Dual-wavelength off-axis digital holography using a single light-emitting diode

Area of Science:

• Optical Engineering
• Metrology
• Holography

Background:

• Low-coherence interferometry is crucial for precise surface profiling.
• Digital holography offers advanced 3D imaging capabilities.
• Off-axis configurations are often preferred for ease of reconstruction.

Purpose of the Study:

• To introduce a novel low-coherence interferometry system.
• To enable dual-wavelength off-axis digital holography.
• To enhance measurement accuracy and speed for surface profiling.

Main Methods:

• Utilizing diffraction gratings to filter two narrow bandwidth beams from a single LED.
• Employing dual-wavelengths for enhanced measurement capabilities.
• Analytical determination of system characteristics for extended coherence length and field-of-view.

Main Results:

• The proposed system successfully extends coherence length and field-of-view for off-axis configurations.
• Demonstrated fast and accurate measurement of surface profiles with micrometer step heights.
• Achieved reduced noise levels in surface profile measurements.

Conclusions:

• The new low-coherence interferometry system is effective for dual-wavelength off-axis digital holography.
• The system provides a significant advancement in precise surface metrology.
• Experimental validation confirms the system's performance on standard height samples.