Abstract: A method and apparatus for ablating features in a substrate, the apparatus includes a radiation source and first and second rotating transparent uniformly thick disks positioned between the radiation source and a substrate to be irradiated. The method comprises irradiating the substrate with radiation that has passed through the first and second rotating disks, wherein the first and second disks are independently rotating at different angular velocities to create a predetermined irradiation pattern on the substrate. The disks may have a relative acceleration. The method and apparatus may be used to ablate nozzles having longitudinal axes which are non-orthogonal with the surface of the substrate and which are not parallel to each other.