Shape measurement of phase objects using fringe projection technique

Abstract

Due to the advancements in the field of optical metrology, it has found its applications in various areas such as biomedical, automotive, semiconductors, aerospace, etc. The popularity of optical techniques for metrology has increased by multiple folds owing to its non-invasive nature with ease of setup, fast data acquisition, and remote sensing ability. Optical techniques include hologram interferometry, speckle photography, speckle interferometry, moire interferometry, photoelasticity, fringe projection technique, etc. The holographic interferometry technique works by quantifying the optical phase of the object by measuring the change in the interference fringes due to the shape of an object. This technique has a large number of advantages, but a steep object leads to a large number of fringes in the field of view, which are not resolvable as they fail to satisfy the Nyquist criterion. In this work, the fringe projection technique, which is a noninterferometric, non-invasive technique for generating 3D surface information is employed to measure the shape of a phase object like a wedge. Fringe projection is presented as a robust and compact technique for shape measurement of phase objects as it utilizes lesser components and has less complexity compared to the holographic technique.