(a)
(b)
(c)
Fig. 10.2 Envelope functions observed in electron microscopy. a Weak (1), moderate (2), strong
(3) and critical (4) envelope functions. (4) Imposes a strong limit on resolution typical for a sample
preparation by negative staining. Strong envelope function (3) is a combination of four applied
moderate envelope functions (2). b Digital Quantum Efficiency of electron detectors may be
considered as envelope functions. c Resulting envelope function is at best a product of all the
applied envelope functions. It results in a lower signal transfer that is important to consider at the
experimental design stage
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M. Kudryashev