Fast Acquisition and Processing Method of Optical Frequency Scanning Interferometry Ranging Signal

The optical frequency scanning interference absolute distance measurement system needs to correct the optical frequency scanning nonlinearity and refine the signal distance spectrum so that it has low data collection and processing efficiency. Therefore, it is difficult to meet the length measurement requirements in large-scale digital manufacturing scenarios. This paper designs a data collection and processing system introducing auxiliary interference signals as the digital signal acquisition system clock, and the nonlinearity of the frequency sweep is corrected meanwhile in the signal collection process, and hence the efficiency of the designed system is high. Sparse fast Fourier transform is used to determine the range of the spectrum refinement interval. Based on the zoom fast Fourier transform, the refinement of the distance spectrum is realized and the efficiency of precise distance calculation is effectively improved. The experimental results show that the data processing speed of the designed system is more than 10 times faster compared with traditional systems using the chirp Z transform. Compared with the commercial interferometer, in the equivalent space distance range of 15. 4-16. 1 m, the error of the measurement is kept within 10 mu m, and the measurement repeatability is better than 6 mu m.