MicroscopyInnovations 2018 Microscopy Today Innovation Awards

T e editors of Microscopy Today congratulate the winners of the ninth Microscopy Today Innovation Award competition. T e ten innovations described below advance microscopy in several areas: light microscopy, electron microscopy, and X-ray microscopy. T ese innovations will make microscopy and microanalysis more powerful, more productive, and easier to accomplish.

Single-Shot Three-Dimensional Electron Imaging École Polytechnique Fédérale de Lausanne, Switzerland Developers: Emad Oveisi and Cecile Hebert

T is new method for 3D imaging in the TEM promises to be more effi cient in both acquisition time and electron dose compared to conventional TEM tomography techniques. T e method is an integrated approach to stereo imaging in the scanning TEM (STEM) using segmented detectors

and algorithmic feature reconstruction. By considering the solid cone of incident electrons that forms the STEM probe as consisting of parallel rays of diff erent illumination angles, opposing sets of these convergent rays are selected within the direct beam of the diff raction pattern to image the sample stereographically. Both rays are recorded simultaneously using a new segmented STEM detector.

Compared to other 3D imaging methodologies, this simultaneous imaging technique has the advantages of faster acquisition speed and limited electron beam exposure for studying beam-sensitive materials. In addition, it eases the 3D imaging of crystalline defects under well-defi ned diff raction contrast conditions. In fact, for a crystal orientation where a systematic row of refl ections is excited, choice of opposing incidence angles perpendicular to the direction of the diff racted beams corresponds to the same excitation condition. By selecting the intensities of two counterparts on opposing sides of the (000) direct beam disc for image formation, a pair of stereo images may be recorded with exactly the same deviation from the Bragg diff raction condition—an important criterion for imaging a 3D network of crystal dislocations. T e reconstruction of the 3D morphology takes place via a proprietary image-processing algorithm. T e algorithm uses the prior knowledge of line-shaped objects to bypass the missing wedge limitation of conventional tilt-series


tomography, yielding reliable 3D reconstructions even with the limited stereographic tilt angle governed by the conver- gence angle of the electron probe. Since the specimen remains un-tilted, this method is eff ectively “tilt-less.” T e effi ciency of data acquisition and reconstruction is increased by two orders of magnitude compared to standard TEM tomography techniques. By exploiting ongoing instrumental developments in both hardware (new segmented and pixelated detectors, in situ holders, and cryo-STEM), soſt ware (faster acquisition), and image processing, this methodology has the potential to transform certain research areas, perhaps making possible real-time 3D imaging of in situ dynamics.

High Numerical Aperture, High Effi ciency X-ray Lenses

Deutsches Elekronen-Synchrotron (DESY), Germany

Developers: Saša Bajt, Andrzej Andrejczuk, Sabrina Bolmer, Henry Chapman, Andrew Morgan, and Mauro Prasciolu

The penetrating nature of hard X-rays, photons with wavelengths below 0.1 nm, make them attractive for imaging of objects such as biological cells at resolutions beyond that of visible light and without the

need for sectioning or thinning the sample as is the case for transmission electron microscopy. This property of hard X-rays also makes them difficult to focus. Soft X-rays, with wavelengths longer than 0.1 nm, can be focused with thin diffractive Fresnel zone plates (similar to a circular transmission grating), but high aspect ratio diffracting structures are required to focus hard X-rays. This was achieved by forming these structures layer by layer using magnetron sputtering. The lens is sliced from the multilayer structure in a direction perpendicular to the layers to produce what is known as a multilayer Laue lens (MLL). Several improve- ments were made to the fabrication process to achieve high efficiency and to extend the numerical aperture (NA) beyond what was previously possible. By scanning a small focused spot of hard X-rays, imaging at spatial resolutions below 10 nm is possible with diffraction efficiencies exceeding 80%. Two MLLs with slightly different focal lengths are used to produce a focused spot, similar to two cylindrical lenses. The lenses are typically 10–100 µm tall (aperture size), 100 µm wide and several µm thick (optical depth) with focal lengths of 1–10 mm. They are fabricated from many tens of thousands of layers. Sharp interfaces between layers

doi: 10.1017/S1551929518000822 • 2018 September

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