Dynamic displacement measurement beyond half-wavelength in phase-modulated optical interferometer.

Area of Science:

• Optical Physics
• Metrology
• Signal Processing

Background:

• Optical interferometers are crucial for precise displacement measurements.
• Traditional methods are limited by the wavelength of light, restricting the measurement range.
• Extending the measurement range without accuracy loss is a significant challenge.

Purpose of the Study:

• To develop an interference signal-processing method for extending the measurement range of dynamic displacement.
• To maintain high measurement accuracy beyond the conventional half-wavelength limit.
• To validate the proposed method through experimental and simulation studies.

Main Methods:

• A phase-modulated optical interferometer was employed.
• A novel algorithm focusing on the peak direction of interference signal waveforms was developed for range extension.
• Data processing techniques were implemented to remove noisy datasets and ensure accuracy.
• Experiments utilized a pseudo-vibrator and a lead zirconate titanate (PZT) device.

Main Results:

• The proposed method successfully extended the dynamic displacement measurement range beyond half the light wavelength (1537 nm).
• Dynamic displacements up to 3127 nm were accurately measured.
• Proof-of-principle simulations confirmed the method's capability and indicated minimal measurement error.
• The system demonstrated high measurement accuracy, avoiding deterioration despite the extended range.

Conclusions:

• The developed signal-processing method effectively extends the measurement range of dynamic displacement in optical interferometers.
• The technique maintains high measurement accuracy, overcoming the limitations of traditional methods.
• The findings have significant implications for advanced metrology and precision engineering applications.