A method for null-testing fast convex aspheric optical surfaces is presented. The method consists of using a cylindrical screen with a set of lines drawn on it in such a way that its image, which is formed by reflection on a perfect surface, yields a perfect square grid. Departures from this geometry are due to imperfections of the surface, allowing one to know if the surface is close to the design shape. Tests conducted with a full hemisphere and with the parabolic surface of a lens show the feasibility of the method. Numerical simulations show that it is possible to detect surface departures as small as 5 μm.
© 2000 Optical Society of America
(120.6650) Instrumentation, measurement, and metrology : Surface measurements, figure
(220.4840) Optical design and fabrication : Testing
(350.4800) Other areas of optics : Optical standards and testing
Rufino Díaz-Uribe and Manuel Campos-García, "Null-Screen Testing of Fast Convex Aspheric Surfaces," Appl. Opt. 39, 2670-2677 (2000)