High precision 3D optical detection technology based on shear interferometry with arbitrarily shear amounts.

Area of Science:

• Optical Engineering
• Metrology
• Surface Characterization

Background:

• Differential interferometry offers high contrast but requires complex optical elements for shear.
• Existing methods struggle with adjustable shear amounts and directions, limiting flexibility.
• The
• duplicate image
• problem persists in conventional shear interferometry.

Purpose of the Study:

• To propose a novel 3D shape reconstruction algorithm for optical defects.
• To enable arbitrary shear amounts and directions in shear interferometry.
• To simplify optical testing systems and reduce costs.

Main Methods:

• Developed a 3D shape reconstruction algorithm based on shear interference.
• Employed an iterative phase addition approach to resolve duplicate images.
• Utilized image interpolation to handle large gradient defects and phase ambiguity.

Main Results:

• Successfully reconstructed 3D morphology of surface irregular defects with arbitrary shear.
• Achieved a maximum reconstruction error as low as 10^-11 m.
• Designed a simplified optical testing system using a mirror for shear adjustment, eliminating extra optical elements.

Conclusions:

• The proposed algorithm effectively reconstructs 3D defect morphology with high accuracy.
• The simplified optical testing system demonstrates feasibility and cost-effectiveness.
• This method overcomes limitations of traditional differential interferometry for optical defect analysis.