This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.

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The point resolution, determined by C_s and the wavelength λ, is given by the Scherzer expression d₀ = 0.66 C_s^1/4 λ^3/4. That means the Scherzer resolution only depends on the electron wavelength and spherical aberration coefficient, and may be improved by reducing either.

For modern median voltage TEMs, the Scherzer point resolution is lower than the information limit, which is controlled by the temporal coherence of the electron source.

Based on C_s correction, extending Scherzer’s point resolution to information limit of the microscope can optimize the positive phase contrast from a weak-phase object. Assuming g_Sch = g_max and a defocus of Z_Sch = -8/(3λg²_max) , one can obtain, [1]

          ---------------------- [4261a]

The resulting contrast delocalization is given by,

          ---------------------- [4261b]

[1] Lentzen, M., Jahnen, B., Jia, C.L., Thust, A., Tillmann, K. & Urban, K. (2002). High-resolution imaging with an aberrationcorrected
transmission electron microscope. Ultramicroscopy 92, 233–242.