Traveltime tomography generates a velocity model of the subsurface from the observed traveltime response through the subsurface. In focusing operator inversion, the traveltime response is the traveltime of the focusing operator.
Traveltime tomography contains three main steps: parameterization of the velocity in the subsurface; forward modeling through the subsurface model to obtain modeled focusing operators; and optimization in which the difference between the traveltimes of the observed and the modeled focusing operators is used to optimize the velocity model and the focus points positions. If the traveltimes of the observed and the modeled focusing operator correspond, an accurate velocity model is obtained. The strategy for focusing operator inversion is presented in Figure 3.

flow
Figure 3 Strategy flowchart of inversion of focusing operators