Adaptive Spiral Diffractive Lenses—Lenses With a Twist

A new concept of thin, flat, transparent variable lenses with unprecedented performance in terms of active diameter and focal distance range is presented. The diffractive lens consists of two cascaded variable liquid crystal-based spiral diffractive lenses. Changing concertedly the topological charge changes the focal length with no mechanical motion. The implemented lens has a focal range from -2 to +2 diopters, an active diameter of 25 mm, a low operating voltage (<10 V), and a fill factor of 98%. These characteristics are unique in planar tunable lenses, opening for applications ranging from human vision correction to space applications.