Tilt-less 3-D electron imaging and reconstruction of complex curvilinear structures

Abstract

The ability to obtain three-dimensional (3-D) information about morphologies of nanostructures elucidates many interesting properties of materials in both physical and biological sciences. Here we demonstrate a novel method in scanning transmission electron microscopy (STEM) that gives a fast and reliable assessment of the 3-D configuration of curvilinear nanostructures, all without needing to tilt the sample through an arc. Using one-dimensional crystalline defects known as dislocations as a prototypical example of a complex curvilinear object, we demonstrate their 3-D reconstruction two orders of magnitude faster than by standard tilt-arc TEM tomographic techniques, from data recorded by selecting different ray paths of the convergent STEM probe. Due to its speed and immunity to problems associated with a tilt arc, the tilt-less 3-D imaging offers important advantages for investigations of radiation-sensitive, polycrystalline, or magnetic materials. Further, by using a segmented detector, the total electron dose is reduced to a single STEM raster scan acquisition; our tilt-less approach will therefore open new avenues for real-time 3-D electron imaging of dynamic processes.

Three-Dimensional Reconstruction of Planar Deformation Features from Single Electron Micrographs

“…[3] for the slopes of the 2D projections of the intersections between the sample surface and both twin boundaries and (ix) a relation of the ratio between the projection widths of both twin boundaries w 2 =w 3 from Eq. [9]. A solution with c s >0 is chosen to ensure that the reconstructed geometry corresponds to the setup adopted in Figure 1.…”

“…If the orientations of the crystal and the sample are known, Eq. [9] can also be used to determine the thickness of the sample.…”

“…However, a newly developed tilt-less tomography technique drastically reduced the required microscopy time by effectively rotating the electron beam within STEM instead of the sample, followed by a dedicated reconstruction algorithm. [9] Dislocation reconstruction from stereo pairs of electron micrographs avoids some of the aforementioned complexities by imitating the way in which animals perceive depth. [10] Two views of the same region at different orientations result in a depth-dependent displacement of the features, also known as parallax, from which a three-dimensional perspective can be formed.…”

Multibeam Electron Diffraction

“…Perhaps surprisingly, even these small angular ranges can provide useful information in TEM experiments. One example was shown by Oveisi et al (2017), who performed 3D reconstructions of dislocations using only two beams, separated by 1.56°. This experiment demonstrated that with sufficiently strong prior assumptions (in their case, assuming a 1D curvilinear object), useful 3D information can be obtained from small angular ranges.…”

3D Reconstruction of Curvilinear Structures with Stereo Matching DeepConvolutional Neural Networks

“…It only requires a few images. Unfortunately, state-of-the-art methods [8,9,10,11] still involve substantial manual intervention for line detection and matching.…”