A system and method are provided for establishing precise locations for a focal point of a laser beam within a predetermined scanning range during ophthalmic laser surgery. An important aspect of the present invention is the use of a tolerance for deviation of the laser beams focal point from the laser beam path. The purpose of the tolerance is to ensure that the surgical procedure is effective and that collateral damage to non-targeted tissue does not occur. The present invention accounts for deviations caused by various factors during a procedure. A computer is provided to ensure that the cumulative effect of all deviations maintains the focal point within the tolerance.
