摘要
合成孔径激光雷达(SAL)能实现远距离目标的高分辨率成像。然而,由于所用激光波长很短,SAL系统中微小机械振动都可能在目标回波信号中引入巨大相位误差,所以,SAL很难实现稳定的相位史数据,高分辨率SAL图像的形成往往要应用额外的相位误差消除技术,特别是相位梯度自聚焦(PGA)技术。演示了一个运转良好的条带模式SAL实验室成像装置。采用一台1 550 nm波段的线性调波长激光器作为探测光源,该装置能够形成聚焦良好的高分辨率图像。通过细致的系统设计,基本抑制了在回波信号中产生相位误差的各种振动。该装置产生的相位史数据非常稳定,高分辨率图像的形成仅需简单遵照标准的SAL成像理论,无需额外借助PGA。采用点目标定标,测量得到该成像装置的方位和距离分辨率接近其理论估计。详细给出了2.4 m距离上多种目标的良好聚焦图像及相应的稳定相位史数据。
Synthetic aperture ladar （SAL） has the potential to image long distance objects with high resolutions. However, due to the short laser wavelength used, tiny mechanical vibrations in the SAL system will possibly course enormous phase errors in the target backscattered signals. As a result, it is difficult to obtain stable phase history data in SAL and high resolution SAL images are usually formed by additional phase error removing techniques, especially phase gradient autofocus（PGA） technique. In this paper, a well﹣performed stripmap mode SAL is demonstrated in the laboratory. Using a linearly wavelength scanning laser in the 1 550 nm range as the detecting source, the SAL can generate well﹣focused high resolution images. By carefully designing the system, most mechanical vibrations that will introduce phase errors into the backscattered signals are suppressed. The phase history data generated in the SAL are so stable that high resolution images are formed by straightforwardly following the standard SAL image formation theory and not relying on PGA. Using dot target calibration, both the azimuth and range resolutions of the SAL are measured to near its theoretical estimations. At target distance of 2.4 m, well focused SAL images with various targets, together with their stable phase history data, are illustrated in detail.
出处
《红外与激光工程》
EI
CSCD
北大核心
2014年第11期3559-3564,共6页
Infrared and Laser Engineering
基金
国家自然科学基金(61178071)
国家863计划(2007AA12Z107)
