Imaging cells and sub-cellular structures with ultrahigh resolution full-field X-ray microscopy

X-ray phase contrast tomography from whole organ down to single cells

“…3 For hard x-rays, coherent scanning diffraction microscopy also yields the complex valued object transmission function which contains absorption and phase information. 4,5 For intermediate and scalable resolution and field of view, propagation based phase contrast as described in ?, [6][7][8] offers great potential.…”

3d virtual histology of neuronal tissue by propagation-based x-ray phase-contrast tomography

“…In the case of a paraxial wave, the wave vector component along the optical axis is much larger compared to the perpendicular parts (k 2 ⊥ k 2 ). Therefore, the phase factor of the free-space propagator can be approximated via a first order Taylor expansion 26) Inserting this into the expression for the propagated wave field (1.20) yields 27) with the Fresnel diffraction operator…”

“…As the phase shift is not directly measurable, it has to be converted to object specific modulations in the intensity images. For this purpose various methods exist as, e.g., zone-plate microscopes with Zernike phase contrast [26,151,159], Talbot interferometry [111,134,152,188], edge illumination [64,116] or speckle-based imaging [13,113,199], which are all full-field imaging techniques. In contrast to scanning techniques like ptychography [36,72,189] acquisition time is significantly reduced which is an important factor in tomographic imaging, requiring several projection images of the sample from different angles, especially with regard to the stability of degrading biological specimens.…”

Cone-beam x-ray phase-contrast tomography for the observation of single cells in whole organs

“…Each method has its advantages and drawbacks and can be applied depending on the length scales and applications [99,193]. For example, if Zernike phase-contrast in zone-plate based microscopes is utilized, a resolution down to some ten nanometers has been achieved in 2D [99], which however can not be achieved on specimen exceeding a thickness of about 300 micron [34]. Grating based phase-contrast imaging offers a very high sensitivity [193] and is compatible with low-brilliance laboratory sources [138], but the best resolution achieved so far is in the range of some micrometers [139], limited to the quality of the necessary gratings.…”

“…There are several ways of implementing x-ray phase-contrast, like Zernike phase-Introduction contrast in zone-plate microscopy [34,156], grating interferometry [39,111,138], scanning diffraction microscopy [41,167] and phase contrast based on coherent free-space propagation behind the sample [37,125,185]. Each method has its advantages and drawbacks and can be applied depending on the length scales and applications [99,193].…”