Direct imaging for extended targets (2 Sound-hard target (Neumann boundary condition) The scattered field is GN(, y)dy The scattered wave received at x is 0C0(y,x) N(aj, y)dy on The response matrix is P ago(y)or g(ydy g (過两科学大季 A Direct Numerical Imaging Method 14 National University of Defense TechnologyA Direct Numerical Imaging Method Direct imaging for extended targets 14 (2) Sound-hard target (Neumann boundary condition) The scattered field is The scattered wave received at xj is The response matrix is