LAAS-CNRS, University of Toulouse, INP-ENSEEIHT, 31000 Toulouse, France.
Department of Electrical Engineering, National University of Sciences and Technology, NUST, Islamabad 44000, Pakistan.
Sensors (Basel). 2021 May 19;21(10):3528. doi: 10.3390/s21103528.
In this paper, a method based on the inherent event-based sampling capability of laser optical feedback interferometry (OFI) is proposed to assess the optical feedback factor when the laser operates in the moderate and strong feedback regimes. Most of the phase unwrapping open-loop OFI algorithms rely on the estimation of to retrieve the displacement with nanometric precision. Here, the proposed method operates in open-loop configuration and relies only on OFI's fringe detection, thereby improving its robustness and ease of use. The proposed method is able to estimate with a precision of <5%. The obtained performances are compared to three different approaches previously published and the impacts of phase noise and sampling frequency are reported. We also show that this method can assess on the fly even when is varying due to speckle. To the best of the authors' knowledge, these are the first reported results of time-varying estimation. In addition, through estimation over time, it could pave the way not only to higher performance phase unwrapping algorithms but also to a better control of the optical feedback level via the use of an adaptive lens and thus to better displacement retrieval performances.
本文提出了一种基于激光光学反馈干涉测量（OFI）固有事件采样能力的方法，用于评估当激光在中等和强反馈条件下工作时的光学反馈因子。大多数开环相位解缠 OFI 算法都依赖于对光学反馈因子的估计来实现纳米精度的位移测量。这里，所提出的方法采用开环配置，仅依赖于 OFI 的条纹检测，从而提高了其鲁棒性和易用性。该方法能够以<5%的精度估计光学反馈因子。所获得的性能与之前发表的三种不同方法进行了比较，并报告了相位噪声和采样频率的影响。我们还表明，即使由于散斑导致光学反馈因子在变化，该方法也能够实时评估光学反馈因子。据作者所知，这是首次报道的时变光学反馈因子估计结果。此外，通过随时间进行光学反馈因子估计，不仅可以为更高性能的相位解缠算法铺平道路，还可以通过使用自适应透镜来更好地控制光学反馈水平，从而实现更好的位移测量性能。
