High-dynamic-range areal profilometry using an imaging, dispersion-encoded low-coherence interferometer

Area of Science:

• Metrology
• Optical Engineering
• Surface Science

Background:

• Accurate surface characterization is crucial in various scientific and industrial fields.
• Existing profilometry techniques often face limitations in axial resolution or require mechanical scanning.

Purpose of the Study:

• To design and characterize a new areal surface profilometry approach.
• To achieve sub-nanometer axial resolution for surface profiling.
• To enable non-contact, high-resolution surface measurements.

Main Methods:

• Development of a low-coherence interferometer enhanced with a dispersive element.
• Utilizing an imaging spectrometer to detect optical path differences.
• Employing equalization wavelengths for spectral fitting to determine surface profiles.
• Performing measurements without mechanical scanning over extended ranges.

Main Results:

• Achieved a minimal axial resolution of 0.1 nm.
• Demonstrated an axial measurement range of nearly 80 µm.
• Successfully acquired surface profiles up to 1.5 mm in length.
• Validated the system's capabilities on height standards.

Conclusions:

• The developed approach offers high-precision areal surface profilometry.
• The system provides sub-nanometer axial resolution and a significant measurement range without mechanical scanning.
• This technique has potential applications in fields requiring detailed surface analysis.