Microelectromechanically-driven miniature adaptive Alvarez lens

A miniature solid-state varifocal lens based on Alvarez principle with lens elements having free-form surfaces is reported. The Alvarez lens elements are implemented with diamond-turning and replication molding processes. They are integrated with electrostatically-driven MEMS comb-drive actuators fabricated using SOI micromachining. Dynamic tuning of focal length more than 1.5 times (from 3 mm to 4.65 mm) is experimentally demonstrated with only small MEMS-driven lateral movements of 40 μm. Such varifocal lens may be useful in miniature cameras for autofocus and zooming due to its advantages including ease of packaging and fast tuning speed.