Wide-Field Scanning Electron Microscopy

Stereo Scanning Electron Microscopy

Harvard’s Wide-Field Electron Optics Laboratory specializes in the development of new Scanning Electron Microscopy imaging techniques for the high-throughput structural and compositional analysis of hierarchically ordered biological materials and synthetic constructs. 

One major drawback to a greatly enhanced depth of field in traditional scanning electron microscopy is the perceived loss of the apparent three dimensionality of an object.  As a result, the images can often appear flat and critical topographical features can be obscured. Stereo scanning electron microscopy can help resolve these issues by revealing previously undetectable three dimensional architectural complexities. To create this effect, two SEM images are acquired from different tilt angles, and the images are digitally combined to create an incredibly realistic composite. SSEM.html
Wide Field Scanning Election Microscopy (WF-SEM) permits whole specimen imaging of objects measuring up to 10 cm across with almost a 0.5 m depth of field, revealing levels of detail never before possible using standard optical imaging techniques, and with greater surface detail than is achievable using tomography-based approaches.  Through manipulation of the incident beam geometry, we can achieve these capabilities with no image stacks or tiling, thus permitting the visualization of multiple levels of structural hierarchies simultaneously in a single image.WFSEM.html
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Polychromatic Scanning Electron Microscopy

The ability to simultaneously collect element-specific x-rays from multiple energy dispersive spectrometers has two main advantages.  First, it significantly reduces shadowing artifacts during elemental mapping of samples with complex surface topographies (left).  Secondly, it significantly reduces the time required for performing traditional elemental mapping, thus permitting high-throughput sample characterization. Using multiple high signal-to-noise silicon drift detectors, the acquisition time for large-area full-color elemental maps can be reduced from hours to minutes.MCEDS.html
Using a radial array of electron detectors, we can deconstruct and spatially resolve the entire electron scatter field emitted from the surface of a sample.  After color-coding the electron detection profiles from multiple angles, we can subsequently  recombine these signals for the generation of a polychromatic electron micrograph where variability in surface topography is revealed in a dazzling array of hues.  The high angular sensitivity of this technique permits the effective illustration of subtle differences in surface profile in structurally heterogenous materials.  PCSEM.html

Multi-Channel Energy Dispersive Spectroscopy