1972 年 28 巻 10 号 p. 547-552
A holographic side looking sonar is thought to be used for mapping sea-bottom from the surface. The principle of the holographic side looking sonar is the same as that of a side looking radar with optical data processing. For conventional mapping methods a two dimensional map can be obtained by either a complicated scanning of a transducer with sharp directivity or by a simple scanning of a transducer with broad directivity upon reducing angular resolving power. For the holographic side looking sonar, however, only a simple scanning is necessary because the resolving power increases when the directivity becomes broad. This method, therefore, seems to be useful for practical operations of sea-bottom mapping. A holographic side looking sonar is experimentally studied by using a transducer with resonant frequency of 455kHz in a water bath(shown in Fig. 4)and reconstructed images are obtained by a He-Ne laser. (Reconstructed images and their originals are shown in Figure 6)The experimental result shows the possibility of the practical use of the holographic side looking sonar for mapping sea-bottom from the surface.