Virtual Imaging

One of the primary uses of 4D STEM diffraction is for virtual imaging, achieved by generating:

• Virtual selected area diffraction image: Sum the diffraction images from multiple selected real space probe positions (pixels) in the 4D data cube
• Virtual bright/dark field image: Apply certain math (e.g., sum, subtract) to the intensities of a subset of pixels in the diffraction domain and assign the resulting value to the corresponding pixels in the virtual image

In comparison to conventional STEM imaging, virtual imaging:

• Allows for design and application of a variety of geometry and combination of STEM detectors that would be otherwise impossible to manufacture and use in a real microscope physically
• Removes the limitation of having to use a certain number of and the relative angular range of STEM detectors that can be used simultaneously during an experiment
• Produces images with a higher signal-to-noise ratio and is not as much affected by specimen bending and dynamical scattering (Ultramicroscopy 155, 1–10, 2015)