Compact mechanical Alvarez lenses with a wide varifocal range using a cam-driver

This study proposes compact Alvarez varifocal lenses with a wide varifocal range, which consist of a set of Alvarez lenses and three sets of ordinary lenses. The Alvarez lenses have a double freeform surface and are driven by a cam-driven structure. The axial size of the proposed varifocal Alvarez lenses is only 30.50 mm. The experimental results show that the proposed varifocal lens can achieve a focal length range from 15 to 75 mm, and the imaging quality is still in an acceptable range for optical lens requirements. The compact varifocal Alvarez lenses are expected to be used in surveillance systems, industrial inspection, and machine vision.