Three-dimensional displacement measurement for diffuse object using phase-shifting digital holography with...

Area of Science:

• Optics and Photonics
• Metrology
• Image Processing

Background:

• Accurate measurement of object displacement is crucial in various scientific and industrial fields.
• Traditional methods may lack the sensitivity or resolution required for micro-displacements.
• Digital holography offers a promising non-contact approach for displacement measurement.

Purpose of the Study:

• To develop and validate a novel method for measuring the displacement of diffused objects.
• To achieve high sensitivity and accuracy in quantifying both lateral and longitudinal movements.
• To utilize phase-shifting digital holography with a polarization imaging camera for enhanced displacement analysis.

Main Methods:

• Acquisition of four digital holograms in quadrature using a polarization imaging camera.
• Calculation of a phase hologram from the quadrature holograms.
• Application of Fourier transforms to phase holograms before and after object displacement.
• Determination of phase slope and intercept for lateral and longitudinal displacement calculation.

Main Results:

• A phase slope proportional to the lateral displacement was obtained.
• Sensitivity achieved was less than one pixel size in the lateral direction.
• Longitudinal displacement was measured separately from the phase axis intercept.
• The method demonstrated precise quantification of diffused object movement.

Conclusions:

• Phase-shifting digital holography with a polarization imaging camera is an effective technique for measuring diffused object displacement.
• The method provides high sensitivity for lateral displacement and allows for separate measurement of longitudinal displacement.
• This approach offers a valuable tool for precise metrology applications involving micro-displacements.