A geometrical analysis is presented for the aspect ratio determination
of a spheroidal particle by stereo observation. Orthogonal projection
s of particle shape are obtained from images in electron micrographs.
The aspect ratio of the spheroidal particle is expressed as a function
of the changes in the shape and direction of the projected images cau
sed by tilting. Although two different values of the aspect ratio are
generally obtained from a pair of stereo micrographs, the ambiguity ca
n be avoided if the particle is observed from three different directio
ns. As an example, the results obtained are applied to the analysis fo
r the shape change of liquid B2O3 particles induced by plastic deforma
tion of a Cu matrix.