However, in principle it should be possible to construct zoom lenses that do not rely on the movement of some of its components. Instead, the change in magnification is achieved by changing the optical power of at least two lenses within the system (optical power zoom - OPZ). Moreover, for broadband applications it is highly favorable to use mirrors instead of lenses due to the absence of chromatic aberrations.
Based on a "Schiefspiegler" approach an all-reflective OPZ objective with a zoom power of three consisting of four mirrors has been designed. Two mirrors are assumed to have a variable radius of curvature for changing optical power. During aberration correction special consideration has been given to the reduction of field curvature, since the optical power change strongly influences field curvature for different zoom positions. The simulation shows adequate image quality for photographic applications over the whole zooming range.
For the realization of such an OPZ objective deformable mirrors with a comparatively large stroke are needed. Before starting a complex development of such devices three setups with different fixed focal lengths were built to prove and evaluate the concept for digital imaging.