Simultaneous multidimensional deformation measurements using digital holographic moiré.

Area of Science:

• Optics and Photonics
• Experimental Mechanics
• Metrology

Background:

• Digital holographic interferometry (DHI) is a powerful technique for deformation analysis.
• Accurate measurement of both in-plane and out-of-plane displacements is crucial in many engineering applications.
• Existing DHI methods may face limitations in simultaneously capturing multi-directional displacement information.

Purpose of the Study:

• To develop and demonstrate a novel DHI technique for simultaneous measurement of in-plane and out-of-plane displacements.
• To enhance the capability of DHI for comprehensive deformation analysis of objects.
• To provide a robust method for extracting multi-phase information from interference patterns.

Main Methods:

• Simultaneous illumination of the object from multiple directions with a single reference beam.
• Numerical reconstruction of complex object wave-fields for pre- and post-deformation states.
• Generation of moiré interference fringe patterns from reconstructed complex amplitudes.
• Phase extraction using spatial carrier introduction and Fourier transform analysis.

Main Results:

• Successfully demonstrated simultaneous measurement of in-plane and out-of-plane displacements.
• Developed a method to extract multiple phase values from moiré fringes.
• Validated the accuracy of displacement measurement through sensitivity vector analysis.

Conclusions:

• The proposed DHI technique offers an elegant and effective solution for simultaneous displacement measurement.
• This method enhances the comprehensiveness of deformation analysis in optical metrology.
• The technique has potential applications in non-destructive testing and structural health monitoring.