= Theodore D. Doiron
{c}
= Ted Doiron
{c}
{synonym}
\b[Ted Doiron], identified as \b[Theodore D. Doiron] in NIST's official publication record, is a <dimensional metrology> researcher and coauthor with <John S. Beers> of <The Gauge Block Handbook by Ted Doiron and John S. Beers>. The preface uses Ted Doiron and attributes substantial changes to the handbook's measurement-assurance program to the author abbreviated TD.<The Gauge Block Handbook by Ted Doiron and John S. Beers>[Preface, printed p. iii; official NIST publication record, Theodore D. Doiron and John S. Beers, published June 1, 1995]{ref}
The scientific challenge is to obtain a reproducible <length> from a material artifact under changing environmental and measurement conditions. <Thermal expansion> is a particularly clear example. For a small temperature change,
$$
L(T)\simeq L(T_0)[1+\alpha(T-T_0)],
$$
where $\alpha$ is the linear expansion coefficient. An original example with $L(T_0)=100\,\mathrm{mm}$, stipulated $\alpha=11.5\times10^{-6}\,\mathrm{K^{-1}}$ and $T-T_0=0.1\,\mathrm K$ gives a length increase $0.115\,\mathrm{\mu m}$. A small temperature difference can therefore matter when comparing precision <gauge blocks>.
Even a shared temperature does not cancel every thermal effect. For two equal nominal lengths with different expansion coefficients, the first-order differential change is
$$
\Delta L_{\rm differential}\simeq L(\alpha_1-\alpha_2)\Delta T.
$$
Using $L=100\,\mathrm{mm}$, coefficient difference $1\times10^{-6}\,\mathrm{K^{-1}}$ and common offset $0.2\,\mathrm K$ gives $20\,\mathrm{nm}$. This <gauge-block thermal mismatch> survives a simple subtraction even though both blocks have reached the same temperature. A temperature difference between the blocks introduces another contribution.
The handbook treats temperature corrections and their control alongside comparison procedures and measurement assurance.<The Gauge Block Handbook by Ted Doiron and John S. Beers>[Chapter 4; Section 5.4.3.1, temperature effects and equation 5.8; Section 5.4.3.2, control of temperature effects]{ref} A useful experiment compares the corrected result over controlled environmental changes and checks an independent <measurement standard>, rather than equating a stable display with an accurate physical length. The examples above are illustrative calculations, not an attributed material dataset or a claim about current NIST instrument performance.
Back to article page
