The present invention relates to vibration-insensitive point-diffraction interferometry. For the purpose of obtaining high immunity to vibration, a single-mode optical fiber is used to generate the reference wave, by means of point diffraction, directly from the measurement wave reflected from test objects. The capability of vibration desensitization is further strengthened by adding a spatial phase-shift devise that enables to obtain four interferograms of different amounts of phase shift simultaneously with no time delay between interferograms. The present invention may be effectively used in the design of measuring systems for in-line applications where measurements need to be performed in the presence of significant level of vibration.