Accuracy Improvement of Two-Dimensional Shape Reconstruction Based on OFDR using First-order Differential Local Filtering

The accuracy of two-dimensional (2D) shape reconstruction is highly susceptible to fake peaks in the strain distribution measured by optical frequency domain reflectometry (OFDR). In this paper, a post-processing method using first-order differential local filtering is proposed to suppress fake peaks and further improve the accuracy of shape reconstruction. By analyzing the principles of 2D shape reconstruction, an explanation of how fake peaks lead to shape reconstruction errors is provided, along with the introduction of an error evaluation standard. The principle of first-order differential local filtering is presented, and its feasibility is verified by simulation. An OFDR 2D shape reconstruction system is built, with three groups of 2D shape reconstruction experiments carried out, including up bending, down bending and arch bending. The experimental results show that the end errors of the three groups of shape reconstruction are respectively reduced from 2.33%, 2.97%, and 1.07% to 0.25%, 0.78%, and 0.20%, at the shape reconstruction length of 0.5 m. The research demonstrates that the accuracy of OFDR 2D shape reconstruction can be improved by using first-order differential local filtering.