We discuss the design, manufacturing and characterization of a miniaturized zoom camera objective featuring two gravity-immune liquid-tunable aspherical lenses and three spherical glass lenses. The aspherical tunable lenses, which are 3 mm in diameter, 8 mm in nominal focal length and neutral to gravity effects, can be pressuretuned within a large focal length range with very low spherical aberration. This leads to high optical resolution across the entire zoom range despite the limited number of optical elements in the system. The effective focal length of the objective continuously shifts from 4.5mm to 9 mm, with the field of view changing from 40° to 20°. All the optical components are assembled on a three-layer optical platform, which provides a lateral and axial positioning accuracy of ±10 µm for all components. Furthermore, the platform also maintains fluidic access to the tunable lenses for pressure tuning via an external pressure controller. The total dimensions of the objective are 5 mm×6.5 mm×17 mm, making the system compatible with mobile imaging applications. The highly compact system with the thickness of 6.5mm was achieved by folding the optical path using a 45° mirror. The optical performance of the system is characterized across the entire zoom range through imaging measurements.
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