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DiATOME makes diamond knives for ultramicrotomy. The manufacturer's materials-oriented descriptions illustrate why knife geometry is part of an imaging measurement: a suitable edge must cut a thin section without introducing unacceptable distortion or damage. Its listed 35° and 45° knife families distinguish a knife wedge angle from such separate quantities as cutting feed and knife clearance angle.^[ref]

For an original ideal geometry, suppose two otherwise identical symmetric wedges have included angles 35° and 45°. At a fixed distance behind the tip, their widths are proportional to $\tan (\beta /2)$. The 35° wedge therefore has about 24% less width there than the 45° wedge. This is a geometric comparison, not a corresponding percentage prediction for force, wear or performance of an actual knife.

A second diagnostic concerns section compression. Suppose a marked polymer interval initially measures $10\mu \mathrm{m}$ in the cutting direction. If two stipulated preparations yield intervals of 8.5 and 9.5 micrometres, their shortening fractions are 15% and 5%, respectively. A lower shortening fraction supports better preservation of that interval under the stated test, but the data alone do not identify whether angle, edge condition or another preparation variable caused the difference.

A controlled materials comparison therefore records knife geometry, specimen, feed, orientation and the measured section dimensions. The manufacturer's product descriptions are primary evidence for the equipment's stated purpose and configurations; they are not independent measurements of the chosen examples above.