Wang Ning, Wang Ran, Mo Di, Li Guangzuo, Zhang Keshu, Wu Yirong
Appl Opt. 2018 Jan 10;57(2):230-236. doi: 10.1364/AO.57.000230.
A long-distance inverse synthetic aperture LADAR (ISAL) imaging experiment outdoors over 1 km for cooperative targets is demonstrated, which gets a two-dimensional high-resolution image with resolution exceeding 2.5 cm. The system utilizes an electro-optic in-phase and quadrature modulator to output a linear frequency-modulated continuous waveform (LFMCW) with a bandwidth of 6 GHz and pulse repetition frequency (PRF) of 16.7 KHz. For the problem of the coherence of the laser, the effects of the coherent processing interval (CPI) and time delay of the local oscillator (LO) on the coherence are discussed. The fiber delay line is set and the CPI is reduced to lower the requirement of the frequency stability of the laser source. The images are formed by two-dimensional Fourier transform and joint time-frequency transform methods, respectively. In this paper, we present the system structure, imaging processing, and the experiment result in detail. The experiment result validates the performance of our system for ISAL imaging.
展示了一次针对合作目标在超过1公里的户外进行的长距离逆合成孔径激光雷达（ISAL）成像实验，该实验获得了分辨率超过2.5厘米的二维高分辨率图像。该系统利用电光同相和正交调制器输出带宽为6吉赫兹、脉冲重复频率（PRF）为16.7千赫兹的线性调频连续波（LFMCW）。针对激光的相干性问题，讨论了相干处理间隔（CPI）和本地振荡器（LO）的时延对相干性的影响。设置了光纤延迟线并减小了CPI，以降低对激光源频率稳定性的要求。图像分别通过二维傅里叶变换和联合时频变换方法形成。在本文中，我们详细介绍了系统结构、成像处理和实验结果。实验结果验证了我们系统用于ISAL成像的性能。
