3D Scanning system based on tunable cylindrical lenses

We present a compact micro-optical system with capability to change the focus position in depth as well as in lateral direction. In this way we reduce the influence of field aberrations by scanning the object space with a decreased field of view. With the same system we are able to capture a wide range in depth by refocussing the system. The scanning element is a set of cylindrical lenses shifted laterally to the optical axis. Thus it has a prismatic effect and deflects the light which can be tuned by changing the lens curvature. The imaging element is a pair of cylindrical lenses with separately tunable focal power in x and y. So we are able to compensate astigmatism caused by the scanning element. We demonstrate an optimized membrane design to achieve a cylindrical surface shape over the squared aperture of the optical system. The actuation is realized by applying pressure to the immersion fluid. The tunable lenses are immersed membranes of aluminum nitride with a high dynamic response and long term stability.