Simple and efficient realization of transverse linear dark beams by azimuthal phase-shifted square zone plate

Herein, we are about to introduce a novel, reliable and straightforward method to create controllable dark lines employing an azimuthal square zone plate. As a matter of fact, this diffractive element is a square zone plate whose zones are phase-shifted azimuthally. As we illustrate, one way to construct it is combining a square zone plate and radial grating having period m. Considering its focusing behavior, we came to the result that a dark line surrounded by linear bright zones is generated for odd m, as well as a cross-like dark zone is produced when m is even. Furthermore, we illustrate that the length of the dark lines depends on the grating period. Finally, the simulation predictions are verified by experimental results.

Automated summary

In this paper, a novel method using an azimuthal square zone plate to create controllable dark lines is introduced. The simulation predictions are verified by experimental results, and it is illustrated that the length of the dark lines depends on the grating period.