Compact laser interferometer for dynamic nanometer-level ranging.

Area of Science:

• Optics and Photonics
• Mechanical Engineering
• Aerospace Engineering

Background:

• Hexapod positioning systems are crucial for industrial and research applications like satellite testing and motion simulation.
• Simulating spacecraft dynamics, including jitter, requires high-precision positioning systems.

Purpose of the Study:

• To develop a novel interferometer architecture for nm-level ranging as an external reference system.
• To address the insufficient resolution of internal sensors in hexapod positioning systems.

Main Methods:

• A simple optical layout with directly bonded components on a titanium baseplate.
• Active alignment using a closed-loop controller for beam superimposition.
• Performance evaluation in air and vacuum environments.

Main Results:

• Achieved nm-level ranging capability with a noise floor under 1 nm/√Hz (1 mHz–1 Hz).
• Demonstrated effective tracking of hexapod motion up to 5 mm/s.
• Identified thermo-elastic variations as a primary noise source.

Conclusions:

• The novel interferometer system meets performance requirements for nm-level ranging in demanding applications.
• The system effectively identifies inaccuracies in hexapod internal sensors.
• Parallel operation of interferometers further reduces noise levels.