A Backscattering Angular Response Removal Method Combining Kirchhoff Approximation with Mathematical AR Curves

Acoustic backscatter from seafloor is dependent on incident angle, and generally the angular dependence is removed by angular response (AR) models. For the research of high-frequency multi-beam sonar, not many angular response models have been proposed, most of which are obtained by simple mathematical averaging methods, which leads to the problem of low reliability of backscatter strength in the nadir spectral reflection area. To solve this problem, in this study, the traditional acoustic scattering method (Kirchhoff approximation) constrained by the genetic algorithm is combined with the mathematical method to build a new AR model. The range of incident angle is divided into two domains, and the AR models in different domains are established separately according to different methods to improve the correction effect of the sonar image. R2Sonic 2024 multi-beam echosounder dataset (400 kHz) collected in the Jiaozhou Bay is used to test the validity of proposed method, and the experimental results show that the standard deviation of the backscatter strength deviations of the conjugate points in the overlapping area is reduced from 7.41dB to 4.87dB, which meets the error requirement. The proposed method is verified to effectively eliminate the backscattering angular dependence and improve the quality of the multi-beam sonar image.