菲涅耳望远镜合成孔径激光成像雷达实验室验证

对菲涅耳望远镜合成孔径激光成像雷达进行了实验室尺度条件下的原理验证实验。实验中利用不同曲率半径、垂直正交偏振的两个球面波通过二维(2D)扫描方式照明远距离处的目标,接收望远镜接收到的目标回波经过偏振分光镜分成两束作为信号光和本振光进入2×4 90°桥接器,桥接器输出的四路光信号被两个平衡探测器接收,平衡探测器输出电信号经模数转换后经过复数化、两维相位二次项匹配滤波算法处理后可以重构出目标图像。对4.3m处点目标和2D面目标进行了成像实验,取得了具有良好成像分辨率和对比度且带有散斑效应的预期成像结果,证明了该合成成像激光雷达概念的正确性。

Demonstration of a Laboratory Fresnel Telescope Synthetic Aperture Imaging Ladar

A laboratory demonstration of Fresnel telescope synthetic aperture imaging ladar system is presented. The target is two-dimensional (2D) scanned by a beam that is combined by two concentric and coaxial quadratic wavefont laser beams with orthogonal polarization. The scattered signal light from the target is collected by a telescope and is split into two beams by a polarized beamsplitter. The two separated beams then pass through a half and quarter waveplate, respectively, and enter a 90 degree 2×4 optical hybrid. The four outputs of optical signals from optical hybrid are detected by two pairs of balanced detectors and then stored in computer using AD converters. The image of the target can be reconstructed from the data acquired by 2D scanning through data processing. A point image of 0.3 mm×0.3 mm and 2D Chinese character are reconstructed in experiments with high resolution and contrast. The expected speckles are also observed in the reconstructed image that commonly existed in coherent imaging. The experimental results prove the correctness of the concept of the Fresnel telescope synthetic aperture imaging ladar.