High-precision polarized dual low-coherence scanning interferometry for rapid step height measurements

Area of Science:

• Optical Engineering
• Metrology
• Interferometry

Background:

• Low-coherence scanning interferometers are widely used for surface profiling.
• Typical interferometers require strict scanning conditions, increasing measurement time.
• Existing methods face limitations in reducing measurement duration and complexity.

Purpose of the Study:

• To propose a novel polarized dual low-coherence scanning interferometer.
• To overcome the limitations of conventional low-coherence scanning interferometers.
• To reduce measurement time and scanning distance without compromising accuracy.

Main Methods:

• Utilizing a spatial phase-shifting technique.
• Implementing the concept of dual low coherence.
• Developing a polarized scanning interferometer design.

Main Results:

• The proposed interferometer eliminates critical scanning interval conditions.
• Visibility and phase are obtained immediately during scanning.
• A 10-fold reduction in total scanning distance was achieved.
• Surface profiles of a plane mirror and step height specimen were accurately measured.

Conclusions:

• The polarized dual low-coherence scanning interferometer offers a significant advancement in metrology.
• The system effectively reduces measurement time and scanning distance.
• This technique provides a more efficient and practical approach to surface profiling.