Accuracy of measurements in stereoscopic observations by using transmission electron microscope

To evaluate the accuracy of measurements using stereoscopic observation employing a transmission electron microscope (TEM), the thickness (∼0.6 μm) of platelet-type α-Fe₂O₃ particles was investigated by stereoscopic observation using TEMs and imaging plates. The accuracy of these measurements was evaluated by comparing t_s with t_g, where t_s and t_g were the thicknesses determined by stereoscopic observation and geometric calculation taking the particle's shape into account, respectively. The standard deviation of the difference between t_s and t_g decreases with increased tilt angle up to 20°. The minimum standard deviation of the difference was evaluated to be 4.8% at a tilt angle of 20°. From the present study, it was found that a particle's shape, such as thickness on a sub-micrometer scale, can be evaluated by stereoscopic observation using a TEM set at the highest accuracy at a tilt angle of about 20°.