激光麦克风是一种利用光学多普勒效应获取远场语音信息的技术，其语音质量受到探测系统自身特性、光探测路径以及目标物等多个方面的影响。为了从远距离声场下的目标物获取更高质量的语音信息，文中通过单频声激励实验获得了4种典型目标物（A4纸片、A4纸盒、瓦楞盒、塑料瓶）的声致振动频率响应，发现了其在频率上的非均匀性。在此基础上，提出了一种基于ResUnet和TFGAN网络的激光语音增强方法，其通过ResUnet网络预测去噪梅尔谱图，并利用TFGAN网络由预测的梅尔谱图恢复出激光语音的时域波形。然后，利用实验室自制的激光麦克风在4种目标物上进行了远距离语音采集实验，采用文中提出的方法对采集到的激光麦克风语音进行了处理，并与非线性函数谐波重构法、DNN+谐波重构法进行了比较。最后利用客观语音质量评估（PESQ）和时域分段信噪比（SNRseg）对处理后的激光语音进行了量化评估。实验结果表明，在4种目标物上采集到的激光语音，经过非线性函数谐波重构方法和DNN+谐波重构方法处理后，语音质量均无明显提升，其相应的PESQ和SNRseg分值无明显提高。而经过文中所提的ResUnet+TFGAN网络方法处理后，激光语音取得了更高的PESQ和SNRseg分值，语音质量明显提升。因此，文中提出的方法在激光麦克风应用中具有更好的激光语音增强效果。此外，由实验结果可知，此方法在频率响应一致性较差的目标物上，仍然可以较好地重建频谱，恢复出高质量的语音信息。

激光语音探测是一种非接触远距离信息获取技术，具有灵敏度高、探测距离远、抗干扰等优点被广泛应用。但是，在目标物的后向光散射特性的影响下，该技术探测性能受到机位角度、目标材料、表面粗糙度影响，严重者有效信号将湮灭到噪声里致使系统探测失效。针对此，结合传统的微分交叉相乘解调（PGC-DCM）算法，开展归一化自相除相位载波解调算法研究，解决目标物后向光散射特性差异所带来的光强扰动问题。首先，建立消光强扰动算法数学模型，利用LabView构建仿真模型，通过该模型进行新算法的频谱响应与消光强能力的仿真分析，发现该算法可实现对干涉信号中B值，一倍频G、二倍频H以及一阶贝塞尔函数J₁和二阶贝塞尔函数J₂影响的消除；其次，针对不同光强度B值，进行了PGC-DCM和新算法性能对比分析，结果表明新算法可以解调出语音信号，在弱光环境下，优势更加明显；而PGC-DCM解调方法在光强度较小情况下时(例如B=0.5 mW)，语音信号湮灭，无法还原出信号；最后，建立了远距离光强扰动抑制实验系统，进行了光强扰动消除能力实验。实验结果表明：该算法在探测光功率为10、20、30、40 mW条件下，系统解调输出语音信号幅度一致，消除了光强不同对信号探测的影响。

This Letter proposes a coordinate difference homogenization matching method to solve motion influence in three-dimensional (3D) range-intensity correlation laser imaging. Firstly, features and feature pairs of gate images are obtained by speeded-up robust figures and bi-directional feature matching methods. The original mean value of the feature-pair coordinate differences is calculated. Comparing the coordinate differences with the original mean value, the wrong feature pairs are removed, and then an optimized mean value is updated. The final feature-pair coordinates are re-registered based on the updated mean value. Thus, an accurate transformation is established to rectify motion gate images for 3D reconstruction. In the experiment, a 3D image of a tower at 780 m is successfully captured by our laser gated imaging system on a pan–tilt device.

This Letter proposes a high bit-depth coding method to improve depth map resolution and render it suitable to human-eye observation in 3D range-intensity correlation laser imaging. In this method, a high bit-depth CCD camera with a nanosecond-scaled gated intensifier is used as an image sensor; subsequently two high bit-depth gate images with specific range-intensity profiles are obtained to establish the gray depth map and finally the gray depth map is encoded by an equidensity pseudocolor. With this method, a color depth map is generated with higher range resolution. In our experimental work, the range resolution of the depth map is improved by a factor of 1.67.

We present a method of time coding with ABAB synchronization timing control for real-time 3D super-resolution range-gated imaging (3DSRGI). To meet the high precision of time delay and pulse width in ABAB synchronization time sequencing, phase shift is implemented to achieve ns-scaled delay and width accuracy without restoring to high clock frequencies. Theoretical analysis and experiments prove that 1 ns delay and width precision is obtained by our timing control unit based on a single field-programmable gate array with 5 ns clock cycle. Finally, a prototype experiment of 3DSRGI is demonstrated at a 10 Hz video rate with 696 pixels×520 pixels.