Purchase of a Laser Ablation tool for Specimen Preparation

Background information on Project

The vision is firstly, to develop correlative tomography to radically increase the nature and level of information (morphological, structural and chemical) that can be obtained for a 3D volume of interest (VoI) deep within a material or component by coupling non-destructive (3D+time) X-ray tomography with destructive (3D) electron tomography and, secondly to exploit this new approach to shed light on damage accumulation processes arising under demanding conditions. Successful completion of this project will provide new 3D & 4D insights across many areas & yielding key experimental data for multiscale models.

There has been an emphasis on bringing together 2D imaging techniques on the same surface, or near surface, region of interest. Coined correlative microscopy this approach is now routinely being applied in the life sciences, primarily to bring together light and electron microscopy.

Today there are many methods capable of providing 3D information, either non-destructively or destructively. Non-destructive methods tend to rely on penetrating beams such as X-rays, whereas destructive methods involve progressive material removal and can range from large scale mechanical serial sectioning down to the removal of atoms atom by atom, as in atom probe microscopy. Conventionally, information has been brought together from different samples at different scales statistically to build up a multi-scale picture (e.g. hierarchical pore structures).

Recently the proposer has linked together X-ray and election microscopies to obtain a multidimensional and multi-faceted 3D picture of a selected volume of interest. Calling this approach correlative tomography it promises to radically increase the level of information one can obtain about features of interest.

Precision milling by focused ion beam (FIB) milling has made it possible to excise a region tens of microns in size, identified by X-ray tomography, say for subsequent higher resolution imaging or tomography within the scanning electron microscope, or from serial section SEM tomography for higher resolution electron or atom probe tomography. However, FIB milling is limited to regions tens of microns in dimensions and tens of microns below the surface limiting both the volume that can be examined by electron optical methods and the depth from which it can be excavated. In this respect laser and plasma beam milling offer significant advantages in terms of milling rates and accessible depths and volumes of interest. The proposer's recent experiments suggest that new plasma beam-SEM instruments appear to be a particularly promising prospect opening up volumes of interest hundreds of microns in size for serial sectioning recovered from significant depths.

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