Research on the Improved Least Squares Reverse Time Migration Imaging Method Xiaodan Zhang, Dongxiao Liu, Guizhong Liu, Haiyang Gou, Rui Li, Zhiyu Zhang and Lin Cui E3S Web Conf., 236 (2021) 04017 Published online: 09 February 2021 DOI: 10.1051/e3sconf/202123604017