Double gate interferometer configuration for fringe projection profilometry with complex fringe patterns

OpenAlex · English

Abstract In this study, we present a double-Gate interferometer based on three beam splitters that generates, in a single exposure, a superimposed orthogonal fringe pattern formed by two orthogonal sinusoidal fringe families. By controlled rotation of the second and third beam splitters, the spatial carriers of the vertical and horizontal fringes can be tuned independently, allowing either complementary directional sampling or simultaneous use of two distinct carriers within the same frame. The superimposed components are separated and demodulated using a two-dimensional continuous wavelet transform (2D-CWT) with a reliability-guided selection strategy, followed by phase unwrapping and triangulation-based height recovery. Experiments on smooth and complex-shaped objects show that combining the two reconstructions improves robustness in regions where one fringe orientation becomes locally distorted or weakly modulated. In a dual-step demonstration, the high-frequency channel resolves the 1 mm step while the low-frequency channel preserves the 3 mm step, enabling both heights to be recovered from a single-shot image (1.017 mm and 3.06 mm). The proposed architecture provides an all-optical, mechanically stable route to flexible single-shot fringe projection profilometry without digital projection or multi-shot frequency switching.