Computer-image simulation

Computer image simulation may be achieved by several different techniques (12), but the most common method is the multislice calculation. In this method, input consists of a structural model, the projection direction through the structure, and parameters describing the electron microscope. Slight misorientations of the structure from the ideal projection direction may also be simulated. 

Drs. D. A. Jefferson and Jose Gonzalez-Calbet for helpful discussions, Drs. L. A. Bursill and A. Wilson for computer image simulation, and Drs. P. B. Weisz (Mobil), D. Stewart and M.Barlow (BP) for kindly providing us with samples of ZSM-5/ZSM-11. 

A special mention is in order of high-resolution electron microscopy (HREM), a variant that permits columns of atoms normal to the specimen surface to be imaged the resolution is better than an atomic diameter, but the nature of the image is not safely interpretable without the use of computer simulation of images to check whether the assumed interpretation matches what is actually seen. Solid-state chemists studying complex, non-stoichiometric oxides found this image simulation approach essential for their work. The technique has proved immensely powerful, especially with respect to the many types of defect that are found in microstructures. 

Figure 2.2 Crystallographic analogy of lens action. X-rays diffracted from the object are received and measured by a detector. The measurements are fed to a computer, which simulates the action of a lens to produce a graphics image of the object.

E. J. Kirkland, Advanced Computing in Electron Microscopy , Plenum Publishing, New York, 1998. An excellent how to do book for electron diffraction and image simulations using the multiple slice method. 

---