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Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator
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    Noise significantly challenges two-frequency phase-shifting for 3D shape measurement. This study introduces a method using geometric constraints to reduce noise impact, enhancing 3D measurement accuracy without needing more patterns.

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    Area of Science:

    • Optics and Photonics
    • Metrology
    • Computer Vision

    Background:

    • Two-frequency (or two-wavelength) phase-shifting algorithms are susceptible to noise, limiting their use in absolute 3D shape measurement.
    • Higher-frequency phase-shifting algorithms are often preferred in noisy environments, but may require more data acquisition.
    • Digital fringe projection systems are widely used for 3D reconstruction.

    Purpose of the Study:

    • To develop a noise-robust method for absolute 3D shape measurement using digital fringe projection.
    • To enhance the performance of two-frequency phase-shifting algorithms by mitigating noise sensitivity.
    • To enable the use of temporal phase unwrapping with multiple equivalent phase maps.

    Main Methods:

    • Proposing a novel method that leverages geometric constraints inherent to digital fringe projection systems.
    • Utilizing multiple periods of an equivalent phase map for temporal phase unwrapping.
    • Implementing and experimentally validating the proposed noise reduction technique.

    Main Results:

    • Successfully demonstrated substantial reduction in noise impact on 3D shape measurement.
    • Achieved enhanced performance of the two-frequency phase-shifting algorithm in the presence of noise.
    • Verified that the improved performance was obtained without an increase in the number of projected patterns.

    Conclusions:

    • The proposed method effectively reduces noise sensitivity in two-frequency phase-shifting algorithms for 3D shape measurement.
    • Geometric constraints in digital fringe projection systems can be exploited for robust temporal phase unwrapping.
    • This approach offers a practical solution for accurate 3D measurements in noisy conditions without compromising data acquisition efficiency.