Method of high-precision spatial distance measurement based on optical-carried microwave interference

Area of Science:

• Metrology and Measurement Science
• Optical Physics
• Microwave Engineering

Background:

• High-precision spatial ranging is crucial for scientific research and industry.
• Existing equipment struggles to simultaneously achieve high speed, precision, and long-distance measurement capabilities.
• Optical carrier-based microwave interferometry (OCMI) offers a promising avenue for advanced metrology.

Purpose of the Study:

• To develop and demonstrate a novel method for high-precision spatial distance measurement.
• To overcome the limitations of current technologies in achieving simultaneous high speed, precision, and long-distance measurement.
• To leverage OCMI principles for robust and versatile distance determination.

Main Methods:

• A microwave-modulated broadband optical signal is transmitted through an interferometer with a free-space optical echo receiving system.
• Distance is resolved by scanning microwave frequencies and analyzing the resulting interferogram.
• Interference spectrum processing in the microwave domain ensures insensitivity to optical waveguide types and polarization states.

Main Results:

• The proposed method demonstrates high precision in spatial distance measurement.
• Experimental results show a root mean square error (RMSE) of 0.016 µm at 0.5 m and 0.023 µm within a 1 m distance over ten repeated measurements.
• The system effectively represents length measuring capabilities for practical applications.

Conclusions:

• The developed OCMI-based method offers a significant advancement in high-precision spatial ranging.
• The technique's insensitivity to optical properties and demonstrated accuracy validate its potential for scientific and industrial use.
• This approach provides a robust solution for simultaneous high-speed, high-precision, and long-distance measurements.