Systems and techniques for laser surgery based on imaging a target tissue by nonlinear scanning are presented. In one implementation, a method for guiding an eye surgery can include the steps of: positioning an eye in relation to an imaging system； creating first scan data by determining a depth of an eye target region at a first set of points along a first arc； creating second scan data by determining a depth of the eye target region at a second set of points along a second arc； determining target region parameters based on the first and second scan data； and adjusting one or more surgical position parameters according to the determined target region parameters.
