Long-range, high-precision optical calibration path based on an optoelectronic oscillator

We propose a laser ranging calibration optical path system using multiple optoelectronic oscillators (OEOs) that provides long range, high precision, low cost and high stability. A phase locked loop is used to control the length of the calibration optical path, which is measured with high precision by alternating the oscillations between the measurement loop and the reference loop. The calibration optical path length exceeds 9000 m with the stability of 6.8 µm during 3 minutes, and the relative measurement accuracy of the calibration optical path reaches 6.9 × 10