Regression-based technique for improved optical rangefinding using tunable focus lenses

Reza S. A.; Khwaja T. S.; Mazhar M. A.; Niazi H. K.

摘要

In this paper, we present a novel method of target range estimation by tuning the spot size of a Gaussian beam at the plane of a reflective target. The beam spot size tuning is achieved through the use of a tunable focus lens (TFL). Using a carefully aligned sensor assembly, the diameter of the reflected beam is recorded at the plane of an imaging detector for different TFL focal length settings. This dataset is then used to estimate the distance of the target from the TFL. The proposed rangefinder is compact and requires minimal post-data-acquisition signal processing resulting in a fast response time compared to other spatial signal processing-based sensor designs. The estimation of target distance through a multiple data-point measurement dataset also ensures that the proposed method is robust to errors associated with obtaining range estimates from a single measurement data point. Experimental results demonstrate an excellent agreement with theory. With our proposed estimation method, we show a significant improvement in the measurement dynamic range of the sensor as well as its resolution compared to similar sensing schemes in prior art. We also experimentally demonstrate the possibility to extend the measurement dynamic range by incorporating a bias lens of a fixed focal length with the sensor module. The proposed sensor module is electronically controlled and consequently can be fully automated and compactly packaged with the use of commercially available miniature optical components. (C) 2018 Optical Society of America

机译：在本文中，我们通过在反射目标的平面上调谐高斯光束的光斑尺寸来提出一种目标范围估计的新方法。通过使用可调聚焦镜头（TFL）实现光束点尺寸调谐。使用仔细对准的传感器组件，反射光束的直径被记录在成像检测器的平面上，用于不同的TFL焦距设置。然后使用该数据集来估计目标从TFL的距离。所提出的测距仪紧凑，并且需要最小的后数据采集信号处理，导致与其他基于空间信号处理的传感器设计相比的快速响应时间。通过多个数据点测量数据集的目标距离的估计也确保了所提出的方法对与从单个测量数据点获取范围估计相关联的错误是鲁棒的。实验结果表明了与理论一致。利用我们提出的估计方法，与现有技术中的类似感测方案相比，我们对传感器的测量动态范围以及其分辨率的测量动态范围显着改善。我们还通过将固定焦距的偏置透镜与传感器模块结合到传感器模块来进行实验证明可以扩展测量动态范围的可能性。所提出的传感器模块是电子控制的，因此可以通过使用市售的微型光学部件来完全自动化和紧凑地封装。（c）2018年光学学会

Regression-based technique for improved optical rangefinding using tunable focus lenses

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