Quantitative-phase-contrast imaging of a two-level surface described as a 2D linear filtering process.

Area of Science:

• Optics and Photonics
• Surface Metrology
• Image Processing

Background:

• Quantitative phase imaging (QPI) is crucial for analyzing surface topography.
• Understanding the relationship between surface geometry and phase images is essential for accurate metrology.

Purpose of the Study:

• To develop and validate a quantitative phase imaging approach for two-height-level surface reliefs.
• To investigate the dependence of phase imaging on surface geometry.

Main Methods:

• Modeling the imaging process as a linear system.
• Utilizing Fourier transform analysis, including factorization for periodic surfaces.
• Experimental verification using digital holographic microscopy.

Main Results:

• The Fourier transform of the phase image is a product of the surface's Fourier transform and a coherent transfer function.
• The Fourier transform of periodic surface reliefs can be factorized into lattice and structure amplitudes.
• The developed approach successfully relates phase image characteristics to surface geometry.

Conclusions:

• The proposed quantitative phase imaging method accurately characterizes two-height surface reliefs.
• The theoretical framework provides insights into the influence of surface geometry on phase imaging.
• Digital holographic microscopy serves as an effective tool for experimental validation.