Multi-Wavelength Interferometric Absolute Distance Measurement and Dynamic Demodulation Error Compensation.

Area of Science:

• Optical Metrology
• Precision Measurement Systems

Background:

• Traditional interferometry faces limitations in absolute distance measurement range.
• Phase-shifting interferometry (PSI) is a key technique for high-accuracy distance determination.

Purpose of the Study:

• To develop a high-precision absolute distance measurement system with an extended unambiguous range.
• To address limitations of conventional interferometric methods for absolute ranging.

Main Methods:

• Implementation of a three-wavelength synchronous phase-shifting interferometry system.
• Establishment of a synthetic wavelength chain using three semiconductor lasers in an all-fiber Fizeau interferometer.
• Integration of piezoelectric transducer (PZT)-driven phase modulation, multi-channel synchronous sampling, and fractional multiplication for phase demodulation.

Main Results:

• Achieved an unambiguous measurement range of 240 μm.
• Demonstrated static measurement precision better than 0.6 nm.
• Obtained dynamic displacement measurement accuracy superior to 2 nm compared to a reference device.

Conclusions:

• The proposed system offers a robust and high-precision solution for absolute distance measurement.
• The method shows significant potential for industrial precision inspection and optical sensing applications.
• Systematic analysis and compensation of error sources, including PZT nonlinearity, enhance measurement reliability.