Comb-calibrated frequency sweeping interferometry for absolute distance and vibration measurement

Area of Science:

• Metrology
• Optical Engineering
• Precision Measurement

Background:

• Accurate distance measurement is crucial in various scientific and industrial applications.
• Traditional interferometry methods face limitations in absolute distance determination and precision.

Purpose of the Study:

• To develop an absolute distance measurement system with improved precision.
• To demonstrate the effectiveness of frequency sweeping interferometry calibrated by a frequency comb.
• To achieve high-resolution vibration measurements.

Main Methods:

• Utilizing frequency sweeping interferometry for distance measurement.
• Calibrating the sweeping laser's instantaneous frequency using a frequency comb and narrow bandpass filter.
• Employing fringe counting in sub-measurements for enhanced precision.

Main Results:

• Achieved 75 nm precision for distances around 0.84 m (89×10⁻⁹ relative precision).
• Demonstrated a tenfold improvement in precision through sub-measurements.
• Obtained 1.7 nm RMS noise for vibration measurement.

Conclusions:

• The frequency sweeping interferometry system calibrated with a frequency comb offers high-precision absolute distance measurements.
• The sub-measurement principle significantly enhances measurement accuracy.
• The system is suitable for precise vibration monitoring.