多频合成全息探测成象

本文分两个部分。第一部分从理论上探讨了全息成象应用于探测时的特点,提出了“全息探测成象”的概念。指出对地层介质使用弹性波或电磁波时,关键问题是纵向分辨力低。作者从信息论和天线阵理论的观点探讨了单频全息成象,研究全息成象和相关检测、匹配滤波以及相控阵之间的联系,提出了多频合成全息探测成象作为解决纵向分辨力的一个方法。探讨了它的原理,指出了它和“脉冲全息成象”的关系,导出了纵向分辨力公式,并给出了二维理论模型计算的结果,以说明方法的可行性和应用前景。 第二部分为实验部分,叙述了多频合成微波全息探测成象的试验。采用二维干涉型全息图做了简单模型的水槽试验,由计算机成象的结果证实了多频合成法的高分辨力和良好的成象质量。

MULTIFREQUENCY SYNTHETIC DETECTING HOLOGRAPHY

The paper includes two parts. The first part is a theoretical part,in which the characteristics of holography as applied to detection is discussed,and the notion of "detecting holography" is proposed. The principal difficulty encountered in applying elastic or electromagnetic waves to the earth media is the poor longitudinal resolution of monochromatic holography. Prom the viewpoint of the communication theory and the antenna array theory,the monochromatic holography is examined,and its relations to correlation detection,matched filters as well as phased array anteenas are illustrated. Multifrequency synthetic detective holography is developed as a possible approach to the solution of longitudinal resolution problem. Its principles are discussed,its relations to the "impulse holography" and the formulas for the longitudinal resolution are deduced. Finally,examples of two-dimensional computer simulation are presented to illustrate the feasibility of the method.The second part is an account of experiments made in water-tank for the microwave multifrequency synthetic detecting holography. The results of computer reconstruction using interference-type holograms give evidence to prove the high resolution and good imaging quality of the method.