Electron tomography produces high-resolution three-dimensional views of materials. This microscopy technique is poised to have a leading role in structural characterization and development efforts of next generation nano-scale samples of energy materials. The goal and product of electron tomography is to acquire images 2D projections) of the specimen at different angles and reconstruct them into a 3D representation of the sample. For a given processing algorithm, the ultimate quality and spatial resolution of the tomogram depends on the quality and spatial resolution of its parent tilt series, the set of acquired 2D raw images at different angles. With the advancement in the aberration corrected TEM high-resolution imaging at low acceleration voltage and direct electron detectors, the high-resolution imaging of nano-scale samples at atomic resolution can be routinely realized. Therefore, the current limitations in the way that tomograms are obtained to construct 3D maps, are found in the lack sample stability. This is due to how the sample is rotated in the TEM as images are acquired; using the built-in TEM stage which was never designed with the requirements in mind needed for these high- resolution 3D tomograms. As a result, the time it takes to acquire image data is very slow. For example, any image shift during rotation requires manual re-alignment of the location and focus of the sample this all cost time and can add up specifically when small angle steps are taken for highest quality reconstruction. This extra time also results in additional electron dose to the sample. These mechanical limitations hinder advances in the technique, limiting the quality and spatial resolution of tomograms as well as the velocity at which tomograms can be acquiredthis latter parameter is paramount for samples that need to be dose-limited during characterization. The main goal of this SBIR project is to build a continuous, ultra-stable, low-vibration, dedicated tomography imaging TEM sample holder and a continuous tomography in-situ biasing TEM sample holder with the purpose of collecting 360 degree tomograms in under 60 seconds. This holder will also specifically use the ability of current generation of high-frame rate TEM cameras to collect data as sufficiently high quality as the sample rotates. We will also develop support hardware to enable FIB sample preparation of samples with an exact concentric center. We will leverage the internal capabilities at Hummingbird Scientific to design, build and test electron microscopy and FIB sample holder systems to develop the hardware in proposed in this project. Materials research groups focused on studying the in-situ and ex-situ 3D structure of nano-scale materials would be the main customer of this product as this hardware can be used in any existing TEM with side-entry stage.
