Multi-heterodyne interferometric absolute distance measurements based on dual dynamic electro-optic frequency combs.

Area of Science:

• Metrology
• Optical Physics
• Instrumentation

Background:

• Traditional multi-heterodyne interferometry faces limitations in non-ambiguous range (NAR) and measurement accuracy due to synthetic wavelength generation.
• Accurate large-scale distance measurements are crucial for advanced scientific and industrial applications.

Purpose of the Study:

• To propose and demonstrate a novel multi-heterodyne interferometric absolute distance measurement method.
• To achieve high-accuracy, large-scale distance measurements using dual dynamic electro-optic frequency combs (EOCs).

Main Methods:

• Utilized dual dynamic electro-optic frequency combs (EOCs) with synchronously controlled modulation frequencies for dynamic frequency hopping.
• Constructed variable synthetic wavelengths ranging from kilometers to millimeters, traceable to an atomic frequency standard.
• Implemented a phase-parallel demodulation method for multi-heterodyne interference signals using FPGA.

Main Results:

• Achieved agreement within 8.6 µm compared to He-Ne interferometers over a 45 m range.
• Demonstrated a standard deviation of 0.8 µm and a resolution better than 2 µm at 45 m.
• Successfully performed absolute distance measurements with high precision and large scale.

Conclusions:

• The proposed dual dynamic EOC method offers a flexible and accurate approach for large-scale absolute distance measurements.
• This technique overcomes the NAR limitations of conventional methods and provides traceable measurements.
• The method is suitable for demanding applications in precision manufacturing, space missions, and length metrology.