Aberrationless phase difference amplification in holographic interferometry.

Two improved techniques of aberrationless phase difference amplification are presented. Both make use of double-exposure holographic interferometry. In contrast to the ordinary technique, not only the state of the tested object is changed between exposures but also the direction of the hologram fringes. This approach allows one to separate desired higher diffraction orders of the double-exposed hologram, to eliminate setup aberrations, and, consequently, to achieve an amplification of the phase difference given by the tested object alone.