The Diamond Manchester Imaging Branchline (I13-2)

The Diamond Manchester Imaging Branchline performs real space imaging and tomography in the 8-30keV energy range. Absorption contrast and in-line phase contrast imaging are both available.

Imaging can be conducted with both pink and monochromatic light. Pink light includes all available wavelengths and is incredibly bright; flux at I13 is over a million times higher than that of a laboratory X-ray source or 'X-ray tube'. Monochromatic light represents a single wavelength which may be chosen according the sample.

The high flux of a synchrotron enables images of high signal:noise to be recorded very quickly. Rapid dynamic processes can therefore be studied. Examples at I13 include electrochemical deposition (for understanding battery failure), bubble dynamics in molten metals (for understanding how metals solidify and therefore fail) and the dynamics of the closed cochlea (the part of the ear that converts sound waves to electrical signals).

The partially coherent radiation at the Imaging branch enables contrast enhancement at the edges of structures. This 'in-line phase contrast imaging' is particularly useful for biomedical applications in which absorption contrast between structures is weak. Phase contrast imaging can be utilised with both pink and monochromatic light, although the effect is particularly pronounced with the latter.

The energy of the monochromatic beam can be tuned easily and accurately. This makes it possible to distinguish chemical elements by recording data above and below their absorption edges ('absorption edge tomography' and 'X-ray absorption near edge spectroscopy' or XANES tomography).

The Diamond Manchester Imaging Branchline operates in two imaging modes:

• Micro-imaging - samples of 0.1-10 mm thickness are imaged with spatial resolutions which can extend a little beyond a micron.
• Nano-imaging - samples of 10-50µm thickness are imaged with resolutions up to 50nm.

At the Diamond Manchester Imaging Branchline, X-rays are converted to visible light by a scintillator; the visible light is then magnified and collected by a detector. In nano-imaging, an X-ray microscope is used to increase magnification further.

A condenser lens known as a Fresnel zone plate focuses the incoming light onto the sample. The light is then collected by a second zone plate (the objective lens) and a magnified image of the sample is projected onto the scintillator. If required, phase contrast imaging can be performed with a Zernike phase plate.

The Diamond Manchester Imaging Branchline is funded via a collaboration between Diamond Light Source and The University of Manchester.