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An ultramicrotome is a precision cutting instrument for producing very thin sections or successively exposing new specimen faces for electron microscopy. Ultramicrotomy combines a controlled specimen feed with a cutting stroke across a sharp diamond knife or suitable glass knife. A polymer block is one example of a specimen for materials work. JEOL describes preset feeds of tens of nanometres and notes that actual section thickness can differ from the setting.^[ref]

The mechanism must distinguish the feed direction, which sets the intended removed thickness, from the much longer cutting stroke across the block. Section collection supports transmission electron microscopy; an in-chamber version supports serial block-face scanning electron microscopy by imaging the remaining surface.

For an original cutting-budget example, suppose a polymer block is advanced by $60\mathrm{nm}$ per cut. After 250 uniform cuts the nominal removed thickness isIf one entire section is lost during collection, its neighbors' centers are $120\mathrm{nm}$ apart rather than $60\mathrm{nm}$, assuming all feeds were correct. The total removed thickness remains $15.0\mu \mathrm{m}$; the lost section leaves an observation gap. Recording only the number of surviving images would conceal that gap.

A physical check compares the intended feed with an independent thickness or accumulated-depth measurement, while recording specimen and knife conditions. A fine actuator increment alone does not establish the actual section thickness. Compression, uneven cutting and missing sections affect the geometry subsequently assigned to an image stack.

Ultramicrotomy prepares extremely thin physical sections by advancing a specimen block through a controlled increment and cutting across it with an ultramicrotome. A diamond knife or suitable glass knife removes the section; collected sections can then be examined by transmission electron microscopy. The instrument's feed setting and the geometry of the recovered section are related quantities, but they need not be equal. JEOL explicitly notes dependence on specimen material and temperature.^[ref]

For a materials example, consider a polymer block containing an initially $20.0\mu \mathrm{m}$-long marked interval parallel to the cutting direction. Suppose the recovered section measures $17.0\mu \mathrm{m}$ along that interval, with unchanged transverse width. Its section compression is $1-17/20=15\%$. Under an explicitly ideal volume-conserving model, a nominal $60\mathrm{nm}$ layer would then have recovered thicknessThe altered area and thickness give the same model volume: $0.85\cdot 70.6\simeq 60$. This is an original diagnostic calculation, not a universal correction rule. Material loss, transverse strain or nonuniform deformation would invalidate the model.

A motivating preparation check therefore compares dimensions of recognizable material features before cutting and in the recovered section, while recording cutting direction and specimen conditions. An independent thickness measurement tests whether the feed is a good depth calibration. Image registration can align section images but cannot generally reverse unknown physical deformation. For serial-section electron microscopy, preserve section order and gaps in the image stack as well as the chosen image stack axis calibration.

Yanhui Zhang supplied the transmission electron microscopy image reproduced in Nickel based superalloy: dislocation structure by H. K. D. H. Bhadeshia. It shows paired dislocation loops in a nickel-based superalloy after creep testing. The source credits the image explicitly; this establishes the contribution without inferring an unrelated same-name biography.^[ref]

A researcher who coauthored liquid-phase production of graphene from graphite. Suitable solvents stabilize separated sheets, helping balance the energetic cost of exfoliation. The study checked the sheets with Raman spectroscopy, transmission electron microscopy and electron diffraction, and demonstrated conducting films and composites. It addressed the manufacturing problem of obtaining useful quantities while preserving the material's structure.^[ref]

A crystallographic direction shared by a set of planes. Aligning a transmission electron microscopy beam along a suitable zone axis can excite multiple useful lattice reflections.