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Precision PGC demodulation for homodyne interferometer modulated with a combined sinusoidal and triangular signal
Optics Express
|February 25, 2018
Summary
This study introduces a novel phase-generated carrier (PGC) demodulation technique using combined sinusoidal and triangular modulation. This method achieves precise real-time ellipse fitting and nanometer-accuracy displacement measurements, overcoming limitations of traditional PGC demodulation.
Area of Science:
- Optical Metrology
- Interferometry
- Signal Processing
Background:
- Homodyne interferometers commonly use phase-generated carrier (PGC) demodulation.
- Traditional PGC demodulation suffers from periodic nonlinearity due to various disturbances.
- Accurate displacement measurements are crucial in scientific and industrial applications.
Purpose of the Study:
- To propose a precision PGC demodulation method for homodyne interferometers.
- To enhance ellipse fitting accuracy and real-time correction of quadrature components.
- To eliminate periodic nonlinearity in PGC demodulation for improved displacement measurements.
Main Methods:
- Modulating a homodyne interferometer with a combined sinusoidal and triangular signal.
- Generating a continuous phase-shifted interference signal for ellipse fitting.
- Implementing real-time ellipse fitting and correction of AC amplitudes and DC offsets.
Main Results:
- The proposed method effectively eliminates periodic nonlinearity in PGC demodulation.
- Precise real-time acquisition of elliptical parameters for quadrature components was achieved.
- Nanometer accuracy was demonstrated in displacement measurements.
Conclusions:
- The combined sinusoidal and triangular modulation offers a robust solution for PGC demodulation.
- This technique significantly improves the accuracy and reliability of displacement measurements.
- The proposed method is feasible and validated through experimental evaluations.
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