Multi-channel Absolute Distance Measurement Based on Optical Carrier-Based Microwave Scanning Interferometry

Cost-efficient multi-objective synchronous ranging solutions are highly desired in many fields such as manufacturing and infrastructure. However, traditional laser ranging methods have limitations in absolute ranging and multi-channel expansion. In this paper, a multi-channel absolute distance measurement method based on optical carrier-based microwave scanning interferometry (OCMSI) is proposed. After microwave scanning and synchronous demodulation, the amplitude spectrums and phase spectrums of interference signals are established. The transmission signals of each channel can be separated and reconstructed by using the discrete Fourier inverse transform. Additionally, it is demonstrated that the designed global optimization algorithm for extracting free spectral range can effectively reduce the impact of detection errors and channel interference. Existing interferometers can achieve multi-channel parallel absolute distance measurement without the need for additional modulation, demodulation, and optoelectronic detection devices. Experimental results have shown that the system structure is simple, and the ranging accuracy of for 3 channels is higher than ± 60 μm within at least 35 m optical path.