holographic interferometry

Holography is a technique that records and reconstructs a three-dimensional image of an object without using a lens. It captures not only the intensity of light reflected from an object but also its phase, which is the alignment of light wave fronts. This is achieved by recording the interference pattern between the light diffracted by the object and a coherent reference beam. When this recording, called a hologram, is illuminated by a coherent light source like a laser, it reconstructs a three-dimensional image of the original object.12

Holographic interferometry is an application of holography used to detect minute changes in an object. It involves recording multiple holograms of an object at different times or under different conditions. When these holograms are reconstructed and superimposed, interference fringes appear, revealing distortions or deformations in the object. This technique is valuable for studying vibrations, elastic deformations, and other subtle changes in objects, often surpassing the capabilities of traditional interferometry.31