Fiber Probe Based on Dispersive Interferometry With an Improved Demodulation Algorithm

We present a microfiber probe based on dispersive interferometry (FPDI) for measuring high-aspect ratio structures with an improved demodulation algorithm and an offset correction method. To accommodate the need for weak signal-to-noise signal demodulation and accurate measurements in FPDI applications, we propose a composite algorithm for dispersive interferometry to improve the accuracy and noise immunity. Then, to simplify the alignment process of the fiber probe, we propose an offset correction method based on an optimization algorithm. Experimental results show that the fiber probe with our proposed algorithm has less repeatability error and linearity in applications than traditional algorithms. The axial resolution of the fiber probe is better than 0.1 µm, with a repeatability error of 0.011 µm and a linearity of 0.03%. In addition, we measure a 1.2-mm standard ring gauge with FPDI. After correcting the offset, the difference between the measured diameter and the standard value is less than 0.03%