合成孔径激光雷达成像之匹配滤波器

Matched Filter in Synthetic Aperture Ladar Imaging

基于光学衍射理论,探讨了采用准单色光照明的条带模式合成孔径激光雷达(SAL)的成像过程,给出了几种情况下,方位合成孔径成像匹配滤波器的解析表达形式及相应的成像分辨率。结果表明,条带模式SAL方位成像匹配滤波器的表达式除了与激光发射波长、成像距离和雷达坐标有关外,还与发射光束特性、接收光路结构参数等有关。因此,在实验室采用高斯光束作为探测光源进行SAL演示成像时,目标放在发射光束光腰处、瑞利范围之内、多倍瑞利范围之外等不同位置所需要的方位成像匹配滤波器有所不相同。为了获得高的合成孔径成像分辨率,目标应置于多倍瑞利范围之外。

The imaging process of a strip-map mode synthetic aperture ladar（SAL） ultilzing quasi-monochromatic light illumination is investigated based on optics diffraction theory.The theoretical expressions of the matched filters and the corresponding azimuth resolutions for synthetic aperture imaging under several conditions are given.Results show that the matched filter in a strip-map mode SAL is not only expressed in transmitting wavelength,target distance and SAL azimuth coordinate,but also coupled with the transmitting beam and the configuration of the receiving optics.As a result,for a laboratory-scale SAL demonstration system utilizing Gaussian beam as the detecting light,the expressions of the matched filter for azimuth synthetic aperture imaging vary slightly as the target plane is positioned at the beam waist,inside Rayleigh range or outside multiple Rayleigh range of the transmitting beam.It is suggested that the target should be placed outside the multiple Rayleigh range in order to obtain the high azimuth resolution.