Wide dynamic range quadrature interferometer with high-gain approach and sliding mode control

Area of Science:

• Optoelectronics and Measurement Science
• Control Systems Engineering
• Applied Physics

Background:

• Interferometry, particularly Michelson interferometers, is crucial for precise measurements but often requires complex phase unwrapping.
• Existing control strategies can limit dynamic range and bandwidth, hindering real-time applications.

Purpose of the Study:

• To develop and apply a novel sliding mode control strategy for two-beam quadrature interferometers.
• To eliminate the need for phase unwrapping algorithms in the demodulation process.
• To enhance the real-time measurement performance of a bulk Michelson interferometer.

Main Methods:

• Modeling and development of a high-gain sliding mode control strategy.
• Implementation on a digital platform for controlling a bulk Michelson interferometer.
• Experimental determination of system performance, including dynamic range and bandwidth.

Main Results:

• The control strategy enables direct demodulation without phase unwrapping, yielding a linear relationship between the output signal and phase shift.
• The implemented system achieved real-time measurement capabilities.
• Demonstrated wider dynamic range (52.5 rad low frequencies) and bandwidth (5.8 rad up to 500 Hz) compared to literature values.

Conclusions:

• The novel sliding mode control strategy offers significant improvements in interferometer performance.
• The system's capabilities can be further enhanced by increasing feedback gain.
• This approach provides a robust and efficient method for real-time optical measurements.