Heinz Horstmann

Heinz Horstmann is a researcher credited with the experimental development of serial block-face scanning electron microscopy. His 2004 paper with Winfried Denk describes repeatedly cutting a resin-embedded sample and imaging the newly exposed surface inside a scanning electron microscope. Its contribution statement credits both authors with performing experiments and supplying materials or analysis tools.^[ref]

The apparatus addresses a practical reconstruction problem. Collecting separate thin sections can introduce handling and alignment difficulties; imaging the remaining block face after each cut retains a more directly ordered sequence of surfaces. A moving knife and a controlled specimen advance turn sectioning and imaging into repeated steps within the instrument.^[ref]

The specimen advance used a lever to reduce the displacement of a motorized micrometer by a ratio of $0.11$. Applied to the quoted $50\mathrm{nm}$ actuator-position uncertainty, this gives $0.11\times 50=5.5\mathrm{nm}$ at the reduced-motion side. This is the scaled contribution of that actuator uncertainty, not a measurement of the total uncertainty in every removed section.^[ref]

A separate constructed sampling example highlights an interpretation limit. Two hundred nominal $50\mathrm{nm}$ layers cover $10\mu \mathrm{m}$ in depth. If the lateral pixels are $5\mathrm{nm}$ wide, depth sampling is ten times coarser. Interpolating the image stack onto smaller depth steps can make a display smoother but does not supply observations of the missing intermediate planes. Horstmann and Denk's work therefore connects instrument mechanics with the geometry and limits of a three-dimensional biological reconstruction.