ACHROMATIC FRESNEL DIFFRACTION PATTERNS

A novel method for obtaining a single, but arbitrary, achromatic Fresn el diffraction pattern of any pupil with broadband parallel illuminati on is presented. The optical device simply consists of an achromatic o bjective and an on-axis zone plate. A criterion for selecting the syst em parameters in order to minimize the residual chromatic aberrations is given. The recording of the selected diffraction field is obtained with low chromatic aberrations even for white-light illumination. An e xperimental verification is shown to illustrate this approach.