Focus & astigmatism test canvas

By P. Fraundorf, Department of Physics & Astronomy, University of Missouri - St. Louis

This page is intended to demonstrate the feasibility of using JavaScript and the HTML5 canvas element for computationally intensive real-time 256×256 strong-phase-object electron-phase-contrast image simulations. If the images are blank at first, hitting page reload may help. The simulation is for a 300 keV TEM with point-resolution just under 2 Å. The direct-space image field-width is about 112.9 Å, while the Nyquist spatial-frequency cutoff in the power spectra is about 128/112.9 ≈ 1.13 cycles/Å.

- - - - ⇑ projected potential ⇑ - - - - - - - - - - - - ⇑ diffraction pattern ⇑ - - - -
- - - - ⇓ simulated image ⇓ - - - - - - - - - - - - ⇓ image power spectrum ⇓ - - - -
deFocus=±[Å] at angle=[deg]
To test your skill at optimizing focus, check out our electron phase-contrast challenge here.
Thanks to the author of the javascript FFT routines we are using to do the calculations. This page is hosted by the University of Missouri Saint Louis Department of Physics and Astronomy. The person responsible for errors is P. Fraundorf, whose mobile-friendly electron detectives construction is here and whose most ancient webpage on electron phase-contrast focus optimization may be found on the web here.