Reduction of spherical and chromatic aberration in axial-scanning optical systems with tunable lenses.

Optical systems with integrated tunable lenses allow for rapid axial-scanning without mechanical translation of the components. However, changing the power of the tunable lens typically upsets aberration balancing across the system, introducing spherical and chromatic aberrations that limit the usable axial range. This study develops an analytical approximation for the tuning-induced spherical and axial chromatic aberration of a general optical system containing a tunable lens element. The resulting model indicates that systems can be simultaneously corrected for both tuning-induced spherical and chromatic aberrations by controlling the lateral magnification, coma, and pupil lateral color prior to the tunable surface. These insights are then used to design a realizable axial-scanning microscope system with a high numerical aperture and diffraction-limited performance over a wide field of view and deep axial range.