Modified five-step phase-shift algorithm for 3D profile measurement

A modified phase measurement profilometry based on five-step phase-shift algorithm, is proposed in this paper to achieve 3D profile measurement, which can not only accelerate the measurement speed, but also extend the measurement range in the same quantized level. A stair phase, used as codeword, is embedded into sinusoidal fringes, in which the sinusoidal component is used to guarantee the precision of the phase while the stair phase coding component is designed to identify the fringe orders. Fringe orders and wrapped phase distribution are calculated simultaneously, and thus absolute phase can be obtained without phase unwrapping processing, therefore, it has the potential merit of increasing the measurement speed. Moreover, this method can encode more fringe orders than composited two-frequency methods for the unwrapping processing of measurement phases map. Experiments demonstrate that this technique is robust and suitable for measuring complex objects or separated objects.