Localized Rotation for 3D Visual Reconstruction
Fundamental to the task of generating three-dimensional information from a sample in an electron microscope is the ability to view the sample from a variety of different angles. Previously, the inability to generate local rotations at suitable scales has required any rotational actuator to be accompanied by translational actuators that move the area of interest to the estimated rotation axis. Due to factors such as calibration, drift, and backlash, the system does not perform a true eucentric rotation and additional steps must be taken for data acquisition.To avoid these problems, a dual-chirality nanobelt can be used to generate localized rotations, thus simplifying the requirements of the sample stage. The use of localized goniometers allows for a simpler sampling paradigm, an increased specimen rotation range, and reduces the requirements for the automated translation stage and the data acquisition.
The figure on the left shows an experiment where an individual pollen grain is attached to a helical nanobelt and rotated. The sample motion is locally generated by a helical nanobelt. By extending the nanobelt, a rotation is induced at the point where coiling direction changes. This mechanism is a highly efficient solid-state motion converter, and is able to generate localized rotations without the use of bulky and high-precision motion stages. Using techniques such as structure-from-motion, the motion can be tracked and three-dimensional data can be gathered from the sample as shown below.
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