Rosette gratings as generators of nondiverging intensity patterns

In this paper we present and investigate binary phase diffraction gratings whose phase reliefs have form of rosettes-the so-called rosette gratings. They are constructed by the equiphase lines of the cosine-profiled phase Siemens star axicon-a hybrid optical element consisting of an axicon and a phase optical element with azimuthal cosine profile. It is shown that the rosette gratings transform the incident Gaussian laser beam into a sum of odd-diffraction orders beams, nondiverging in defined propagation intervals. The amplitude and intensity distributions of the separate diffraction orders, as well as the interference between them are studied. Under certain conditions these gratings can act as suitable substitutes for the cosine-profiled phase Siemens star axicons in their applications.