High-precision and ultra-precision machining are the key technologies in the manufacture of high-precision surfaces with tolerances in the submicron range. In addition to rotationally symmetric geometries, more and more non-rotationally symmetric surface geometries are required. Examples are eye glasses, laser mirrors and micro structured surfaces. In this context the research activities of the Transregional Collaborative Research Center ”Process Chains for the Replication of Complex Optical Elements” SFB/TR4 of the Universities of Aachen, Bremen and Stillwater (USA) have the objective to lay the scientific foundations for a deterministic and economic mass production of optical components with complex geometries, e.g. aspheric, non-rotational asymmetric or microstructured surfaces eventually superimposed on free-form geometries. For the manufacturing of free-from surfaces the Fraunhofer IPT has developed different Fast Tool Servo systems (FTS). A PC-based controller is used for set point calculation and for the position and velocity control loop of the drives. For the manufacturing of free form surfaces based on the mathematical description of Non Uniform Rational B-Splines (NURBS) an online trajectory generator was developed [1]. The paper presents the layout of the online tool path calculation as well as results of the manufacturing of a free form surface. Introduction In case of using the replication processes injection molding or glass pressing ultraprecision manufacturing of mold inserts is required and precision machining processes like diamond turning and fly-cutting are essential. To manufacture complex lenses with high accuracies the mold inserts must be fabricated with an adapted geometry to compensate form deviations caused by the machining process or typical shrinking effects during the replication process. To determine the suitable geometry of the mold inserts several iterations loops are necessary. For manufacturing an adapted mold geometry the trajectory generation is fundamental for ultra precision machining. Starting from the given data set of the surface (NURBS data format) the free form surface is analyzed and prepared for the manufacturing process in a Matlab routine. A radius compensation of the diamond tool is considered in this step. After this the NURBS surface is loaded to the control unit of the Fast Tool Servo. The calculation of the tool path is processed online. Therefore the actual positions of the axis and the spindle of the ultra precision lathe are used for the calculation of the tool path. The tool centre point is calculated online by an optimization routine to detect the positions of the knot vectors and also the position on the surface. Optic Design In the following an optical system using a 3-D tailored free-form surface designed by the company OEC AG is presented. 3-D tailoring is a constructive method for the design of free-form illumination optics [2]. Light from a light source is intercepted by the free-form mirror or lens surface and redirected in a way to cast exactly the prescribed illuminance distribution on a target surface. The shape of the surface is found by solving a set of differential equations which connects the continuity of the surface, the desired trimming and the redirection of radiation defined by the slope and curvature of the surface. The sketch in Fig. 1 shows a 3-D tailored free-form mirror which redirects the light from a LED to form the Fraunhofer IPT logo as brighter lines in front of an evenly lit square. This illuminance distribution is produced by means of geometric optics with a single reflection at the free-form mirror surface. The mirror has a diameter of 50 mm. The scaleable illumination Mirror (diameter = 50 mm) Light source (LED)