High-precision three-dimensional shape reconstruction via digital refocusing in multi-wavelength digital holography

Area of Science:

• Optical Metrology
• 3D Imaging
• Holography

Background:

• Depth-of-field constraints limit 3D shape reconstruction and metrology accuracy.
• Existing focus-detection methods struggle with high axial accuracy for out-of-focus 3D objects.
• Extended-focus imaging (EFI) offers potential for improved measurement range and precision.

Purpose of the Study:

• To present a holographic imaging solution for accurate 3D object measurement over a large depth range.
• To overcome limitations of classical depth-of-field constraints in 3D metrology.
• To enhance axial accuracy in profiling 3D objects using extended-focus imaging.

Main Methods:

• Incorporation of digital refocusing with multiwavelength interferometry.
• Development of a holographic imaging system for extended-focus imaging.
• Validation through digital simulations and refocusing experiments.

Main Results:

• The proposed EFI technique demonstrates accuracy and repeatability.
• Digital simulations and experiments confirm the method's effectiveness.
• High-precision 3D measurements of objects exceeding the classical depth of field were achieved.

Conclusions:

• The holographic EFI technique accurately measures 3D objects over extended depth ranges.
• This method overcomes significant depth-of-field limitations in 3D metrology.
• The approach enables high-precision 3D shape reconstruction for challenging objects.