Alvarez lens enters the real world.

An optical curiosity called the Alvarez lens has been transformed into a practical device by researchers at Lawrence Livermore National Laboratory (LLNL; Livermore, CA). As originally conceived more than 30 years ago, the Alvarez lens contains two transmissive refractive plates, each having a piano surface and a surface shaped in a two-dimensional cubic profile. The two cubic surfaces are made to be the inverse of each other, so that when both plates are placed with their vertices on the optical axis, the induced phase variations cancel out.

However, if the two plates undergo a relative lateral translation, a phase variation is induced that is the differential of the …