Binary fringe pattern in infrared phase measuring deflectometry

Infrared phase measuring deflectometry (IR PMD) is a superior PMD technique, which builds the direct relationship between phase and depth to directly calculate 3D shape of the non-continuous specular object from the phase data, instead of integrating the local slope data. IR PMD has been extensively studied because of its advantages of non-contact operation, high-precision measurement, and reducing influence of ambient light. However, there are certain requirements for the depth of field (DOF) in IR PMD system because many specular surfaces have large depth range. To tackle this issue, this paper proposes a novel method based on defocusing binary fringes. This method combines binary fringe defocusing technique and IR PMD technique. This paper discusses the measurement principle and binary defocusing technique, and conducts simulated and practical experiments. The experimental results validate the effectiveness and accuracy of the proposed method.