kernel_fresnel_monochrome_2d 2D monchrome kernel for amplitude and first arrival
 
  Call:
    [kernel_t,kernel_a]=kernel_fresnel_monochrome_2d(v,x,y,S,R,omega);
  or
    [kernel_t,kernel_a]=kernel_fresnel_monochrome_2d(v,x,y,S,R,omega,L,L1,L2);
 
  Based on Liu, Dong, Wang, Zhu and Ma, 2009, Sensitivity kernels for
  seismic Fresenl volume Tomography, Geophysics, 75(5), U35-U46
 
  See also, kernel_fresnel_2d