1. An apparatus for directing a surgical laser beam onto tissue in a treatment area of an eye of a patient during ocular surgery, the apparatus comprising: a beam delivery system for generating and guiding the surgical laser beam along a beam path to a desired focal point in the treatment area; a means for using the eye to establish a reference datum; an optical detector for creating a cross-sectional image wherein the image includes visualizations of the reference datum and the treatment area; and a means, connected to the beam delivery system and to the optical detector, for positioning the focal point in the treatment area relative to the reference datum in the image, for guiding the beam during surgery.