Sandwich hologram interferometry. 4: Holographic studies of two milling machines

The deformation of two milling machines was studied using real time holography, double exposure holography, and sandwich holography. The about 2-m high machines had a weight of about 2 tons each, and the experiments were made directly on the floor of ordinary machine laboratories using continuous lasers. The machines were deformed by static forces of the same magnitude and direction as ordinary cutting forces. The main advantages of sandwich holography were that it made possible detection of the signs of displacement, measurement of small deformations without influence of large rigid body motions, measurement of larger displacements than possible with ordinary holography, and study of local deformations of details down to fractions of a fringe. Some vibration measurements were also made using the conventional time average method.