Random-phase-shift Fizeau interferometer

Area of Science:

• Optical Metrology
• Interferometry
• Surface Measurement

Background:

• Traditional interferometers are sensitive to environmental vibrations, limiting their precision.
• Existing vibration compensation methods can be complex or costly.
• Accurate surface measurement is crucial in various scientific and industrial applications.

Purpose of the Study:

• To demonstrate a new, cost-efficient Fizeau-principle interferometer tolerant to vibrations.
• To develop a system capable of high-precision surface measurement in non-ideal environments.
• To achieve high repeatability in surface measurement despite random vibrations.

Main Methods:

• Integration of an image sensor (high spatial resolution) and photodiode sensors (high temporal resolution).
• Continuous measurement of random phase shifts caused by vibrations at three noncollinear surface points.
• Development of a novel random-phase-shift algorithm to calculate a virtual plane representing surface position and orientation.

Main Results:

• The system demonstrated vibration tolerance when tested on an optical table without isolation.
• Achieved a measurement repeatability of approximately 0.004 wave (2.5 nm at 632.8 nm wavelength).
• Successfully compensated for environmental vibrations using the combined sensor approach and new algorithm.

Conclusions:

• The novel interferometer design offers a potentially cost-efficient solution for vibration-tolerant surface measurements.
• The combination of high spatial and temporal resolution sensors effectively mitigates vibration effects.
• The developed random-phase-shift algorithm enables accurate surface characterization under dynamic conditions.