Absolute interferometric testing of a flat surface based on the Laplacian method.

Area of Science:

• Optical Metrology
• Surface Metrology
• Interferometry

Background:

• Accurate surface characterization is crucial in precision engineering and scientific research.
• Traditional interferometric methods can face limitations in absolute phase retrieval and spatial frequency fidelity.

Purpose of the Study:

• To introduce and validate a novel absolute interferometric testing method.
• To enhance the reconstruction of surface phase distributions, preserving high spatial frequencies.
• To compare the proposed method's performance against existing techniques like the conjugate differential method.

Main Methods:

• Utilized an interferometer to measure phase difference distributions at five reference surface positions relative to a test surface.
• Calculated the Laplacian of the phase distribution from the measured data.
• Reconstructed the reference phase distribution by solving the Laplacian equation using the Fourier method.

Main Results:

• The Laplacian method demonstrated superior preservation of spatial frequencies compared to conjugate differential methods.
• Investigated the method's accuracy under varying displacement amounts and noise levels through simulations.
• Presented successful experimental validation of the developed absolute interferometric testing technique.

Conclusions:

• The proposed Laplacian-based absolute interferometric testing method provides accurate surface phase reconstruction.
• This method offers advantages in maintaining high spatial frequency information, crucial for detailed surface analysis.
• The technique is robust and validated for practical applications in optical metrology.