光频扫描干涉测距信号快速采集与处理方法

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

光频扫描干涉绝对距离测量系统需校正光频扫描非线性、细化信号距离谱,因此系统的数据采集及处理效率低,难以满足大尺度数字化制造场景中长度测量需求。本文设计的数据采集与处理系统,引入辅助干涉信号作为数字信号采集系统时钟,在信号采集过程中,同时校正等光频采样的光频扫描非线性,因此效率较高。并采用稀疏快速傅里叶变换确定距离谱细化区间,基于细化-快速傅里叶变换实现距离谱细化,有效提高距离的精密解算效率。实验结果表明:本文设计的系统,在数据处理速度方面,较使用线性调频Z变换的传统系统提高10倍以上;与商用干涉仪比对,在15.4~16.1 m等效空间距离范围内,测量结果误差保持在10μm以下,测量重复性优于6μm。

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 μm, and the measurement repeatability is better than 6 μm.