912J High Tilt Tomography Holder for URP pole pieces

Applications

Tomography is becoming an increasingly more important technique in the visualisation of small three-dimensional structures. Electron tomography is a useful technique that can be used to obtain three-dimensional (3D) reconstructions of electron transparent objects. A series of tilted images is taken in the TEM and these two-dimensional (2D) images are then back projected to generate a three dimensional reconstruction. There are many software packages available to do this. Depending on the maximum tilt range available in the microscope configuration a certain wedge of data may not be sampled. (see Figure 1). This effect may be reduced by acquiring another series of images with the
specimen rotated by 90º to the first series.

Tomograms contain an enormous amount of information and are essentially a three-dimensional map of the structure being studied. Many biological and materials science questions can be answered by electron tomography. Specific structures may be located by the use of high density labelling.

Holder Features

The model 912 high tilt tomography holder is designed to overcome the dimensional limitations of narrow gap polepieces by achieving the high tilt angles needed for tomography applications. The holder reduces the size of the missing wedge in the acquired data set. Special grids or cut down standard grids, 1.6mm disk specimens or FIB tips are bonded to removable specimen tips. These tips are also used to store and protect the delicate specimens. A storage box is provided taking up to 10 specimens. Each tip is quickly and easily inserted into the holder using a pair of forceps. The tip has a flat machined on it, which orients the tip rotationally within the holder. Each tip is then simply pressed back to an end stop, which accurately sets its longitudinal position.

Z height adjustment is incorporated into the holder to allow precise lens settings to be used and optimal goniometer alignment thus optimising the imaging conditions.

Accessories

A disk cutting accessory 601.03331 is available for the Gatan model 601 Tuned Piezo Cutting Tool for the preparation of materials science specimens.

Fig 1. Principle of tomography