With today's current wave of quality consciousness, our quality control people tell us we MUST calibrate our instruments using standards that are traceable to the national laboratories (NIST - National Institute of Standards and Technology in the U.S.,. NPL - National Physical Laboratory in the UK, and others). But, is it really magnification that should be calibrated?

While recently walking around the exhibit floor at the Microscopy & Micrcanalysis ‘98 Conference, I noticed the large SEM image display screens that now present our highly magnified specimens. Almost all vividly show a micron (using SI units this should be a “micrometer”) marker as well as the magnification. No doubt the accuracy is within the ± 3% that is commonly quoted by the manufacturers.