Green laser interferometric metrology system with sub-nanometer periodic nonlinearity.

Area of Science:

• Optical Metrology
• Laser Interferometry
• Precision Engineering

Background:

• Accurate length measurements are crucial for scientific and industrial applications.
• Traditional interferometers face challenges in stability and ease of adjustment.
• The need for high-precision, reliable metrology comparison systems is growing.

Purpose of the Study:

• To design and build a heterodyne laser interferometer system for metrology comparison.
• To enhance measurement accuracy and reduce alignment complexity.
• To calibrate a commercial interferometer using the developed system.

Main Methods:

• Utilized an iodine-stabilized Nd:YAG laser (532 nm) as the light source.
• Employed acousto-optic modulators to generate spatially separated beams with offset frequencies.
• Integrated interferometry components into a monolithic prism for stability and ease of alignment.
• Conducted experiments within a vacuum chamber for environmental stability.

Main Results:

• Achieved a sub-nanometer periodic nonlinearity, primarily attributed to ghost reflections.
• Demonstrated the system's applicability for measurement comparison using piezo nanopositioners and precision translation stages.
• Successfully calibrated a commercial interferometer with the developed system.

Conclusions:

• The designed heterodyne laser interferometer offers high accuracy for metrology comparisons.
• Monolithic integration and vacuum environment enhance system stability and reliability.
• The system provides a viable solution for calibrating other precision measurement instruments.