Ranging system based on optical carrier-based microwave interferometry

Area of Science:

• Optics and Photonics
• Metrology
• Microwave Engineering

Background:

• Refractive index variations introduce errors in optical carrier-based microwave interferometry (OCMI).
• Accurate measurement of the single-arm optical path is crucial for OCMI system performance.

Purpose of the Study:

• To design and validate a ranging system for measuring the single-arm optical path in OCMI.
• To compensate for refractive index errors and improve measurement accuracy.

Main Methods:

• Utilized a high-speed photodetector and downconversion for microwave envelope acquisition.
• Employed Hilbert transformation for precise phase detection.
• Adjusted microwave frequency to resolve phase ambiguity.

Main Results:

• Simulations demonstrated a linear phase-optical length relationship within a period.
• Experimental results achieved a standard deviation of 10^-5 at a 1.5 GHz modulation frequency.

Conclusions:

• The developed ranging system effectively measures the single-arm optical path.
• The system successfully compensates for refractive index errors in OCMI.
• High measurement precision is achievable with the proposed method.