This apparatus aims to quantitatively measure mechanical deflection of simple structures (i.e. a metallic beam) using contactless optical holographic imaging instead of a standard mechanical strain gauge approach. The setup uses a fiber-coupled, single-frequency red helium-neon laser. As the light emerges from the fiber, it encounters a beamsplitter, with 90% being reflected (“object beam”) and the other 10% transmitted as the “reference beam.” The reflected object beam passes through an additional beamsplitter before bouncing off the object and reflecting toward the imager. Just before the digital camera imager, an additional beamsplitter recombines the reference beam and the object beam so that they interfere with each other, as in a Mach-Zehnder interferometer. The light then passes through a lens, forming an image of the object on the camera. Some digital filters are applied in a Matlab app, and the image is displayed with bright and dark fringes modulating across it. Counting fringes then allows one to determine the total deflection at any point along the metal beam.