Bright Field, Dark Field, Lattice Imaging of a Polycrystal

Diffraction Spot Microscopy on Idealized Lattice.  Notice that when you select pairs of spots, that particular atom planes are visualized. Use the purple aperature to select a spot on the same ray (i.e., with the same plane normals), the modulation doubles. You are visualizing (abc)-planes in one case and (abc)/2 planes in the second case.  When two apperatures are used, you are using "lattice image"  or "structural image" mode.



Diffraction Spot Microscopy on Noisy Lattice.  Notice that when you select pairs of the brightest spots, you still get a fairly robust image of those planes, even though they are not perfectly alligned in the original image.  Most of the information is contained in the sharp peaks and those must represent perfect modulations at that point. The noise information is diffused over the entire Fourier spectrum.



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