Two-wavelength electronic speckle-pattern interferometry for the analysis of discontinuous deformation fields

Area of Science:

• Optics and Photonics
• Materials Science
• Metrology

Background:

• Electronic speckle-pattern interferometry (ESPI) is a powerful optical technique for non-contact deformation measurement.
• A key limitation of ESPI is the ambiguity in converting phase measurements to deformation values, restricting its practical use.
• This phase ambiguity arises from the inherent properties of interferometric measurements.

Purpose of the Study:

• To address the phase ambiguity issue in electronic speckle-pattern interferometry.
• To investigate the effectiveness of employing a two-wavelength approach to resolve ESPI phase ambiguity.
• To enhance the applicability of ESPI for accurate deformation analysis.

Main Methods:

• Implementation of a dual-wavelength system for ESPI measurements.
• Acquisition and processing of speckle interferograms at two distinct wavelengths.
• Analysis of phase data to determine deformation values, mitigating ambiguity.

Main Results:

• The two-wavelength method successfully resolved the phase ambiguity inherent in single-wavelength ESPI.
• Accurate conversion of phase measurements to deformation values was achieved over a larger range.
• The applicability of ESPI for deformation measurement was significantly expanded.

Conclusions:

• Employing two wavelengths is a highly effective strategy to overcome phase ambiguity in ESPI.
• This advancement broadens the scope of applications for ESPI in fields requiring precise deformation monitoring.
• The dual-wavelength technique offers a more robust and reliable approach to interferometric deformation analysis.