Fast and precise multi-angle interferometry for efficient 3D surface profiling.

Area of Science:

• Optical Metrology
• Surface Metrology
• Interferometry

Background:

• Traditional multi-angle interferometry (MAI) faces a trade-off between high precision (using longitudinal scan function - LSF) and low computational load.
• Conventional MAI methods often require computationally expensive optical propagation calculations for LSF evaluation.

Purpose of the Study:

• To introduce a novel, low-complexity MAI method that resolves the precision-computation trade-off.
• To enable real-time surface topography measurement with high accuracy and reduced computational complexity.

Main Methods:

• Elimination of computationally expensive LSF-evaluation optical-propagation calculations.
• Utilizing phase differences for surface height calculation and maximum pairwise LSF (max-pLSF) selection at each pixel for reliability.
• Incorporating surface-height-induced tilt-component compensation, precision-enhancing feedback, and continuous max-pLSF monitoring.

Main Results:

• Achieved high precision over a range of ±20 μm.
• Demonstrated a flat-surface standard deviation within 150 nm.
• Enabled real-time surface topography measurement with significantly reduced complexity.

Conclusions:

• The novel MAI method successfully integrates high accuracy with low computational cost.
• This technique is suitable for practical high-speed, high-precision surface profiling applications.
• The method ensures reliability through phase differences, max-pLSF selection, and error propagation prevention.