The field of the invention is that of methods for measuring the deformation of a reflective surface (10) of an object. The measurement device comprises a lighting pattern (21) comprising light points (22), a camera (30, 31) and an image-analysis device (40), the lighting pattern and the camera being arranged so that, in measurement position, the virtual or real image (23) of the lighting pattern is visible by the detector of the camera through the surface, said image representing the deformation of the lit area (11). The method according to the invention comprises the following steps: − Measuring a distance between the images of two light points; − Calculating the ratio between said measured distance and a reference distance; − Calculating, from said ratio, the enlargement in a predetermined direction; and − Calculating the deformation of the reflective surface in said predetermined direction.
