Using computer-generated holograms to test cubic surface

Computer-generated holograms (CGH) have been widely used to evaluate symmetrical aspherical surfaces in combination with Fizeau interferometers. Because the CGH can create any wavefront shape it, can also be used in unsymmetrical aspherical surfaces testing. Taking the cubic surface as an example, this paper gives a thinking of testing unsymmetrical surfaces. First we deduce the expression of the aberration for the cubic phase when propagating and the CGH null lens design has been carried out while taking into consideration the higher order aberrations. The separation of the diffraction orders of the CGH is discussed. We fabricated the CGH using e-beam photography and tested a 13-mm diameter cubic surface. (C) 2009 Elsevier B.V. All rights reserved.