Design of a continuous zoom system using hybrid Alvarez metalenses and refractive lenses.

To meet the demand for lightness and compactness continuous zoom system, a zoom system using hybrid Alvarez metalenses and refractive lenses is proposed and designed. The system avoids axial movement of the lens group, instead adjusting the focal length by lateral movement of Alvarez metalenses. The optical design and optimization consider the aberrations of the non-central fields and a large aperture size of an actual imaging system. A starting point construction method is proposed by integrating a Galileo afocal telescope and a rear focus lens, which overcomes the problem that feasible starting points are rare for such systems using metasurfaces. The method of reducing the impact of zeroth-order diffraction effects is proposed in order to improve the imaging performance. The continuous zoom system has an F-number of 3.75, an FOV ranging from 10°×10° to 20°×20°, and a focal length ranging from 22.5 mm to 45 mm. The proposed hybrid system, as well as the design method, opens a new pathway for the next generation compact zoom imaging system with large FOV and aperture.