基于啁啾调幅涡旋场水下目标激光探测的新原理、新方法、新技术研究

激光雷达在水下的应用要克服的主要问题是散射，散射不仅会引入光的衰减，还会引入噪声。后向散射占据水下激光探测很大的动态范围，强烈的后向散射会导致探测器饱和，假目标的出现和测距精度、空间分辨率、成像对比度的下降。伴随目标回波的前向散射也会引起成像激光雷达的空间分辨率、成像对比度和距离精度的下降。如何降低散射的影响是水下激光雷达面临的最大挑战。.本申请从散射波与目标回波在时域、频域、空简相干性等方面的差异着手，提出使用涡旋光场作为载波和空间滤波，抑制前向散射；使用基于独立元分析的盲信号分离技术实现自适应滤波，降低后向散射的影响；采用啁啾调幅频域反射探测方法，实现远距离、高精度、多目标探测。分别从光源的调制、回波的接收和信号处理等方面研究抗散射的新原理、新方法和新技术。提高水下激光雷达的整体性能。使激光雷达技术在水下目标的搜索与探测、海底测绘等领域发挥更大优势。

The main problem that lidar needs to overcome in underwater applications is scattering of the light signal in water. Scattering not only induces the attenuation of light, but also introduces noises and reduces the signal-to-noise ratio of the echo. Backward scattering occupies a large dynamic range of underwater laser detection, which can saturate the detector, resulting in the appearance of false targets. Strong backward scattering in turbid water can also reduce ranging accuracy, spatial resolution and imaging contrast. The forward scattering accompanying the target echoes also causes deteriorations of spatial resolution, imaging contrast and ranging accuracy of the imaging lidar. How to reduce the impact of scattering is an important issue to be solved in underwater lidar..Based on the analysis of the differences in time domain, frequency domain and spatial coherence between the scattered wave and the target echo, we propose the use of a vortex light field as a carrier and a spatial filter to suppress the forward scattering. The effect of backscattering is reduced by using blind signal separation technique based on independent element analysis. The chirp amplitude modulated frequency-domain reflectometry detection method is used to achieve long ambiguous range and high ranging accuracy in a multi-target simultaneous detection scenario. The new principles and new methods of anti-scattering are proposed respectively from the aspects of light source modulation, echo detection and signal processing to improve the overall performances and enlarge the applications of underwater lidar.