Embedded Files
Example pages so far include:
our unknown-nanostructure explorer page,
our image-only focus & astigmatism challenge page,
our JS/HTML5-canvas strategy review page,
our first JS/FFT test page.
A program for doing detective work on HR-TEM images that were taken with real electrons should be available soon as well.
The strong (i.e. exponential) phase/amplitude-object (single-slice) algorithm [1-3], along with FFTs running in the Javascript/HTML5-canvas platform, allows one to propagate wavefields and to do spatial-frequency analysis through a browser in something close to real time. This platform also works on (sufficiently fast) mobile devices not capable of running Java or Flash.
Our electron detectives project is just beginning to experiment with JS/HTML5. If images on the webpages discussed below are blank at first ... hitting page-reload in FireFox (and/or going to another one of these pages and returning in Chrome) often helps. We've also seen them run I think in Opera, and at reduced speed in Safari on an iPad, in Dolphin on an Android phone, and in IE on some xBoxes. Reports on what works, and doesn't, in that context would be welcome as we try to grow our understanding of this platform.
The first page in the above list makes available a number of "unknown" three-dimensional nanostructure models for on-line characterization by a high resolution (electron phase contrast) transmission electron microscope (TEM) with strong-phase-object (single-scattering) optics. A wide range of physical and diffraction contrast mechanisms are thereby made available without the processing-time needed for multi-slice calculations. Moreover the photos that you take are pretty much guaranteed to be unique, since each reload randomizes orientations modifiable only in one-degree increments, precise enough to characterize structures but not to replicate images.
What kinds of empirical observation exercises might these pages, and pages like them, be able to offer to budding nano-detectives in your neck of the woods? Suggestions are more than welcome in that context. For example, another application of Fourier analysis involves construction of a real-time sheet-music device like this, albeit one which uses logarithmic complex-color to provide information on sound amplitude and Fourier phase.
Related references:
[1] John C. H. Spence (1988 2nd ed) Experimental high-resolution electron microscopy (Oxford U. Press, NY) ISBN 0195054059.
[2] Earl J. Kirkland (1998,2010) Advanced Computing in Electron Microscopy (Plenum Press, NY) preview.
[3] P. Fraundorf, Stephen Wedekind, Taylor Savage and David Osborn (2016) "Single-Slice Nanoworlds Online", Microscopy and Microanalysis 22:S3, 1442-1443 pdf hal-01362470
The last entry in the list above was simply a test page to see how 256x256 FFTs would work using this platform on a given device.
The second list entry makes available a number of 2D 3D projected potentials for analysis using a wider range of visualizations in logarithmic complex-color, including point-spread/contrast-transfer function images, and digital-darkfield phase-gradient (strain) visualizations that are also available for use on your data in a set of plugins for Wayne Rasband's ImageJ. Uses for these tools are outlined in slides here from a May 2014 talk in Seattle.
The third link in that list points to a 2D "focus & astigmatism challenge" given a TEM image but no live-image power-spectrum, an irreplaceable skill for folks using older microscopes. The projected-potential in this challenge contains both thin amorphous-material and perforation-edges that face in more than one direction, both of which can be quite useful. The perforation-edges may be used to directionally "even out" the edge Fresnel-fringe, which is dark/bright in over/under-focus conditions, while the amorphous material offers up "speckle contrast" that should appear isotropic (directionally unbiased), and in fact featureless near Gaussian focus, when astigmatism is eliminated.
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