between imaging in amplitude and phase contrast mode. Phase contrast has the advantage of considerable higher image contrast and reduced radiation dosage compared to amplitude contrast. A cryogenic object chamber has been implemented on the x-ray microscope. First experiments have shown that at cryogenic temperatures the structural stability of biological specimens is increased by three orders of magnitude in comparison with unfixed wet specimens at room temperature.

Broader view on extreme ultraviolet masks: adding complementary imaging modes to the SHARP microscope

“…We recognize that this technique has the potential to enhance the contrast of phase defects and phase features on EUV masks in a similar way, thus improving the sensitivity of actinic mask imaging or inspection tools. 9 Zernike phase contrast microscopy in the soft x-ray spectral range using a zoneplate lens and phase ring has been demonstrated by Schmahl et al 10 With well-collimated illumination, the required phase shift of the undiffracted light can be achieved within the zoneplate pupil, sparing the need for an additional phase-shifting element, and simplifying the design and alignment. 11 Figures 4(a) and 4(b) show cartoons of a standard, off-axis zoneplate and an off-axis zoneplate for Zernike phase contrast, in comparison.…”

Resonant soft x-ray techniques to resolve nanoscale magnetism

“…Full field imaging microscopes require a condenser optic to illuminate the sample, followed by a high resolution zone plate to project an image onto a 2-dimensional detector [117,118]. Coarse resolution zone plate lenses are often used as the condenser, although focusing mirror condensers may also serve this purpose.…”

X-ray Phase Imaging and Tomography Using a Fresnel Zone Plate and a Transmission Grating

“…In the early 1990s, several imaging techniques measuring the phase shift of x-rays were proposed; this so-called x-ray phase imaging has attracted considerable attention owing to its sensitivity to light elements three orders of magnitude higher than that of absorption contrast imaging (see, for example, [1,2]). Zernike phase-contrast microscopy [3] has been applied for hard x-rays [4][5][6], but it is not quantitative for a strong phase object. Various x-ray phase imaging microscopy methods have also been proposed [7][8][9][10][11][12][13][14], but they require specially designed x-ray optics and/or a wave field that is almost perfectly coherent on their objective lenses.…”