A vortex lens is used to convert a planar wavefront into a helicoid (spiral-shaped) wavefront. Through this rotation, the wavefronts cancel each other out at the center. This transformation occurs through a spiral-shaped structure on a planar substrate (see figure).
These lenses are used, for example, in astronomy, optical tweezers, or optical pattern recognition.
The vortex lenses are made of quartz glass and ZnSe, both of which are currently available. Standard elements have 4, 8, or 16 steps for each of the wavelengths 10.6 µm, 1064 nm, or 800 nm. Based on the number of steps, efficiency can be optimized up to >95%.
