REPRODUCIBILITY AND ACCURACY OF SPATIAL MEASUREMENTS FROM DIGITALLY CAPTURED IMAGES IN THE ENVIRONMENTAL SCANNING ELECTRON-MICROSCOPE

Accurate spatial measurements in a scanning electron microscope (SEM) require calibration of the magnification as a function of working dist ance and microscope operating conditions. This work presents the resul ts of the calibration of an environmental SEM for the accurate spatial measurement of dimensions and areas in experiments, both for the meas urement of strain in steel specimens under applied loads and the measu rement of dimensional changes in timber with changes in relative humid ity.