Deformation measuring method for esp. loading frame of test machine

The method involves using a laser light source (8), a measuring place (4), and a reference place (5) on a frame member (1) of a frame (1-3). The laser source is fitted at the reference place. The main measuring beam (8) of the laser is directed to the measuring place. The relative shift (xB) between the main beam and the measuring place under the frame deformation, is then determined in at least one cross direction. An inclination measuring beam (9) is split off from the main measuring beam in the at least one cross direction. This split beams inclination displacement (zA) under the frame deformation is then determined. The lateral displacement (x) of the measuring place (4) is computed from the measured relative shift and the measured inclination displacement.