Figure 5.

Light and scanning electron micrographs showing the principle of controlled ablation to change the curvature of a substrate. In the light micrograph (a) and the scanning electron micrograph (b), an Excimer laser was directed through a progressively opening aperture (an iris diaphragm) and as a result progressively ablated different areas with the resultant step structure in the surface. By driving such an aperture with a motor under control of a computer, smooth curved surfaces could be produced and are demonstrated in (c).