Digital Holography and Grating Interferometry: A complementary Approach

摘要

In this work we propose to extend the Grating Interferometry scheme by Digital Holography. The main advantages of this complementary approach are that no imaging lens is needed and that the reconstruction is not limited to the image plane as it is using a lens. Additionally, this technique provides sensitivity to both directions, normal and parallel to the surface under test. Because the grating is directly integrated into the surface, this allows measuring the displacement of that surface under long term conditions within the magnitude of the used wavelength. Good qualitative results are obtained using a single illumination direction. Quantitative results are obtained using multiple illumination directions and the in-plane sensitivity of the presented technique is shown to be equivalent to that of the Grating Interferometry.